It is well known that maintaining a healthy diet and lifestyle is good for general health, but could it actually prevent cancer? A great deal of research has been trying to answer this question over the past few years, and now scientists believe that being a healthy weight is one of the most important things you can do to reduce your risk.

There is now convincing evidence that body fat is a cause of six different types of cancer, including breast and bowel. So it is important that adults do all they can not to put on weight.

It comes as no surprise that the best way of preventing weight gain is to limit your intake of energy-dense foods such as chocolate, pizza and biscuits. Instead, have foods that are lower density, such as fruit, vegetables and wholegrains.

There is also evidence that fruit and vegetables may protect against cancer, including cancer of the mouth, pharynx, larynx and stomach.

Another way to help prevent weight gain is by avoiding sugary drinks, including fizzy drinks and cordials, says Lisa Cooney, head of education for the World Cancer Research Fund (WCRF).

“They are quite high in calories but do not make us feel full,” she adds. “Even with fruit juice, it is best not to drink more than one glass a day.” Try having water as a substitute, Lisa advises, or unsweetened tea and coffee.

Meanwhile, the message regarding alcohol can be confusing. While there is evidence that it increases some forms of cancer - including breast cancer for women and bowel cancer among men - there is also evidence that modest amounts may help prevent heart disease.

“With alcohol, when it comes to cancer prevention, the best amount to have is none at all,” says Lisa. “However, if you do drink, we recommend limiting your intake to two drinks a day for a man and one a day for a woman.”

Advice over red meat is also contradictory. Frequently linked to cancer in media reports, red meat can form part of a healthy diet according to the WCRF. However, you should have less than 500g of red meat a week, remembering that a medium steak amounts to about 145g, while a portion of roast beef weighs in at about 90g.

And what about the hype surrounding so-called “superfoods”, which we are told can reduce the risk of cancer and heart disease?

These claims have sent sales of salmon, blueberries, walnuts and spinach through the roof. But is it all just a marketing ploy?

“Eating a wide range of fruits and vegetables in a variety of colours is your best bet for a healthy diet that will help reduce your cancer risk,” says Richard Evans of the WCRF. “That is the only way you can get the full range of benefits of all the different substances found in these foods. Doing this, being physically active and maintaining a healthy weight is much better than spending lots of money on the latest fashionable berry.”

To encourage healthy eating among pupils, visit www.greatgrubclub.com. For free KS1 and 2 healthy lifestyle resources, or details on Fruity Friday on May 16, visit www.fruityfriday.org.