Healthy eating to lower your cancer risk

Listen to top health experts explore the ins and outs of lifestyle habits that can lower your risk of developing cancer significantly:

• ‘What is cancer?’, here.
• ‘The Cancer Journey’, here.

According to CANSA, for the great majority of people who are not smokers, the most important modifiable determinants of cancer risk are weight control, levels of physical activity and dietary choices. “Only 5 to 10% of all cancers occur as a result of inherent genetic alterations,” says registered dietician Jeske Wellmann. “It’s estimated that one third of anticipated cancer deaths can be attributed to nutrition and lifestyle behaviours - poor diet, physical inactivity, alcohol and tobacco use and being overweight or obese. And, with the World Health Organization (WHO) predicting a 70% increase in global cancer rates by 2035, the only way to achieve a good quality of life - and reduce your cancer risk - is by taking control of your lifestyle, with nutrition playing a central role.”

Foods that increase your cancer risk

Wellman explains that there are a number of scientifically acknowledged cancer enhancers, or high risk factors that promote cancer, including alcohol, increased body weight, excessive fat and protein intake, as well as the consumption of smoked, preserved and charred food. “Alcohol intake is associated with an increased risk for cancers of the mouth, pharynx, larynx, oesophagus, lung, colon, rectum, liver, and breast (for pre- and post-menopausal women). Being overweight increases your risk of developing breast, uterine, cervical, pancreatic, prostate, lung and colon cancer. This is because an increase in body weight is associated with an impaired immune system, an increase in inflammation, as well as insulin resistance which leads to an increase in the production of Insulin-like growth factor (IGF-1), a potential cancer-causing compound”. High fat diets are also not cancer-friendly as they often involve a higher meat intake with less veggies in the diet, which, says Wellman, “results in increased energy intake and increased obesity. Charring or cooking meat at high temperatures over an open flame (200°C and higher) is also not recommended as this can cause the formation of polycyclic aromatic hydrocarbons (PAHs) which are highly carcinogenic. And, every 50g of processed meat you consume each day increases your risk for colorectal cancer by 18%.”

What you should eat

Current prevention guidelines suggest that individuals who eat more vegetables and fruit experience less weight gain and greater satiety and are less likely to develop obesity, thereby reducing their overall cancer risk, says Wellman. “In addition, plant foods may aid in cancer prevention by functioning as cancer inhibitors through anti-inflammatory mechanisms, while the phytochemicals, vitamins, minerals and dietary fibre found in fruit, vegetables and whole grains have also demonstrated functions in preventing and treating lifestyle diseases.”

Wellman advocates following the traditional Mediterranean diet if you want to lower your cancer risk and improve your overall health in line with the American Cancer Society’s and CANSA’s recommendations. This involves eating a high proportion of plant foods - at least 2.5 cups of vegetables and fruits each day - and limiting the consumption of high-fat food and foods from animal sources, including red and processed meat - no more than 500g (cooked weight) a week of red meat, such as beef, pork and lamb and little, if any, processed meat such as ham and bacon.

The Mediterranean diet emphasises eating primarily plant-based foods, such as fruits and vegetables (Mediterranean people who eat this way take in up to ten antioxidant servings a day), whole grains, legumes and nuts and using herbs and spices instead of salt to flavour food. Fish and poultry are consumed twice a week – seafood emphasised - while red meat is limited to a couple of times a month. Avocado, nuts and extra virgin olive oil are examples of healthy fats included in this diet. Red wine is enjoyed but very much in moderation and other forms of alcohol are limited. Meals are enjoyed with family and friends and plenty of exercise is encouraged. Saturated and trans-fats, processed flours and grains, colourants and food additives are absent in this way of eating.

CANSA offers the following additional risk reduction recommendations:

1. Remember that the best way to achieve a healthy body weight is to balance energy intake (food and beverage intake) with energy expenditure (physical activity). Keeping track of food intake and physical activity has been shown to be effective in weight management.
2. Kilojoule intake can be reduced by decreasing the size of food portions - limiting between-meal snacks and limiting the intake of foods and beverages that are high in kilojoules, fat, and/or added sugars, and that provide few nutrients (e.g. many fried foods, cookies, cakes, candy, ice cream, and sugar-sweetened beverages). Rather replace with healthy choices such as vegetables and fruits, beans, whole grains, and lower kilojoule beverages.
3. Choose fish and poultry instead of red and processed meats. Beans are another healthy source of protein as they are especially rich in biologically active constituents and nutrients that may protect against cancer.
4. Aim to move more and sit less with the goal of exercising for at least 30 minutes a day, most days of the week .
5. Avoid all forms of tobacco and limit your alcohol consumption.