That bad food choices can have an adverse effect on your health has been borne out by a rising number of illnesses, from diabetes and cardiovascular disease to tooth decay, sleep apnoea and eating disorders. What’s less commonly known is that a poor diet has been associated with a higher risk of cancer.
A 2019 study published in the medical journal JNCI Cancer Spectrum estimates that diet-related factors may account for 80,110 of the new invasive cancer cases reported in 2015 or 5.2 per cent of that year’s total among US adults. Combined with cancer burdens related to excess weight (7 to 8 per cent) and physical inactivity (2 to 3 per cent), diet-related lifestyle factors contributed nearly 20 per cent of the cancer burden.
“There has been an alarming increase in cancer cases in all parts of the world, and lifestyle changes, along with an ageing population are the main reasons for this increased cancer incidence,” says Dr Arun Warrier, Visiting Consultant – Oncology, at Aster Hospital in Dubai’s Mankhool area, adding, “Diet has been singularly blamed as an important preventable risk factor.”
He points to a global transition from a predominantly rural, fresh and vegetarian diet to one with more of fats and processed foods. “Different components of the diet, whether nutrients, drinks and solid foods, interact with each other, and with other factors. So, diet has to be considered in a holistic, comprehensive manner.”
Overall, cancer causes one in eight deaths worldwide, according to the World Health Organisation’s International Agency for Research on Cancer. It identifies three types of causative factors that interact to affect the cancer process: genetic or host factors such as heredity and inflammation, environmental factors such as viruses and UV radiation, and diet and lifestyle factors, which include nutrients, energy intake, physical activity and smoking.
“Ongoing research on modifiable risk factors for cancer, including dietary habits, estimated that a large percentage of cancer is preventable by behaviour modification,” says Dr Wafaa Ayesh, Director of Clinical Nutrition at Dubai Health Authority. She cites a 2017 scientific review, where a team of Italian, British and American researchers analysed 93 research studies from around the world, covering over 85,000 cases and 2,000,000 exposed individuals. “The most convincing evidence supported an association between healthy dietary patterns and decreased risk of colon and breast cancer. The results suggest a potential role of diet in preventing certain cancers,” she says.
Overall, comprehensive research on diet, physical activity, and weight conducted for the World Cancer Research Fund and the American Institute for Cancer Research (AICR) indicate the benefits of eating mostly foods of plant origin, Dr Wafaa says, while eating more red and processed meats may increase your chances of developing cancer.
“There is no single superfood that protects against the disease but it is a cumulative effect of good dietary habits and behavioural factors that prevent cancer risk.”
For Dubai residents looking to reduce their risk of developing cancer, the experts offered the following recommendations.
Maintain a healthy body weight. Several studies have shown that obesity is linked to a higher risk of many cancers. Dr Warrier advises bringing your weight down to the lowest possible number on the Body Mass Index (BMI) and keeping it there. Your BMI is calculated by dividing your weight in kilogrammes by the square of your height in metres, with a healthy range between 18.5 and 24.9 kg/m2. “Fluctuations in weight are best avoided as this can cause hormonal changes in the body which may be a trigger for some cancers.”
Add plenty of fruits, vegetables and wholegrains to your diet. “Studies suggest that people who eat meals that are rich in fruits and vegetables have a lower risk of cancer,” Dr Wafaa says. “Foods rich in antioxidants such as vitamin C, lycopene, and beta-carotene — these include broccoli, berries, and garlic — showed some of the strongest links to cancer prevention. A variety of chemicals from plants known as phytochemicals also seem to protect cells from harmful compounds in food and in the environment, as well as prevent cell damage and mutations,” she explains.
AICR literature shows that phytochemicals likely help stimulate the immune system, prevent food and drink from becoming carcinogenic, reduce inflammation and oxidative cellular damage, and slow the growth rate of cancer cells. They are grouped into three categories: carotenoids found in red, orange, yellow, and some dark-green vegetables; polyphenols found in herbs, spices, vegetables, tea, coffee, chocolate, nuts, apples, onions, berries; and allium compounds from chives, garlic, leeks, and onions. Eating non-starchy vegetables is thought to protect against oesophageal and some types of lung and breast cancer, while consuming wholegrains and foods containing dietary fibre protects against colorectal cancer, Dr Warrier says. Aim for at least 30g of whole grains such as barley, whole wheat, brown rice or oats per day.
Red and processed meat
Eating more red and processed meats may increase your chances of developing cancer. “The increased consumption of red and processed meats raise the most concern in terms of cancer risk,” Dr Wafaa says. “Any amount of processed meat and more than around half a kilo of fresh meat per week are most strongly linked with a higher risk of cancer.”
Cut out junk food and limit sugary drinks. “Processed and fast foods are high in fats, starches and sugars,” Dr Warrier says. High in calories but low in nutritional value, they come with the risk of developing colorectal, breast and endometrial cancer, he adds.
Sugar-sweetened drinks quickly cause havoc in the body, with the sugar being turned into fat. Try coffee or tea without added sugar instead.
“Coffee may be protective against liver and endometrial cancers. Fruit juices, even without added sugars may promote weight gain and many national guidelines are against consumption of excess fruit juices nowadays,” Dr Warrier adds.
Live a healthier life
Skip the so-called preventive supplements. A large number of studies have been conducted to determine whether vitamins, minerals and other nutrients can reduce the incidence of cancer when taken in pill form, but none of them have been positive, Dr Warrier says.
“The supplementation of carotenoids actually increase the risk of lung cancer. Even in developed countries, vulnerable sections and the elderly have been found out to be lacking in the essential nutrients. Instead, the focus should be on strengthening access to normal food requirements.”