Caffeine is commonly found in beverages like coffee, tea, and cocoa, but it's also commonly added to soda, energy drinks, and fat loss supplements. We all consume caffeine in some form or another. Before we get into the details of safe caffeine doses, let's first look at where caffeine comes from.

How much caffeine is contained in common beverages?

The chart below shows common caffeinated drinks and how much caffeine they contain. Keep in mind that for a given energy drink, the amount of caffeine in each bottle is consistent, but the amount of caffeine in coffee or tea tends to vary.

How much is too much?

The safety of caffeine is relative and depends on the dose and your health level. Some people drink several cups of coffee a day without any symptoms, while others drink one cup of coffee and get a headache, disturbed sleep, and even high blood pressure. Next, I will make a recommendation on the safety of caffeine, but remember that this is just a general guide and there will be differences between individuals.

1. Adults

The European Food Safety Authority (EFSA) and the US National Academy of Sciences (NAS) believe that for adults, consuming up to 400 mg of caffeine per day will not have any health effects [1,2]. Although you can consume more, 400 mg is the amount that most healthy adults can consume without side effects.

EFSA also notes that for most people, consuming 200 mg of caffeine at once is not a health concern. However, consuming 100 mg of caffeine close to bedtime can affect sleep quality. Remember that the half-life of caffeine is 5 hours (this is an average, and it varies from person to person) [3], which means that you may still have caffeine in your blood for 10 hours after consuming it.

2. Women who are breastfeeding or pregnant

EFSA recommends that women who are breastfeeding, pregnant, or trying to conceive should limit their daily caffeine intake to less than 200 mg. Other literature suggests that 300 mg is also safe [4,5], but it is best to be careful because excessive intake can cause nausea.

There are few randomized controlled trials on caffeine intake in breastfeeding and pregnant women, so it is wise to lean towards the lower range. Also, during pregnancy, the body takes longer to break down caffeine.

3. Children and teenagers

EFSA notes that there is insufficient information on safe caffeine intake for children and adolescents, but recommends using the upper limit for adults (3 mg/kg body weight/day). However, Health Canada and non-governmental organizations recommend a lower intake - 2.5 mg/kg body weight/day.

Many organizations have called for more research on this group, and until more evidence comes out, it is wise to limit children's caffeine intake.

4. People with cardiovascular problems

Caffeine consumption increases blood pressure within 3–4 hours, but this effect usually decreases with regular caffeine consumption. Fortunately, in healthy adults, consuming 400 mg of caffeine per day does not increase the risk of cardiovascular disease [5]. However, the long-term effects of regular caffeine consumption in people with hypertension or contraindications are less clear. Moderate consumption is acceptable, but a doctor should be consulted regularly.

How much intake would reach the 400mg limit?

To track your caffeine intake, you have to be aware of the caffeine content of the beverages you drink. The chart below shows how many bottles of the same beverage you need to reach the upper limit.

What happens if you consume too much caffeine?

As for the oral dose of caffeine, 15 mg per kg of body weight is toxic, and 150 mg/kg of body weight may be fatal [6,7]. Therefore, for a 68 kg person, 1 g of caffeine will be toxic, and 10 g will be fatal. However, it is not so easy to take this dose...

Caffeine powder is different. The FDA warns that one teaspoon of pure caffeine powder contains as much caffeine as 28 cups of regular coffee. Therefore, it is easier to overdose on caffeine powder than on beverages.

Occasional high doses of caffeine can help your performance, but long-term intake above the recommended upper limit can affect your health. Depending on your fitness goals, it may be best to cycle your caffeine intake.

References:

[1]EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Safety of caffeine . EFSA Journal. (2015).

[2]Food and Nutrition Board. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. . The National Academies Press. (2014).

[3]Committee on Military Nutrition Research, Food and Nutrition Board. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations (2001).

[4]Nawrot P, et al. Effects of caffeine on human health. Food Addit Contam. (2003).

[5]Wikoff D, et al. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children. Food Chem Toxicol. (2017).

[6]Temple JL, et al. The Safety of Ingested Caffeine: A Comprehensive Review . Front Psychiatry. (2017).

[7]Yen M, Ewald MB. Toxicity of weight loss agents. J Med Toxicol. (2012).