Help Make GreenEyedGuide Even Better – Your Feedback Needed!

As 2017 draws to a close, my head has started spinning with all the exciting plans, news, and events which will become reality in 2018. If you are part of the 90% of the US population which consumes caffeine on a daily basis, I encourage you to take the survey below. This survey will help shape the future of GreenEyedGuide as I enter my 5th year of

When I started this blog in September 2013, only 69 people visited my site that whole month.  Now it’s nearly 10,000 per month. I want it to be 50,000, but I need your help. How can I make this site better? How can I better serve you, the caffeine consumer? 

Click this link to navigate to the End of Year Survey (you’ll only need 3 minutes, max, to complete)

EOY Survey 2017

Thank you in advance for your time, and remember…

For every survey response

Caffeine and College Exams – GreenEyedGuide presents at Cal State Fullerton

The video below includes a portion of GreenEyedGuide’s presentation from California State University-Fullerton, Peer Health University Network meeting. Learn how caffeine content isn’t always what it seems, how consumption changes as people get older and how caffeine helps one focus for exams.



Watch the video above to learn how to become an advocate for safe caffeine consumption

Thank you to Cal State Fullerton’s Peer Health Univerity Network for hosting this presentation!

Related Content:

To contact GreenEyedGuide about speaking at your event, use the contact form below:



Caffeine versus Guarana – Book Excerpt of the Week


When I was doing research for my book, “Are You A Monster or a Rock Star: A Guide to Energy Drinks-How They Work, Why They Work, How to Use Them Safely”, I was disappointed over learning what guarana does.

Book Excerpt of the Week

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Everything guarana can do, caffeine can do better.

Guarana is a natural source of caffeine, and many time getting caffeine from a natural source is preferable. We’ve reviewed a few energy drinks with guarana.

But unlike green tea extract, guarana doesn’t come with its own unique set of benefits.

Stay tuned for next week’s book excerpt as we continue our page-by-page exploration through the Energy Drink Guide (now on Audible!!!).

Get your copy of MY BOOK: “Are You a Monster or a Rock Star: A Guide to Energy Drinks — How They Work, Why They Work, How to Use Them Safely”


Let’s connect!

Energy Drinks in the News – The effects of Alpha-GPC versus caffeine on mood, cognitive function, and performance

Here at, my goal is to share the science behind energy drinks and their ingredients. In a study published in the Journal of the International Society of Sports Nutrition, caffeine goes head to head against Alpha-GPC in a battle of jitters and performance metrics. Which do you think is going to win?

This article is Open Access (hurray!) but, because it’s a poster presentation, it’s only two-pages long (aww….). Still, let’s dissect the details, shall we?



Is A-GPC vs Caffeine a fair fight?

According to the authors of this study, “Alpha-glycerylphophorylcholine (Alpha-GPC) and caffeine supplementation have been shown to improve mental and physical performance.”

[GEG: shown by whom? how convincingly? in what creature?]

All by itself, Alpha-GPC increases the release of the neurotransmitter acetylcholine. Neurotransmitters are chemicals that affect the ways nerves function.

Book Excerpts

Neurotransmitter 101 – an excerpt from The Energy Drink Guide (written by GreenEyedGuide):

“Speaking of delivering things, a neurotransmitter is a substance that sends a signal to its neighboring cells, prompting a reaction. The neurotransmitter histamine triggers allergic reactions like a runny nose and watery eyes. Serotonin triggers a calming sensation while norepinephrine and epinephrine trigger the “Fight-or-Flight” response in stressful situations. These neurotransmitters and a few others are made from amino acids, all with the help of B6.”


Alpha-GPC supposedly facilitates learning and memory.
So does caffeine. But which one does it better?


What Happened in the Study?

In this study, twenty people got one of four treatments:

  1. Caffeine – 200 mg
  2. Alpha-GPC – 200 mg
  3. Alpha-GPC – 400 mg
  4. Placebo – ???…no helpful details of any kind…

This study was randomized and cross-over, meaning everyone got to try each of the treatments on a different day, in different orders. This study was also double-blind, placebo-controlled, which means neither the scientists nor the participants knew who got what.

When a Research Paper Lets You Down

There are two phrases that burst my bubble of nerdy excitement when I’m reading a scientific study involving caffeine: “…in laboratory rats” and “not statistically significant”.

When an ingredient has promising health benefits….in laboratory rats, it makes me feel like the results are next to meaningless. I get that testing rats can be a precursor to testing people but, in my opinion, there’s too much uncertainty to assume people would see the same benefits.

When results are not statistically significant, half of me wants to stop reading the article. If your numbers are not statistically significant, then it’s all theory and trending assumptions. Yes, sometimes the things that are not “significantly significant” are significant in their importance.

The (Surprising and Disappointing) Results

When the participants had Alpha-GPC, their Serial Subtractions Test scores were ~1 second faster than when they had the caffeine (6.19 + 2.21 s versus 7.32 + 5.67 s). If you’re playing Jeopardy, that could be significant (See what I did there).

When the participants had Alpha-GPC, their Vertical Peak Jump Power was higher than when they had caffeine (2,041.3 + 547.2 W versus 1,920.4 + 689.6 W). Even though these results were depicted in the sole graphic figure in this paper presentation, it’s unclear whether this difference is significant.

When the participants had caffeine, they were more jittery as measured by a Visual Analog Scale for six different moods. Not only was this difference significant, statistically, it’s significant because these people only got 200 mg caffeine. And they were college age people!

  • A healthy adult can have up to 400 mg caffeine per day
  • Most flavors of Monster Energy contain ~160 mg caffeine
  • Some flavors of Rockstar Energy contain ~240 mg caffeine
  • A Starbucks Grande (plain black) coffee contains 330 mg caffeine
  • And 200 mg caffeine led to statistically significant jitters in this study?

What We Don’t Know

  • Whether the participants consume caffeine on a daily basis
  • What dosages of Alpha-GPC have been shown effective (IN PEOPLE)
  • Whether Alpha-GPC does anything meaningful (or “significant”) in terms of memory, mood, or performance (IN PEOPLE)
  • How long people have to take Alpha-GPC before it starts to give them a significant advantage
  • What was in the placebo
  • How the results would have compared if for one round the participants got BOTH Alpha-GPC + Caffeine

What’s Next?

Are you or do you know a grad student studying caffeine? Are you a professor or teacher leading a discussion on energy drinks and their ingredients? Are you looking for a caffeine expert to present to your class or at an event? If so, I want to hear from you!

I’ve studied energy drinks and their ingredients for over 10 years. I am constantly surprised by how many healthy alternatives or “new wave” energy drinks look nothing like their forefathers. I am also surprised how some energy drink rumors just won’t die (e.g., no, taurine does not come from bull sperm). My goal is to guide you, with my green eyes.

Get your copy of MY BOOK: “Are You a Monster or a Rock Star: A Guide to Energy Drinks — How They Work, Why They Work, How to Use Them Safely”


Let’s connect!






Science Behind Xyience Energy Drink

The world of energy drinks is vast, and there isn’t enough time to give every drink the full “Energy Drink of the Month” deep dive review. In my attempt to guide my fans through this world of energy drinks, I like to share the science behind the various caffeinated beverages I come across in my travels.

On a request from one of my fans via Instagram, here is the Science Behind Xyience!

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Caffeine comes from plain caffeine and from guarana seed extract. There’s 176 mg caffeine per can (88 mg per serving and 2 servings per container). According to Caffeine Informer, Xyience used to be 200 mg per can. Either way, it’s Fatigue Level 3.

Key Ingredients

This drink contains B-vitamins, and some stereotypical energy drink ingredients including guarana, glucuronolactone, taurine, ginseng root extract, and inositol.

  • Glucuronolactone might feed one reaction that helps the body generate energy, but glucuronolactone has to go through some small transformations first, and this reaction (the Pentose Phosphate Pathway) isn’t a major reaction, energy wise
  • Taurine is a taxi cab that helps shuttle water-hating fat molecules to the place they need to be metabolized
  • Ginseng is supposed to help with stress but a systematic review of almost 500 studies involving Panax Ginseng found the only benefit was for glucose metabolism in animal models
  • Inositol helps with insomnia…(kind of ironic, right?)
  • B-Vitamins include 100% of niacin (my favorite vitamin), 250% of B6, 80% of B12, and 500% (why?) of Pantothenic Acid
    • Niacin is part of over 200 reactions in the body, most of them involving the production of ENERGY.
    • B6 helps our bodies make those non-essential amino acids and also helps us maintain optimal blood sugar levels.
    • B12 helps our bodies make healthy red blood cells
    • B5 helps with the metabolism of carbs, fat, and protein, but there’s so much of it in every food group no one needs a B5 supplement (in my opinion)

Other Notes

Preservatives in this drink include potassium sorbate, potassium benzoate, and sodium citrate.

  • Potassium sorbate – this anti-microbial preservative prevents yeast and mold growth in sodas and other foods. The Center for Science in the Public Interest (CSPI) rates this as safe. If the CSPI, who has a reputation for fear-mongering and chemophobia, rates this safe, you should definitely feel at ease. [See Panera KNOW-No Project Part IV]
  • Sodium Benzoate – Did you know that benzoate salts like this one prevent the growth of microorganisms like yeast and mold? Benzoate salts are often used with other preservatives especially at low pH (acidic food). People can ingest up to 5mg per kg of body weight of benzoic acid and its salts according to European Commission – Scientific Committee on Food. 
  • Sodium Citrate and Citric Acid – both are abundant naturally in citrus fruits and are used in beverages to help control the pH.

Fruit and vegetable juice is used for color, but this drink has artificial sweeteners Ace-K and Sucralose. But there are only 2 grams of carbs (from the juice, most likely) and zero Calories, zero grams of sugar.

What drink should I review next?

You can find more about the science behind energy drink ingredients here at and within my book, “Are You a Monster or a Rock Star: A Guide to Energy Drinks- How They Work, Why They Work, How to Use Them Safely” on Amazon (and now on Audible!!!).

Let’s connect!