Diet and exercise
We know that overweight and obesity, physical inactivity, poor diet and drinking alcohol all contribute to cancer risk. There are also indications that a healthy lifestyle can improve quality of life for cancer patients and reduce the risk of the disease recurring.
Much of the evidence of these links has emerged only in the past decade. It continues to be a busy area of research and one that has attracted significant media and public interest. There are almost daily reports of new research claiming certain foods can reduce our cancer risk, exposing the public to messages which are often conflicting and inconsistent.
Cancer Council can help you interpret this information, and provides clear recommendations on how you can minimise your cancer risk through improved nutrition and physical activity.
The obesity chapter, which also covers overweight, physical activity and nutrition, of our National Cancer Prevention Policy provides comprehensive information on the role these factors play in cancer, including statistical data, the evidence base, policy context and priorities.
Cancer Council Australia's Nutrition and Physical Activity Committee has developed a number of position statements addressing the link between nutrition and cancer.
Meat and cancer prevention
The relationship between meat consumption and the risk of cancer especially colorectal (bowel) cancer, has been controversial. The consumption of red meat and processed meat appears to be convincingly associated with a modest increased risk of colorectal cancer.
There is limited suggestive evidence that red meat may be associated with an increased risk of oesophageal, lung, pancreatic and endometrial cancer, and processed meat with oesophageal, lung, stomach and prostate cancer.
Despite these concerns, Cancer Council recognises that lean red meat is an important contributor to dietary iron, zinc, vitamin B12 and protein in the Australian diet.
Cancer Council recommends people consume moderate amounts of unprocessed lean red meat. People should also limit or avoid meats high in fat and salt and those that are charred or burnt, and instead choose lean cuts of meat and chicken, eat more fish and plenty of plant-based foods such as fruit, vegetables and wholegrain cereals.
This position statement explains these and other recommendations, and documents the evidence base that supports them.
Fruit, vegetables and cancer prevention
Fruit and vegetables are high in nutrients that are potentially protective against cancer. They also play an important role in weight management. As obesity is a known risk factor for cancer of the colon, breast (in postmenopausal women), endometrium, kidney and oesophagus, fruit and vegetables may also protect against cancer indirectly by helping to maintain a healthy body weight.
Cancer Council recommends that people eat a variety of different fruit and vegetables to obtain maximum benefits.
Although there has been a slight weakening of the evidence supporting the role of fruit and vegetables in reducing the risk of some cancers, overall the evidence is suggestive of a protective effect. Recent studies show that fruit and vegetables are protective against oral, laryngeal, oesophageal, colorectal and lung cancers.
This document summarises the evidence on how fruit and vegetable consumption can contribute to reducing cancer risk.
Fibre, wholegrain cereals and cancer
Consumption of fibre and wholegrain cereal foods is associated with a lower risk of obesity and related lifestyle illnesses such as type 2 diabetes and cardiovascular disease. Evidence is now building for the importance of regularly consuming wholegrain foods as part of a cancer prevention diet.
Dietary fibre probably decreases the risk of colorectal cancer, while there is limited suggestive evidence it may also be associated with a lower risk of oesophageal cancer.
(There is insufficient evidence on dietary fibre to make a conclusion regarding other cancers, such as breast, prostate and ovarian.).
Dietary fibre is therefore encouraged as part of a varied and nutritious diet. Women are advised to eat 25 grams of dietary fibre per day and men to eat 30 grams per day.
As the benefits of fibre may derive from multiple nutrients working together, it is also better to consumer fibre through whole foods rather than a dietary supplement.
This position statement describes dietary fibre and explores the epidemiological evidence and biological mechanisms in relation to fibre consumption and its impact on reducing cancer risk.
It explains why Cancer Council Australia recommends people eat at least two serves of wholegrain or wholemeal foods every day (or ensure about half their daily serves of breads and cereals are wholegrain or wholemeal varieties) and eat at least two serves of fruit per day and five serves of vegetables per day including legumes.
Dairy foods, calcium and cancer prevention
Calcium is an important nutrient for bone and dental health, with dairy foods being the major source of dietary calcium in Australia. Dairy foods such as milk, yoghurt and cheese are also good sources of calcium, protein, vitamin A, vitamin B12, magnesium, phosphorus, potassium, riboflavin and zinc.
In terms of cancer risk, dairy foods and calcium have shown both protective and harmful effects. Overall the proven health benefits of dairy foods outweigh the unproven harms.
Dairy foods should be encouraged as part of a varied and nutritious diet as they are essential to maintain good bone and dental health. Cancer Council supports the Australian Dietary Guidelines, which encourage people to eat at least three serves of dairy foods (milk, cheese and yoghurt) each day. This position documents the evidence that supports Cancer Council's position, as well as further information about the protective and potentially harmful effects of consuming dairy products.
Soy, phyto-oestrogens and cancer prevention
Phyto-oestrogens are bioactive substances found in plant foods, with naturally occurring oestrogenic activity. Soy beans and other foods containing soy, such as tofu, tempeh and soy milk, are rich sources of phyto-oestrogens.
There is limited suggestive evidence that soy foods may lower the risk of prostate and stomach cancer. The evidence for soy foods and cancer of the pharynx, oesophagus, pancreas, breast and endometrium is limited with no conclusion possible. There is no association between soy foods and the risk of other cancers, including bowel cancer.
While they may have a protective effect, there is also some evidence that phyto-oestrogens might stimulate the growth of existing hormone dependent cancers.
This position statement describes phyto-oestrogens and explains why Cancer Council supports the consumption of soy foods in the diet.
Cancer Council does not recommend or support the use of supplements such as soy protein isolates or isoflavone capsules for healthy men and women to prevent cancer.
Cancer Council does not recommend or support the use of supplements for breast cancer survivors. There is evidence to suggest that women with existing breast cancer or past breast cancer should be cautious in consuming large quantities of soy foods or phyto-oestrogen supplements.
Salt and cancer risk
Salt is a compound of the elements sodium and chlorine, and is commonly used to flavour and preserve foods. Most of the salt we eat comes from processed and packaged foods such as sauces, processed meats, stock cubes and soups as well as breads and cereals.
Both salt and salt preserved foods are probably associated with an increased risk of stomach cancer. Salt is also a leading cause of high blood pressure and cardiovascular disease.
This position statement explores the epidemiological evidence around salt and cancer risk and explains why Cancer Council supports the recommendation made by the National Health and Medical Research Council (NHMRC) Dietary Guidelines. Cancer Council recommends that people choose foods low in salt, and avoid adding salt at the table or in cooking.
Cancer Council supports efforts to reduce population salt intakes, particularly through reducing salt levels in processed and takeaway foods.
For general health and wellbeing, people should aim to consume no more than 2300 mg of sodium (6 grams of salt) per day.
Ways to limit salt intake include purchasing ‘no added salt’ or ‘low salt’ foods in the supermarket, flavouring foods with herbs and spices instead of salt, eating more fresh fruit and vegetables and limiting processed and take-away foods.
The consumption of sugar-sweetened beverages is associated with increased energy intake and in turn, weight gain and obesity. It is well established that obesity is a leading risk factor for some cancers.
The term ‘sugar-sweetened beverages’ refers to all non-alcoholic, water-based beverages with added sugar, including sugar-sweetened soft drinks, energy drinks, fruit drink, sports drinks and cordial.
The consumption of sugar-sweetened beverages is particularly high among young Australians, men, and in lower socio-economic groups.
This position statement outlines Cancer Council Australia's recommendations to encourage children and adults to reduce their consumption of sugar-sweetened beverages.
Tea and cancer prevention
Tea is one of the most widely consumed beverages in the world. Studies in cell cultures and animal models have linked tea intake with a reduced risk of cancer.
Overall, epidemiological studies show that drinking tea is more likely to be beneficial than harmful in terms of cancer risk, although the risk of cancer appears to be reduced only slightly. Green tea may lower the risk of colorectal cancer, but the amount of evidence for this association is limited.
It is unclear if tea drinking is linked to oesophageal, stomach, colorectal prostate, breast, pancreatic, lung and kidney cancer, as studies have shown inconsistent results. However a slight trend towards risk reduction has been seen for green tea and cancers of the prostate, breast and stomach.
The evidence does suggest there is no association between tea drinking and oral, pharyngeal, nasopharyngeal, ovarian, bladder and thyroid cancer.
This position statement explores the epidemiological evidence around tea and cancer prevention. Cancer Council supports people drinking tea, whether it is green, black or oolong. Tea is a rich source of antioxidants, which are an important component of a healthy diet.
Cancer Council recommends caution in the consumption of tea or other beverages at very high temperatures, due to the risk of scalding and the evidence that hot tea may increase the risk of oesophageal cancer.
Omega-3 fatty acids, fish and cancer prevention
Omega-3 (n-3) fatty acids (FAs) are associated with a range of health benefits. Oily fish such as swordfish, Atlantic salmon, gemfish and Spanish mackerel, are rich sources of n-3 FAs.
There is limited suggestive evidence for an association between increased fish consumption and a reduced risk of breast, colorectal and prostate cancer; and between a higher n-3 to omega-6 (n-6) FA ratio in the diet and a reduced risk of breast cancer.
This position statement explores the epidemiological evidence around omega-3, fatty acids, fish and cancer prevention. The available research studies are too limited in number, consistency and quality to permit a conclusion of a probable or definite link between n-3 FAs and a reduction in cancer risk.
The scientific evidence for a range of health conditions clearly supports people including n-3 FAs from both marine and plant sources as part of a balanced diet. n-3 FAs are known to help reduce the risk of heart disease, lower triglycerides and relieve inflammatory conditions such as rheumatoid arthritis and inflammatory bowel disease.
Therefore Cancer Council recommends people eat fish (preferably oily) at least two times per week and include some plant foods and oils rich in n-3 FAs in their diet.
Cancer Council encourages all people to follow the recommendations of the Foods Standards Australia and New Zealand (FSANZ) about consumption of fish high in mercury.
Beta-carotene and cancer risk
Beta-carotene is a type of carotenoid, an important precursor to vitamin A. Vitamin A is essential for biochemical and physiological processes in the body including vision, reproduction, cellular differentiation and immunity. Beta-carotene can be obtained from dark-green leafy vegetables and some (not all) yellow and orange coloured vegetables and fruits, as well as dietary supplements.
Studies have shown there is an association between beta-carotene supplements and an increased risk of lung cancer in current smokers. Beta-carotene supplements are unlikely to have a substantial effect on the risk of prostate and non-melanoma skin cancers.
Dietary beta-carotene probably reduces the risk of oesophageal cancer and is unlikely to have a substantial effect on the risk of prostate and non-melanoma skin cancers.
Cancer Council recommends people obtain their nutritional requirements from whole foods, rather than individual nutrients in a supplement form, and avoid taking high doses (>18 mg) of beta-carotene supplements, especially if they smoke. This position details a number of other Cancer Council recommendations and the evidence that supports them.
Folate and reducing cancer risk
Folate is a water soluble B-vitamin present naturally in foods such as wholemeal bread, legumes, green leafy vegetables (e.g. broccoli, lettuce and cabbage) and liver that is essential for biochemical and physiological processes in the body.
There is probable evidence that foods containing folate reduce the risk of pancreatic cancer and limited suggestive evidence that they reduce the risk of oesophageal and bowel cancer. Cohort studies suggest that a high dietary folate intake may reduce the risk of post-menopausal breast cancer, particularly for women with a family history of breast cancer.
There does not appear to be any significant association between folate intake and the risk of lung cancer, and limited evidence suggests there is no association between folate intake and ovarian, stomach and prostate cancer.
Selenium is found in cereals, meat, poultry, seafood, and eggs. It acts as an antioxidant and helps to prevent tissue damage caused by free radicals.
The food industry wants to be able to make health claims on food labels suggesting selenium protects against cancer. This is a proposal Cancer Council does not support, based on limited evidence of a link.
This position statement provides background information about selenium and selenium supplements, and summarises the evidence from studies of selenium to prevent cancer.
Benefits of healthy diet and physical activity for cancer survivors
More than a quarter of a million Australians have survived cancer. These men and women may be at increased risk of other health problems which could be reduced through lifestyle changes.
This position statement, developed by Cancer Council's Nutrition and Physical Activity Committee, summarises the evidence about the impact of lifestyle factors on quality of life, cancer recurrence and overall survival. It covers body weight, physical activity, diet, diet supplements, alcohol consumption and food safety, and makes recommendations based on this evidence.
Front-of-pack food labelling
Front-of-pack labelling can support consumers to select healthier food products and encourage industry to produce healthier foods. Currently, food labels do not present nutrition information in a way that is easily understood or that encourages consumers to make healthy choices.
Government intervention is required to ensure that an interpretive front-of-pack nutrition labelling system that can be understood by all consumers is available on all food products.
Cancer Council recommends that consistent and interpretive front-of-pack food labelling be introduced into the Australian grocery market to encourage shoppers to make healthier choices. This should be part of a broader obesity prevention strategy and be supported by a social marketing campaign that enables and encourages Australians to use food labels to make healthier choices.
Food marketing to children
Restricting unhealthy food and beverage marketing to children has been recognised by the World Health Organization as an important area for action in the prevention of obesity.
Reviews have found that children are not fully aware of the persuasive intent of food marketing and that food marketing influences the food preferences of children, generate positive beliefs about the foods advertised, influences purchase requests of children, and influences children's food consumption.
Research on food marketing to children from Australia has focused primarily on measuring exposure to television food advertising. This research has consistently shown that children are exposed to high levels of unhealthy food advertisements on television.
Cancer Council recommends that Government develop specific food marketing regulations which restrict the marketing to children of unhealthy food and beverage, determined using nutrient profiling, across all media.
Importantly, any regulatory system must reflect children's media use, including the broadcast periods when the highest numbers of children are watching or using media, and the types of persuasive marketing techniques used to target children.
Currently 63% of Australian adults are overweight or obese and around one in four Australian children are overweight or obese.
As obesity is a modifiable risk factor for cancer, it is important that a range of appropriate policies and strategies to promote healthy eating and reduce overweight and obesity are implemented within the community.
Food taxes have been proposed or introduced in a number of countries as part of efforts to improve diets, address rising rates of obesity and reduce diet-related chronic disease. This position statement assesses the evidence relating to the effectiveness of food taxes and subsidies to improve public health in Australia and overseas.
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