Caffeine versus Green Tea – Book Excerpt of the Week

When I was writing my book, “Are You A Monster or a Rock Star”, it was fun to discover all the ways green tea and caffeine DON’T play nice.


Photo Editor-20171127_165917Yes, there’s caffeine in green tea so you COULD SAY they “coexist”, but sometimes the health benefits of caffeine (by itself) counteract the benefits of green tea (by itself).

For example,  a review of 11 different trials with green tea showed catechins like EGCG significantly decreased body weight and helped people maintain weight loss.

However, the people that normally consumed more than 300 mg of caffeine per day didn’t get as big of an impact with their green tea treatment.

It’s as if caffeine intake interferes with green tea’s weight loss magic!

I’ve also shared a scientific study in which the combo of caffeine and theanine resulted in WORSE performance on cognitive function tests than caffeine alone: See [How do Caffeine Theanine Interactions Affect Mood and Attention?

There are a few ways caffeine and green tea DO work together and some ways people get the benefits of caffeine REGARDLESS of where it comes from. If this interests you, please check out (<- Library Pun) my book: “Are You A Monster or a Rock Star: A Guide to Energy Drinks”. Available on Amazon and Audible.

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”


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Science Behind Dark Dog Organic energy drink – Quick Review

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.

Science Behind Dark Dog Organic energy drink

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Energy Drink of the Month – September 2017: Guru Energy Water

The year I started college, Monster and Rockstar were just hitting US markets. Welcome to September 2017, where Red Bull is older than the people entering college this fall. Whether you’re a student, a parent of school-age kids, or an adult savoring the last days of summer, September can bring changes that drain your energy. It’s a great time to consider a new energy drink, but one that won’t blow your summer body, one that keeps you hydrated and refreshed through the summer heat, and one that isn’t too strong. After all, you want to save those strong energy drinks for finals week and Black Friday shopping. Read more

How do Caffeine Theanine Interactions Affect Mood and Attention? Caffeine/Energy Drinks in the News

We associate caffeine with being hyper and tea with being calm, so what happens when a person has caffeine and theanine together?  I reviewed a paper by the Department of Psychology at Tufts University in which they gave 36 people caffeine, theanine, or both. These participants had to watch disturbing episodes of Band of Brothers to get them all emotional, then take tests to rate their mood and attention. The results indicate just how well theanine and caffeine play together (or against each other).

But first… Materials and Methods

On the day of the experiment, study participants were given one of four treatments:

  1. 200 milligrams caffeine + 200 milligrams theanine = “C + T”
  2. 200 milligrams caffeine + 0 milligrams theanine = “C”
  3. 0 milligrams caffeine + 200 milligrams theanine = “T”
  4. 0 milligrams caffeine + 0 milligrams theanine (placebo control)

Neither the scientists nor the participants knew which treatment they were getting because the caffeine and theanine were given in pill form. This is what’s called a double-blind, repeated-measures design. The way the study went, each participant went through all four treatments on different days. This is important because people react to caffeine in different ways, so you can’t base your experiment results on the assumption that people react to caffeine the same way. Instead, you want to compare how a particular person handled all four different treatments.




When people got the C + T pills, they reported increased tension, depression, anger, confusion, and total mood disturbance compared to the placebo. This result is surprising because it suggests the calming influence of theanine was totally overshadowed by the effects of caffeine. In fact, the only mood profile where theanine made a difference was vigor. For whatever reason, people who took the C+T pills reported feeling less vigor than the people who took the caffeine pills.




Other studies before this one have found caffeine increases our attention on the big picture while theanine increases our attention on the details. This is called global processing bias and local processing bias. Global processing bias means you might pay more attention to the size and shape of a mountain while local processing bias means you might pay more attention to the jagged cliffs and random tree clusters on that mountain.

In this study, the caffeine pills gave the participants a bias toward global attention, and the theanine pills gave the participants a bias toward local attention…just like the other experiments in the past had suggested.

*Scientists high-five! the experiment worked as it was supposed to*


When the participants had the C+T pills, the caffeine and theanine canceled each other out, and the attention bias was no different than placebo!




Imagine you were holding a picture where one medium-sized arrow was pointing left, but it was surrounded by dozens of smaller arrows pointing right. This is a rough description of the Attention Network Test (ANT). The ANT measures a few different types of attention. One of those is called the Executive Control Network Function.

Executive Control Network measures the extent to which incongruent-relative-to-congruent arrows interfere with determination and response.

I wonder if it’s called “Executive Control” because if you were an executive of a company you’d have to ignore lots of bad ideas surrounding one good idea and act upon it quickly…

When participants had the caffeine pills, they showed the best executive control. Having theanine (without caffeine) gave the participants the worst executive control. When participants had T+C pills, caffeine and theanine canceled each other out, and the result was no different than placebo.

Does that mean if you’re an executive or someone who needs to have a strong BS meter, you should avoid theanine…?

Apparently being in an emotional state really makes a difference whether theanine helps or hinders your executive control. In calm situations, theanine can help the same way mindfulness and meditation improve Executive Control scores. However, this was not a calm situation. The participants in this study were all triggered into an emotional state beforehand, and, in this state, the calming effects of theanine can be counterproductive. Theanine in stressful situations is like listening to a slow-dance song while you’re sprinting.



The Limit Does Not Exist - Mean Girls
This is a Mean Girls reference…

All results from this study came from stressful situations. There was no second round of trials where the participants were fed caffeine, theanine, or C+T pills and allowed to sit quietly for their tests.

How great would it be to redo this study and show these same participants episodes of Bob Ross?

Ideally, we could compare the way C+T pills affect people’s moods when they are stressed out and emotional versus when they are calm and happy. But this study only looked at the stressful situation, and other similar studies have only looked at calm situations.




Yes, cheating is bad, but it’s kind of a big deal when one scientist is able to copy another scientist’s experiment AND get the same results. When an experiment is reproducible, it suggests the results of that experiment are not a fluke. This is why scientists talk about what other scientists have done when they’re sharing their own results.

There have been other experiments on the effects of caffeine and theanine on attention and cognitive processes. That’s the good news. The bad news is that they’re inconsistent. Here are some of the findings from other studies:

  • 100 mg caffeine + 46 mg theanine improved attention task switching compared to placebo
  • 40 mg caffeine + 100 mg theanine improved attention task switching compared to placebo
  • 50 mg caffeine + no theanine improved attention task switching compared to placebo
  • 50 mg caffeine + 100 mg theanine reduced errors on sustained attention tasks, but only caffeine reduced response times
  • 150 mg caffeine + 250 mg theanine reduced response times but only caffeine reduced errors

Wait, what? So does theanine really help or is it caffeine doing all the work? Those last two contradict each other! AHHH! How come TV-show scientists never have this problem?

The takeaway message here is that the interactions of caffeine and theanine aren’t always consistent. This study shows that in stressful situations where emotions are running high, theanine is not going to counter the increase in tension, anger, and confusion. Theanine is not going to help you pause the situation, calm down and think. In fact, theanine might make your thinking and reactions worse than if you just had caffeine alone.


What are your thoughts? How do caffeine and theanine combinations affect you?

You can share your comments below or chat me up on Social Media.

Let’s chat!


  1. Caffeine and theanine exert opposite effects on attention under emotional arousal
    Grace E. Giles, Caroline R. Mahoney, Tad T. Brunyé, Holly A. Taylor, Robin B. Kanarek
    Canadian Journal of Physiology and Pharmacology, 2017, 95(1): 93-100,

Read more from the caffeine/energy drinks in the News series – here


Energy Drink of the Month – June 2017: Guru Organic Energy

So many puns… Does your energy come from an Organic source or is it an innate, inherent, organic burst of energy? If Organic Chemistry is the study of carbon-based molecules and coal is combustible compressed carbon matter, can we call coal “organic energy”? Can we call a beverage Organic if it’s carbon-ated? All puns aside (for now), let’s talk about a carbonated energy drink that is certified-Organic.


The Energy Drink of the Month for June 2017 is Guru Organic Energy.

Guru has other energy drinks to offer, but for this month we’ll focus on the original.  As with any energy drink, we need to discuss the WHO, WHAT, and WHEN:

  • Who is this for? What ingredient phobias and preferences does it cater to?
  • What are the key ingredients and what do they do?
  • When should someone drink this, based on caffeine content and the 5 Levels of Fatigue?

Who It’s For: Ingredient Preferences and Phobias

Guru is certified-Organic, gluten free, non-GMO Project Verified, and artificial free. The drink is sweetened with Organic cane syrup and also Organic white grape juice concentrate. In total, there are 30 grams of sugar.

This is an energy drink without the stereotypical energy drink ingredients that strike fear into the hearts (bad pun, #arrthymia) of those that think all energy drinks are more dangerous than coffee.  Guru Organic Energy does not contain taurine, carnitine, glucuronolactone, or any B-vitamins. It does contain guarana though, but we’ll get to that. Don’t panic.

Did you know the word “Organic” has more regulations around it than the words “energy drink”? You can’t use the word “Organic” on the label unless the product meets specific regulations, and that compliance is confirmed through certification. Of course, these regulations are not without flaw and Organic products are not immune to consumer confusion about the implications of the term.



What’s In It: Key Ingredients and Functions

  • Citric Acid and “Apple Acid”
    “Apple acid” is a synonym for malic acid, but perhaps “malic acid” sounds more chemical-y to some people. The genus for apple is Malus, and malic acid is what gives apples their characteristic tart taste. Both citric and malic acids are organic acids that occur naturally in fruits like lemons and apples. Some sugar-free energy drinks get carried away with the use of citric acid because it can provide a tartness that makes up for a lack of sugar. However, too much citric acid can sting the tongue. That’s not a problem for Guru, fortunately.


Compound Interest Acids
Check out the full article for Common Fruit Acids at Compound Interest


  • Green Tea Leaf Extract
    Green Tea Leaf Extract is the predominant source of caffeine in Guru Organic Energy. In addition to the caffeine, green tea extract also provides health benefits in the form of epigallocatechin gallate (EGCG). This mouthful of an antioxidant is one of the reasons green tea is the healthiest beverage on the planet (second only to water).
    The catechin and polyphenol content in this beverage are not claimed, so Guru cannot be called an “antioxidant beverage”. Nonetheless, the more green tea you can get in your diet, the better (the same cannot be said for caffeine, however). The benefits of green tea extract are vast — especially in isolated cells, test tubes, and lab rats. Green tea’s benefits for humans are harder to prove but, to quote from this informative and delightful article by our friends at Compound Interest,

“…the combination of L-Theanine and caffeine can improve speed, performance and accuracy in cognitively demanding tasks – put simply, L-Theanine ‘smooths out’ the stimulating effects of caffeine. – Compound Interest, The Chemistry of Tea

  • Guarana Seed Extract
    Guarana has a lot in common with Snape, oops, I meant Professor Snape. When energy drinks first came out, people were afraid of guarana and claimed it was dangerous and devious. Now it’s an ingredient people are proud of and happy to see.
    Way back in the mid-2000s, (before I started this blog, unfortunately) guarana was considered bad because of the additional caffeine it provided. Drinks that had both caffeine and guarana were thought to be the most dangerous of all because of the cumulative caffeine content. Note, this was before energy drink companies started putting “Caffeine from All Sources” on the labels. With the whole food and artificial free movement, guarana became more acceptable and appreciated because it is a natural source of caffeine
  • Panax Ginseng
    Did you know that not all ginseng offers the same health benefits? Panax ginseng, also called Asian or Korean ginseng, is the good kind. Siberian ginseng doesn’t contain any of the characteristic chemical compounds, called ginsenosides, that make ginseng “Ginseng”. When harvested, ginseng can be dried and bleached to become white ginseng, or steamed and air dried to become red ginseng.
    If you were a lab rat, ginseng might improve memory. With humans, the data is less convincing. Ginseng allegedly helps reduce stress but that’s only when it’s sipped warm or when the root is chewed. How convenient that the act of holding a warm object is also attributed to stress reduction. So is the act of mastication. Suffice to say I’m not sold on the power of ginseng…but it either doesn’t help you or it does. Nothing suggests it’s going to hurt you, especially in the amounts found in energy drinks.


Source: Caffeine Informer


When To Consume: Caffeine Content and the 5 Levels of Fatigue

This product contains 142 milligrams of caffeine from the green tea extract and the guarana seed extract combined. As a reminder, people under 18 should have no more than 100 milligrams of caffeine a day, and healthy non-pregnant adults should have no more than 400 milligrams of caffeine a day.

This may be an Energy Drink in Disguise, but it has almost as much caffeine as a Monster Energy (Guru: 142 milligrams, Monster, most flavors, 160 milligrams). That makes this FATIGUE LEVEL 3! This is not a drink you want to drink every day because you want to save the stronger caffeinated beverages for when you are more than just dehydrated or a little tired.

We talked about Fatigue Level 3 during the 10 Day Caffeine Challenge. Here’s a refresher about why this level is special:

Bottom Line

Guru Organic Energy is a great alternative to stronger caffeinated beverages like Monster Energy. With 142 milligrams of caffeine, this is not something you want to consume every day. However, with its artificial free, certified-Organic, Non-GMO, gluten free ingredients, this is a beverage you can be proud to drink.




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