Sunday, October 20, 2013
Do high doses of vitamin C raise prostate cancer risk? Study shows popping too many supplements could give men tumours
Men who take high doses of vitamin supplements could be increasing their risk of lethal prostate cancer by nearly 30 per cent, say researchers.
A study of 48,000 men spanning more than two decades suggests popping too many vitamin pills can put them in danger of tumours that are more likely to be fatal.
The researchers linked high doses of vitamin C to an increased risk of lethal and advanced prostate cancer.
The results, by experts from Harvard School of Public Health in Boston, in the US, and the University of Oslo in Norway, are not the first to raise the alarm over the dangers of excess vitamin consumption.
Nearly a quarter of adults in the UK are estimated to take antioxidant supplements or multivitamins regularly in the hope that it will help protect them against illnesses such as heart disease and cancer. The market for such products is worth around half a billion pounds a year.
In recent years, high-dose vitamins have become popular, with people taking more in the belief that it is better for them.
For example, health food shops now sell vitamin C tablets in doses of 1,000mg each, but the body needs only about 40mg a day to keep cells healthy and promote healing.
In the latest research, the scientists set out to see if antioxidants in vitamin pills and food could reduce the chances of a prostate tumour.
From 1986 to 2008 they followed 48,000 men aged between 40 and 75. Every four years, the men completed food questionnaires designed to record their dietary habits. The researchers followed them up to see which ones developed prostate cancer.
The results, published in the International Journal Of Cancer, show that total antioxidant intake – from foods or pills – neither increased nor decreased the risk of a tumour. Antioxidants fight the process, called oxidation, that destroys cells.
There was some suggestion antioxidants from coffee had a slightly protective effect.
But the most alarming finding was that men with the highest intake of antioxidants from vitamin pills were 28 per cent more likely to get lethal prostate cancer than those who took the lowest amount of pills or none.
Those with the highest intake of antioxidants from vitamin pills were 15 per cent more likely to get advanced prostate cancer – a tumour that spreads quickly beyond the prostate, reducing the chances of survival.
In a report the researchers said: ‘High intake of antioxidants from supplements was associated with increased risk for lethal and advanced prostate cancer.
'The main contributor is vitamin C, and this finding warrants further investigation.’
But the researchers stressed that, until more research is carried out, they cannot be sure that vitamin tablets actually cause cancer.
It may be that the cancer victims felt unwell for several months before their diagnosis and simply increased vitamin intake to try to ward off symptoms such as fatigue.
Dr Carrie Ruxton, of the Health Supplements Information Service, which is funded by supplements makers, said: ‘It is entirely possible that these men may have had prostate-related symptoms and fatigue long before diagnosis. 'The cancer may have had nothing to do with the supplements.’
New HRT drug may help to PREVENT breast cancer in British women
A menopause treatment which could prevent breast cancer, rather than causing it, may soon be available for British women.
Evidence shows the new hormone replacement therapy pill is even more effective at combating menopause symptoms, such as hot flushes, than the standard treatment.
But crucially, early trials show it may prevent growth of breast cancer tumours. Existing forms of HRT, by contrast, are thought to cause the disease.
Researchers say it could be given to millions of women worldwide who are too afraid to take menopause treatment due to the risk of breast cancer.
And they also believe it could be given to younger women with a strong family history of the disease to prevent it occurring.
The pill – called Duavee – has just been approved for use in America and will be available in chemists there from January.
It is now being considered for use in Britain by the EU watchdog – the European Medicines Agency – which is expected to make a decision in the next few months.
The drug contains the hormone oestrogen which combats symptoms of the menopause including hot flushes, night sweats, sleeping problems and thinning of the bones, or osteoporosis.
But the problem with oestrogen, which is in standard HRT, is that it is thought to trigger the growth of cancer tumours.
To combat this, a chemical called bazedoxifene is added to the Duavee pill, blocking the cancer-causing effects of oestrogen. This means the drug has all the benefits of reducing menopause symptoms as normal HRT but does not trigger breast cancer.
Trials on 8,000 women have shown it reduces hot flushes by 85 per cent – making it more effective than standard HRT, which cuts them by 75 per cent. It also prevents fractures caused by bone thinning by 40 per cent and participants said it had improved their overall happiness.
But in tests on mice the chemical prevented the growth of breast cancer tumours – and scientists are convinced it will have the same effect on women.
Professor Richard Santen of the University of Virginia, who is an expert in the role of oestrogen in breast cancer, said: ‘If this does what we think it does this is huge.’
Unveiling the findings at the American Society for Reproductive Medicine conference in Boston, he added: ‘I’ve been around for 45 years studying breast cancer and when you look at the effects of these agents in animals, the animals have really predicted what’s going to happen in patients.’
Breast cancer is the most common form of the disease in women and in the UK there are just under 50,000 new cases each year and 11,500 deaths.
In 2001 and 2002 two major US studies suggested breast cancer was being triggered by HRT leading to millions of women worldwide abandoning the drug. In Britain, the numbers of women on HRT fell by half – only a million now take it today.
Doctors are concerned that many are suffering the debilitating symptoms of the menopause and putting themselves at risk of osteoporosis because they are too afraid to take HRT.
The new drug’s manufacturer Pfizer has not revealed the cost of the pill – which would be taken once a day – but say it would be comparable to current forms of HRT, which is between £2 and £7 for a month’s supply depending on the type.
Professor Santen said that if it was shown to prevent breast cancer, it could be given to thousands of younger women at high risk of the disease. This summer the NHS began offering these women the drug Tamoxifen, but it can have very unpleasant side effects such as depression, tiredness, blood clots, hot flushes and headaches.
The professor said trials had so far shown the new pill had limited side effects.
The drug could be available in Britain next year if the EU watchdog approves it, although it may take several years to show it prevents breast cancer in humans.
Posted by jonjayray at 12:24 AM