Coffee is part of the daily routine for millions, but in these health-conscious days the question has to be asked – is coffee good for you, or bad?
Over the past year coffee drinkers have been told that they may be cutting their stroke risk, protecting against superbugs, staving off dementia and Alzheimer’s disease and reducing the likelihood of one form of diabetes.
Men have been told that drinking coffee may be slashing the risk of prostate cancer and women that they may be cutting the risk of breast cancer.
But it’s not all good news. Those who drink a lot of coffee may be clogging their arteries and losing concentration and women may be reducing their chances of conception.
Put all these studies together and the common thread is hard to find, probably because coffee is far more than a conduit for caffeine. It is a complex food containing about 1,000 compounds, all with potential to be good or bad for the body.
A further problem for coffee drinkers is that scientists have yet to tell us how much coffee is needed to produce the desired – or undesired – effects. Methods of preparing the drink must also be factored in – filtering, for example, reduces more coffee compounds than pressing the grains in a cafetière.
Then there are the studies conducted with no significant findings. According to the Medical Research Council, inconclusive clinical trials must publish the negative findings, but they are not usually the stuff that media headlines are made of.
One of the world’s leading researchers into nutrition is Rob Martinus Van Dam, a professor at Harvard and the University of Singapore who studies obesity, diabetes and cardiovascular diseases. In his view, it is reasonable to say more than four cups a day constitutes heavy coffee consumption, but it depends on the size of cup. The research is usually based on coffee that is black or with a little milk or sugar, not the 500-calorie whipped cream versions on sale in coffee chains, he warns.
Men have been told that drinking coffee may be slashing the risk of prostate cancer
Van Dam led a team at Harvard that followed 130,000 volunteers in their 40s and 50s for between 18 and 24 years, tracking their diet and lifestyle habits. “We did not find any relationship between coffee consumption and increased risk of death from any cause, death from cancer or death from cardiovascular disease,” he says. Even those drinking up to six cups a day were at no higher risk. In addition, he says, there is some evidence that coffee consumption may protect against type 2 diabetes, Parkinson’s disease, liver cancer and liver cirrhosis.
It would be prudent for pregnant women to reduce their consumption to one cup a day because caffeine goes through to the foetus, which metabolises it slowly.
But for the general population the evidence suggests coffee does not have any serious detrimental health effects, Van Dam says: “People wanting to improve their health should focus on other things, such as quitting smoking and taking more exercise.”