Energy Drink Safety from 3 Different Food Science Lenses [YouTube]

How can we talk about the safety of energy drinks in the context of food science? How do Food Packaging, Food Chemistry, and Food Microbiology all impact the safety of a caffeinated beverage?
The following is a presentation given by GreenEyedGuide for the Food Science and Consumer Studies department at California State University – Long Beach in March 2018.

FULL TRANSCRIPT

[1] Hello everyone and thank you so much for having me today. Who here likes coffee? Who here likes prizes? Great, because today I’m talking about caffeine in general. Statistically, only 10% of you in here are energy drink consumers, most of you like coffee. So even if you don’t like energy drinks, I encourage you to think of questions and play along with the pop quizzes I have in here, because if you do, you’ll get a prize. Even if you guess wrong, you’ll get a prize. Even if people laugh at your question or you ask a question other people know the answer to, you’ll get a prize. Why? Because we’re scientists, and science is nothing if not the pursuit of questions, right? And if you don’t want to ask your question out loud, you can write your question anonymously on one of these sheets of paper and I’ll answer it that way – but no prize for you.

Okay, here we go!

[2] Think of the last time you woke up EXHAUSTED. Any new parents in here, perhaps? Any Ph.D. students? Regardless, we’ve all had those days. Your alarm goes off, you start moving around and you feel it. In your eyes, all over your body – you’re exhausted! And right then and there, part of you knows that this day is going to be awful because your day is just getting started.

This was my life throughout high school.

I was a straight-A student with all honors and advanced placement classes. I did gymnastics 20 hours a week and competed nation-wide. I helped my mom (a single working mom) take care of my 3 siblings. I constantly got 5 hours of sleep or less and fell asleep in class.

That doesn’t sound THAT special, we all struggle to balance our commitments in life, but at that time, when I was in high school, Starbucks didn’t exist. Energy drinks didn’t exist. Coffee wasn’t cool, it was for old people like college students. If you wanted caffeine you drank Mountain Dew.

A wondrous thing happened when I decided to mashup my love for nutrition and chemistry and became a Biochem major – that was the same year Monster Energy was invented. Anyone know what year that was? (I’m revealing my age but I don’t care) While people everywhere were asking questions and trying these new “energy drink” things, I was learning about the ingredients and what they do in my classes. I was fascinated from the very beginning, and I’ve never stopped studying them.

[3] The reason I find energy drinks so fascinating is that they are not one product, like studying coffee, or tea or milk – caffeinated beverages lie on a spectrum. When people talk about energy drinks, they’re usually talking about a very narrow band on this spectrum which creates a few complications. And when I say complications, I mean – things I get to geek out over:

1)How do you create an effective energy drink ban when this Starbucks Doubleshot has the same main ingredients as the wannabe coffees from Rockstar and Monster?

2)How do we use reports of hospitalizations involving energy drinks if we don’t know what brand of energy drink?

3)How can we as food scientists come up with a caffeinated beverage for people who don’t like the taste of plain coffee or tea and want a portable ready to drink source of caffeine that isn’t going to kill them?

[4] The Science of Energy Drinks is a pretty broad topic, and I could talk for hours. I could, and I have written a book about energy drinks because I have so much to say. But let’s narrow our focus to some of the IFT Core Sciences. Where are my future packaging engineers in here? Let’s start with caffeine safety and food packaging.

[5] I’m going to ask you for permission to combine packaging with serving size and servings per container. This isn’t really the same as food packaging and food grade films, etc., but for the moment, let’s talk about how food is packaged when we say “food packaging”.

Here we have a jumbo muffin, multivitamins that look like candy, a bottle of Patron, and a steak. At what point does the packaging change whether or not something is healthy? What happens when a muffin is packaged in a way where the consumer is going to eat the whole thing and it turns out that one muffin was 6 servings? What happens when a vitamin looks so good and has cartoons on the bottle so that a kid wants to eat a whole bunch of them?

[6] This same question applies to caffeinated drinks too. At what point does the way something is packaged affect its safety? To answer that, we need to know more about caffeine consumption.

[7] POP QUIZ!!!

Does anyone want to guess how much caffeine you’re allowed to have a day if you’re under 18?

The American Academy of Pediatrics says those under 18 should avoid caffeine but since it’s in chocolate and soda, they should not consume more than 100 milligrams of caffeine a day.

Does anyone want to guess how much caffeine you can have per day if you’re a healthy adult? Several organizations, including Health Canada, the EFSA, and the FDA agree 400 milligrams is the max.

So right away we see the caffeine crisis in America isn’t as bad as one might think. We’re actually don’t ok – I’m sure there are some people who are outliers, but as a population in general, we’re doing okay.

This graph is the most accurate representation we have for Caffeine Consumption, from any source, excluding medication, in the US.

This figure comes from a study published in 2012. When I read it, I loved it so much, I wrote an email to the author. She wrote me back – it was awesome.

In this study, they surveyed ~42,000 people from all age groups and demographics. They made sure their sample was representative of the US population. They asked people how much caffeine they consumed, and they did something no other study has ever done before or since.

When I read research articles about “Caffeine in the Military” they ask how many energy drinks did you consume. They don’t ask which ones, they don’t distinguish sports beverage from energy shot from coffee or tea.

In this study, they got specific. They got the specific brands and flavors of energy drinks, coffee, tea, energy shots, sports beverages, chocolate beverages. Then they used the Caffeine Informer database to calculate exactly how much caffeine was in that brand, that size, that flavor.

[8] If you have time, I highly recommend reading this paper – it gets so much better. They broke down how much caffeine each age group consumes a day, right, that’s what we saw on the last slide, but they also broke down how much caffeine comes from where. We can look at the biggest sources of caffeine for each age group, and how people change their caffeine habits over time.

[9] For example, here’s a look at how caffeine habits change from teen years to college years. For college-age people, soda is still the #1 contributor. And tea is still #2! But look at how much coffee has grown.

Energy drinks are still in last place! And these two age groups have the highest energy drink consumption across the whole age range. It never gets better (or worse?) than 10% of the age group.

[10] But back to our point here about caffeine and packaging – when we talk about caffeine safety, we absolutely have to talk about serving size, servings per container, and Volumetrics, or energy density.

Here, by energy, I don’t mean the fuzzy “energy = lack of fatigue” terms we use to talk about energy drinks, and I’m not talking about physiological energy as ATP. Volumetrics normally means the number of Calories in a given unit. So here we’re talking about caffeine per oz.

Now that you know a healthy adult can only have 400 mg caffeine per day, you know that concentrated forms of caffeine can be inherently more dangerous. Take this Redline and this giant Monster can (technically 4 servings per container). If you’re the kind of person that has trouble nursing your caffeine, then the Redline is going to be inherently more dangerous than this big giant can.

With a hot coffee, it has built-in speed control. You can’t shotgun a coffee, that’s not how coffee works. Also, it’s usually too hot or too iced to chug. Since there’s physically more fluid, you have more time for that caffeine to kick in before you finish the whole thing. This is why I don’t like energy shots. If you’ve never had a shot before and don’t know your limits, you could take the shot, think, “Hmmm, I don’t feel it, I should take another one”…and then by the time the caffeine kicks in, it’s too late.

These are things we have to consider when we talk about caffeine safety.

[11] Let’s look at another IFT Core Science. Where are my future food chemists? This was my specialty – as a Biochem major, I learned a lot about how ingredients react in the body. I know how ingredients affect metabolism like fatty acid oxidation, glycolysis, etc. Sometimes this is too much biochem for some of my fellow food scientists, so for today, let’s talk about chemistry as in the reactions that happen in the food.

[12] When it comes to Food Chemistry and caffeine safety, the big question is this – when do safe ingredients become unsafe when combined? In other words, what is it about Monster that makes it more dangerous than a cup of coffee? What about if we compare it to this V8+Energy? What about this Starbucks drink that has added stereotypical energy drink ingredients such as taurine, guarana, and ginseng? How do we know where to draw that line and say a caffeinated beverage is not safe?

[13] Hey look, another pop quiz!

Assuming you drank the whole container, which drink has the most caffeine?

Surprising, right? The Starbucks coffee has way more than the Monster, and Also surprising that this juice-looking Bai drink has about the same amount of caffeine as Red Bull. If you want to ban energy drinks, how do you handle products like this V8?

The reason I’m showing you these amounts is there are two conflicting proposals:

1)Energy drinks are dangerous because of the high amounts of caffeine;

2)Energy drinks are more dangerous than coffee because of ingredient interactions.

It looks like the first theory (the high amounts of caffeine) isn’t inherently true. Anytime there’s a news article about energy drinks, what brands do they show? Red Bull, Monster, and Rockstar – the big three. But we can see Red Bull is “weak sauce” compared to Monster and this coffee.

What about the second theory, the one about ingredient interactions?

[14]. Do Ingredient Interactions make energy drinks more dangerous than coffee? Yes, for three reasons:

1)Energy drinks are sometimes combined with alcohol, which has led to dangerous and high levels of blood alcohol contents. Normally, when you’ve had too much to drink, you pass out. Your body literally prevents you from drinking more alcohol by putting you to sleep. But what if you didn’t fall asleep? Then you’d stay awake long enough to drink that much more alcohol.

2)This isn’t really an ingredient interaction but energy drinks can contain multiple sources of caffeine: caffeine, guarana, yerba mate, guayusa, green tea extract… These different forms of caffeine aren’t interacting with each other, but they are all increasing the total amount of caffeine you are consuming, and that’s the dangerous part – the total caffeine consumption. When energy drinks first came out, they were not disclosing the total amount of caffeine from all sources. Red Bull paved the way for this labeling, and other energy drinks (though still not all of them) follow suit.

3)Getting caffeine from a carbonated source it will feel stronger than if you got the same amount of caffeine without the carbonation. You know how people get tipsy faster off champagne than beer? The bubbles irritate the stomach lining slightly, and caffeine and alcohol are two substances which are absorbed in the stomach – everything else has to wait till it gets to the small intestine.

By a show of hands, did anyone feel like something is missing from this list? Among the reasons I mentioned why energy drinks ARE more dangerous, I did not mention heart arrthymias.

[15] Last year, a teen in South Carolina died from a caffeine overdose. Among the things he drank that day:

  • Mountain Dew
  • McDonald’s latte
  • Undisclosed energy drink

The energy drink was the last thing he consumed. We don’t know how much caffeine was in that drink, or what other ingredients were in it. Which means we can’t talk about ingredient interactions. We’re missing some critical data, but several news articles that reported his death referred to this article published in the Journal of the American Heart Association. According to the press, this research article found, “energy drink consumers could be at higher risk of abnormal heart beats and dangerous changes in blood pressure.”

Unfortunately, the scientists who wrote this paper would disagree with that statement.

[16] This study was randomized, double-blind, placebo-controlled, but they only used 18 people in their mid-20s. That’s not a big sample size, but the other big problem is that they used 320 mg caffeine. The EFSA says you can have how much per day? (400 mg), and only 200 mg at a time. So this is more caffeine than you’re supposed to have at a time.

In this study, there was no difference in heart rate or blood pressure between the two groups at any time. The did find a small but statistically different change in something called a QTc, but even the authors are saying this shouldn’t be alarming and that the risk may be negligible.

Where does that leave us in our big question on ingredient interactions?

[17]. Do Ingredient Interactions make energy drinks more dangerous than coffee? No, for three reasons:

1.A review of multiple studies on the effects of caffeine on heart arrhythmias found moderate caffeine is okay for people with heart arrhythmias. There is no scientific evidence that caffeine causes heart arrhythmias in those with a healthy heart. Nor is there any evidence that drinking caffeinated beverages long-term will cause an arrhythmia to develop. However, some people could be unaware that they have an arrhythmia or that they are prone to developing one based on their genetics, which is why caffeine should always be consumed in moderation.

  1. The EFSA determined it’s unlikely there is any interaction between caffeine, taurine, and glucuronolactone.
  1. Many energy drinks feature caffeine, B-vitamins, and a bunch of other ingredients which aren’t in large enough doses to do anything, physiologically.

[18] When it comes to food chemistry and caffeine safety, at this point, we have more evidence that there are NO interactions in energy drinks than evidence to the contrary. This question may be impossible to answer as new energy drinks come out with different combinations of ingredients. In order to challenge or improve our understanding of ingredient interactions, we shouldn’t talk about people who get sick from energy drinks without talking about the total caffeine content or the other ingredients present.

[19] Let’s talk about one more IFT Core Science before we wrap up. Are there any future food microbiologists in here?

[20] Food Micro was never my favorite part of food science. I know enough to geek out when the CDC publishes their report on foodborne illness outbreaks, and when food has been in the “temperature danger zone” too long… but I still struggle with which food preservatives inhibit yeast and mold or what to use when the water activity and pH are high enough for your drink to become a hospitable environment for undesirable microbes.

But there are two things I can tell you two things that you should remember:

1)I’ve been on the Quality Audit team for almost 5 years – it was my job to review specifications of ingredients suppliers, review audit reports, review food micro testing regimens and HACCP plans and flow charts and testing results and use all that information to complete a risk assessment for that ingredient. I’ve seen things that scare me. I’ve read audit reports that make me glad I didn’t have time to eat lunch. I’ve talked to ingredient suppliers who clearly have no idea what they’re doing, and some who are even reluctant to test because “this is what we’ve always done”.

2)Red Bull has been more transparent than any other energy drink brand in opening up their facility and inviting inspections of their manufacturing and advertising practices. I trust Red Bull’s manufacturing more than Monster or Rockstar and WAY more than some of the “natural energy” drinks I see that are only sold online.

With all supplements, in fact, with all online food and supplements, I encourage consumers to look for red flags, to exercise caution. Natural doesn’t always mean safe.

[21] If I had to boil down all my research, all my thoughts about caffeinated beverages, it would come down to two phrases:

1)Not All Energy Drinks – There are SO many caffeine-containing drinks out there that look nothing like their energy drink forefathers. Generalizing energy drinks is like calling sandals, Uggs, and stilettos all “shoes”. Some of them are functional and convenient, some of them are all looks no function, some will hurt you the moment you try them if you don’t know what you’re in for

2)The best way to approach caffeine safety is through the 5 Levels of Fatigue

[22] With this system I have helped bartenders cut back from 4 Monsters a day to half a can a day. I have helped my family, friends, and strangers on the internet avoid caffeine toxicity, dependence, and tolerance.

Here’s how it works:

[23] At Fatigue Level 0, you need no caffeine – you’re feeling great, awake, alert, alive. Maybe you just aced a final. Maybe that person you’ve been crushing on smiled at you. Maybe your favorite team just made the playoffs. This is your baseline.

[24] Fatigue Level 1. Dehydration causes fatigue. If you’re feeling tired, whether it’s 5 in the morning or 3 in the afternoon, your first task is to drink water.

It doesn’t have to be plain water. Put some cucumbers in it, get carbonated water, add regular MIO, whatever, just don’t reach for caffeine. Not yet.

[25] Fatigue Level 2. At this point, you have ruled out dehydration. Time to get some help. There are plenty of energy drinks with less than 100 mg per container, and with caffeine from a natural source. Here are some of my favorite examples.

For best results, you’re looking for something with natural caffeine, something NON-carbonated, and something with no sugar. You can put plain black coffee in this level, just watch your serving size (think small/tall, not Grande).

Carbonation and sugar do not belong in Fatigue Level 2.

[26] Fatigue Level 3. Struggle City, population = you.

For best results, do not exceed 200 mg. That’s the limit for a single serving anyways.

You STILL don’t want anything carbonated – not yet.

Instead of carbonation, look for something with at least some juice content. That juice should give you a teeny bit of sugar, and drinks with juice are almost never carbonated. We don’t want carbonation yet.

[27] Fatigue Level 4. out of 5. This is it. This is “Fall Asleep Standing” mode. This is “need to pull an all-nighter” or double-shift time.

Do. Not. Consume Fatigue Level 4 on a daily basis. Why? Because this is for emergencies only. What would happen if you had a fire drill at your school or work every day? You’d start ignoring it. And so it goes if you have this much caffeine every day. If you want the caffeine to work, you must not consume this caffeine on a regular basis.

Because it’s an emergency, it’s okay to go above the 200 mg – at – a time limit. This is also the point where we introduce carbonation. Why? Caffeine gets in through the stomach, and when there’s carbonation involved, it gets in that much easier.

So if you had two energy drinks, each with 100 mg caffeine – the carbonated one is going to feel stronger. This is why the 5 levels of fatigue is a scale. There are incremental increases based on ingredients like sugar and caffeine.

[28] Level 5 is sleep. There comes a point where no amount of caffeine can save you. There comes a point where you must give in and get some rest. When you hear stories about people who can drink coffee right before bed or fall asleep while drinking an energy drink, either they have a genetic polymorphism where they can metabolize caffeine so quickly that it doesn’t affect them, OR it’s because they have reached their limit. It’s extremely difficult to ask for help, to accept our limitations. But if we’re going to stay healthy, we have to acknowledge when we reach that point.

[29] I am on a quest to learn as much as I can to help me answer the question, “Are energy drinks safe?” If you would like to learn more about some of the caffeinated drinks I’ve mentioned today, some of the research I’ve cited my book, a particular ingredient, please save this page in your favorites and let’s connect on social media.

[30] Thank you all. Who has questions?

 

Is V8 Really an Energy Drink? A Primer on the Science of Energy Drinks in Disguise [GreenEyedGuide on ScienceMeetsFood]

In this article I wrote for ScienceMeetsFood.org, I address the problem behind the term “energy drink” and the science behind energy drinks in disguise. (There’s also a Guardians of the Galaxy metaphor!) It’s a great primer if you’ve never heard the term “energy drink in disguise”, or if you never realized that V8 and Ocean Spray make energy drinks. Read this article in its entirety at ScienceMeetsFood.org

“I’ve been studying energy drinks since 2003 and they continue to both fascinate and horrify me. They fascinate me because I’m a biochemistry major, or maybe it’s the other way around. Energy drinks are the reason I pursued my masters in food science (and the reason I survived grad school). Metabolic biochemistry is the closest I’ll ever come to engineering – for me, studying biochemistry is studying the secret rules to how things work.

Energy drinks horrify me because it feels like people with no science background are behind some of the products you can buy online. Sometimes I’ll read a label and think, “What are they doing? Who thought this was a good idea?” The most concerning aspect of energy drinks is we don’t have a proper nomenclature to classify them properly. (#WhatWouldIUPACDo?) Using the term “energy drink” the way we do is like calling pure ethanol “booze”. Let’s talk about why the lack of classification is a problem.

Is V8 Really Energy Drink
Read this on ScienceMeetsFood

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Energy Drink of the Month – May 2017: Zevia Zero Calorie Energy

Sometimes we just want life to be simple. In high school, life was not simple, but at least my schedule was predictable. Each hour was dedicated to a specific subject; a chiming bell was enough to break my To Do list into neat little blocks of time. With graduation season upon us, many will leave their predictable schedules and somewhat-organized world for the unpredictable chaos that comes with adulthood. As a tribute to that unavoidable complexity, this month we review (yet another) energy drink with clean, simple ingredients. If you’re familiar with my mission on GreenEyedGuide.com, you know I love nothing more than busting the energy drink stereotype.

This month’s pick is another “energy drink in disguise” that doesn’t fit the water, juice, tea, or soda category. With 120 milligrams of caffeine per can, it’s undeniably an energy drink but also undoubtedly not “a deadly concoction of caffeine and sugar”.  

The Energy Drink of the Month for May 2017 is Zevia Zero Calorie Energy.  

20170311_145122
Zevia’s new energy drink line

At the time of this post, there were four flavors available: Grapefruit, Kola, Mango/Ginger, and Raspberry/Lime. They all have 120 milligrams of caffeine per can, zero Calories, zero grams of sugar, zero vitamins, zero preservatives (not counting the acids), and nearly identical ingredient lists. As you might’ve guessed from our other Energy Drink of the Month winners, I’m a berry person, so my favorite is Raspberry/Lime.

20170311_145146
Zevia energy facts panels

Key Ingredients 

Carbonated Water

We’ve talked about carbonation many times before, so here’s some refreshing (pun!) insight from Popular Science’s article on why humans like fizzy drinks

“Chemically, adding CO2 to water creates carbonic acid, which is tasted by sour-sensing taste cells. Research has suggested that a certain enzyme, carbonic anhydrase, sits on those cells and reacts with the acid to cause carbonated water’s familiar popping sensation. (Fun fact: climbers who take altitude-sickness drugs that block the enzyme, then drink champagne, report the bubbly as having a dishwater-y taste.”

Citric Acid and Tartaric Acid

The Kola flavored Zevia Zero Calorie Energy has tartaric acid and citric acid, whereas the other three just have citric acid. This excellent infographic from our friends at Compound Interest explains the science behind these two popular acids.

 

Compound Interest Acids
http://www.compoundchem.com/2016/02/25/a-guide-to-common-fruit-acids/

 

Stevia Leaf Extract

Finding a high-quality stevia extract is no simple task. Oh sure, we know what molecule is responsible for the sweetness, but isolating that molecule and delivering it is far more complicated than producing table sugar. Sugar is sugar is sugar, right? But water doesn’t always taste the same, even if it’s just water. The same goes for Stevia. In fact, tasting Stevia samples was one of the tasks I dreaded most while I worked as a product developer for a major supplement company. One bad sample, and you’d be experiencing a bitter metallic aftertaste the rest of the day (or week: See “A Food Science Horror Story”).

It turns out that some people are Stevia Super Tasters so they will get a bitter metallic aftertaste with Stevia when many others would taste only sweetness. This bitter metallic aftertaste is why stevia is often paired with another natural sweetener, erythritol.

Caffeine Comparison 

The top three best-selling energy drink brands are Red Bull (80 mg caffeine per 8 oz can; 114 mg caffeine per 12 oz can), Monster Energy (160 mg caffeine per 16 oz can), and Rockstar Energy (240 mg caffeine per can, most flavors). Since Zevia Zero Calorie Energy is an “energy drink in disguise” that breaks the energy drink stereotype, it makes more sense to compare its caffeine content to similar products, other healthy alternatives.  Below are the caffeine contents listed in the Caffeine Informer database:

When to Consume = Fatigue Level 3 

When it comes to caffeine content, 200 and 400 are special numbers. Quoting from the “Scientific Opinion on the safety of caffeine” from the European Food Safety Authority:

“Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies was asked to deliver a scientific opinion on the safety of caffeine, providing advice on caffeine intakes, from all dietary sources that do not give rise to concerns about adverse health effects for the general healthy population and subgroups thereof. Possible interactions between caffeine and other constituents of so-called “energy drinks”, alcohol, p-synephrine and physical exercise should also be addressed. Single doses of caffeine up to 200 mg (about 3 mg/kg bw for a 70-kg adult) do not give rise to safety concerns. The same amount does not give rise to safety concerns when consumed < 2 hours prior to intense physical exercise under normal environmental conditions. … Habitual caffeine consumption up to 400 mg per day does not give rise to safety concerns for non-pregnant adults…” 

The 5 Levels of Fatigue is a system I developed during my years of researching energy drinks. The 5 Levels of Fatigue helps people find the product most appropriate for how tired they are, thus minimizing caffeine dependence, toxicity, and tolerance. Anything with more than 200 milligrams caffeine should be saved for more dire energy emergencies like Fatigue Level 4. A product with 100-200 mg caffeine belongs with Fatigue Level 3. Since this product has 125 milligrams of caffeine per can, this product fits Fatigue Level 3. It is a carbonated product, which usually means the caffeine would feel stronger than a non-carbonated equivalent like the caffeinated (still) water from Avitae due to carbonation’s effects on the stomach.

Bottom Line 

If you are looking for a strong, sugar-free, artificial-free carbonated energy drink Zevia is a great option. You don’t have to fret about “the dangerous of energy drinks” with this product. Zevia Zero Calorie Energy is simple. Life is complex enough.

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Review the entire ENERGY DRINK OF THE MONTH SERIES

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GreenEyedGuide Caffeine Challenge Day 4/10 – How Caffeine Saves Lives

March is Caffeine Awareness Month! For Day 4 of the GreenEyedGuide Caffeine Challenge, we talk about how caffeine can SAVE LIVES!

One of the most important reasons to use the 5 Levels of Fatigue is so you don’t build up a tolerance, so caffeine will still work for you when you need it the most! It’s also important to remember that the 5th Level of Fatigue is Zombieland, in other words, that point at which there is no amount of caffeine that can save you. At that point, only sleep will help.

Learn more about the 5 Levels of Fatigue here

***PLAY ALONG – post a picture or your story about how caffeine has saved lives on Instagram/Facebook/Twitter and tag @GreenEyedGuide, or on the Caffeine Challenge Event page at Facebook.com/GreenEyedGuide/events

Through this challenge, you’ll learn how to use the 5 Levels of Fatigue to reap the benefits of caffeine while avoiding addiction, dependence, tolerance, and toxicity.

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