Confused? Try our A-Z of conflicting health advice

Jeremy Laurance: A daily aspirin was good for us, then it was dangerous. So when can we trust expert guidance?

Every week, it seems a scientific study appears disproving what last week's study showed. Yesterday saw a classic medical volte face: aspirin, which has been prescribed to millions of people over the decades as a protective measure against heart disease, may have more drawbacks than benefits, according to a review in the Drug and Therapeutics Bulletin.

Although a daily aspirin helps prevent a second heart attack or stroke in people who have already had one, in healthy people any protection against cardiovascular disease may be outweighed by an increased risk of internal bleeding, researchers say. Bleeding is a well-known side effect of aspirin and similar drugs that act as irritants to the stomach lining.

After years of headlines about the benefits of aspirin, yesterday's read: "Aspirin is bad for you". In the last couple of weeks, we have also learnt that a father's presence at childbirth is bad for the mother, that drinking three cups of coffee a day protects against liver disease (for people with hepatitis C) and that consuming alcohol cuts a woman's chances of conceiving by IVF. Yet fathers have been encouraged to attend childbirth for decades, coffee has been implicated in umpteen health scares, and alcohol is known to be good for the heart.

Click here to launch our A-Z guide to the ups and downs of medical research