Source: http://www.therecord.com
June 8, 2007

Canadian Cancer Society recommends supplement as body of evidence grows

TORONTO (Jun 8, 2007)

Canadian adults should consider taking a specific amount of vitamin D, says the Canadian Cancer Society, basing its new recommendation on an expanding body of evidence linking the vitamin to reduced risk for colorectal, breast and prostate cancers.

The recommendation coincides with a study published in a U.S. journal today which found that taking vitamin D supplements and calcium substantially reduced all cancer risk in post-menopausal women.

The four-year study, conducted by researchers at Creighton University in Nebraska, initially enrolled 1,180 women who were over the age of 55 and living in a nine-county rural area of the state.

Of the 1,024 who completed the trial, those randomly assigned to take calcium and vitamin D and who had higher levels of both in their blood were 77 per cent less likely to develop cancer after the first year compared to those taking placebos or calcium alone.

The Canadian Cancer Society released its recommendation today for adults in Canada to consider taking a vitamin D supplement of 1,000 international units daily during fall and winter.

The recommended amount takes into consideration vitamin D intake from other sources, including food, water and a multivitamin, said Heather Logan, director of cancer control policy at the Canadian Cancer Society.

Adults at risk of having lower Vitamin D levels should consider maintaining the recommended intake level year round, the organization said in a release. This includes people who are older, have darker skin, don't go outside often and wear clothing covering most of their skin.

"A thousand units is really a reasonable recommendation (for) people, according to the evidence and guidelines that exist currently across North America,'' Logan said.

But she cautioned that total vitamin D intake -- from supplements and diet -- should not surpass 2,000 international units.

In addition to the Nebraska research findings, the cancer society said another study released in May suggests women who consume more calcium and vitamin D may be less likely to develop breast cancer before menopause.

"This is a really exciting, emerging area of cancer prevention research and we'll continue to follow it carefully, and as new information emerges we will update our recommendations accordingly,'' said Logan.

The organization said Canada's geographic location was also a motivating factor for issuing the recommendation.

The country's northern latitude, coupled with weakened sun rays in fall and winter, result in Canadians not producing enough vitamin D from sunlight.

But Joan Lappe, lead investigator on the Creighton University study, published in the American Journal of Clinical Nutrition, said the implications of her study aren't to suggest people living closer to the Equator in warmer climates require any less of the vitamin.

"Their vitamin D health is probably more optimal, but the point is that many people further north in the northern hemisphere . . . north of the 37th latitude just do not get enough months of sunlight exposure to give them optimal vitamin D in the whole year,'' she said in a phone interview from Omaha, Neb.

That doesn't mean Canadians should spend too much time in the sun, basking under harmful ultraviolet rays where they face overexposure, a prime risk factor for skin cancer, Logan said.

"We're definitely not talking about going out to get a tan, or to go in the middle of the day when the UV index is high,'' she said.

"(Supplementation) maximizes the potential benefits in reducing the risk of developing cancer with very few side effects at the doses that are recommended.''

Lappe said based on the study findings, examining the role calcium played requires further investigation.

"In the group that received calcium only there was a decreased incidence of cancer, but it wasn't as strong as in the group that had both calcium and vitamin D.''

"We know from studies that calcium can bind some by-products in the colon that actually prevent colon cancer in that way, but I'm not aware of any studies that show what (the) combination does together.''

Logan said while the Nebraska study is "compelling,'' there are limitations to applying the results looking at a very specified group of subjects in one American state to the Canadian population at large.

"A large-scale clinical trial would include a much larger participant group that were more representative of the Canadian population, given our diversity, and they would be followed for a longer period of time,'' she said.

"If these results can be replicated in a large-scale clinical trial they really would be a remarkable result.''

At this time, the Canadian Cancer Society said it does not have a recommendation for vitamin D supplementation for children.

Recent research highlighting the protective effect of early sun exposure on cancer risk outlines the need to consider boosting vitamin D intake for those at a younger age, said Dr. Reinhold Vieth, director of the bone and mineral lab at Mount Sinai Hospital in Toronto.

"It's plausible, I think, that vitamin D over a relatively short period like the four years of study here does help to prevent cancer, but you can even take it another step further and start earlier in life to prevent the cancers,'' Vieth said.

More vitamin D early in life also influences predisposition to get diabetes and multiple sclerosis, Vieth said.

While there are different schools of thought in regards to calcium and cancer, the influence of vitamin D is more difficult to dispute, Vieth said.

"The thing that is unambiguous, zero debate is that more vitamin D is good,'' he said.

"This is one agent that has a lot of different science backing it up.''

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Original story can be obtained here.

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