By Dr. Manoj Sharma-
(Dr. Sharma is a Professor and Chair of the Social and Behavioral Health Department and an Adjunct Professor in Internal Medicine at the University of Nevada, Las Vegas (UNLV). He is a global expert in health promotion.)
A recent news story in the media claimed that frequent coffee drinkers may be risking their hearts. Is that true? Is caffeine, the active ingredient in coffee, injurious to health? What is the current evidence regarding caffeine on health? We examine some of these questions closely.
Caffeine is a central nervous system stimulant found in coffee, tea, soft drinks, energy drinks, and chocolate. The United States Food and Drugs Administration (USFDA) recommends consuming no more than 400 mg of coffee daily which translates to not more than 4 cups of coffee daily. An average 8-ounce cup of coffee contains 80-100 mg of caffeine and has 5 hours of half-life meaning that 40-50 mg will remain in the system after 5 hours after drinking a cup of coffee. Black tea contains 47 mg/8 oz, green tea 30 mg/8oz, Coca-Cola 35 mg/8oz, and energy drinks that usually come in 16 oz servings may contain up to 200mg of caffeine.
It is generally agreed that consuming 200 mg of caffeine per day is not harmful and may provide some benefits. Studies have suggested that in such a low dose of consumption in the short run caffeine may improve alertness, decrease fatigue, improve cognition, and enhance athletic ability. Some studies have also shown evidence that caffeine, in the long run, may lower the likelihood of heart disease, type 2 diabetes, Parkinson’s disease, liver and endometrial cancers, and depression.
The key however is to consume caffeine within limits and caution should be kept in mind since it can be habit-forming and potentially abused by some. Leaving the habit may cause withdrawal symptoms. The symptoms vary in severity from person to person and generally include fatigue, irritability, headache, decreased energy, diminished alertness, drowsiness, depressed mood, trouble concentrating, loss of clear-headedness, and reduced satisfaction.
A recent article published in the Journal of the International Society of Sports Nutrition discussed some of the misperceptions about caffeine through current scientific evidence and found that in most studies maternal consumption of caffeine was associated with major adverse pregnancy outcomes. Hence, women intending to become pregnant must wean out of caffeine consumption habit. Caffeine consumption should be avoided during pregnancy.
The important question that the current news story raised about heart health needs discussion. Heart health is influenced by a myriad of factors. Some of these factors in the context of caffeine include the amount consumed, how long it has been consumed, the way it is consumed, and a person’s genetic and metabolic makeup. Other heart comorbidities and other ailments also play a role in how the heart is affected by caffeine. As mentioned earlier, coffee drinking within limits may in fact be beneficial for the heart.
There is also evidence that more than 400 mg of caffeine consumption is associated with loss of bone mineral density and fractures, especially among older women. Excessive consumption of caffeine can precipitate or worsen anxiety, lead to sleep disturbances and even result in mental aberrations. Hence, the limit of 2 cups of coffee or 200 mg daily of caffeine should not be exceeded.
