Healthy eating – what does the evidence say?

There's no shortage of advice about how to eat healthily. But what's the evidence behind those guidelines? Can you really cut your risk of cancer or heart attack by changing your diet? Where does the evidence for '5-a-day' come from?

The BMJ Group's consumer health team looked for the answers to these and other key questions, and came up with some surprising answers. The results of their analysis is now on the Group's consumer health website, Best Health (besthealth.bmj.com).

Here's a selection of findings:

Eating more fruit and vegetables seems to reduce the risk of heart disease, but only by a small amount. One study found that eating five portions of fruit and vegetables a day reduced the chances of heart disease by about six in 1,000 compared to people eating three or fewer.
Low-fat diets work to lower cholesterol by a small amount, and reduce the risk of heart attacks and strokes for people with heart disease, but we don't know what effect they have on healthy people.
Keeping to a healthy weight, not drinking too much alcohol, not eating too much red meat, and taking plenty of exercise are the best ways to avoid cancer. There's no magic diet or superfood that prevents cancer.
The Mediterranean diet is one of the healthiest ways to eat. There's evidence to show that people who eat this type of diet are likely to live longer, less likely to have heart attacks, and less likely to get certain types of cancer. In one study, the researchers calculated there would be three to five fewer deaths each year among 1,000 people who ate a mainly Mediterranean diet.

Anna Sayburn, Head of Consumer Health at BMJ Group, said: "It's easy to get confused about healthy eating, when we're bombarded by stories that tell us a particular food either causes or cures cancer, and when complicated diets followed by celebrities are featured in magazines. That's why we thought it was time to look at the science behind food advice."

The team reviewed published research about diet and health to draw together an analysis of what the evidence tells us about healthy eating.  The results are published on the Best Health website, which provides news and in-depth information about medical conditions and treatments, all based on what the evidence says.

Ms Sayburn added: "We already have a wealth of information for people who have a medical condition to help them make decisions about their treatments. We wanted to use our rigorous standards of evidence appraisal to help healthy people make good choices about their diet, so they can stay healthy."

The team plans to look at alcohol and exercise in the next appraisals.

To view the Healthy Eating topic, visit: http://bit.ly/NJ2Sse