Coffee and tea are among the most popular beverages worldwide and contain substantial amounts of caffeine, making caffeine the most widely consumed psychoactive agent. A variety of plants contain caffeine in their seeds, fruits, and leaves. Besides coffee and tea, these plants include cacao beans (an ingredient of chocolate), yerba matte leaves (used in herbal tea), and guarana berries (used in various beverages and supplements). Caffeine can be synthesized and is added to foods and beverages, including soft drinks, energy drinks, energy shots, and tablets sold to reduce fatigue. Caffeine and analgesics are used together in some pain medications, for example headache medications.
Coffee and tea have been consumed for hundreds of years and have become part of cultural traditions and social life. In the U.S., 85% of adults consume caffeine daily, and the average intake is 135 mg a day, roughly equivalent to 1.5 standard cups of coffee (standard being 8 oz). As for caffeine content, 12 oz of brewed coffee shop coffee has 235 mg of caffeine, 1 oz of espresso has 63 mg, 8 oz of black tea has 47 mg, and 12 oz of a cola soft drink has 32 mg.
Concerns have long existed that coffee and caffeine may be harmful, but recent research has uncovered evidence of health benefits. Coffee contains hundreds of other biologically active ingredients including phytochemicals, melanoidins, the alkaloid trigonelline, and magnesium, potassium, and niacin (vitamin B3). These compounds reduce oxidative stress, improve the composition of gut microbes, and modulate glucose and fat metabolism. In contrast, the diterpene cafestol, which is present in unfiltered coffee, may raise cholesterol levels. Thus, research findings for coffee and caffeine-containing beverages should be interpreted carefully, since effects seen may not be due to caffeine itself.
Consumption of two to five standard cups of coffee per day has been associated with reduced mortality in studies done across the world, especially in people of European, African American, and Asian descent. With consumption of more than five cups a day, the risk of death was similar to the risk seen in non-coffee users, after adjustment for confounding factors like smoking. Interestingly enough, consumption of caffeinated coffee and decaffeinated coffee were similarly associated with reduced risk of death from any cause, suggesting that the benefits of coffee consumption were not associated with caffeine.
A large body of evidence suggests that consumption of caffeinated coffee, the main source of caffeine intake in adults in the U.S., does not increase the risk of heart disease and cancer. In fact, consumption of two to five standard cups of coffee daily has consistently associated with a decreased risk of several chronic diseases. However, high caffeine intake can have various adverse effects, and limits of 400 mg per day for adults who are not pregnant or lactating and 200 mg a day for pregnant and lactating women have been recommended. Current evidence does not recommend caffeine or coffee intake for disease prevention but suggests that, for adults who are not pregnant or lactating and who do not have specific health conditions, moderate consumption of coffee and tea can be a part of a healthy lifestyle.
By Peter Galvin, MDBLOG COMMENTS POWERED BY DISQUS