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Food controversies and supplements

It is unclear if particular foods can reduce the risk of prostate cancer coming back (recurrence). Research has looked at a number of different foods and supplements.

We need more research to find out for sure whether any of these can slow the growth of prostate cancer or reduce the risk of recurrence.

Tomatoes and lycopene

Tomatoes and tomato based foods contain lycopene. There is more in cooked and processed tomato products than fresh tomatoes.

Eating foods that contain lycopene reduces the risk of prostate cancer developing

It is not clear whether lycopene slows the growth of the cancer, or stops the cancer coming back in men who have had prostate cancer. 

So, while food containing lycopene can be included in a healthy diet, doctors don’t recommend that men take supplements.

Pomegranate

Pomegranate (Punica granatum) is a good source of fibre and vitamins.

Studies looking into whether pomegranate can reduce the risk of prostate cancer coming back have had mixed results. Some show no benefit from drinking pomegranate juice or taking pomegranate extract.

But a small study followed men who drank pomegranate juice every day. The researchers found that their prostate cancer took longer than normal to progress. So, at the moment it’s unclear whether pomegranate is helpful for men with prostate cancer. We need more research in large trials to be certain.

It’s fine to include pomegranate in a healthy diet.

Green tea

Green tea is a drink made from the dried leaves of the Asian plant Camellia sinensis. Many people in Asia drink it. The number of people getting many types of cancer is lower in Asia than other parts of the world. Some people believe this is because of the high intake of green tea. 

There is not enough evidence to say that green tea can help to treat cancer or reduce the risk of it coming back. 

Dairy foods and calcium

Some research has shown that men who have a diet high in calcium may have a higher risk of developing prostate cancer. And men may be more likely to have prostate cancer that is more advanced or aggressive. But there is no evidence to say that excluding dairy foods and calcium from the diet will slow the growth of prostate cancer, or reduce the risk of recurrence.

Men with prostate cancer should aim for a healthy balanced diet that includes adequate amounts of calcium. It plays an important part in the way our bodies work. For example it helps keep our bones strong and healthy and helps our muscle to work.

Adults need 700 mg of calcium each day, which most people can get from a balanced healthy diet. Choose low fat and low sugar dairy products.

Good sources of calcium include

  • dairy foods such as milk, cheese and yoghurts
  • tinned fish that contains the bones, for example, salmon or sardines
  • green leafy vegetables
  • nuts such as almonds and brazil nuts
  • seeds such as sesame seeds

It’s difficult to give examples of specific amounts. But a daily 700mg of calcium could include all of the following

  • a small tin of pilchards or sardines
  • a 50g portion of broccoli
  • 200 mls of milk

It is particularly important if you are having hormone therapy to have adequate amounts of calcium. This is because bone thinning (osteoporosis) is a side effect of this treatment.

Talk to your GP if you are struggling to eat a balanced diet and ask whether you need to take supplements. 

UK guidance says that calcium supplements up to a dose of 1,500mg do not cause problems. Doses higher that this could cause side effects, such an upset stomach. And could lead to other health problems.  Your GP will prescribe a dose below this amount.

So it’s important to have adequate amounts of calcium, but you should not take high dose supplements.

Vitamin D

We need vitamin D to absorb calcium. Together they play an important part in keeping bones healthy.  A lack of vitamin D (deficiency) in adults could lead to bone problems, such as osteoporosis.

Vitamin D is very important for men having hormone therapy because of the risk of bone thinning.

People at particular risk of vitamin D deficiency include those:

  • who wear clothes that cover the whole or most of their body
  • who are older
  • who are housebound
  • skin cancer patients
  • who deliberately avoid the sun
  • with dark skin from African , Afro-Caribbean and South Asian backgrounds

We mainly get vitamin D from sunlight and some foods.

Public Health England recommend that in winter and autumn, people in the UK should consider taking a daily supplement of vitamin D containing 10 micrograms.  This is because it is difficult for people to get enough vitamin D through their diet.

Those people from certain ethnic groups with dark skin might not get enough vitamin D from sunlight in summer or winter. So they might want to consider taking a supplement all year round.

Talk to your GP about your situation and whether or not you should take a vitamin D supplement.

You get vitamin D in your diet from:

  • oily fish such as salmon and sardines
  • some fat spreads and cereals
  • eggs

There has been some research showing that men with prostate cancer who took vitamin D supplements had a drop in their PSA levels. The PSA is a protein in the blood called prostate specific antigen. The PSA blood test is used to help diagnose prostate cancer as well assess how well the treatment has worked.  But the evidence is not strong enough to say that vitamin D supplements can reduce the risk of cancer coming back.

Taking more than 25 microgram of vitamin D supplements for long periods of time could be harmful. It could lead to kidney and bone problems.

So, do include vitamin D rich foods in your diet and have safe amounts of sunlight if you are able to. Take supplements if you are at risk of having low levels or are deficient and stick to the recommended dose.

Soy

Soybean is a product of the soybean plant. It is also in soy products such as tofu, soya milk or miso and as a supplement.

It is unclear whether soy slows the growth of prostate cancer, or reduces the risk of it coming back. This is because the research so far has produced conflicting results.

Many trials have looked at the role of soy in men with prostate cancer both before and after their treatment. These trials have mainly looked at the effects of soy supplements, but some have also looked at the use of soy foods, such as soya milk.

The different trials used various ways to measure the effect of soy on a man’s cancer. The main way was to look at the level of PSA in the blood.

While some trials showed a reduction in PSA levels for those men taking soy supplements others did not show this. The main side effect of taking supplements is an upset stomach.

You can include soy foods in your diet as part of a healthy diet.

Selenium

Selenium is a naturally occurring chemical found in plant foods such as vegetables, fish, shellfish, some meats, grains, eggs, brewer's yeast, and wheat germ.

Early research in the laboratory showed that selenium stopped cancer cells from growing. But most of the clinical trials in humans have not produced the same results.  

One study looked at the use of selenium supplements in men following their diagnosis of cancer and found that this supplement may mean that men are more likely to die from their prostate cancer.

So, doctors don’t advise men to take selenium supplements until they know more.

There is international research going on looking at the use of selenium supplements for prostate cancer and other types of cancer.  

Vitamin E

Vitamin E is an antioxidant found in a variety of foods including nuts, seeds, green leafy vegetables and vegetable oil. You can also take it as a supplement.

Research so far doesn’t show that vitamin E reduces the chances of cancer coming back. Or that it slows the growth of existing prostate cancer.

One study looked at whether Vitamin E could prevent prostate cancer. The researchers found that the men who took vitamin E supplements had a slightly higher risk of prostate cancer.

Several trials have looked at whether antioxidants during treatment could reduce side effects. Some trials found that vitamin E did reduce the side effects, but they also found that antioxidants may stop the treatment from working as well.

So, doctors don’t recommend that men take high doses of antioxidants with radiotherapy or chemotherapy until we know it is safe

It is safe to eat foods containing vitamin E as part of a healthy diet. But we don’t know how useful vitamin E supplements are for men who have, or have had prostate cancer.

Multivitamin supplements

There is no strong evidence to say that multivitamin supplements are helpful as a treatment for prostate cancer. Doctors only recommend you take them if you can’t eat a normal diet.

Vitamins and minerals in food are an important part of a healthy balanced diet. They carry out many different roles in the body including bone health, healing and helping the immune system to fight infection.

Vitamins are in a variety of foods such as vegetables and fruit, milk and dairy foods and eggs. You find minerals in foods such as cereals, meat, fish, vegetables and nuts.

The exception to this is vitamin D supplements. Public Health England recommend that people in the UK should consider taking a daily supplement of vitamin D. And people from certain ethnic groups with dark skin might need to take a supplement of vitamin D all year round. Talk to your GP about your situation and whether or not you should take a vitamin D supplement.

Questions you may want to ask your doctor

  • Can I see a dietitian to help me with my diet?
  • Can I take multivitamins or other supplements with my prescribed medicine or cancer treatment?

Information and help

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