Here’s how to eat right to prevent cancer
The article below appeared in the Feb 3 issue of Health with Perdana, a regular column in The Star by Perdana University faculty members. This week’s article is contributed by Prof. Srikumar Chakravarthi, Professor of Pathology and Acting Dean at the Perdana University Graduate School of Medicine.
One-third of all cancer deaths are preventable and can be attributed to lifestyle choices that we all make every day. Poor diet, lack of physical activity, and consuming alcohol and tobacco are all associated with an increased risk of cancer.
Simply changing what and how much we eat can significantly reduce the risk. It is also important to note that a healthy, balanced diet should come from natural and whole foods, not from vitamin supplements.
Being overweight or obese has been linked to cancers of almost all the organs in the body, including kidney, pancreas, liver and breast. Given the lethality of some of these cancers, we have to be mindful of our weight and control our caloric intake.
Indeed, the most important factor in the relationship between diet and prevention of cancer is healthy weight maintenance throughout life. Weight maintenance can be achieved by balancing caloric intake from food and beverages, with physical activity.
Research suggests that too much dietary fat, especially unhealthy fats like saturated and trans fat, may lead to an increased risk for a variety of cancers such as colon, rectum and prostate cancer.
The fat content in meat may contribute to the production of secondary compounds in the body that act as carcinogens. Major sources include cheese, pizza, desserts and red meat.
Perhaps we can replace that “cheese leleh burger” with foods containing healthy fats, i.e. essential omega-3 fatty acids found in seafood and most plant-based oils.
Meanwhile, a high intake of processed meat and red meats (beef or pork) may be associated with an increase in stomach and colorectal cancers. Evidence suggests that risk for colon and rectal cancer may increase by 15%-20% for every 100g of red meat or 50g of processed meat per day.
Red meat contains compounds such as iron that may cause the formation of free radicals. Processed meats contain nitrates, which have been shown to cause cancer in laboratory animals and are suspected of causing cancer in humans.
Consumption of processed meat also increases one’s exposure to carcinogenic chemicals from methods of preservation that involve smoke or salt.
There are still no robust studies that have conclusively shown that you should eliminate them entirely from your diet, but for those who are already predisposed to cancer (e.g. having family members with cancer), it is smart to limit your consumption of these two foods.
Carcinogens are also present in certain foods and evidence suggests that eating salt-cured, smoked, pickled or charcoal-broiled foods can increase the risk for cancer. Rates of stomach and oesophageal cancer cases are especially high in parts of the world where food is often prepared using these methods.
We should also be mindful of how we cook. A substance called benzopyrene is formed when fat from meat drips on to hot coals during broiling. The rising smoke then deposits this carcinogenic substance on the meat.
High-temperature frying may convert some of the meat proteins into products that damage our cells, which can lead to tumours and cancers.
The fat in foods like the cheese and meat in this burger may contribute to the production of carcinogens in the body.
Specific nutrients and food constituents of fruits, vegetables and whole grains may act as anti-cancer substances when consumed in the proper amounts found in a varied diet.
Consuming fruits, vegetables, and whole grains may also help in healthy weight maintenance – the ultimate goal in cancer prevention, according to research.
Wholegrain plants such as wheat, oats, rice and barley contain vitamins, minerals and dietary fibre, which may help prevent cancers of the gastrointestinal tract, such as colon and rectal cancer.
Dietary fibre is the material from plant cells that the body cannot digest completely and it is found in vegetables, legumes, fruit, whole grain cereals, nuts and seeds.
Fibre provides bulk in the diet and it helps move food through the intestines and out of the body at regular intervals. However, fibre supplements are not recommended.
Plants contain many beneficial compounds such as vitamins, minerals, antioxidants, phyto-chemicals and fibre, which may act to reduce the risk for cancers such as lung, mouth, pharynx, larynx, oesophagus, stomach and colo-rectal.
There are several groups of fruits and vegetables that may offer particularly protective effects, such as dark green and orange vegetables, cruciferous vegetables (cabbage, broccoli), flavonoids (soy, tea), legumes, sulphides (garlic, onion) and tomato products.
Antioxidants are compounds present in fruits and vegetables that help protect tissues from being damaged. Tissue damage is linked to increased cancer risk; therefore antioxidants may play a role in cancer prevention.
Types of antioxidants include vitamin C (ascorbic acid), vitamin E, and the carotenoids – vitamin A and beta-carotene. Their protective effect is only observed when one consumes antioxidants from plant foods such as fruits and vegetables, and not from supplements.
Phytochemicals (or phytonutrients) include dark green and orange vegetables, cruciferous vegetables, flavonoids and sulphides, and show a decrease in risk for cancer, but the relationship is unknown.
Take In Moderation
Heavy consumption of alcoholic beverages (more than two drinks per day for men and more than one drink per day for women) increases the risk of mouth, pharynx, larynx, oesophagus, liver, pancreas, bladder, colorectal and breast cancers.
The link between cancer and alcohol is complex because frequent alcohol consumption may result in many health problems. The carcinogenic effect may result from the direct contact of alcohol on the mouth, pharynx and oesophagus.
Heavy drinking can result in liver cirrhosis, which may lead to liver cancer. Alcoholics commonly have nutritional deficiencies because alcohol contains only empty calories, and food intake is often compromised. If heavy drinkers also smoke cigarettes, the risk for cancer is compounded.
Alcohol is high in calories and low in nutrients. Calories from alcohol can contribute to weight gain, again a risk factor for cancer. The risk factors for cancer act cumulatively to contribute to the occurrence of cancer; they are not necessarily the cause of cancer.
Lifestyle risk factors for cancer are usually preventable and avoiding certain factors may lower one’s risk in developing cancer. Avoid excess weight gain by limiting high caloric foods and beverages, decreasing food portions, limiting high calorie snacks and engaging in regular physical activity.