There is some evidence that men can reduce their risk of prostate cancer through what they eat, although there isn't any definite proof that changing your diet can prevent prostate cancer.

Some doctors think that a diet low in animal fats and high in vegetables, cereals and fish may help to protect men against prostate cancer. This diet is also good for general health and especially the heart.

Animal fats

Prostate cancer is much less common in countries with a low fat diet (like Japan and India) compared to those with a high fat diet (like the UK and USA). But, we don't fully understand why animal fats found in meat (especially red meat), milk, cheese and butter may increase the risk of prostate cancer. Some scientists have suggested animal fats may increase the level of hormones such as testosterone and insulin-like growth factor (IGF-I) in men. Having higher levels of these hormones has been linked to a greater risk of prostate cancer.

Studies that have looked at the effects of animal fats in men's diets have given different results. So we can't say for sure that reducing animal fats in your diet reduces the risk of prostate cancer, although it does have many health benefits.

Fish oils

Some studies have linked diets that include fish containing omega-3 fatty acids, such as trout, tuna, salmon and mackerel, to a lower risk of prostate cancer. Research is still looking into whether this may be helpful.

Calcium and vitamin D

Taking large amounts of calcium has been linked to a higher risk of prostate cancer. One study found that men taking more than 2000 mg of calcium daily increased their risk of prostate cancer compared to men taking lower amounts. But, it is important to balance this with the fact that you need about 800mg of calcium every day to keeping your bones strong and healthy. Most men in the UK get this amount of calcium from their diet.

Taking high levels of calcium can also reduce the amount of vitamin D in the body. vitamin D is found in enriched margarine and spreads, as well as in meat and fish. It is also made by our bodies when our skin is exposed to sunlight. Several studies have linked low levels of vitamin D to a higher prostate cancer risk.

Fruit and vegetables

Studies haven't proven whether your intake of fruit and vegetables can affect your risk of prostate cancer. But, there are many nutrients found in plant based foods that may be helpful.

Tomatoes contain lycopene. Lycopene is a strong antioxidant (a substance that helps the body repair damage to cells). Lycopene also seems to decrease levels of IGF-I in the body, (high levels have been linked to increased risk of prostate cancer). Several, but not all, studies have linked a diet rich in lycopene with a reduced risk of prostate cancer. So taking more tomatoes in your diet may help to protect you against prostate cancer. Cooking, processing or serving tomatoes with oil all increase the amount of lycopene that can be absorbed by the body.

Researchers have suggested various substances found in fruits, vegetables and red wine that may be protective. These substances include isoflavones, polyphenols, sulforaphane and indole-3 carbinol. Taking a range of fruit and vegetables of different colours each day will help you to include all of these in your diet. However, results of studies looking at the effect of these substances on prostate cancer risk have varied so the evidence is not so convincing for them.

Vitamin E and selenium

Studies have found that low levels of vitamin E may be linked to a higher risk of prostate cancer. Although, sometimes the benefit of increasing vitamin E intake has only been shown for men who smoke or who have recently stopped smoking. And some studies haven't shown any effect either way. Olive oil, nuts especially brazil nuts and seeds are all good sources of vitamin E.

Diets low in selenium (which is common in cereals) may also increase the risk of developing prostate cancer. A large study called the SELECT trial is looking into whether taking supplements of vitamin E, selenium or a combination of both of these may help to reduce prostate cancer risk.

Points to consider

There is no evidence that changing your diet is an effective treatment for prostate cancer.

Following a healthy balanced diet low in animal fats and rich in a variety of fruit, vegetables nuts and seeds doesn't always prevent cancer but it may can reduce your risk of heart disease and of many other cancers including prostate cancer.

Reference

• Role of diet in prostate cancer development and progression. Chan et al Journal of Clinical Oncology 2005 23(32) 8152-8158