Caffeine 101

I’m sure you have heard about caffeine. There are many people who love coffee because of caffeine.

There are a number of articles written about caffeine, and this article has the objective of explaining some of the practical effects of caffeine ingestion. The first part will give a short overview about caffeine.


What Is Caffeine ?

Before we go to the benefits of caffeine, it is important to know what caffeine is. A number of people are aware that coffee contains caffeine.

But not many know what caffeine is or what foods contain caffeine. Here we explain all that you need to know about caffeine.

Everybody knows that coffee has caffeine. However, do you have any idea what caffeine is? Caffeine is a stimulant which you can find naturally in leaves, nuts and seeds of plants. According to an article from ResearchGate, caffeine is a member of a class of naturally occurring substances called methylxanthines. There are two other methylxathines found in food, one is theobromine found in cocoa and the other one is theophylline found in small amounts of tea and coffee.

Caffeine is the most unregulated stimulant in the world. The USA Today reported that the US is one of the biggest caffeine drinkers with 83% of adults in the US consume coffee, and the average amount of coffee drank by those Americans is 3 to 4 cups daily.

  • Not many people believe that caffeine is a drug, but that’s what it is. It is perfectly safe when drank moderately, however, drinking too much coffee can lead to caffeine overload.
Of American adults

...consume 3-4 cups of coffee per day


Where Does It Come From ?

Do you ever wonder where caffeine comes from? Do you know that aside from coffee beans, there are many natural and artificial sources of caffeine. You might even be surprised about the other ways where you can get your caffeine fix.

Here, we list both the artificial and natural sources of caffeine.


Caffeine is an alkaloid occurring naturally in a number of plant species, of which cocoa beans, kola nuts, tea leaves and coffee beans are the most popular. The amount of caffeine consumed in drinks differs greatly and depends on the strength of the beverage, and the amount drank with cup size playing a significant part. Here are the top sources of caffeine in beverages:

Coffee beans

According to an article from Livestrong, caffeine levels in coffee can be different depending on the kind of bean and its roasting process. A typical Arabica bean has 1.2 percent to 1.8 percent of caffeine. Robusta beans has 50% more caffeine than Arabica beans with as much as 2.4 percent. Roasting coffee does not increase the caffeine levels.

Even though dark roasts have a richer and bolder flavor, they usually have less caffeine because roasting decreases caffeine levels by 10 to 15%. A dark-roasted bean has 15 or 20% less caffeine than a lighter roast variety.


If you’re looking for the flavor of tea with the biggest dose of caffeine, then you should try drinking black tea. Mayo Clinic says that black tea has around 80 mg of caffeine which is almost equal to a cup of coffee.

Consuming black tea regularly can help reduce the risk of diabetes. A study from the National Center for Biotechnology Information reveals that those drinking black tea had a 70% lower risk of getting diabetes.


Dark chocolate is a good addition to a balanced diet, and unknown to many people, has a small amount of caffeine which is around 10 mg. On the other hand, according to an article from Paleohacks, chocolate has theobromine and theophylline which are mild stimulants.

The darker the chocolate, the healthier it is. When buying dark chocolate, look for a chocolate bar that has around 70% of cocoa, fair trade, organic and GMO free.


If you see kola nut listed as an ingredient in an energy blend or formula, it will have a standard of 10 to 20% caffeine. In an article from, it says that kola extracts usually have a nutty taste, odor and brownish appearance to whatever is combined with the ingredient.

It is not coincidental that soda-flavored products are called “cola”. Kola nut was an ingredient in the original Coca-cola and Pepsi –Cola soft drinks.

Yerba Mate

Yerba Mate ( a South American beverage) is becoming more famous in various health circles. It has the health benefits of tea and can boost the brain which is found in hot chocolate.

According to the National Center for Biotechnology Information, Yerba has a little bit of caffeine but has 20 vitamins and minerals, over 10 amino acids, and big dose of antioxidants. Another advantage to yerba mate that is not found in coffee is that it can help improve digestion.

Many South American natives have drank Yerba Mate because of this reason for many years. If you’re curious to try Yerba Mate, the beverage manufacturer Guayaki makes a good organic version that has a lot of caffeine.


Taurine is an amino acid that has a big role in neurological development and has antioxidant properties. According to Mayo Clinic, up to 3000 mg of taurine is safe and the kidneys excrete excess taurine.

It is added to many energy drinks as a caffeine adjuvant. Caffeine and taurine are not the same. Caffeine is a stimulant while taurine is an amino acid naturally produced in the body.


Guarana berry is commonly sold as a supplement but it can be made into a tea. According to an article by an NCBI researcher Moustakas, guarana has 200% more caffeine than coffee beans, which makes it a better source of energy for those who did not have a good night sleep.

Guarana is added to many drinks around the world because of its benefits of better energy, alertness and mood. Many sports players believe that guarana has given them better focus and higher levels of energy.


A number of caffeinated alcoholic beverage drinks were reformulated after investigators found out that the products were being sold to underage drinkers. According to the Journal Sentinel, the Center for Science in the Public Interest sued MillerCoors to cease from marketing the beverage Sparks, which, according to a lab analysis by a Miami TV newstation, has 214 milligrams of caffeine per 16-ounce can.

Anheuser-Busch ceased manufacturing fruit-flavored beer Bud Extra, which had 55 milligrams of caffeine, which is the same as a cup of tea, as well as the malt beverage Tilt.

Energy Drinks

Energy drinks contain many herbal supplements (such as taurine and guarana) and many vitamins and minerals, but the vast majority of these drinks include large the doses of caffeine. Generally, the main ingredients in energy drinks are caffeine, taurine and glucuronolactone.

Caffeine in energy drinks is usually derived from guarana or yerba mate. The caffeine that is found in energy drinks is exactly the same as the caffeine that we can find in an average cup of coffee, except at higher levels. According to an article from Caffeine Content, caffeine content in energy drinks is around 200 mg.

Energy Shots

Acording to Today’s Dietitian, energy shots, compared with energy drinks, contain more concentrated sources of caffeine, have fewer ingredients and fewer calories, and generally are sold in small 50-mL containers.

Energy Drinks

5-Hour Energy makes up nearly 89% of the energy shot category. Energy shots are a specialized type of energy drink that contain a dose of the stimulant caffeine. Energy shots are usually sold in 2 fluid oz. plastic bottles.

Energy shots can contain the same total amount of caffeine, vitamins or other functional ingredients as their larger versions, and may be considered concentrated forms of energy drinks. "Micro shot" energy drinks also exist, containing only 1-5 teaspoons of liquid.

Caffeinated Alcoholic Beverages

Caffeine is usually added to soft drinks which range from 30 to 40 mg of caffeine per 12 oz. serving.

Caffeine in soft drinks comes from the ingredients used or is an additive resulting from decaffeination of coffee or from chemical synthesis.


How Much Caffeine Do We Consume ?

Many people around the globe have consumed drinks containing caffeine. There are a number of studies which reveal that show how much caffeine we consume.

According to the European Food Safety Authority (EFSA), average daily intakes are different for member states, but are in the following ranges:


Average caffeine intakes/day

Very elderly (75 years and above)

22-417 mg

Elderly (65-75 years)

23-362 mg

Adults (18-65 years)

37-319 mg

Adolescents (10-18 years)

0.4-1.4 mg/kg bw

Children (3-10 years)

0.2-2.0 mg/kg bw

Toddlers (12-36 months)

0-2.1 mg/kg bw

In many surveys covered by EFSA’s Food Consumption Database, coffee was the main source of caffeine for adults, contributing between 40% and 94% of total consumption. On the other hand, tea was the primary source for Ireland and United Kingdom, with 59% and 57% of total caffeine consumption respectively. There are big differences among countries on the contribution of various food sources to total caffeine consumption among teenagers.

Chocolate was the primary contributor in six surveys, coffee in four surveys, cola beverages in three, and tea in two. In most countries, chocolate was the primary source of caffeine for kids aged 3 to 10 years, next is tea and cola drinks.

One cause for the differences in levels of intake, apart from cultural habits, is the different concentrations found in a number of food products. Concentrations in coffee drinks rely on the manufacturing process, the kind of coffee beans used, and the kind of preparation (e.g. drip coffee, espresso). The levels found in cocoa-based drinks rely on the amount and kind of cocoa found in various brands.


How Much Caffeine Is It SAFE To Consume ?

Caffeine has its benefits, however, it can have some issues too. Although caffeine is generally safe for adults, there are suggested doses for children and pregnant women.

Find out how much caffeine is safe to consume.

EFSA’s Panel on Dietitic Products, Nutrition and Allergies (NDA) assessed the impact of caffeine in combination with common ingredients of energy drinks particularly taurine and D-glucorno-y lactone and made a conclusion that it is safe for healthy people to drink caffeine with other energy drinks at the levels that they are found in energy drinks.


Single doses of caffeine up to 200 mg – about 3mg per kilogram of body weight from all sources are safe for the general healthy adult population. The primary source of caffeine intake for adults and older people in the EU is coffee except for Ireland and UK where the main source is tea.

In healthy adults and older people, single doses of caffeine of up to 200 mg which is around 2 ½ espressos or 4 cups of tea, do not raise any health risks. For regular drinking, EFSA claims that caffeine consumption up to 400 mg over the course of 24 hours will not be harmful to the adult drinker. These levels are also safe for healthy adults doing intensive physical exercise.

Single doses of 100mg of caffeine can affect sleeping patterns and duration in a number of adults, specifically when drank before sleeping.

Single doses of caffeine of up to 200 mg are considered unlikely to hide the feeling of intoxication in people consuming alcohol. This level of caffeine is safe at blood alcohol levels (BAC) of 0.08% (above 0.05% the level which you are deemed unfit to drive in many EU countries). It is also safe to combine moderate alcohol drinking with regular caffeine drinking of up to 400 mg per day.

Pregnant And Breastfeeding Women

EFSA claims that regular caffeine consumption of up to 200 mg per day is safe for the unborn baby or breastfed child. This is equivalent to just over 2 cups of filter coffee or 4 cups of tea.

Children And Adolescents

It is recommended that children and teenagers drink no more than 2.5 mg of caffeine per kg of body weight per day.


Effects of Caffeine

Caffeine has a number of good effects on the body.

Caffeine has been shown to improve mood and cognitive performance. Moreover, it has also been proven to improve athletic performance.

Effects Of Caffeine On Mood And Cognitive Performance

It has been found out by a study from Cardiff University that caffeine consumption has good effects on improving cognitive performance. Low doses of caffeine improve working memory performance, while higher doses are discovered to reduce it, possibly because of over-stimulation.

Comparable results have been found out in low-load memory tasks versus high-load memory tasks. Caffeine has been discovered to have good effects on performance in both low-difficulty and low-load memory tasks.

High-load and complicated tasks induced increased arousal by themselves: so in these tasks, caffeine could result to over-arousal. Thus caffeine seems to enhance working memory performance under conditions that otherwise generate low arousal states.

A review by A. Nehlig reveals that repeated administration of 75 mg of caffeine (the equivalent of one cup of coffee) every four hours can lead to a pattern of sustained enhancement of mood during the day. On the other hand, high intakes may be link with an increase in tense arousal including anxiety, nervousness and jitteriness.

A dose-related improvement in subjective measures of calmness and interest were discovered after drinking caffeine, implying that mood improvement may depend on baseline arousal. Highly-fatigued participants may be more likely to have bigger subjective mood swings than non- or moderately-fatigued participants.

Caffeine And Physical Performance

This concern has often been considered in connection to sports performance. A recent position paper on this topic from the International Society of Sports Nutrition can be summarized as follows:


Caffeine is effective for improving sport performance in skilled athletes when drank in low-to-moderate dosages (~3–6 mg/kg) and overall does not lead to further improvement in performance when drank in higher dosages (≥ 9 mg/kg).


Caffeine gives a higher ergogenic effect when drank in an anhydrous state as compared to coffee.


It has been proven that caffeine can improve vigilance during bouts of extended intensive exercise, as well as periods of sustained sleep deprivation.


Caffeine is ergogenic for sustained maximal endurance exercise, and has been proven to be highly effective for time-trial performance.


Caffeine supplementation is good for high-intensity exercise, including team sports such as soccer and rugby, both of which are classified by intermittent activity within a period of prolonged duration.


The literature is unclear when looking into the impact of caffeine supplementation on strength–power performance, and further research in this area is needed.


The scientific literature does not support caffeine-induced diuresis during exercise, or any harmful change in fluid balance that would negatively impact performance.


Sources Of Caffeine In Diets Of US Children And Adults: Trends By Beverage Type And Purchase Location

National Health and Nutrition Examination Surveys (NHANES) were used to estimate population-level caffeine consumption, using information from 24-h dietary recall.

Caffeine Consumption

The table shows the total caffeine consumption and caffeine consumption by age, gender, race, family income, education, and employment status from 2011 to 2012. Adults had a higher caffeine consumption than children and adolescents, with 173 mg/day and 35 mg/day respectively. Males have a higher intake than women with 196 mg/day and 151 mg/day in turn.

For both adults and children, the non-Hispanic white group had the highest caffeine consumption while the non-Hispanic group had the lowest. Although there were no major effects of income, higher-income adults consume more caffeine than lower-income adults.

This difference was driven by the fact that lower-income adults were also younger. There were no systematic effects by education, though adults with some college education with no degree drank more caffeine than adults with a college degree.

On the other hand, higher caffeine consumption was connected to employment. Working adults drank remarkably more caffeine than adults who were unemployed. Adjusting for age and limiting the analysis to those 20-64 years did not change the link between higher caffeine consumption among working vs. non-working adults.

Fourteen-Year Trends in Caffeine Consumption

The graph shows the fourteen-year trends in total caffeine consumption, and by food/beverage source, for both children and adults. For both children and adults, caffeine consumption decreased from 175 mg/day in 1999-2000 to 142 mg/day in 2011-2012, mainly driven by a drop in caffeine from soda (41 mg/day to 21 mg/day). Among children overall, there was a declining trend, with average caffeine consumption declining from 51.8 mg/day in 1999-2000 to 35.3 mg/day in 2011 to 2012.

There was a moderate rise in caffeine from coffee from 5.0 mg/day to 6.8 mg/day and no change in caffeine from tea. Soda was the main source of caffeine for children, however, caffeine from soda declined from 30.5 mg/day to 12.3 mg/day. Caffeine from energy drinks rose significantly from zero in 1999-2000, to 0.24 mg/day in 2003-2004, and 2.3 mg/day in 2011-2012.

Fourteen-Year Trends in Caffeine Consumption by Age Group

The graph shows the fourteen-year trends in caffeine consumption by age group and by beverage type from 1999-2001 to 2011-2012. For children and young adults, there was a decrease in total caffeine intake. There was no evidence of a trend in diminished total caffeine for older adults. There was also no evidence of an interaction by age group for the trend in caffeine from coffee or tea.

The trend in caffeine from soda did differ by age group and decreases were seen for all age groups, with the highest seen for adults age 14-19 years and young adults 20-34 years, groups which had the biggest baseline caffeine consumption from soda.

Trends in Location of Origin for Caffeine, 2003–2012

The graph shows the caffeine intake by purchase location of origin, separately for children and adults. Total caffeine consumption decreased between 2003-2004 and 2011-2012 for both children and adults.

Next, the bulk of caffeine drank (67% from children and 78% from adults) came from store-bought coffee, tea, soda and other foods/beverages. On the other hand, there is a declining trend in store-bought caffeine, but there is a sharp rise in 2011-2012 for caffeine from fast food restaurants.

The graph demonstrates the time trends for caffeine consumption by adults from 2003-2012 by location of origin and beverage type. As we can see, 99 mg/day of caffeine came from store-bought coffee. Another 21 mg/day came from store-bought tea and 20 mg/day from store-bought sodas followed by coffee from a common pot and from fast food restaurants or coffee shops.

The second graph shows a decrease in caffeine from store bought soda and a rise in caffeine from FFR and coffee shops. Both trends are remarkable.


The current study used nationally representative NHANES 1999-2012 information to give the first analysis of trends in population level caffeine consumption by age group, beverage type, and purchase location of origin. In 2011-2012, children aged 4 to 8 years consumed the least caffeine (15 mg/day), and adults aged 51-70 years consumed the most (213 mg/day). The population mean was 135 mg/day, driven mainly by coffee (90 mg/day), tea (25 mg/day), and soda (21 mg/day).

For the 14-19 years and 20-34 years age groups, energy drinks contributed 6 mg/day and 5 mg/day, in turn. The bulk of caffeine came from store-bought coffee and tea. For both children and adults combined, caffeine consumption declined from 175 mg/day to 142 mg/day, mainly driven by a drop in caffeine from soda.

Store-bought coffee and tea remain the main drivers of caffeine consumption in the US. Sodas and energy drinks contributed little to overall caffeine consumption.

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