Diet to Reduce Cancer Risk

It is estimated that about a quarter of all deaths in the industrialised world are caused by different types of cancer. In the United Kingdom one out of three people are at risk of developing cancer. There are over 100 different types of cancer and it is thought that there are many different causes.

The consensus of medical opinion is that maybe 60% of all cancers could be prevented simply by doing only two things. These are: giving up smoking and following a healthy diet in order to reduce your cancer risk.

The consensus report written by the World Cancer Research Fund estimates that up to 40% of cancers (4 million cases throughout the world) could be prevented by maintaining the correct body weight and eating the right type of diet.

Increase your dietary consumption of a wide variety of fruit and vegetables

In the fight against cancer it seems that eating fruit and vegetable is extremely important. An increased intake of fruit and vegetables is associated with, for example, a reduced risk of cancer of the stomach, lung, breast, prostate, mouth, pancreas and bladder. In one study, the rate of cancer deaths in vegetarians was found to be about 40% lower than people who were not vegetarians.

Fruits and vegetables contain vitamins, minerals and fibre which are essential for health. It is now known that they also contain a number of important compounds which reduce cancer risk. These are the biologically active non-nutrients which are present in food known as phytochemicals.

There are many different groups of phytochemicals. These include flavonoids, indoles, sterols and phenols. Within each group there are yet more specific chemicals each with its own function or functions. It has been discovered that many of these compounds are excellent at helping to prevent block or suppress carcinogens, tumours or cancers. Here are some examples:


Tomatoes contain the carotenoid lycopene which is a member of the phenol group. This lycopene is known to protect against cancer-causing pollutants. One medical study found that men who ate at least 10 servings of tomato a week had a 45% reduced risk of developing prostate cancer. However, other trials involving tomatoes and prostate cancer risk have not shown such a dramatic effect. If you suffer from gastro-esophageal reflux disease (GERD) then tomatoes may aggravate your symptoms of heartburn. However some acid reflux disease sufferers are still able to eat tomatoes and it is worth trying to include these in your diet if possible.


Broccoli is a member of the brassica family and contains indoles, which are a group of cancer preventing agents. Broccoli is known to contain glucosinolates which are broken down by the body to form sulphorophanes which help to reduce the risk of cancer of the colon and lung. GERD sufferers are usually able to include broccoli in their GERD diet.


Watercress is known to be rich in phenethylisothiocyanate, which is particularly effective at preventing lung cancer. Yams. Yams are rich in phyto-estrogens which are to help protect against breast cancer and other related hormone driven types of cancer.

Carrots and broccoli

Carrots, broccoli and all dark green, orange, yellow and red vegetables contain carotenoids which are very effective at protecting the immune system and also helped to reduce the risk of lung cancer.

Brussels sprouts

Brussels sprouts are known to contain another glucosinolate called sinigrin. This is a chemical which has been found to suppress precancerous activity.

Citrus fruits

Citrus fruits such as oranges are rich in antioxidant flavonoids, linolene and the phenol lutein. These flavonoids help to reduce the risk of cancer of the colon, breast and skin. Individuals who are following a GERD diet are usually advised to avoid citrus fruits because they are acidic and can aggravate heartburn and acid reflux. However citrus fruits are extremely healthy and if you are able to eat them without a worsening of your symptoms of acid reflux disease then it is worth trying to include citrus fruits in your diet.

Grape skins

Grape skins and many other types of fruit skins are known to contain a compound called resveratrol. This chemical has been found to inhibit cancer development. Red Burgundy wines are a good source of resveratrol. Grapes also contain ellagic acid, which is also found in strawberries and cherries. Ellagic acid is thought to be another cancer preventing compound.

Nuts and seeds

Nuts and seeds contain phytosterols which studies have shown help to reduce the risk of cancer of the breast, colon and prostate. Nuts and seeds also contain gamma tocopherol which may help to prevent lung and prostate cancer.

Oriental mushrooms

Oriental mushrooms such as shiitake mushrooms contain lentinan, which helps to boost the immune system and aids the bodies fight against cancer.

Increase your consumption of starchy plant foods

Starchy foods which are complex carbohydrates such as whole-grain cereals, oats, pasta, rice and potatoes are high in fibre. Eating plenty of high-fibre foods such as these has been found to reduce the risk of cancer of the colon, prostate, pancreas and breast. Medical research also suggests that a compound called butyrate, that is produced when complex carbohydrates undergo fermentation in the bowel is important for the health of the mucosa of the colon. Butyrate is also thought to help prevent conditions which promote cancer and increases the rate of deaths of cancer cells. Including soya in your diet regularly may also help to reduce the risk of colon cancer.

Reduce your dietary consumption of saturated fats and meat

It has long been known that high-fat diets, especially those high in saturated fat are associated with an increased risk of cancer of the colon. This effect is more marked in men. A high-fat diet also is thought to increase the risk of cancer of the breast, prostate and ovaries. In order to improve your cancer risk it is sensible to reduce your intake of high-fat foods such as full fat dairy produce (eg full fat milk, cream, butter and cheese), fatty cuts of meat, and high-fat convenience foods.

An important medical study carried out in Europe found that a high intake of red meat increases the risk of developing bowel cancer. This risk was one third greater when individuals consumed more than two 80 g portions of red meat a week. Eating a portion of fish every other day, on the other hand reduced the risk of bowel cancer by a third. Eating meat increases levels of nitrosamines in the body and this may be one reason why consumption of meat is associated with an increased risk of cancer. Nitrosamines are known to be cancer inducing chemicals. Other compounds found in processed meats and hormones which are present in fresh meat may also be a factor in increasing the cancer risk of meat. Organic meat may contain less chemicals and is free of hormones. Meat which is overcooked, burnt, barbecued and chargrilled is also thought to increase the risk of cancer. This is because the high cooking temperature creates carcinogenic compounds.

Increase your dietary intake of omega-3 fatty acids

If you follow the above guidelines then your total fat intake should automatically br reduced to within levels which are recommended by most cancer research agencies. Most of these agencies agree that a maximum of 30% of total calories should be consumed as fat. As described above, a high-fat diet is linked to several types of cancer and is a major cause of obesity which is also a risk of cancer.

However, some types of fat are necessary in your diet and probably help to reduce cancer risk. Eating adequate amounts of omega-3 fatty acids is thought to prevent against cancer of the breast, bowel, lung and prostate. Researchers think that this may be because omega-3 fatty acids have a calming effect on the inflammatory prostaglandins in the body. Omega-3 fatty acids are found in oily fish and linseed oil. It is therefore recommended that you should replace some of your meat meals in your diet with meals containing oily fish and plant-based meals. Recent research has shown that there is a connection between increased consumption of high monounsaturated (e.g. olive oil) intake and a reduced risk of colon and breast cancer.

Avoid being overweight or obese

It is well known that being overweight increases the risk of breast cancer. The risk is thought to be about one and a half times more likely in postmenopausal women who are overweight compared with these women who have a normal weight. There is also a link between being overweight and the risk of developing cancer of the cervix, gallbladder in women and prostate in men. Though this link is not as pronounced as the link with breast cancer.

Limit consumption of alcohol

Excessive alcohol consumption is known to increase the risk of several types of cancer including: cancer of the mouth, pharynx, larynx, oesophagus, liver and breast. Alcohol may also increase the risk of cancer of the rectum. Beer can be a major source of nitrosamines, which are known to be carcinogenic, and heavy beer drinkers are thought to be at increased risk of colon cancer and pancreatic cancer. Therefore alcohol consumption should be maintained within recommended guidelines. Red wine has been shown to have a protective effect against bowel cancer. This may be because red wine contains resveratrol which is found in grape skins but it is important to drink red wine within safe limits.

Other factors important in cancer risk

Green tea

Green tea is known to contain five times as many cancer preventing antioxidants as black tea.


Garlic contains anti-cancer substances, such as diallyl sulphide and s-allylcycteine, which are thought to help suppress and prevent tumours by about to 60%. It is best to consume fresh garlic because fresh garlic contains better compounds than garlic supplements.


The mineral selenium is an antioxidant and has a powerful effect against fighting the toxic free radicals which are thought to increase cancer risk. Tuna fish and Brazil nuts are both excellent sources of selenium.


Aspirin is thought to help to reduce the risk of developing cancer. Taking 300 mg a day may reduce the risk of cancer of the colon and rectum. If you suffer from gastro-oesophageal reflux disease (GERD) you should avoid aspirin as this can aggravate GERD. If you are in doubt about whether to take aspirin are not then you should discuss this with your doctor.

Nitrate fertilisers

Nitrate fertilisers which are used by commercial growers to fertilise vegetables such as greens and lettuce used to be thought to be a possible cancer risk. However this is no longer thought to be the case and there is some evidence that they can turn into nitric oxide in the body and actually provide some health benefits.


Taking supplements of beta-carotene has been shown to be not effective in cancer protection. In fact one study found that smokers who took supplements of beta-carotene actually had an increased risk of lung cancer. It is not recommended to take supplements of beta-carotene.

Polyunsaturated cooking oils

Polyunsaturated cooking oils can oxidise if they are heated too frequently and kept too long. Polyunsaturated cooking oils are thought to be carcinogenic and they should be stored in a cool dark place and discarded after use.

Smoked and cured foods

Smoked and cured foods, such as bacon and smoked salmon are thought to be carcinogenic and should be eaten in moderate amounts.

Table of anti-cancer foods