There is nothing quite like a cup of hot coffee to banish that feeling of somnolence and get the brain cells chugging away. But quite apart from the sense of wellbeing that a good cup of brew, with its heady aroma, can produce, studies published recently also indicate that this beverage that millions around the world enjoy could be providing some health benefits too.
In May this year, the prestigious medical journal, The New England Journal of Medicine, published a study that examined the effects of drinking coffee in a cohort of over four lakh men and women in the U.S.
Coffee “appeared to be inversely associated with most major causes of death in both men and women, including heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections,” observed Neal Freedman of the National Cancer Institute in the U.S. and his colleagues in their paper.
After taking into account tobacco-smoking and other confounding factors, men who drank six cups or more cups of coffee a day had a 10 per cent lower risk of death compared with those who did not take it at all. Women coffee-drinkers had a 15 per cent lower risk of death. Those who drank caffeine-containing coffee as well as the decaffeinated form were both found to benefit from their habit.
But, as the authors pointed out, it was not possible to conclude from an observational study whether the association that was noticed actually reflected cause and effect.
Then, last month there came another study, this time in Circulation Heart Failure, a journal of the American Heart Association. The study analysed five independent prospective studies, with a total of over 1.4 lakh participants, for links between coffee consumption and heart failure.
This study observed a statistically significant ‘J-shaped relationship’ between coffee and heart failure. Moderate consumption of coffee — up to four servings a day — reduced the risk of heart failure. But excessive coffee drinking had no benefit and may even be dangerous, remarked Murray Mittleman, director of the Cardiovascular Epidemiology Research Unit at Beth Israel Deaconess Medical Center in Boston and senior author of the study, in a press release.
The paper, however, also pointed out that experimental studies had consistently shown that coffee and caffeine were associated with acutely raised blood pressure. A recent analysis had reported that habitual light to moderate coffee consumption increased the risk of developing hypertension but more frequent consumption did not pose any addition risk. It could be that habitual coffee-drinkers develop a tolerance for caffeine, the authors said.
Other studies have suggested that drinking coffee could also be associated with a lower risk of developing type 2 diabetes.
In 1991, the World Health Organisation’s International Agency for Research on Cancer held that “coffee is possibly carcinogenic to the human urinary bladder.” But more recent studies have indicated that coffee could be beneficial, protecting against several cancers, including of the breast, bowel, prostate and liver.
A paper from Jiali Han of the Harvard Medical School and the others that has just been published in the journal Cancer Research found that caffeine intake was associated with reduced risk for developing a form of skin cancer known as basal cell carcinoma.
Roughly 1,000 chemicals have been reported in roasted coffee, point out Jonathan Krell and Justin Stebbing of Imperial College London in a commentary published recently in The Lancet Oncology. The active compounds in coffee associated with anti-cancer properties are largely unknown but antioxidants might have a role. Moreover, the roasting process too was important and affected the antioxidant content.
But they also cautioned that a large proportion of the evidence for the beneficial effects of coffee was derived from epidemiological studies that were open to misinterpretation and error. More well-designed studies were needed to assess this subject further. Meanwhile, “like many aspects of life, ‘everything in moderation’ seems the safest policy to adopt,” they remarked.