Friday, October 19, 2012

Trivial multivitamin benefits 

The effect is far too small to support any causal inferences

Middle-aged men who took vitamins were 8 per cent less likely to develop cancer of any kind

Regular use for more than a decade cuts men’s chances of developing the disease by 8 per cent, say researchers.

They cannot identify a single vitamin or combination that works, but claim the benefit comes from a broad combination of low dose vitamins.

The US study involved only men so the same effect cannot be assumed for women, but experts believe it is likely to be similar.

Almost 15,000 doctors took part in the survey at Brigham and Women’s Hospital, in Boston, and Harvard Medical School.

It is significant as the first trial of its kind, said Michael Gaziano, chief of the Boston hospital’s ‘division of ageing’. He said: ‘Despite the fact that more than one-third of Americans take multivitamins, their long-term effects were unknown until now.’

Millions of Britons buy multivitamins in the hope that they might prevent illness. However, there is little evidence for such benefits and some studies on high-dose vitamins have shown harm.

The latest trial included 14,641 male physicians, initially aged 50 years or older, including 1,312 men with a history of cancer at the start of the study in 1997, with treatment and follow-up through to 2011. Participants received a daily multivitamin or dummy pill and were followed for an average of 11.2 years.

Analysis of the data found men taking a multivitamin had a modest 8 per cent reduction in total cancer incidence, including colorectal, lung and bladder. There was no statistically significant effect on deaths from cancer.

The daily pill was a brand called Centrum Silver for the over 50s containing vitamins A, C, D, E, B6 and B12, calcium, selenium and zinc.

The study was published online in the Journal of the American Medical Association to coincide with its presentation at the Annual American Association for Cancer Research’s Frontiers in Cancer Prevention Research meeting.

The 'modest' reduction is thought to mirror the benefits of eating a healthy diet high in fruit and vegetables

Dr Gaziano said many take multivitamins daily because it might ward off cancer, despite the paucity of evidence.

He said there was speculation about the role of individual vitamins and minerals in cancer prevention, but it was difficult to identify any single mechanism through which components of their tested multivitamin may have reduced cancer risk.

‘Although the main reason to take multivitamins is to prevent nutritional deficiency, these data provide support for the potential use of multivitamin supplements in the prevention of cancer in middle-aged and older men,’ said the study.


Starch kidney failure risk

Another failure of medical fashion

Intensive care doctors should reconsider using a starch fluid to resuscitate patients because it results in higher rates of kidney failure than the alternative saline, researchers say.

In a study of 7000 patients treated in 32 Australian hospitals, researchers from the University of New South Wales' George Institute for Global Health found starch had no clinical benefits over saline.

But patients given starch had a 21 per cent higher risk of kidney failure than those given saline, according to the study published today in The New England Journal of Medicine.

Lead researcher Simon Finfer said starch was widely used overseas and increasingly in Australia, where it was first registered for use in 2008.

Doctors use fluids as a first-line treatment to maintain blood pressure and deliver oxygen and other nutrients to vital organs in acutely ill patients.

Professor Finfer said starch was marketed as being more effective than saline or other fluids on the basis of small studies of its short-term effect on blood pressure and heart rate. But he said little had previously been known about longer-term outcomes in a large patient sample.

The study showed 7 per cent of patients given starch developed kidney failure, compared with 5.8 per cent of those given saline, but found no higher risk of death within three months.

"With patients who are critically ill, there will be a proportion who will develop kidney failure as part of that illness," he said. "But what this tells us is that if we use starch as opposed to saline to resuscitate these patients, more of them will develop kidney failure and need dialysis.

"Approximately 100,000 patients are treated in intensive care units in Australia each year. If everybody got starch, it might result in an extra thousand people having kidney failure."

Professor Finfer said the findings reinforced concerns "that starch is deposited in the kidney and other tissues and might cause kidney injury in that fashion".

He expected doctors worldwide would change their practice in light of the study.

The Austin, Frankston and Western hospitals in Melbourne and the Royal North Shore, St George and Royal Prince Alfred hospitals in Sydney participated in the study.


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