In December 2007, the World Cancer Research Fund (WCRF) and American Institute for Cancer Research (AICR) announced an update of their 1997 recommendations for the prevention of cancer with a healthy diet and exercise. So what do the guidelines mean for people on a day-to-day basis?
Professor Jim Mann, Professor of Human Nutrition and Medicine at Otego University, New Zealand, member of the expert panel that compiled the WCRF/AICR report believes that addressing the obesity problem is key to reducing the incidence of cancer. "Obesity and lack of physical activity increase the risk of a whole range of cancers, including some of the commonest cancers we know.
Reducing the incidence and prevalence of obesity is an absolutely critical factor in cancer risk reduction," said Professor Mann. He advises that the best protection against cancer requires a balanced eating pattern, including a variety of fruit, vegetables and other foods high on fibre, combined with regular physical activity to promote a healthy body weight.
The incidence of cancer in Asia has risen over the past few decades with deaths from cancers overtaking previous causes of mortality as we race to catch up with Western countries. Cancers of the bowel, breast and lung are now all too common. But there is some good news. Scientists now believe that most cancers are caused by external factors, many of which we can control. That means that, in theory at least, many cancers are preventable. So how do we reduce our risk of cancer?
Putting it into practice
Here's what the recommendations actually mean for the average person trying to follow a healthy diet.
Recommendation 1: Be as lean as possible within the normal range of body weight
What it means: Children and adolescents should keep a healthy weight throughout childhood and adults should try to avoid that gradual creeping up of the scales that often goes hand-in-hand with increasing age. The BMI (weight in kg/height in metres squared) for a healthy weight is usually 20 - 25. The WCRF report recommends that people aim for a BMI at the lower end of the normal body weight range, say a BMI of 21 - 23.
Recommendation 2: Be physically active as part of everyday life
What it means: Try to be moderately active (this means brisk walking or something similar) for at least 30 minutes a day. Aim to gradually increase the time (up to 60 minutes) or the intensity of exercise and cut back on screen time (TV, computer, and gaming consoles).
Recommendation 3: Limit consumption of energy-dense foods.
What it means: Energy-dense foods are foods that are high in calories. While any food will cause weight gain if we eat too much of it, these foods offer calories but little in the way of additional nutrients so they should be consumed in moderation. Energy-dense foods include cakes, biscuits, pastries, soft drinks, sweetened drinks, confectionery, fried and fast foods.
Recommendation 4: Plant foods - fruits, vegetables and grain foods
What it means: Aim for 5 servings of fruits and vegetables every day. The more colourful the better - so aim to include a variety of fruits and vegetables - red, green, purple, yellow, orange.
Choose high fibre cereals and pulses to increase fibre intakes. And avoid grains or nuts that are spoiled or have not been properly stored as they may be infected by toxins from fungus (aflotoxins) which can cause liver cancer.
Recommendation 5: Animal foods
What it means: The WCRF recommendation is to eat no more than 500g of cooked red meat (beef, lamb, pork or goat) a week and to make sure the meat is lean and trimmed of fat. This translates to about 750g of raw meat. The report recommends that processed meats (such as ham, bacon, salami, frankfurters) should be avoided or taken only occasionally in small amounts.
Recommendation 6: Limit alcoholic drinks
What it means: The recommendation is similar to that of most public health authorities - if alcohol is consumed, men should have no more than two standard drinks a day and women should take no more than one drink a day.
Recommendation 7: Watch your salt intake
What it means: Salt and foods that are preserved using salt (such as pickled vegetables) are thought to be a cause of stomach cancer so it's best to limit the intake of salt and salty foods. Of particular note for people living in China, the Panel warned against eating Cantonese style salted fish. This fish, which is often given to children, is thought to increase the risk of naso-pharyngeal cancer.
Recommendation 8: Aim to meet nutritional needs through diet alone
What it means: You don't need supplements if you are taking a healthy diet. While there are studies suggesting that some supplements may decrease the risk of certain cancers, the evidence is conflicting. A healthy well-rounded diet is the best remedy for cancer prevention.
Recommendation 9: Breastfeeding
What it means: Aim to breastfeed for up to six months.
Recommendation 10: Cancer survivors
What it means: People who have survived cancer are advised to follow the 9 recommendations given above if possible. The panel noted that there is no evidence to provide any separate recommendations for people who are living with cancer or who have recovered from the condition.
(Food Facts Asia)
(1.) World Cancer Research Fund and the American Institute for Cancer Research. "Food Nutrition, Physical Activity and the Prevention of Cancer: a global perspective".