Caffeine Consumption in the USA – Part III: Measuring Caffeine Intake

Imagine you took a poll how many Americans eat salad, and you included potato salad, chicken salad, and fruit salad in the “salad category”. Now imagine you classified potato salad and Caesar salad as different types or “brands” of salad, then re-calculated how many Americans really eat salad. How different do you think the numbers would be?

A study recently published in the Journal of Food and Chemical Toxicology sought to answer this “brand-method” versus “category-method” question, but for caffeine consumption. This study is called “Assessing dietary exposure to caffeine from beverages in the US population using brand-specific versus category-specific caffeine values” and it’s freely accessible to the public. This study builds off the study published in 2014, “Beverage Caffeine Intakes in the US”, which we’ve already discussed in depth here at You can read the 30-second overview *here, and review the specifics and key takeaways *here.

Food and Chemical Toxicology Assessing Dietary ExposureIn this newer study, published June 2015, the goal was to determine whether the caffeine consumption statistics change when a brand-specific or category-specific method is used for the caffeine consumption calculations. Like with our salad analogy above, using a broad category instead of a specific brand may give you different numbers, but are the numbers different enough to insist that one method is better and the other invalid?

The most interesting differences (and whether they’re statistically significant) between the brand-specific method (B) and category-specific method (C) are as follows:

  • Number of caffeine drinkers: 37,602 (B) versus 35,551 (C) [interesting, but not significant]
  • Average amount of caffeine consumed by all ages from all sources of caffeine 164.5 (B) versus 161.2 +0.9 (C) [interesting, but not significant]
  • Proportion of the total amount of caffeine consumed by all ages that comes from coffee, tea, and soda [all statistically, significantly different]:
    >> Coffee: 64% coffee (B) versus 63% (C);
    >>Carbonated soft drinks (CSDs): 17%  (B) versus 16% (C);
    >>Tea: 17% (B) versus 19% tea (C).

So what do these results really tell us?

It’s tempting to want to calculate the amount of caffeine the different age groups are consuming and from what source, especially with public calls for energy drink bans and stories suggesting America’s youth consumes lethal amounts of caffeine. But that’s not what this study is about. In fact, the answers to all those questions (who is consuming how much caffeine, and from where) are all covered in depth in a previous post (click here).

Overall, this study tells us there are important differences when we use one method over another. Think about this: the number of caffeine consumers actually changed between methods! Doesn’t that seem odd? Either you consume caffeine or you don’t. Alas, some brands don’t fit the stereotype applied to their category, so it skews the data. For example, Sprite and Coca-Cola are both in the soda category, but Coca-Cola contains caffeine and Sprite does not. Someone who drinks Coke Zero every morning would not be calculated as a caffeine consumer with the category-specific method.

The good news is the estimated caffeine intake for all ages combined did not change significantly between methods. So if all you wanted to know was how much caffeine America (in general) consumed, you could use either method and get pretty much the same answer. However, if you cared where that caffeine was coming from, like how much caffeine America (in general) gets from coffee, the brand-specific method would give you a significantly different answer. The same goes for tea and soda.

If you cared about the caffeine consumption of a certain age group, the two methods may or may not give a significantly different answer. For all age groups examined, the proportion of caffeine consumed from coffee, soda, tea, and energy drinks was different between methods, but only the result for soda and tea was (statistically) significantly different, and only for the oldest three age groups. These three groups (35-49, 50-64, and 65+) had the most number of study participants, so it seems there just weren’t enough people in the other age groups to detect a significant difference between the two methods. Imagine how much better our caffeine consumption estimates would be if we could categorize every caffeinated beverage purchase by consumer age group!

The study itself captures the implication of these findings most eloquently:

“As the caffeinated beverage marketplace continues to evolve, the use of more detailed, brand-specific data will likely strengthen the assessment of caffeine exposure in the United States.”


  1. Category-specific methods can be misleading, and even something as seemingly-simple as coffee varies wildly in caffeine content. As this study reminds us, “Both coffee and tea are subject to large variability in the caffeine content due to the origin of the crop, the type, and the processing and preparation, including the brewing time and temperature. Note, this is why the claim “contains as much caffeine as one cup of coffee” is a laughable measuring device.
  2. Caffeine Informer is the ultimate source for caffeine. “The Caffeine Informer website is likely the most comprehensive for the caffeine content of foods and beverages. It currently contains caffeine values for over 600 beverages with documented sources for its values and strives to keep the values current,” notes the study authors. The Caffeine Informer database is superior to databases such as the US Department of Agriculture (USDA) National Nutrient Database for Standard Reference, and the Food and Nutrient Database for Dietary Studies. While these two are “the most widely used publicly available referenced databases, [they] rely mostly on generic, single values that represent a broad range of products rather than brand-specific values.”
  3. The more we look into the demographics of caffeine exposure, the more there is to learn, but we have to use the best methods and be the right-kind of specific.

References and Related Reading

Caffeine Informer – Caffeine Safe Limits: Determine Your Safe Daily Dose

Caffeine Consumption in the USA – Energy Drinks in the News

Caffeine Consumption in the USA – Part II: The Specifics

Food and Chemical Toxicology – Beverage Caffeine Intake in the US

Open Letter to Time Regarding Energy Drink Article in the “Answer Issue”

Are You a Monster or a Rock Star: A Guide to Energy Drinks — How They Work, Why They Work, How to Use Them Safely

Discover the key factors that make energy drinks safe or unsafe. Meet the 20 most common ingredients found in energy drinks and learn the basic science to how they work. With this guide and the “Levels of Fatigue” outlined within, anyone can learn the tools for determining which energy drink (IF ANY!) are right for his or her lifestyle and diet goals.

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