All About Caffeine

Caffeine is world’s most widely consumed stimulant and has been consumed for thousands of years. Caffeine is found naturally in many plant-based foods and the main sources in the Western diet are coffee, tea, cocoa (chocolate) products and cola products1. Canadians get about 60% of caffeine from coffee and 30% from tea. Tea contains 66% less caffeine compared to an equal-sized serving of coffee, but enough to provide the cognitive benefits. This means that most people can consume about 8 cups of tea a day compared to only 2 cups of coffee a day and stay below the moderate caffeine intake of 400mg/day.  Tea is also the world’s second most popular beverage after water which is good news for consumers who are looking for a drink that tastes great and is better for them. There are many types, forms and flavours of tea to discover whether it be black, green, oolong or white.


Many Canadians reach for their favourite caffeinated beverage, for a temporary energy boost or to elevate their mood. Because of caffeine’s wide-spread consumption its effects on human health have been extensively studied1. Caffeine is known to increase alertness and reduce fatigue.  Scientists have shown that caffeine’s cognitive benefits not only increase alertness, but also improve reaction time, and it seems like many people can perform complex tasks better, and their memory is improved as well. Caffeine has also been recently linked to weight loss and consequent reduction of the overall risks for developing the metabolic syndrome. Preliminary research is looking at other benefits of caffeine. For example, some people (mostly men) who consume caffeine regularly have a lower risk of developing Parkinson’s disease according to scientists at Harvard School of Public Health in Boston2.

Although in healthy adults, a small amount of caffeine may have positive effects including increased alertness and concentration, some people find that caffeine disturbs sleep, causes headaches, and makes them irritable and nervous3. After consuming caffeine, it is absorbed quickly in the gut, and it takes only 15 to 20 minutes to get into your blood. Caffeine levels in the blood peak at 60–90 minutes after consumption. On average half of the caffeine you consumed would be broken down in 2-4 hours, but in some people the effects of caffeine can last up to 10 hours4.

If caffeine is an issue for you, knowing how much caffeine is in your food and drink is an important step in taking charge of your intake.

Just released data from the European Food Safety Authority (EFSA) outlines the scientific opinion on the safety of caffeine consumption. The report concluded that for healthy adults, with the exception of pregnant women, single doses of caffeine up to 200 mg and total daily caffeine consumption of up to 400 mg are safe5. This recommendation is consistent with Health Canada’s guidelines on caffeine consumption which state that for the average adult, moderate daily caffeine intake at levels of 400 mg/day is not associated with any adverse effects6. Specific advice on moderating caffeine intake applies to women who are pregnant or breastfeeding (300 mg/day) and children (45-85 mg/day)6. EFSA guidelines suggest consumption up to 200 mg per day by pregnant and nursing women.


Figure 1. Tea Association of Canada’s Caffeine Content Graphic

Figure 1 (above) provides typical caffeine levels found in standard 250 ml (1 cup) servings of tea and coffee. Actual caffeine levels are dependent upon specific blends and strength of the brew. On average, there is 45 mg of caffeine in a cup of tea which is about 66 % less caffeine than the amount found in a cup of coffee6. This means that most people can consume about 8 cups of tea OR 2 cups of coffee a day and stay below the caffeine intake at levels of 400 mg/day.

Bottom Line

Caffeine is a natural compound and is considered safe when consumed in moderation. Tea is calorie-free and all-natural beverage that contains 66% less caffeine of compared to an equal-sized serving of coffee, but still enough to provide the cognitive benefits. Enjoy herbal teas or decaffeinated teas if you want to limit caffeinated beverages.

More information is available at

[1] Heckman MA, Weil J, Gonzalez de Mejia E. Caffeine (1, 3, 7-trimethylxanthine) in foods: a comprehensive review on consumption, functionality, safety, and regulatory matters. J Food Sci. 2010 Apr [cited 2013 Feb 20];75(3):R77-87. Abstract available from:

[2] Palacios N, et al, Caffeine and risk of Parkinson’s disease in a large cohort of men and women. Mov Disord. 2012 Sep 1;27(10):1276-82.

[3] Dietitians of Canada, Caffeine and Health Sourced July 2015

[4] Dietitians of Canada, Eatright Ontario

[5] European Food Safety Authority, Scientific Opinion on the safety of caffeine, EFSA Journal 2015; 13(5):4102 doi:10.2903/j.efsa.2015.4102

[6] Health Canada, Caffeine in Food. 2012-02-16,  Retrieved from (July 2015)


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