Rhonda Siddall [NOF special correspondent]  01 November 2007

A landmark report has recommended that everyone should aim to be as lean as possible within the healthy weight range to cut their risk of at least six cancers including breast, bowel and pancreatic cancer.  

Identifying weight as a key factor in many cancers, the World Cancer Research Fund (WCRF) report said that convincing evidence exists that excess body fat is the main culprit in many common cancers. The report is the largest review of links between diet and cancer, based on more than 7,000 studies. Ten years ago, when the WCRF published its previous report on diet and cancer, this review said the evidence showed obesity and overweight were implicated in only one type of cancer (cancer of the womb lining). But the report’s authors say that the evidence that has accumulated over the past decade now shows that excess body fat is a significant risk factor for a range of cancers. Professor Sir Michael Marmot, chair of the expert panel that interpreted the evidence, said that even modest weight gains were associated with cancer risk. He told a press conference at the Royal Society yesterday: “The healthiest thing is to be as low as possible within the normal range.”  

 

Commenting on this finding, Tam Fry of the National Obesity Forum said: "The NOF welcomes this report which find that obesity has been linked as a causal factor in a range of cancers.  But how many people know what the normal range is.  Adults may know that their’s is always between BMI 25 – BMI 18.5 but for children the range varies constantly as they grow up.  Very few parents know what a healthy BMI is for their child at any particular age and they should now be given the information"

The full report,  Food, Nutrition, Physical Activity, and the Prevention of Cancer,  can be accessed from the organisation’s website http://www.wcrf.org/ It includes 10 recommendations from a panel of 21 scientists and says it represents the most authoritative and definitive advice there has ever  been on how the general public can prevent cancer. The recommendations are:

•    BODY FATNESS – Be as lean as possible within the normal range of body weight. Ensure that body weight through childhood and adolescent growth projects towards the lower end of the normal BMI range of 21. Maintain body weight within the normal range from age 21. Avoid weight gain and increases in waist circumference throughout adulthood
   
•    PHYSICAL ACTIVITY – Be physically active as part of everyday life. Aim for at least 30 minutes moderate exercise per day or, better still, 30 minutes vigorous exercise. Limit sedentary activities such as watching television

•    FOODS AND DRINKS THAT PROMOTE WEIGHT GAIN – Limit consumption of energy-dense foods. Avoid sugary drinks. Consume fast foods sparingly, it at all

•     PLANT FOODS – Eat mostly foods of plant origin. Eat at least five portions of a variety of non-starchy vegetables and of fruits every day. Eat relatively unprocessed cereals and pulses with every meal. Limit refined starchy foods

•     ANIMAL FOODS – Limit intake of red meat and avoid processed meat. People who eat red meat to consume less than 500 g (18 oz) per week
 
•     ALCOHOLIC DRINKS – Limit alcoholic drinks to no more than two for men and one drink a day for women

•    PRESERVATION, PROCESSING, PREPARATION – Limit consumption of salt; avoid mouldy cereals or grains. Avoid salt-preserved, salted or salty foods and ensure intake if salt is taken in the diet is less than 6g a day

•    DIETARY SUPPLEMENETS – Aim to meet nutritional needs through diet alone
 
•    BREASTFEEDING – Mothers should breastfeed to reduce their cancer risk and children should be breastfed exclusively up to six months to offer some protection against cancer risk in later life

•    CANCER SURVIVORS – Follow recommendations for cancer prevention.

Echoing Tam Fry, David Haslam added  “ NOF believes that the key message from this report is that even modest weight gain increases health risks and we know that modest weight loss promotes health benefits.  We should be encouraging people to help themselves to stay lean but also be heartened by the fact that losing even small amounts of weight is of benefit. Finally, there are  many reasons why individuals can find it difficult to stick to healthy eating advice and it is important to keep this new advice in perspective: there are healthy diets and unhealthy diets.”