Beans and Leaves: Unravelling the Health Potential of Two Global Beverages
March 5, 2018
By Sylvia Black
You might think of them as the fifth food group: beverages. We know to avoid sugar-sweetened beverages, drink alcohol in moderation if at all, and stay hydrated with water. But what about the health effects of those perennial favourites, tea and coffee? This post will explore the potential of these beverages to promote health and prevent disease.
A lot of myths abound on this topic: that caffeinated beverages are dehydrating (research has shown this to be false) 1, that drinking coffee can lead to bone loss (this does not seem to be the case, at least when consumption is moderate)2, or that black tea has more caffeine than green tea (it’s actually variable).
However, while research is still ongoing, tea and coffee do seem to have the potential to reduce disease risk. Tentative evidence suggests that green tea consumption may be associated with a decreased risk of coronary artery disease and stroke, and may decrease LDL cholesterol in individuals with dyslipidemia3-5. The antioxidants in tea may also help to preserve bone mass when consumed habitually.
Moderate caffeine consumption may also be associated with decreased cognitive decline in older adults without dementia, while long-term moderate consumption of coffee appears to be associated with lower risk of type 2 diabetes6,7.
Most teas contain antioxidants: in the case of teas made from the traditional tea plant (Camellia sinensis), those antioxidants are a type known as polyphenols. (Herbal teas may contain other types of antioxidants, depending on the ingredients of the tea). Many people don’t know that coffee is also a rich source of antioxidants such as chlorogenic acid8.
As for caffeine, the average cup of coffee contains somewhere between 80-180 mg. (The maximum recommended intake of caffeine for adults is 400 mg per day, or 300 mg if pregnant or breastfeeding). A cup of tea may contain between 15 and 60 mg. Herbal teas other than yerba mate do not contain caffeine.
But the health effects of these beverages can go beyond just the sum of their ingredients: drinking tea or coffee can be a social experience, a daily ritual, or a calming activity in the face of stress. Conversely, caffeine can also be an addictive substance, and excess consumption can disrupt sleep and lead to negative health effects9.
While the evidence of benefit isn’t necessarily strong enough to recommend tea or coffee to those who do not currently consume it, it’s undoubtedly good news for those who already enjoy one or both beverages. A cup a day may not keep the doctor away entirely, but it can certainly be part of a healthy lifestyle.
Sylvia Black is a recent graduate of the Nutrition Communication master’s program at Ryerson University, where she also completed her undergraduate degree in Nutrition & Food. She loves to write about nutrition and food politics, and is passionate about creating healthy food policy. Her interests include food security, sustainable food systems, and chronic disease prevention.
- Armstrong LE, Casa DJ, Maresh CM, Ganio MS. Caffeine, fluid-electrolyte balance, temperature regulation, and exercise-heat tolerance. Exerc Sport Sci Rev. 2007;35(3):135-40.
- Nawrot P, Jordan S, Eastwood J, Rotstein J, Hugenholtz A, Feeley M. Effects of caffeine on human health. Food Addit Contam. 2003;20(1):1-30
- Arab L, Liu W, Elashoff D. Green and black tea consumption and risk of stroke: a meta-analysis. Stroke. 2009;40(5):1786-92.
- Wang ZM, Zhou B, Wang YS, Gong QY, Wang QM, Yan JJ, et al. Black and green tea consumption and the risk of coronary artery disease: a meta-analysis. Am J Clin Nutr. 2011;93(3):506-15.
- Kim A, Chiu A, Barone MK, Avino D, Wang F, Coleman CI, et al. Green tea catechins decrease total and low-density lipoprotein cholesterol: a systematic review and meta-analysis. J Am Diet Assoc. 2011;111(11):1720-9.
- Van Gelder B, Buijsse B, Tijhuis M, Dalmijn S, Giampaoli S, Nissinen A, et al. Coffee consumption is inversely associated with cognitive decline in elderly European men: the FINE Study. Eur J Clin Nutr. 2007;61(2):226-3
- van Dam RM, Hu FB. Coffee consumption and risk of type 2 diabetes: a systematic review. JAMA. 2005;294(1):97-104.
- Harvard Health Publishing. What is it about coffee? [Internet]. Harvard Medical School. 2012 Jan [cited 2018 Feb]. Available from: https://www.health.harvard.edu/staying-healthy/what-is-it-about-coffee.
- Reissig CJ, Strain EC, Griffiths RR. Caffeinated energy drinks–a growing problem. Drug Alcohol Depend. 2009;99(1-3):1-10.