hypothesis in energy drinks

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• 17 April 2024

This water bottle purifies your drink with energy from your steps

Electrostatic charge harvested from the skin of the person holding a newly devised water bottle is used to disinfect the bottle’s contents. Credit: Young-Jun Kim

Run out of drinking water on your hike? A new-concept bottle can disinfect water refilled from any freshwater source by harnessing the electricity that your body generates in just ten minutes of walking 1 .

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doi: https://doi.org/10.1038/d41586-024-01074-9

Kim, Y.-J. et al. Nature Water https://doi.org/10.1038/s44221-024-00226-5 (2024).

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Energy Drink Science Project

Ideas for Projects on Energy in the Fifth Grade

The belief concerning energy drinks is that they will, of course, give you energy. But do they really? Some people believe that they do and some believe they don't. The questions are, do they really provide energy and if so, how long does this effect last? These are questions that can be answered by the completion of a science project or two.

Throughout history people have consumed beverages that are purported to provide energy. Two common examples are coffee and tea In Newcastle, England in 1927, a drink called Lucozade was one of the first modern-like energy drinks that came about as a supplementary liquid for patients in hospitals. More recent energy drinks emerged, overseas, in 1960. It wasn’t until 1980 that the first energy drink, Jolt Cola, appeared in the U.S. and, 17 years later, in 1997 Red bull entered the U.S. market.

Modern energy drinks include but are not limited to Red Bull, Full Throttle, Snapple Green Tea, AMP Energy Mountain Dew and SoBe Essential Energy. Certain energy drinks have caffeine while others may also contain extra vitamins, minerals, and herbal supplements. These drinks are often carbonated, contain large amounts of caffeine, and generally are high in sugar.

Students testing the effectiveness of energy drinks learn several things. One is they learn to follow the scientific method. In science, as in many other areas of life, it is important to develop a step-by-step method for answering questions and solving problems. This helps people focus on the problem at hand while eliminating the influence of opinion.

Secondly, science projects on energy drinks help students determine the difference between fact and advertising gimmicks. Advertisers are well known for using flashy images to catch the attention of a viewer and to imply benefits that may not exist. Scientifically proving or disproving these potential benefits helps students make educated decisions when searching for a product in addition to helping them separate fact from fiction.

Science Project

In this science project you will test whether energy drinks provide more energy than the equivalent amount of water. First develop an energy rating survey. Choose a scale from 1 to 5 with 1 being the lowest level of energy and 5 the highest. Next, choose 10 of your classmates to participate in your project; explain the procedure and your rating scale In the beginning, before drinking anything, ask them to rate their current energy levels. Next, direct five students to drink 8 oz. of water and five students to drink 8 oz. of the chosen energy drink. After 10 minutes of rest, ask them to rate their energy levels again.

Once you have established their baseline energy levels, direct the students to complete five minutes of a prescribed activity such as walking, skipping, or running. Whichever you choose, make sure they are all participating in the same activity. At the end of five minutes, ask them to again rate their energy level. Repeat this procedure three more times for a total of twenty minutes of activity.

If you have the human resources, repeat this project every day, at the same time, for five days. There is a good chance your PE/health teacher will agree to “loaning” you the students you need. He may even be willing to act as your assistant, helping you as needed.

Record your data in a table and average out your values. Graph the data on a line graph or a bar graph with time values on the x axis and average energy level ratings on the y axis. Analyze your data and write down your conclusions.

Alternate Project

An option for determining the long-term effects of energy drinks compared with non-energy drinks would be to first choose a class to participate in your activity. Explain your purpose and the procedures you will follow. Direct every student to rate their energy levels before drinking anything. Choose half the class to drink a serving of energy drink and the other a serving of water. Ask them to rate their energy level every 10 minutes until lunch time. Make sure you have their teachers’ permission and that you supply the liquids and the worksheets with rating scales and times included. Again, record your data in a table, determine the averages and create a graph. Analyze your data and form a conclusion about the long-term effects of energy drinks.

Considerations

Due to the placebo effect you may want to choose a flavored, non-energy drink in lieu of water.

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Shop Experiment Electrolytes in Energy Drinks Experiments​

Electrolytes in energy drinks.

Experiment #06 from Food Chemistry Experiments

Introduction

We all need electrolytes in our diet. Why? Electrolytes are used by our nerves and muscles. Among other things, they regulate our blood pressure and pH of our blood and help keep our tissues hydrated. As the name implies, in many cases, electrolytes are involved with carrying electrical current in our bodies. During exertion we can lose electrolytes through sweating, which is why athletes commonly drink beverages high in electrolytes.

Electrolytes are salts and molecules that ionize to some extent. Strong electrolytes completely ionize while weak electrolytes only partially ionize. Nonelectrolytes do not ionize at all. We can classify compounds as strong, weak, or nonelectrolytes by measuring the conductivity of these chemical solutions. 

Strong Electrolytes

Strong electrolytes are usually ionic compounds; they can be expected to dissociate 100% in aqueous solution.

Example:  MX(s) → M + (aq) + X – (aq)

States of matter are expressed as (s) for solid, (aq) for aqueous (dissolved in water). Some substances may be liquid (l) or gas (g) in their native, pure form.

Weak Electrolytes

Weak electrolytes are molecules that can partially dissociate, depending on their strength. Acids ingested as part of our diets are a common example of weak electrolytes in our diets. Some fraction of the molecules of these compounds will dissociate into ions which may then recombine to form the original molecule.

Example:  HA(l) ⇄ H + (aq) + A – (aq)  (<100% dissociation)

Nonelectrolytes

Nonelectrolytes are molecules that usually do not dissociate to form ions. Even though many dissolve in water, the resulting solutions do not conduct electricity very well at all. Contamination may result in higher readings than anticipated for these substances.

Example:  MA(s) → MA(aq)

In this experiment you will analyze the components of a popular sports drink used by athletes  to replenish electrolytes and water lost during physical activity.

• Write equations for the dissociation of compounds in water.
• Use a conductivity probe to measure the conductivity of solutions.
• Determine which molecules or ions are responsible for the conductivity of solutions.

Sensors and Equipment

This experiment features the following sensors and equipment. Additional equipment may be required.

Correlations

Teaching to an educational standard? This experiment supports the standards below.

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This experiment is #06 of Food Chemistry Experiments . The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.

Physical Review Letters

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• Featured in Physics

Forward and Inverse Energy Cascade in Fluid Turbulence Adhere to Kolmogorov’s Refined Similarity Hypothesis

H. yao, p. k. yeung, t. a. zaki, and c. meneveau, phys. rev. lett. 132 , 164001 – published 17 april 2024, see synopsis: link verified between turbulence and entropy.

• No Citing Articles
• Supplemental Material
• ACKNOWLEDGMENTS

We study fluctuations of the local energy cascade rate Φ ℓ in turbulent flows at scales ( ℓ ) in the inertial range. According to the Kolmogorov refined similarity hypothesis (KRSH), relevant statistical properties of Φ ℓ should depend on ε ℓ , the viscous dissipation rate locally averaged over a sphere of size ℓ , rather than on the global average dissipation. However, the validity of KRSH applied to Φ ℓ has not yet been tested from data. Conditional averages such as ⟨ Φ ℓ | ε ℓ ⟩ as well as of higher-order moments are measured from direct numerical simulations data, and results clearly adhere to the predictions from KRSH. Remarkably, the same is true when considering forward ( Φ ℓ > 0 ) and inverse ( Φ ℓ < 0 ) cascade events separately. Measured ratios of forward and inverse cascade probability densities conditioned on ε ℓ also confirm the applicability of the KRSH to analysis of the fluctuation relation from nonequilibrium thermodynamics.

• Received 25 September 2023
• Accepted 28 February 2024

DOI: https://doi.org/10.1103/PhysRevLett.132.164001

© 2024 American Physical Society

Physics Subject Headings (PhySH)

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Link Verified between Turbulence and Entropy

Published 17 april 2024.

The verification of a 63-year-old hypothesis indicates that nonequilibrium statistical mechanics could act as a theoretical framework for describing turbulence.

See more in Physics

Authors & Affiliations

• Department of Mechanical Engineering & Institute for Data Intensive Engineering & Science, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA
• Department of Aerospace Engineering and Mechanical Engineering, Georgia Institute of Technology, North Avenue, Atlanta, Georgia 30332, USA
• Mechanical Engineering & IDIES, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA
• * [email protected]

Article Text (Subscription Required)

Supplemental material (subscription required), references (subscription required).

Vol. 132, Iss. 16 — 19 April 2024

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(a) Spatial distribution of local dissipation rate normalized by ⟨ ε ⟩ on a plane in a small subset of isotropic turbulence at R λ = 1250 . The left portion shows ε ℓ distribution obtained from spherical filtering. (b) Close-up portion of panel (a) also showing a sphere with a diameter ℓ = 45 η marked as the black circle. The black dash arrow represents r separating the two points + and − .

Conditional averages of terms in the scale-integrated local KH equation based on ε ℓ , i.e., Z = Φ ℓ (black symbols and lines), Z = P ℓ (yellow symbols and lines), Z = D ℓ (blue symbols and lines). The red dashed line indicates ε ℓ . Different symbols denote different scales ℓ / L = 0.012 [triangles, ( 30 η ) ], 0.018 [circles, ( 45 η ) ], and 0.024 [squares, ( 60 η ) ]. Data is from DNS at R λ = 1 , 250 (solid symbols) and R λ = 430 at ℓ / L = 0.092 ( 45 η ) (open circles), for which Z = d ˜ k ℓ / d t (purple diamonds) is included.

Conditional averaged Z = Φ ℓ q (symbols) for the isotropic8192 (a) and isotropic1024 (b) datasets, and Z = W ℓ n (dashed lines for the isotropic1024 dataset), for ℓ = 45 η , plotted as function of ε ℓ . Results for q , n = 1 , 2, 3 are shown in black, blue, and green, respectively. All terms display linear trends with ε ℓ , consistent with the KRSH.

Conditionally averaged positive (forward cascade, full symbols, Z = Φ ℓ , cond: Φ ℓ > 0 ) and negative (inverse cascade, empty symbols, Z = Φ ℓ , cond: Φ ℓ < 0 ) for the isotropic8192 dataset, and for three scales ℓ (symbols are the same as in Fig.  2 ). The green stars show the standard 4 / 5 -law quantity based on longitudinal structure function, i.e., for Z = ( − 5 / 4 ℓ ) ( δ u j n ^ j ) 3 , and no additional condition beyond ε ℓ . Blue symbols is Pr ( Φ ℓ > 0 | ε ℓ ) / Pr ( Φ ℓ < 0 | ε ℓ ) ( ≈ 2.0 ).

Conditional PDFs of Ψ ℓ , for ℓ = 45 η conditioned on ranges in bins centered at ε ℓ / ⟨ ε ⟩ = 0.15 (black), 0.45, 0.75, 1.05, 1.8, 3.0, 4.2, and 5.4 (yellow). The gray dashed lines have slopes = 2 (left) and − 1 (right). A natural logarithm is used.

Test of conditional FR for different values of ε ℓ / ⟨ ε ⟩ (same line colors as in Fig.  5 ). The gray line has slope = 1 .

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Paste a citation or doi, enter a citation.

Detrimental effects of energy drink consumption on platelet and endothelial function

Affiliation.

• 1 Department of Cardiology, Cardiovascular Research Centre, Royal Adelaide Hospital, and Disciplines of Physiology and Medicine, University of Adelaide, Adelaide, Australia.
• PMID: 20103032
• DOI: 10.1016/j.amjmed.2009.09.013

Background: Energy drink consumption has been anecdotally linked with sudden cardiac death and, more recently, myocardial infarction. As myocardial infarction is strongly associated with both platelet and endothelial dysfunction, we tested the hypothesis that energy drink consumption alters platelet and endothelial function.

Methods: Fifty healthy volunteers (34 male, aged 22+/-2 years) participated in the study. Platelet aggregation and endothelial function were tested before, and 1 hour after, the consumption of 250 mL (1 can) of a sugar-free energy drink. Platelet function was assessed by adenosine diphosphate-induced (1 micromol/L) optical aggregometry in platelet-rich plasma. Endothelial function was assessed via changes in peripheral arterial tonometry and expressed as the reactive hyperemia index (RHI).

Results: Compared with baseline values, there was a significant increase in platelet aggregation following energy drink consumption, while no change was observed with control (13.7+/-3.7% vs 0.3+/-0.8% aggregation, respectively, P <.01). Similarly, RHI decreased following energy drink consumption (-0.33+/-0.13 vs 0.07+/-0.12 RHI [control], P <.05). Mean arterial pressure significantly increased following energy drink consumption, compared with control (P <.05). Heart rate was unaffected by energy drink consumption.

Conclusion: Energy drink consumption acutely increases platelet aggregation and decreases endothelial function in healthy young adults.

Copyright (c) 2010 Elsevier Inc. All rights reserved.

Health Benefits of Guarana

Guarana ( Paullinia cupana ) is a plant native to the Amazon basin in South America. Guarana seeds have been consumed by indigenous communities in the Amazon region for centuries, both as an energy source and as a natural medicine for conditions such as headaches, period pain, and digestive disorders.

Best known for its stimulating properties, guarana has one of the highest caffeine contents of all plants. It contains approximately four times more caffeine than coffee beans.

Because of its energizing effects, guarana is a common ingredient in stimulant supplements and products, such as energy drinks and pre-workouts. While consuming guarana may benefit certain aspects of health, such as cognitive function and athletic performance, guarana is associated with several side effects and health concerns.

Design by Health / Getty Images

May Improve Energy and Alertness

Guarana has powerful stimulating effects, and products have been used for centuries to boost energy and alertness. Guarana contains several compounds that affect the central nervous system (brain and spinal cord) to help you feel more awake and energized.

Guarana seeds contain up to 8% caffeine by weight. Caffeine crosses the blood-brain barrier—a barrier between the blood vessels of the brain and the brain tissue that prevents harmful substances from reaching the brain. It blocks receptors for adenosine, a neurotransmitter that plays a critical role in the sleep cycle.

Adenosine increases the need for sleep by making you feel drowsy. Caffeine blocks adenosine’s ability to bind with adenosine receptors, which makes you feel less sleepy and more alert.

In addition to caffeine, guarana contains other stimulating compounds, such as catechins and tannins, which may have energy-boosting effects on the body. Studies show that guarana is more effective for increasing energy levels than caffeine alone.

Consuming guarana products like energy drinks and supplements could help you feel more awake. For example, one small 2023 study that included 25 participants found that those who ingested 125 milligrams per kilogram (mg/kg) of guarana experienced significant improvements in alertness scores compared to people who received a placebo treatment (e.g., a sugar pill).

Has Cognitive-Enhancing Properties 

Some study findings suggest that guarana supplements can improve cognitive performance . This may benefit those who need a boost before a mentally taxing task, such as a marathon study session or an important presentation. 

For example, a 2023 review of eight studies found guarana ingestion effective for improving response time during various cognitive tasks. It also didn't have any negative effects on accuracy. Though the improvement seen in this study was small, it suggests that consuming guarana may help boost your performance on time-related tasks.

Additionally, the 2023 study of 25 people mentioned above found that those who took guarana supplements experienced significant improvements in reaction times on cognitive tests before and after intense exercise .

Some research findings suggest that guarana supplements may also increase information processing, which may help you perform better at work or school.

May Boost Athletic Performance 

Guarana may be a useful supplement for athletes and those looking to improve their exercise performance. Study findings suggest that taking guarana before exercising may make your workout feel easier and increase your workout efficiency.

One small 2019 study of 10 high-level athletes found that consuming 300 mg of guarana before and during exercises reduced levels of perceived exertion and improved cognitive performance compared to a placebo.

Additionally, the researchers of the 2023 study of 25 participants suggested that guarana may be helpful for athletes involved in sports and activities that require quick responses, like soccer and hockey, as it helps improve reaction times.

How To Take Guarana 

Guarana is available in several forms, such as capsules, liquids, and powders. It’s often combined with other natural stimulants like caffeine and ginseng in products designed to boost energy and concentration.

Guarana is a popular ingredient in energy drinks, protein bars , and other food and beverage products designed to fight fatigue. It can be taken when you need a boost of energy or want to improve focus and concentration, such as when studying for an exam.

Pre-workouts containing guarana are commonly consumed by gym-goers before a workout to enhance their exercise performance and improve their reaction time and focus. Avoid taking it before bed because it can disrupt sleep and cause insomnia.

Guarana doses typically range from 37.5-222 mg, though higher doses have been used. Research studies have also used doses of guarana ranging from 75-100 mg per day for up to four weeks.

Always read product labels for dosing recommendations, as guarana is commonly combined with different ingredients.

Is Guarana Safe?

Guarana is generally considered safe when taken in recommended doses, but its use has been associated with several health concerns. For example, overuse of guarana-containing supplements and products containing guarana, like energy drinks, might negatively affect heart health and lead to irregular heartbeat, high blood pressure, and several other heart-related side effects. This is especially true for people with pre-existing cardiovascular conditions.

There have also been reports of seizures in healthy young adults who consumed energy drinks containing guarana and other ingredients.

Guarana contains caffeine, so avoid it if you're pregnant , breastfeeding, or sensitive to caffeine. Caffeine may worsen symptoms of some health conditions, such as anxiety and cardiac conditions like arrhythmia (irregular heartbeat).

Caffeine Toxicity

Guarana, which is already high in caffeine, is often combined with other stimulants. Therefore, caffeine toxicity is another risk. Caffeine toxicity can cause dangerous symptoms like seizures , vomiting, and hallucinations. It’s recommended that adults keep their caffeine intake to less than 400 milligrams per day. Although rare, you can consume a fatal dose of caffeine, which is estimated to be between 10-14 grams (g).

This is why it’s important to know how much caffeine is in guarana products, like supplements and energy drinks, and to avoid products that contain very high doses of this stimulant. 

Potential Drug Interactions

Guarana has the potential to interact with several commonly prescribed medications, including:

• Blood-thinners: Guarana may increase the effects of blood-thinning medications , such as warfarin, as it might decrease the body’s ability to clot blood. Though this potential effect hasn't been confirmed in humans, always check with your healthcare provider before supplementing with guarana if you take blood thinners.  
• Adenosine: Adenosine is a drug used to treat heart rhythm disorders. It's also sometimes used during a cardiovascular stress test . Guarana seems to block the absorption of adenosine, so it may interfere with how this drug works. Avoid all caffeine-containing products, including guarana, for at least 24 hours before undergoing a stress test.   
• Clozapine: Clozapine is an antipsychotic medication. Caffeine may increase its effects and worsen psychotic symptoms. 

Guarana may interact with other drugs, so always talk to your healthcare provider before trying it.

What To Look For

If you’re interested in taking a guarana supplement, it’s important to choose a safe supplement from a reputable company. Many supplement companies are certified by third-party organizations like UL, USP, and NSF International, which set strict standards for supplement safety and quality.

Read product labels carefully for other ingredients that might interact with medications or might not be safe for you.

Can You Take Too Much Guarana?

Guarana contains caffeine, which can lead to dangerous side effects if over-consumed. As mentioned above, it’s recommended to keep your caffeine intake to less than 400 mg per day to avoid side effects such as sleep disturbances, irregular heart rate, irritability, and insomnia .

Some guarana-containing products, like energy drinks, contain multiple servings per container, which can easily lead you to over-consume caffeine. Read ingredient labels and note how much caffeine the product contains so you can stay within a safe limit. 

Side Effects of Guarana 

Guarana can lead to many side effects, especially when consumed in high doses. Here are some of the most common:

• Stomach burning
• Vomiting 
• Restlessness
• Nervousness
• Rapid heartbeat 
• Increased urination

The potential for adverse side effects may increase if you’re taking a supplement or ingesting a product that contains multiple stimulants. 

If you experience any side effects, stop taking the product and consult your healthcare provider if the symptoms don’t resolve. 

A Quick Review

Known for its stimulating properties, guarana is a popular ingredient in products like pre-workouts and energy drinks. Some research suggests that supplementing with guarana may improve energy levels, alertness, athletic performance, and cognitive function. However, guarana is high in caffeine and can lead to adverse side effects when taken in large doses.

Guarana isn’t safe for everyone and has the potential to interact with common medications. It can also worsen symptoms of several health conditions. Always consult your healthcare provider before trying it.

National Institute of Diabetes and Digestive and Kidney Diseases. Guarana . In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury; 2023.

Moustakas D, Mezzio M, Rodriguez BR, Constable MA, Mulligan ME, Voura EB. Guarana provides additional stimulation over caffeine alone in the planarian model . PLoS One . 2015;10(4):e0123310. doi:10.1371/journal.pone.0123310 

Gurney T, Bradley N, Izquierdo D, Ronca F. Cognitive effects of guarana supplementation with maximal intensity cycling . Br J Nutr . 130(2):253-260. doi:10.1017/S0007114522002859 

Hack B, Penna EM, Talik T, Chandrashekhar R, Millard-Stafford M. Effect of guarana (Paullinia cupana) on cognitive performance: A systematic review and meta-analysis . Nutrients . 2023;15(2):434. doi:10.3390/nu15020434 

Pomportes L, Brisswalter J, Hays A, Davranche K. Effects of carbohydrate, caffeine, and guarana on cognitive performance, perceived exertion, and shooting performance in high-level athletes . Int J Sports Physiol Perform . 2019;14(5):576-582. doi:10.1123/ijspp.2017-0865

NatMed. Guarana . In: NatMed . NatMed; 2023.

Wassef B, Kohansieh M, Makaryus AN. Effects of energy drinks on the cardiovascular system . World J Cardiol . 2017;9(11):796-806. doi:10.4330/wjc.v9.i11.796 

Costantino A, Maiese A, Lazzari J, et al. The dark side of energy drinks: A comprehensive review of their impact on the human body .  Nutrients . 2023;15(18). doi:10.3390/nu15183922

Rodak K, Kokot I, Kratz EM. Caffeine as a factor influencing the functioning of the human body—Friend or foe? Nutrients . 2021;13(9):3088. doi:10.3390/nu13093088

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Prime class action claims energy drinks contain more caffeine than advertised

• Deadline to file a claim: TBD
• Proof of Purchase Required: No
• Potential Individual Reward: TBD

Anne Bucher  |  April 12, 2024

Category: food.

Prime class action lawsuit overview:

• Who: Plaintiff Lara Vera filed a class action lawsuit against Prime Hydration LLC.
• Why: Vera claims Prime energy drinks contain more caffeine than indicated on their labels.
• Where: The Prime class action lawsuit was filed in New York federal court.

Prime Hydration LLC misrepresents the amount of caffeine contained in some of its energy drinks, a new class action lawsuit alleges.

Plaintiff Lara Vera says she purchased Prime energy caffeine products on several occasions because she believed they contained “200mg of caffeine” as stated on the product label. 

However, product testing found they actually contained 215-225 milligrams of caffeine, according to the Prime class action lawsuit.

A cup of coffee contains approximately 100 milligrams of caffeine, and a 12-ounce can of Red Bull contains about 114 milligrams of caffeine. Therefore, Vera says consuming a Prime energy drink is similar to consuming two cups of coffee or two Red Bull energy drinks.

Alleged Prime energy drink mislabeling especially dangerous for youth, plaintiff says

Popular YouTube personalities Logan Paul and KSI announced a collaboration on the energy drinks in 2022, generating significant social media attention and increasing demand for the products. School-age children and teenage boys were particularly interested in purchasing the energy drinks, according to the class action lawsuit.

“There is no proven safe dose of caffeine for children,” the Prime class action lawsuit says. “Side effects for kids consuming caffeine could include rapid or irregular heartbeats, headaches, seizures, shaking, stomach upset and adverse emotional effects on mental health.”

Because of these health risks, pediatricians and parents are calling for a ban on the sale of high-caffeine energy drinks to minors, according to the class action lawsuit. 

U.S. Senate Majority Leader Chuck Schumer has reportedly already asked the U.S. Food and Drug Administration to investigate the products and their purported health claims, social-media advertising practices, the product labels and warnings and their “eye-popping caffeine content.”

Vera says the alleged Prime energy drink mislabeling violates U.S. Food Drug and Cosmetics Act regulations prohibiting false and misleading labeling of food products. 

The Prime class action lawsuit also asserts claims for violations of various state consumer fraud acts, New York deceptive practices and false advertising laws, breach of express warranty, unjust enrichment and fraud.

Last fall, a separate class action lawsuit claimed the company markets its beverages to youth despite known health risks.

What do you think about the allegations in the Prime Hydration class action lawsuit? Tell us your thoughts in the comments.

Vera is represented by Mason A. Barney and Tyler Bean of Siri & Glimstad LLP; Russell M. Busch, J. Hunter Bryson and Nick Suciu III of Milberg Coleman Bryson Phillips Grossman PLLC; and Jeff Ostrow and Kristen Lake Cardoso of Kopelowitz Ostrow PA.

The Prime class action lawsuit is Lara Vera v. Prime Hydration LLC , Case No. 1:24-cv-02657, in the U.S. District Court for the Southern District of New York.

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167 thoughts on Prime class action claims energy drinks contain more caffeine than advertised

I have consumed a decent amount of Prime. I think I could benefit from this class action law suit.

add us another company mishap

please add me

I purchased for my daughters – not happy to hear this. Add me to this list

I have 3 kids who drank this consistently due to being marketed on YouTube ! And other kid shows ..

The picture above is not of a Prime Energy Drink.

Prime Energy came in cans ONLY The fact that grown adults with kids couldn’t tell the difference and/or couldn’t be bothered to read the ingredients and check the nutritional labels is a sad documentary on American Parents, not American products

I’ve bought these for my kids for a while now thinking they were a good alternative. It’s sad that he is being poisoned by someone he actually looked up to. Logan Paul should be ashamed for promoting a product like this.

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• Front Neurosci

Energy Drinks and the Neurophysiological Impact of Caffeine

Leeana aarthi bagwath persad.

1 Department of Physiology, University of Pretoria, Pretoria, Gauteng, South Africa

Caffeine is the most widely used psychoactive stimulant with prevalent use across all age groups. It is a naturally occurring substance found in the coffee bean, tea leaf, the kola nut, cocoa bean. Recently there has been an increase in energy drink consumption leading to caffeine abuse, with aggressive marketing and poor awareness on the consequences of high caffeine use. With caffeine consumption being so common, it is vital to know the impact caffeine has on the body, as its effects can influence cardio-respiratory, endocrine, and perhaps most importantly neurological systems. Detrimental effects have being described especially since an over consumption of caffeine has being noted. This review focuses on the neurophysiological impact of caffeine and its biochemical pathways in the human body.

Introduction

In today’s fast-paced lives people need vigor to keep up with their demanding schedules and lifestyles. Often, they need some assistance in doing so. Caffeine is a naturally occurring chemical and is referred to as an “ancient wonder drug” (McCarthy et al., 2008 ) for its potential to revive weary workaholics. It was discovered in the coffee bean ( Coffea arabica ) in Arabia, the tea leaf ( Thea sinensis ) in China, the kola nut ( Cola nitida ) in West Africa, and the cocoa bean ( Theobroma cacao) in Mexico (Chou, 1992 ). Caffeine products are so widely distributed these days that abuse of the substance may be unnoticed. In fact, caffeine is the world’s most widely consumed stimulant, with 54% of adults in America consuming on average three cups of coffee a day (Chen and Parrish, 2008 ). Aside from occurring organically in tea and coffee, caffeine is now an additive in soft drinks, energy drinks, chocolates, bottled water, chewing gum, and medication (Mednick et al., 2008 ). The aim of this paper is to elicit an awareness of the neurophysiological effects of caffeine. This article emphasizes caffeine’s potential effects on the nervous system within the context of increased caffeinated energy drink consumption around the world.

Caffeine Consumption

Aside from being added to beverages, caffeine is now being added to food products such as potato chips, chocolates, and bottled water, which confirms its growing popularity (Temple, 2009 ). Since the introduction of Red Bull in 1987, the energy drink market has grown extensively, with hundreds of different brands of varying caffeine content now available (Reissig et al., 2009 ).

There has been an increase in reports of caffeine-intoxication since 1982, with 41 cases of caffeine abuse reported in the United States from 2002 to 2004 (Reissig et al., 2009 ). This could be an indicator of an increase in caffeine dependence and withdrawal symptoms (Reissig et al., 2009 ).

European and North American statistics report that 90% of adults consume caffeine on a daily basis, with an average intake of 227 mg (Reissig et al., 2009 ; Temple, 2009 ). The South African Food Based Dietary guidelines recommend that adults limit their daily intake of caffeine drinks to no more than four cups of coffee per day or eight cups of tea per day, which is in line with the US Food and Drug Administration reporting a moderate caffeine use as safe (a moderate daily dose being 300 mg and below and high daily doses being 500–2000 mg 1 ; Temple, 2009 ). Unfortunately, the statistics on South African consumptions are not readily available 2 , so European and North American statistics are described instead: The top three sources of caffeine are coffee (70%), cold drinks (16%), and tea (12%) in the United States. Table ​ Table1 1 shows the caffeine content in some popular dietary sources.

Types of food and drink caffeine content (Jones and Fernyhough, 2008 ) .

From Table ​ Table1 1 it is clear that brewed coffee has almost three times the amount of caffeine as instant. Energy drinks have twice the amount of caffeine as regular cold drinks and with ever increasing consumption, this constrains us to be informed about the neurological consequences this could have.

Biochemical Characteristics

Caffeine has a chemical structure of is 1,3,7-trimethylxanthine (Figure ​ (Figure1). 1 ). Methylxanthine has a similar structure to purines, adenosine, xanthine, and uric acid (Chou, 1992 ).

Chemical structure of caffeine (Deng et al., 2008 ) .

In nature, caffeine is found in a diversity of plants, kola nuts, cherries, and cocoa beans and is presumed to offer protection to plants by acting as an anti-herbivory and allelopathic agent (Chen et al., 2008 ). In humans, caffeine is quickly absorbed by the gastrointestinal tract. Caffeine from coffee is absorbed faster than caffeine from cold drinks. Some reasons for this could be: the lower temperature of the beverage may decrease the rate of blood flow within the intestines; phosphoric acid in cold drinks could decrease gastric emptying; absorption rate could increase with caffeine dose; sugar in cold drinks could inhibit gastric emptying of caffeine and delay absorption (Ligouri et al., 1997 ). In fact, 99% of the orally ingested chemical is taken up within 45 min (Chou, 1992 ).

Caffeine disperses throughout the body and penetrates the biological membranes, the blood brain barrier and placenta, however it does not accumulate in the tissues or organs (Chou, 1992 ; Temple, 2009 ). Just 15–20 min after oral ingestion, peak plasma concentration is reached. The half-life in adult males is decreased by 30–50% in smokers and is doubled in women taking oral contraceptives and extended further in the last trimester of pregnancy and in patients with chronic liver disease (Chou, 1992 ). This means that there is increased caffeine metabolism in conjunction with cigarets while oral contraceptives, pregnancy, and chronic liver disease delay metabolism of caffeine in the body. This can be accounted for by examining caffeine’s metabolism which is species-specific. In Camellia (tea) species caffeine is degraded via theophylline into primary metabolites. In coffea (coffee) species caffeine is also degraded via theophylline but through a different route (Ashihara et al., 2008 ). Caffeine is converted into dimethylxanthines, dimethyl and monomethyl uric acids, trimethyl and dimethyl-allantoin and uracil derivatives in the liver. Only 2–3% of caffeine is excreted in urine unchanged (Chou, 1992 ; Nehlig, 1998 ). While caffeine itself is eliminated overnight from the body, some primary metabolites such as theobromine and theophylline have longer half-lives.

Caffeine and its primary metabolites, theobromine, paraxanthine, and theophylline are identified in all body fluids (Grosso and Bracken, 2005 ). Paraxanthine levels decrease less rapidly than caffeine and are further metabolized via two independent reactions. These paraxanthine metabolites are found in urine (Grosso and Bracken, 2005 ). Theobromine makes up the largest part of caffeine metabolites, with only 50% excreted in urine. Some of the effects of caffeine in systems other than the nervous system are described.

Cardiovascular and respiratory effects

Caffeine induces various acute cardiovascular effects such as an up regulation of circulating catecholamines. Arterial stiffness and endothelium dependent vasodilatation also result, leading to increases in systolic and diastolic blood pressure (DBP; Riksen et al., 2009 ). An increase in the respiration rate (RR) is the prime effect dependent on the plasma caffeine value (Chou, 1992 ).

Endocrine and metabolic effects

Caffeine enhances circulating catecholamine levels. Owing to this mechanism there is an increase in the basal metabolic rate – this includes lipolysis which releases free fatty acids (Chou, 1992 ).

Gastrointestinal and urinary effects

Caffeine excites the small intestine, causing secretion of water and sodium (Chou, 1992 ). Its pharmacological effects include diuresis.

From a medical view, caffeine has been seen to promote apoptosis in UVB-damaged cells, to antagonize adenosine receptors for regulating contraction of blood vessels and even serves as a psychoactive drug in the treatment of Parkinson’s disease (Chen et al., 2008 ). With its potential utilization in medicine, the safety and effects of caffeine are important issues.

Benefits of Caffeine to the Human Body

Unfortunately, a review of the literature shows two important limitations in caffeine research. Firstly, research on animals uses doses that are hundreds to thousands of times higher than those seen in human consumption. Therefore, relating the results to humans becomes difficult (Chou, 1992 ). Secondly, some studies investigate pure caffeine, while others pose research questions pertaining to coffee, not pointing out the other components in coffee and their potential confounding effects (Chou, 1992 ).

Despite these limitations, extensive explorations of caffeine have been carried out and have provided a great deal of information regarding the effects of caffeine. Under the next few headings the major neurophysiologic effects of caffeine are discussed as the main focus of this article.

Arousal and fatigue

Arousal is considered to be a variable state reflecting the present energetic factors and task-related activation, the degree of “awareness” an individual has and in neuropsychology context an increase in arousal relates to a better ability to carry out a task (Barry et al., 2005 ). There is an apparent link between caffeine effects and dopamine functions. This evidence does not preclude the involvement of other neuromodulator systems, though. In fact, it has been reported that caffeine increases the firing rates in mesopontine cholinergic neurons, which participate in the production of arousal (Lorist and Tops, 2003 ). These cholinergic neurons are inhibited by adenosine, providing a coupling mechanism that links arousal and caffeine, yielding proof for the role of caffeine in the behavioral state of arousal (Lorist and Tops, 2003 ).

A study conducted by Barry et al. ( 2008 ) proves that caffeine does increase arousal by increasing skin conductance level (SCL), while decreasing heart rate (HR) and decreasing levels of DBP. Arousal effects from caffeine were noted in a 30-min period approximately 25 min after ingestion. An increase in RR was noted to peak at 33 min and then decrease with time. The subjects carried out two tasks – an auditory task composed of an active auditory oddball task and a visual task requiring the subjects to focus their vision on a specific spot without excessive blinking. Barry et al. ( 2008 ) suggest that caffeine produced a reduction in reaction time in the tasks carried out, supporting the idea that blood pressure effects reflect effortful task-related activity rather than arousal changes. Caffeine produced an increase in SCL levels and a reduction in alpha power. Alpha generators are unchanged by caffeine and therefore caffeine causes arousal without manipulating task requirements, consistent with caffeine’s antagonistic effects on adenosine receptors reducing inhibition of cholinergic neurons. Post-task effects of caffeine included changes in blood pressure activity and alpha and beta power implying that caffeine may have effects on task performance above arousal effects (Barry et al., 2008 ). Caffeine also has beneficial effects on choice reaction time, especially in the elderly with a daily dosage of 200–400 mg (Smith, 2002 ).

It is noted that caffeine can affect the attention system. Attention can alter the neural activity in cortical areas that may intensify the responsivity of cells to specific stimulus features (Lorist and Tops, 2003 ). A substantial number of studies show that caffeine consumption increases alertness and decreases fatigue (Barry et al., 2008 ; Smith, 2002 ; Biggs et al., 2007 ; Kennedy et al., 2008 ) in large and moderate doses.

To evaluate the effect of caffeine on sleep deprivation and driving Biggs et al. ( 2007 ) conducted a study using 12 regular drivers that are non-smokers, with healthy BMIs, between the ages of 20 and 30 years. Coffee and placebo were administered, with every subject acting as his/her own control. Caffeine was shown to have a beneficial effect on all driving tests and the data suggests that caffeine returned driving performance to baseline (pre-sleep deprivation) levels (Kennedy et al., 2008 ); thereby proving that caffeine does increase alertness and can be beneficial in driving tasks.

Perceptual processing

Perception is a process of gaining some form of knowledge through thought, experience, and the senses (Wang, 2009 ). Lorist and Tops ( 2003 ) used a task consisting of a stimulus quality which was manipulated. The non-degraded stimulus consisted of a dot pattern surrounded by a rectangular frame of dots (see Figure ​ Figure2). 2 ). In the degraded condition dots were placed from the frame into variable positions. This new arrangement impaired the identification of the stimulus. Caffeine increased the ability to process degraded stimuli (see Figure ​ Figure3; 3 ; Lorist and Tops, 2003 ). By contrast, Smith ( 2002 ) conducted a perceptual task requiring participants to discriminate between two targets per trial. The group that received caffeine showed no significant difference in the perceptual task compared to those that did not receive caffeine. Another study conducted by Ruijter et al. ( 2000 ) tested the effect of caffeine on sustained attention required by subjects to work continuously for 10 min in a self-paced task. The task consisted of a color selection task, a spatial selection task, and a concentration task. Subjects were administered a moderate dose of 250 mg of caffeine. The results showed an increase in arousal but no change in perceptual behavior. From this we can see that the effect of caffeine on perception is inconsistent.

Non-degraded stimulus .

Degraded stimulus .

Motor behavior

Motor skill learning is one of the main functions of the central nervous system. It is a process of increasing the spatial and temporal accuracy of movements with practice. Motor skill has two prominent learning phases: an initial fast learning phase and later, slow learning phase (Xiong et al., 2009 ). In the early stage of learning a great deal of improvement in performance is attainable within a few minutes. Precise knowledge of the movement is used to promote the control and co-ordination of specific body action. During the later phase, there is slow learning progress and less attention is needed to perform the task. The prefrontal cortex is responsible for movement in the parts of the body, it also guides eye and head co-ordination (Xiong et al., 2009 ).

Dopamine is a neurotransmitter with excitatory and inhibitory effects. Neurons of the substantia nigra have nerve endings in the caudate nucleus and putamen of the cerebrum, where they release dopamine. Dopamine acts as an inhibitor in the basal ganglia and is excitatory in other areas of the brain (Xiong et al., 2009 ). U-shaped dose–response curves in humans show that either too much or too little dopamine results in diminished prefrontal cortex functioning.

The mesocorticolimbic dopaminergic system mediates approach motivation. Dopamine receptors D 2 regulate neural networks that are involved in selective and involuntary attention (Lorist and Tops, 2003 ). Caffeine increases behavior related to dopamine by inhibiting adenosine A 2A receptors and increasing transmission via dopamine D 2 receptors (Lorist and Tops, 2003 ). Lorist and Tops ( 2003 ) used an echoencephalograph (EEG) to highlight the alpha brain wavelength (alpha power). They found that caffeine intake increased left frontal activation compared to the right, suggesting that dopamine function could be linked to fatigue, with caffeine reducing fatigue.

Mednick et al. ( 2008 ), conducted a study was composed of 61 adults 18–39 years old that were given a motor task requiring them to finger tap a 4-1-3-2-4 sequence on a keyboard with the non-dominant hand. The caffeine group showed significantly impaired motor learning.

Learning and memory

Learning is the acquisition of new information by the nervous system, resulting in changes in behavior or “analytical-specific perceptual skills” (Mangina and Sokolov, 2006 ). Memory is the ability to store, process, and recall learnt information. Modality-non-specific memory is associated with the limbic system, especially the hippocampus (Mangina and Sokolov, 2006 ). Neurons in the hippocampus contribute to the formations of declarative memory units. These neurons can be trained to memorize perceptual images and these “trained” neurons are then arranged in a column in accordance to their learning sequence (Mangina and Sokolov, 2006 ).

Long-term potentiation (LTP) is a major candidate for the neurophysiological basis of learning and memory. The LTP mechanism seems to be dependent on activity of glutamatergic receptors and N -methyl d -aspartate (NMDA) receptors are required for induction of LTP while expression of LTP involves α-amino-3-hydorxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Gamma-aminobutyric acid (GABA) receptors also seem to be involved in the mechanisms of LTP, along with other neurotransmitters such as acetylcholine, dopamine, serotonin, and norepinephrine (Myhrer, 2003 ) Dopamine has an impact on performances, motivational processes, and procedural memory, while acetylcholine interacts with dopamine in cognitive functions and with serotonin acts in cognitive behavior, to a lesser extent serotonin and norepinephrine have a weaker influence.

The results from a perceptual learning task and a motor task according to Smith ( 2002 ) may be explained by the relative level of explicit information involved in learning. The perceptual learning task requires the least explicit material, while the motor task shows a strong explicit component. The information shows that caffeine may help in some tasks but impair others. This may be because caffeine increases alertness and decreases fatigue, causing a better performance in some tasks (Smith, 2002 ).

There is concern regarding strategies that can improve the elderly quality of life regarding the diminished cognitive and motor functions that occur with aging (Costa et al., 2008 ). In a study conducted by Costa et al. ( 2008 ) it is stated that the caffeine administered in adult mice prevented age-associated decline in recognition memory when evaluated 90 min after training (corresponding to short term memory). There is however, the possibility of anxiety being elicited, due to high caffeine doses.

Stress and addiction

Stress can be defined to when the human body is not able to cope suitably to physical or emotional threats. The brain is the major component of interpreting and responding to potentially stressful events and determines what is stressful. It is also the central organ of the behavioral and physiological response to stressors and is also a target for the actions of stress hormones such as glucocorticoids (Ferreira et al., 2004 ).

Studies show that during periods of increased stress, caffeine consumption increases (Yeomans et al., 2007 ). Caffeine increases cortisol secretion by stimulating the central nervous system so it is advisable to individuals with hypertension to avoid caffeine during periods of stress as this further increases blood pressure (Yeomans et al., 2007 ; Dack and Reed, 2009 ). Chronic caffeine consumption causes sensitization of a specific subset of cannabinoid receptors in the striatum, consistent with the psychoactive properties of the compound (Sheperd et al., 2000 ; Herrick et al., 2009 ). This may explain why enhanced relaxation and a sense of well being are some of the reported effects of caffeine use during stressful events. Caffeine mechanism action can be explained as follows.

With regular average doses of caffeine in humans, caffeine acts as an antagonist of the adenosine receptors and exhibits an equal affinity for A1 and A 2A receptors. However when acutely administered caffeine acts dominantly on A1 receptors (as ambient adenosine activates it). Chronic caffeine consumption causes tolerances of the A1 receptors, caffeine then has negligible effects on A1 receptor and dominant effects on A 2A receptors (Rossi et al., 2010 ).

The endocannabinoid, endogenous ligands of the cannabinoids receptors are synthesized when needed, in response to the increased neuronal excitation and activates the presynaptic CB1 receptor, decreases the levels of cyclic AMP (cAMP) released and decreases neurotransmitter release (Rossi et al., 2010 ). Caffeine increases neurotransmitter release by removing inhibitory control for acetylcholine in the hippocampus and prefrontal cortex, regulating the opening of potassium channels which is mediated by A1 receptors, increasing the firing rate of neurons (Rossi et al., 2010 ).

A 2A receptor striatum dendrite spines, here they inhibit Glutamatergic-thalamo-cortical neurons by inducing cell activation and stimulating adenylate cyclase pathway. Caffeine blocks A 2A receptors and decreases stimulatory actions on cAMP induced by adenosine (Rossi et al., 2010 ).

The striatum is the main receiving area of the basal ganglia, consisting mainly of GABAergic neurons that receive excitatory input from the cortex, inhibitory input from the axon collaterals and striatal interneurons, and modulatory input from the midbrain dopaminergic neurons. Impacts of these inputs control the outputs to the substantia nigra and globus pallidus and play a role on the effect caffeine has on the striatal neurotransmission (Rossi et al., 2010 ).

Caffeine can reduce the inhibition on striatal dopamine transmission reducing the activity of striatal neurons and causing thalamo-cortical projections neurons to disinhibit. The activation of A 2A receptors results in cAMP production, activation of D2 receptors decreases the production of cAMP causes a reverse regulation of the activity of cAMP-dependant protein kinase (PKA; Rossi et al., 2010 ). Since caffeine mimics the dopamine action on the striatopallidal neurons, it causes a progressive sensitization of cannabinoid CB 1 receptors controlling GABergic inhibitory postsynaptic currents (IPSCs; Herrick et al., 2009 ). Caffeine blocking the A 2A receptors reduces the activation of cAMP–PKA pathways causing an increase in glutamate release, activation of metabotropic mGlu5 receptors, and endocannabinoid release (Rossi et al., 2010 ). The blockade of adenosine A 2A receptors in the striatum, has been associated with the psychoactive properties of caffeine. Also, evidence shows that a specific genetic polymorphism of the adenosine A 2A receptor influences the habitual caffeine consumption in humans (Herrick et al., 2009 ).

Evidence has also shown that caffeine induces striatal synaptic adaptations and does not alter the sensitivity of glutamate synapses to CB1 receptor stimulation in mice, displaying the existence of differential regulation mechanisms of distinct cannabinoid receptors in the striatum (Rossi et al., 2010 ). The caffeine induced adaptation of the endocannabinoid in mice was reversible and after drug withdrawal, symptoms were reversed with a decline in 15 days and totally reversed in 30 days.

Caffeine induced alteration of cannabinoid transmission may have synaptic consequences during the physiological activity of the striatum since chronic caffeine has been shown to enhance the sensitivity of the GABergic synapses to synthetic cannabinoid CB1 receptors agonist and the endocannabinoids, mobilized to respond to the stimulation of metabotropic receptors (Rossi et al., 2010 ). A study on mice shows at toxic levels, caffeine causes calcium release from intracellular space, inhibition of phosphodiesterase, GABBA receptor antagonism, protein kinase C activity (Rossi et al., 2010 ). It is likely that caffeine effects in humans are more complicated than it is in animal studies.

Evidence exists that cannabinoid receptors are implicated in the mechanism of action of psychoactive drugs and stress, so enhanced activity of the cannabinoid CB 1 receptors plays a role in the rewarding effects of morphine, heroin, cocaine, ethanol, amphetamine, and nicotine (Herrick et al., 2009 ). Caffeine induced alterations of cannabinoid transmission may have relevant outcomes during the physiological activity of the striatum. Caffeine effects on the striatal cannabinoid system were similar to those of cocaine (such as the enhanced synaptic defects prompted by stress). It also has been reported that caffeine and cocaine have additive properties and caffeine reinforces cocaine-seeking behavior following elimination of cocaine self-administration (Herrick et al., 2009 ).

The Disadvantages of Caffeine to the Human Body

As previously stated, caffeine could have detrimental effects on a hypertensive that is stressed and consumes caffeine as ultimately caffeine is a stimulant and as with as all stimulants and substance’s abuse or overuse has negative effects. This review looks at some of the detriments of caffeine on the nervous system.

Deficits in learning

Multiple doses of caffeine are consumed in individuals suffering from insomnia to reduce fatigue and increase alertness (Mednick et al., 2008 ). However caffeine may have negative effects on cognition in general and perceptual memory and learning in particular (Mednick et al., 2008 ). The study by Mednick et al. ( 2008 ) shows a comparison of a nap and caffeine on verbal, motor, and perceptual memory. Caffeine causes an increase in hippocampal acetylcholine. This may block consolidation by congesting replay of memories. A moderate dosage of caffeine impairs motor skill and may not be an adequate substitute for memory enhancements or daytime sleep (Mednick et al., 2008 ).

Neurogenesis is the growth and development of the nervous tissue. Neurogenesis occurs in the hippocampal and olfactory bulbs until adulthood (Guyton and Hall, 2006 ; Wentz and Magavi, 2009 ). A study conducted by Wentz and Magavi ( 2009 ) showed that administering high doses of caffeine (20–30 mg/ml) to adult mice influenced the proliferation of hippocampal neural precursors in a duration-dependent dose. This negatively influenced the neural circuits into which adult-born neurons are integrated (Wentz and Magavi, 2009 ). Caffeine can therefore depress hippocampal neurogenesis.

Anxiety and panic attacks

When a single dose of 300 mg is administered, caffeine can increase anxiety and tension. Meanwhile a 400-mg dose of caffeine increases anxiety when paired with a stressful task (Smith, 2002 ). In general, high doses of caffeine may increase anxiety, but this is rarely seen in normal consumption (Smith, 2002 ).

The study by Nardi et al. ( 2007 ) analyzed in two ways how panic from the caffeine challenge test manifested in subjects that suffer from anxiety. The aim of the study was to determine whether patients with PD experience more caffeine-related symptoms or whether they perceive their symptoms more severely than others.

Nardi et al. ( 2007 ) suggest that patients with panic disorder (PD), when compared to depressive patients, showed increased sensitivity to the effects of low doses of caffeine. Patients with PD have an increase in subject-related anxiety, nervousness, fear, nausea, palpitations, and tremors after administration of caffeine. The precise mechanism underlying caffeine panicogenic potentials is uncertain, with the antagonism of adenosine receptors being the most likely pathway (Nardi et al., 2007 ). Imaging studies of cerebral blood flow using position emission topography indicates a decrease in panic attacks with caffeine and increase in glucose utilization (Nardi et al., 2007 ). However, not all individuals with PD display increased panic attack frequency with caffeine ingestion, suggesting that there might be subgroups of patients with PD with caffeine-provoked panic being linked to long-lasting anxiety symptoms lasting hours (Nardi et al., 2007 ).

Hallucinations

Caffeine users that consume caffeine approximate to seven cups of instant coffee (>300 mg caffeine) a day are more likely to report hallucinatory experiences such as seeing things that are not there and hearing voices, when compared to low-level caffeine users that consume caffeine equivalent to one to three cups of coffee a day (Jones and Fernyhough, 2009 ). Researchers indicate that the hallucinatory experiences may be due to caffeine intensifying the physiological effects of stress, as cortisol is released during stressful periods when people have recently taken in caffeine (Lovallo et al., 2006 ), this additional upsurge of cortisol may link caffeine consumption with a higher tendency to hallucinate (Jones and Fernyhough, 2009 ). Caffeine use can lead to caffeine-intoxication, symptoms of which are nervousness, irritability, anxiety, muscle-twitching, insomnia, headaches, palpitations (Jones and Fernyhough, 2009 ).

Caffeine dependence

Ninety-eight percent of North America consumes some form of caffeine, making it the most widely used drug on that continent (Jones and Fernyhough, 2009 ). Many caffeine consumers proclaim that they are addicted to the substance, however the evidence is inconsistent. Table ​ Table2 2 lists the DSM-IV Criteria for evaluating substance dependency (American Psychiatric Association, 2000 ; Dews et al., 2002 ). Users must meet a minimum of three criteria to be considered dependent on a substance. However, with caffeine, complications arise in the grading of the criteria as the effects of caffeine are highly variable across consumers and because the use of caffeine is socially acceptable. Entire afternoons are planned around coffee dates and many social rituals revolve around the drink.

The DSM-IV criteria for evaluating substance dependence (American Psychiatric Association, 2000 ; Dews et al., 2002 ) .

Using the DSM criteria it was reported that 11% of 6778 daily caffeine users evaluated proclaimed to experience withdrawal symptoms (American Psychiatric Association, 2000 ; Dews et al., 2002 ). Controversy arose when the withdrawal symptoms were reported to be mild to moderately bearable and diminishing over a short period of time, therefore reducing the intensity of withdrawal symptoms (Dews et al., 2002 ; Jones and Fernyhough, 2008 ). According to Keast and Riddell ( 2007 ) only the minority of the caffeine users are actually dependent on caffeine. The debate about the possible addictive strength of caffeine remains unsettled, but caffeine withdrawal has been linked with feelings of fatigue, increased depression, and anxiety (Smith, 2002 ).

In summary, the most salient effects of caffeine can be summarized as follows.

Most people consume caffeine to compensate for a lack of sleep, to complete tiring tasks, or to ease stress. Caffeine products are ubiquitously used for these reasons and more yet, Table ​ Table3 3 indicates that the disadvantages of caffeine are more clearly documented than the advantages. The health benefits from caffeine are increased arousal and facilitating against stress in the human body. These benefits are important in maintaining safety and efficacy in the workplace and other environments. To derive an increase in arousal could lead to individuals over consuming caffeine drinks, this over consumption could then bring about some of the disadvantages such as anxiety and panic attacks (when doses more than 300 mg caffeine are ingested) or cause individuals to hallucinate (again when doses more than 300 mg are ingested). It was noted that when individuals are stressed, their caffeine intake increases and caffeine lead to a sensitization of the cannabinoid receptors to help alleviate stress. Despite this benefit, it could create a larger predicament by causing individuals to become dependent on the substance or exemplifying this by becoming dependent on other drugs. Morphine, heroin, cocaine, and ethanol also cause enhancement of the cannabinoid receptors and caffeine has additive properties (like cocaine). Furthermore it reinforces the cocaine-seeking behavior strengthening the dependence potential of caffeine. While caffeine may be used to increase arousal, in contrast it causes impairment in learning by congesting replay of memories and impairing motor skills with a moderate dose of caffeine.

Summary of some effects of caffeine on humans .

It appears that the most significant benefits derived from caffeine involve increased alertness. Further benefits are generally only derived from high dosages of caffeine. However, such doses cause harmful effects on neurophysiological health, with the exception of the effects on cardiac conditions which are experienced even at low to moderate doses of caffeine.

One of the most important current caffeine concerns involves energy drinks. There has been a vast increase in energy drink consumption in young adults aged 18–24 years (Côté, 2009 ). These energy drinks are not to be confused with sports drinks as they contain high amounts of caffeine and taurine and do not hydrate the body. In 2006 Thailand had the leading energy drink consumption per person but the United States reported the highest sales of energy drinks (Reissig et al., 2009 ). The energy drink industry has grown exponentially with almost 500 brands launched internationally in 2006.

The drinks differ rather dramatically in caffeine content (Reissig et al., 2009 ). From Table ​ Table4 4 it is clear that levels of caffeine in these drinks are very high. These drinks are sold without age restrictions and the majority of these drinks do not have a warning label advising the consumer on the caffeine content and the potential health risks (Reissig et al., 2009 ).

Energy drinks in the United States (Reissig et al., 2009 ) .

* Sold in South Africa .

Aside from the possible addictive potential of caffeine, caffeine intoxication is a recognized syndrome (Reissig et al., 2009 ). The high caffeine content in energy drinks increases the risk for caffeine overdose, so awareness of this is required (Reissig et al., 2009 ). Unfortunately though, there is no regulation of the marketing of energy drinks targeted at the young adults. This is surprising, given that pharmacological and epidemiological studies show an association between caffeine use, dependence on alcohol, nicotine, and drugs such as cocaine, morphine, and heroin because caffeine shares features with these commonly studied drugs (Reissig et al., 2009 ; Dack and Reed, 2009 ).

There is also increased popularization of combined use of alcoholic beverages and energy drinks. This may seem harmless, given that some reports suggest that energy drinks could decrease the intensity of the depressant effects of ethanol (Ferreira et al., 2004 ). In the study by Ferreira et al. ( 2004 ) ethanol in doses of 0.5, 1.0, 1.5, and 2.5 g/kg was combined with a well-known energy drink and administered to mice. The results are found in Table ​ Table5 5 .

Effects of the energy drink combined with ethanol administered (Ferreira et al., 2004 ) .

The data obtained suggests that energy drinks did antagonize the depressant effect of ethanol in the locomotor activity of mice but only at high does of ethanol. Considering that mice have a much faster metabolism than humans, the alterations of the levels of locomotor activity in mice cannot simply be interpreted as a reversion of the symptoms of acute effects of alcohol (Ferreira et al., 2004 ). Furthermore, the combination of energy drinks and alcohol reduces participants’ perceptions of impairment of motor co-ordination but does not decrease objective measures of alcohol-induced impairment of motor co-ordination, reaction time, or breathe alcohol concentration. This may increase the possibility of alcohol-related injury and motor accidents as the individuals may feel that the energy drink has antagonized the effects of alcohol while their co-ordination and judgment are still impaired (Reissig et al., 2009 ).

The massive popularity of caffeine has created a need to discover the possible inflictions on the human body. By delving into the biochemical characteristics of caffeine, findings on its structure and chemical properties have led to findings on its function, absorption in the body and metabolism. The neurophysiological benefits of caffeine are brief and ironically could lead to health disadvantages. Therefore in order to obtain the benefits consumption should be limited to moderate doses. The neurophysiological health disadvantages of caffeine include anxiety and panic attacks and hallucinations brought about by above moderate doses of caffeine. In addition to this caffeine may impair learning and memory. However, most alarming is the similarity of caffeine to other drugs such as morphine, heroin, ethanol, and most importantly to cocaine. Caffeine shows the most similarity to cocaine and reinforces cocaine-seeking behavior after elimination of the drug. This finding strengthens the argument that the potential of caffeine dependence is high and awareness of this should be created.

Regarding caffeine in energy drinks, a number of questions arise out of this review. For example, should such aggressive marketing be allowed for a substance that serves as a portal to other forms of drug dependence? With energy drinks decreasing the perceived depressant effects of alcohol individuals may consume more alcohol and therefore jeopardize their perception and hence safety. Given the neurophysiological implication of caffeine use, advertising and marketing of energy drinks and caffeinated soft drinks should be considered. Research on caffeine in South Africa is very limited and considering the potential negative health impacts of this drug further research to focusing on the negative health impacts of moderate caffeine consumption is needed. In the mean time, awareness on its potential health consequences, caffeine intoxication, withdrawal, and dependence should be mandatory.

Conflict of Interest Statement

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

1 http://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/FoodAdditiveListings/ucm091048.htm [accessed August 31, 2011]

2 http://sun025.sun.ac.za/portal/page/portal/Health_Sciences/English/Centres%20and%20Institutions/Nicus/NutritionFactssheets/Beverage%20Consumption.pdf-beverageconsumption [accessed August 31, 2011]

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It’s worth a shot.

Dallas-based flight attendant Cher Killough is sharing the “king” and “queen” behavior she loves to see on a flight, including one move that might score you a free drink .

She enjoys it when passengers properly store their luggage , when they check the lavatory signs before trying to enter the bathroom, and when they read the safety information card before take-off.

“No. 1 is knowing which way to put your bag into the overhead bin,” Killough, a five-year flight attendant, said in a TikTok last month that has skyrocketed with more than 329,000 views.

“Bags always go wheels in first or wheels in last unless you’re on a tiny airplane,” she continued, as she showed pics of overhead bins while noting there are exceptions to these rules. “If the bins are like this, where the flight attendant has to pull it down to close it, your bag is going to lay flat. … If the bin is like this, where the flight attendant has to push it up to close it, your bags are going to go on their side like this.”

@cherdallas where are my kweenies and kingz #flightattendantlife #falife✈️ #flying #flights #flightattendants #traveloutfit #aviationdaily #falifestyle✈️ #flightreacts #flightattendant #stewardess #flight #flightattendanttraining #flightattendantannouncement #flighthouse #traveltiktok #traveltips #airplanemode #airplane #boeing #airbus #boeing737 ♬ Kanye West – C10

The second all-star action is checking that the seatbelt sign is off and the lavatory light is green before trying to enter the plane’s bathroom .

“[If] the seatbelt sign’s off, now you’re going to look up and you’re going to check, is this light over here green? Green means go and red means occupied,” Killough explained as she showed a lavatory light. “Red means you’re going to be standing with your butt in my face while I’m trying to sit on my jump seat. So please, if you want to be a king or queen, wait until [this light is] green.”

And finally, Killough wishes more passengers paid attention during the safety demonstration — doing so could land you a free drink.

“I don’t care if it’s just for show — if you pull out the safety information card while I’m doing the safety demo, I feel so heard and validated that I am very likely to offer you a free drink,” Killough divulged. “Very few people do it, and that is supreme king and queen energy.”

In the comments section, TikTokers thanked Killough for putting these tips on their radar.

“I don’t pull the safety card, but I remove my headphones and pretend that I have never seen a seatbelt before,” one bragged.

“Ultimate king behavior,” Killough declared.

“Am I crazy, or are more and more flights these days never [turning] the seatbelt sign off,” another TikToker wondered.

“I’ve never understood why people line up at the lav. Good tip on the card. Consider it done!” a third vowed.

In recent months, Killough has also revealed three things never to do on planes and her assumptions about you from the shoes you wear on a flight.

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