Many people are affected by cancer, either directly, or because they know somebody who has the disease. But thankfully, there are some lifestyle measures you can take to reduce your risk.
Each year in the UK, about a third of a million people are diagnosed with cancer. The four most common cancers (lung, breast, bowel (colorectal) and prostate) make up over half of all these cases. It is estimated that more than one in three of us will develop some form of cancer at some point in our lives.
Cancer is a complex disease and there are many factors that influence whether or not an individual develops cancer. These includes exposure to certain risks such as smoking, a person’s genetic make-up and even the country (and hence the environment) where a person lives. For example, smoking 20 cigarettes a day increases lung cancer risk by 20-40 times (a 2,000-4,000% increase in risk!).
Diet can also affect risk of some types of cancers, although the effect is far less than with smoking. The strongest links are with some cancers of the digestive tract – the mouth, throat, stomach and large bowel (colon) - and some hormone-related cancers such as breast cancer. It is estimated that approximately 30% of cancers in Western countries (such as the UK) could be prevented if people changed their dietary habits.
This section provides a summary of how diet and physical activity can affect your cancer risk. The tips on the next page have been produced to help you reduce your risk of cancer.
Lifestyle factors
Smoking
Smokers increase their risk of lung, mouth and throat cancers by 20-40 times compared to non-smokers. Smoking is the strongest predicator of risk amongst the lifestyle factors associated with cancer.
Body weight
Being overweight or obese also increases a person’s risk of developing a number of different cancers, including cancers of the oesophagus (the tube leading from your mouth to your stomach), colorectum (or bowel), pancreas, endometrium (lining of the womb), kidney, gallbladder and breast (in post-menopausal women). For example, obesity increases the risk of colon cancer by 50% in men and 25% in women and about 17,000 cases of cancer in the UK are linked to being overweight. Try to make sure your body mass index (BMI) stays within the healthy range of 20-25; if possible at the lower end of this range. This can be done by eating a healthy varied diet and being physically active.
Physical activity
Not only does being physically active help you to control your weight, but it has additional benefits that can help reduce your cancer risk, such as increasing the frequency of your bowel movements and enhancing your immune system. Research consistently shows that physical activity can help to reduce the risk of colon, endometrial (womb) and postmenopausal breast cancers (independent of body weight), as well as helping to protect against the cancers that are linked to being overweight and obesity.
To help reduce your risk of cancer, aim to include in your daily routine some moderate intensity physical activity, for at least 150 minutes over the week in bouts of 10 minutes or more. Physical activities to improve muscle strength that works all major muscle groups (i.e. legs, hips, back, abdomen, chest, shoulders and arms) should be carried out on at least two days per week. Try and incorporate physical activity into your daily routine: for example take a brisk walk in your lunch break, use the stairs instead of the lift, or get off the bus one stop before you usually do and walk the rest of the way to your destination.
Alcohol
In addition to smoking, alcohol is one of the main risk factors for cancers of the mouth, throat and oesophagus. Alcohol is also one of the main diet-related risk factors for liver cancer, and it can increase the risk of breast cancer in women and colorectal cancer, especially in men. To help reduce your risk of developing these types of cancer, try to limit your alcohol consumption to no more than 3-4 units per day for men and no more than 2-3 units per day for women (half a pint of 4% lager,= 1 unit, a small glass of wine (125ml) = 1.5 units, single spirit and mixer = 1 unit).
Dietary factors
Fruit and vegetables
A number of studies suggest that fruit and vegetables help reduce the risk of certain cancers including mouth, throat, stomach, prostate and lung cancers. It has been suggested that the apparent, beneficial effect of fruit and vegetables might be due to the package of nutrients and other bioactive substances that they contain, many of which have antioxidant properties. However, hard evidence to support a particular role of antioxidants in general or of a specific plant substance is still required, as there is limited information available on how these plant bioactives work in the body.
So, consuming a diet rich in fruit and vegetables can help you to reduce your risk of cancer. But we don’t yet know how exactly this works or which types are most beneficial, and so choosing a wide variety of different types is particularly important. Aim to eat at least 5 (portion 1 portion = 80g) of fruits and vegetables each day, and make sure that within this you include lots of variety. Not only will this provide you with a range of vitamins and minerals, but fruits and vegetables are also low in energy (calories) and high in fibre, and so could help to prevent weight gain.
Aim for a diet containing plenty of fruits and vegetables, rather than relying on supplements to get the vitamins and minerals these provide. Whilst fruit and vegetables are thought to help protect against cancer, dietary supplements are not advised as a means of avoiding cancer. This advice is based on research that has shown an increased risk of some cancers in some people taking specific antioxidant supplements in large doses.
Red and processed meat
Several studies have suggested that a high consumption of red and/or processed meat is linked with an increase in risk of colorectal (or bowel) cancer. The evidence is stronger for processed meat but research suggests that any effect of meat may be reduced when it is eaten as part of a high fibre diet. There has been a lot in the media about processed meats, such as ham and bacon, and cancer risk. Overall studies suggest that eating 30g of processed meat a day (around 1 ½ slices of ham or a slice of bacon) may increase colorectal cancer by up to 36%. Although it is wise to watch you intake of processed meat, this effect on risk is modest and to put it in perspective, the effect of smoking 20 cigarettes a day on lung cancer risk is 100-200 times greater than this.
Red meat includes pork, lamb, beef and goat, and processed meat (for which the evidence is stronger) includes meats preserved by smoking, curing or salting, or by adding chemical preservatives. There is currently some uncertainty regarding the exact definition of processed meat but salami, ham and bacon are all examples of such products. Current advice is to limit consumption of processed meat, and to keep your consumption of red meat to 500g of cooked meat a week or less (a medium portion of roast beef/pork = ~90g, 1 medium steak = ~145g) ; this would equate 4 to 5 portions of cooked red meat such as roast beef a week. Remember that red meat is a good source of protein, iron and zinc so if you do cut down you need to make sure you include other foods containing these nutrients in your diet.
Salt
A high intake of salt and salted foods is linked with an increased risk of stomach cancer, so it is important to keep your salt intake below the recommended maximum: 6g a day for adults and older children. The information available on food labels can help you to identify which foods are high in salt.
Breastfeeding
Breastfeeding is recommended for protection against infections in infancy, some childhood diseases, and also to help with mother and child bonding. Breastfeeding has long-term health benefits and protects both mother and child from certain diseases including cancer risk later in life. The Department of Health recommends that infants are breastfed exclusively for 6 months.
What do these recommendations mean for me?
These recommendations provide guidance for reducing your risk of cancer. They emphasise the importance of following a healthy, varied diet, and being mindful of the need to stay physically active and maintain a healthy body weight. It is now recognised that it is better to consider overall dietary pattern rather than singling out particular items to eat more of or avoid. No single food can provide all the essential nutrients that the body needs, and any one food is unlikely to cause harm if you eat it in moderate amounts. It is therefore important that you eat a wide variety of different foods, to ensure that you maximise your chances of staying healthy and happy well into your old age!