It is estimated that over 30 to 50 % of the cancer cases and cancer deaths each year can be attributed to diet as well as other related lifestyle factors according to WHO and UICC reports. The food we eat can affect our risk of developing cancer, both directly and indirectly. Food preparation & habits have been developed over centuries based on considerable knowledge by the ancestors. Currently the food habits world over are changing from traditional to western diet due to many factors leading to a major lifestyle change. Scientists understand the relationship of diet and cancer by lot of research and studies such as case control studies, cohort studies and cross sectional studies.
The food and cancer are related in many ways :
- The food contains substances which can promote cancer (carcinogens) as well as cancer preventing chemicals. Cancer preventing agents are naturally occurring such as antioxidants, phytochemical etc. These are abundant in coloured vegetables and fruits.
- Whole cereals have high fibre and nutritive value than refined products. Consumption of whole cereals is considered to be protective against many lifestyle diseases. A variety of high fibre containing cereals is beneficial. Wholegrain foods are higher in fibre and nutrients, which can help fill you up for longer and keep a healthy weight. Fibre from whole-grains can also help reduce the risk of bowel cancer.
- Total caloric intake of the diet is directly related to cancer. Excessive calories can lead to obesity and thus cancer. High-calorie foods and drinks (such as fried foods, biscuits, savoury snacks, confectionery, sugary drinks and fast foods) can lead to weight gain, as it’s easy to take in lots of calories from smaller amounts of food. In particular, researchers have found that a diet that causes blood glucose levels to spike is associated with an increased risk of several cancers, including stomach, breast and colorectal cancers.One study in over 47,000 adults found that those who consumed a diet high in refined carb were almost twice as likely to die from colon cancer than those who ate a diet low in refined carbs.
- It is well established that overweight is associated with increased incidence of some cancers. Keeping a healthy weight is the second best thing you can do to cut the risk of cancer, after not smoking.
- Adequate exercise is necessary along with healthy food, which can keep overweight in check and by itself an independent risk factor for cancer.
- Excessive sugars, salt, oils and fats can directly and indirectly lead to increase incidence of cancers. Aerated, sweetened drinks and sugary drinks in excessive quantities add to calories and thus weight.
- Consumption of meat and processed meat are directly related to the higher incidence of cancer due to high content of carcinogens in the meat and acquired by the various cooking and preservation processes. Many studies have concluded of this fact and in many countries dietary guidelines have incorporated the recommendation of least consumption of red meat and processed meat. Observational studies found a direct relationship between red meat and the risk of bowel cancer, stomach and possibly pancreatic cancer. Processed and red meats can also be high in calories, which can contribute to weight gain. Healthier choices of protein foods include fish, fresh chicken, pulses (e.g. beans, lentils and chickpeas) and eggs. Processed meat includes ham, bacon, salami and sausages. Red meat includes all fresh, minced and frozen beef, pork and lamb.
- Fruits and vegetables contain antioxidants which help repair damaged cells. Of these, cruciferous vegetables and berries pack an extra punch with a multitude of vitamins, fibre, and disease-fighting phytochemical. In addition to berries, top choices include broccoli, kale, cabbage, radishes, and rutabaga. Low intake of fruits and vegetables has clearly been demonstrated to be associated with more cancers. Carcinogens do not exist in most vegetarian diet but may form during high temp grilling, burning etc.
- High intake of total and saturated fat is associated with increased risk of breast, colon, lung and prostate cancers. High fat diets are associated with obesity, which is linked with cancer of the colon, rectum, oesophagus, gall bladder, breast, endometrium, pancreas, and kidney.
- Observational studies and case control studies indicate that fiber-rich diets are associated with a protective effect in colon cancer. High fiber is present in fruits, vegetables, whole cereals, pulses, and low in junk and fast food,
- Fast food and junk food of all types only add to calories and do not have much nutritional value without much or any vitamins, minerals or roughage and are associated with 1.5 times of cancer than with normal diet.
- The method of preparation of food and storage can determine ability of food to increase susceptibility to cancer. Heating to very high temperatures with grilling, frying, sautéing, broiling and barbecuing, can produce harmful chemicals and their prolonged exposure has been associated with increased cancers. While steaming, stewing or boiling or marinating decrease the incidence of cancer.
- Alcohol consumption of any kind and quantity can lead to increased incidence of cancers.
Food additives, spices and garnishings
- Food additives can also determine the ability of food to cause cancer. More than 2,500 chemical substances are intentionally added to foods to modify flavor, color, stability, texture, or cost. In addition, an estimated 12,000 substances are used in such a way that they may unintentionally enter the food supply. These substances include components of food-packaging materials, processing aids, pesticide residues, and drugs given to animals. An unknown number of naturally occurring chemical contaminants also find their way into food. The most notable of these are the products of mold growth called mycotoxins, which include the aflatoxins, which are associated with increased cancer risk. Residues of pesticides that can induce tumors may contaminate foods through their application directly on crops or from other sources of environmental contamination.
- Various spices in food in small quantities help in prevention of cancer. Literature is abound with information on spices, herbs, garnishing, about their health benefits such as prevention of cancers, atherosclerosis, and other lifestyle diseases. Spices such as cur-cumin found in turmeric is referred to as “mother of spices” as it is assumed to have many properties such as anti-inflammatory, anti-septic, anti-carcinogenic, anti-atherogenic etc. Other spices such as cloves, cinnamon, black pepper, saffron, garlic, coriander seeds, cumin seeds also are known to have many preventive properties. Way of cooking spices also makes a huge difference in their beneficial properties. A study clearly showed that deep frying in oil retained the properties of selected spices such as turmeric, Probably this is the basis of the traditional ‘tadka’ !! The old generation knew a lot about the food than our generation.
- Garnishing such as coriander, onions, lemon, green chillies have their own health benefits of vitamins, minerals apart from visual and fragrance.
- It also must be remembered that spices can be harmful if used in excesses. It is also well established excessive chillies and other spices is also associated with gastric cancers. This is seen in southern part of India and north eastern states.
- Use of Moderate spices and garnishing of good quality made in traditional way is probably the best way.
- Improper storage can lead to conversion of existing chemicals turn into harmful substances, which can be carcinogenic. Studies have convincingly revealed that use of refrigerator for food storage decreases the gastric cancers. Food prepared, stored in low food hygiene conscious food sellers, have higher incidence of the incidence of gastric, colonic and rectal cancers. Overnight left over food especially non vegetarian food might get infected and also chemicals may get changed to carcinogenic substances.
Fasting and cancer protection
Recent studies have indicated that fasting periodically can decrease the incidence of cancers in the long run.
Adopting healthy approaches to living can reduce the risk of cancer recurrences and improve outcomes during treatment.