A third of cancers are caused by diet and lack of exercise and could be prevented, according to a new report from the World Cancer Research Fund that took 200 scientists 5 years to produce. They reviewed 7,000 studies on causes of cancer and have now published the most authoritative overview of the role that food, drink, obesity and exercise play in causing cancer. So here¹s their top 7 tips for a healthier life, free of cancer, followed by two more from me at the end:

1. Avoid being overweight. Excess body fat was found to trigger various cancers and a body mass index (BMI) of 25 or less should be your goal. To calculate your BMI, divide your weight in kilograms by your height in meters squared. For example 80kgs divided by 1.8 meters squared = 24.7. Over 25 is overweight, and over 30 is obese. Under 18.5 is considered unhealthy also.

2. To keep that weight off, the next tip is an obvious one: Exercise regularly. Thirty minutes of vigorous exercise daily, or 60 minutes of moderate exercise. If like me you know you should but don¹t make the time ­ it's time to start.

3. Still on the theme of avoiding excess weight, the third tip is to avoid energy dense foods rich in fat and sugar. Obvious culprits are fried foods, fast food, and sugary soft drinks.

4. So on a more positive note, what should you eat? Lots of fruits and vegetables. At least 5 portions a day, though nine is better. Nutritionists actually used to recommend 9 portions of fruit and veg a day, and the advice only changed to 5 to give people eating very little fruit and veg a more realistic target! I once asked Craig Sams what he thought of the 5-a-day campaign and he replied, 'I'm not halving my fruit and veg intake for anyone!' In addition to fruits and vegetables the WCRF recommend eating cereals, grains or pulses with every meal.

5. Next is a controversial tip that was all over the media when this report was first released. Eat less red meat, and don't eat preserved meat like ham and bacon at all. Too much red meat was found to raise the risk of various cancers, and regular consumption of meats preserved with sodium nitrite, like ham and bacon, were found to raise the risk of cancer by around 10 per cent. See my additional tip 9 below for an important caveat to this advice.

6. Don't drink too much alcohol. The WCF panel recommended women should have no more than one drink a day, and men no more than two.

7. Reduce your salt intake to no more than 6 grams a day. Salt's been known to raise your blood pressure for years, but excessive consumption of salt or salty foods has now also been linked to a greater cancer risk.

So they're the WCRF¹s top 7 tips for avoiding cancer, but there are at least two more I think really should be pointed outŠ

8. If you smoke, quit. According to the WCRF, the seven tips above ³could play almost as big a role as stopping smoking in preserving us from disease.² So you can see how significant a difference stopping smoking can make ­ a bigger difference than the next 7 anti-cancer tips combined! If you don¹t smoke, it may be a revelation to you that not exercising or eating healthily is almost as bad as smoking, so a good incentive to follow these seven tips, huh?

9. And finally, a capstone tip that the WCRF overlooked. Go organic.

Occupational and environmental exposures to pesticides have been repeatedly linked to various cancers, and dietary exposures are an unnecessary burden on your body. So yes, eat more fruit and veg as in tip number 4 above, but make them organic. You¹ll feel better about eating them and probably find it easier to eat more fruit and veg because of it. Furthermore, the advice in tip 5 above needs one important caveat: If you enjoy red meat, ham and bacon, enjoy them in moderation by making them organic. Organic red meat actually contains more of various substances known to be cancer-protective, and organic ham and bacon aren¹t preserved with sodium nitrite ­ the main risk factor leading to the WCRF advice to avoid them completely.

By Shane Heaton, BFA Nutritionist

www.bfa.com.au