Friday, August 29, 2014



A simple vitamin to prevent cancer has finally been accepted by the mainstream.

Long after natural "cures" such as shark cartilage and laetrile from peach pits flopped comes the first study of its kind to show that vitamin D is a potent cancer stopper.

The Canadian Cancer Society has used that finding and others in deciding to recommend for the first time that adult Canadians lower their cancer risk by taking 1,000 international units (IU) of vitamin D daily — five times the current recommended daily amount for people under age 50.

The lead author of the new study called the Canadian move "outstanding," but said she would go even higher and recommend healthy adults pop between 1,500 and 2,000 IU of vitamin D daily.

"It's inexpensive, it's safe, and it's easy to take. It's something that should be considered by a lot of people," says Joan Lappe, professor of nursing and medicine at Creighton University School of Medicine in Omaha, Neb. "It's low-risk with maybe a high pay-off."

Lappe's team studied nearly 1,200 post-menopausal women from rural eastern Nebraska and found that those taking a combination of vitamin D and calcium had about a 60% lower risk of cancer, including breast, lung and colon cancer, over four years of follow-up.

"In other words, it cut more than half the cancers over a four-year period," Lappe says.

Moreover, the higher the level of vitamin D in the blood, the lower people's cancer risks, according to the study, published today in the American Journal of Clinical Nutrition.

An expert in cancer biology called the idea of using vitamin D to cut cancer risk one of the most important advances in cancer prevention. Dr. Michael Pollak, professor of medicine and oncology at Montreal's McGill University, said it may be time for public health authorities to consider mandating higher levels of vitamin D in milk and adding it to other foods, such as bread and flour.

When it comes to breast cancer prevention, drugs such as tamoxifen can help, Pollak says, "but here we're seeing important risk reductions with a vitamin. That's much more acceptable for many women. In a sense it's a more 'natural' way to minimize cancer risk."

Pollak did, however, caution that the women were followed for just four years and that larger studies are needed to confirm the findings.

People take in vitamin D from foods, including egg yolks and oily fish such as salmon and sardines, as well as fortified milk and margarine. Because ultraviolet rays also trigger the synthesis of vitamin D in the skin, sunlight is an important source of the vitamin. In their study, the researchers tested vitamin D3, or cholecalciferol, the kind humans make when they are exposed to sunlight.

Many of the cells in the body have vitamin D receptors, meaning they need adequate amounts of the vitamin to do their work. Those cells work mostly through the immune system and help prevent cells from becoming malignant.

Lappe says people living at latitudes north of the 37th parallel — meaning all of Canada — can't get their vitamin D naturally during the winter months because of the sun's angle. As well, people would get fat if they tried to get optimum vitamin D by drinking milk, which contains about 100 units per glass.

Health Canada currently recommends 200 IU of vitamin D daily for 19- to 50-year-olds, 400 IU for 51- to 70-year-olds, and 600 IU for older people — amounts many experts say are far too low for maximum health benefits.

The Canadian Cancer Society says the daily upper safety limit is 2,000 units, and that their recommendation of 1,000 IU takes into account vitamin D from diet and other sources.

"If you consider that most people get between 250 and 400 units [of vitamin D] in food and water, you're already at 400. As well, a lot of people take a multivitamin and most of those contain 400," says Heather Logan, director of cancer control policy.

"If you add 1,000 more units, you're getting close to the upper tolerable limit."

The cancer society recommends adults take 1,000 IU daily during fall and winter, or year round for those at risk of vitamin D deficiencies. That includes the elderly, people with dark skin and people who don't go outdoors often or wear clothes that cover most of their skin.

But sun "is a good cop, bad copy story," Pollak says. "Obviously, you'll have increased rates of skin cancer if you spend days frying in the sun in a bikini with no protection." Almost 70,000 Canadians are diagnosed with skin cancer each year, making it the leading cancer among women and men.

It's not clear how much sun exposure is necessary for health, "but that optimum amount is not zero," Pollak says.

Lappe said evidence suggests 10-15 minutes of unprotected sun exposure during the middle of the day, between 10 a.m. and 3 p.m., "would give you somewhere between 1,000 and 1,500 IU of vitamin D."

"For anyone concerned about sun exposure, supplements are the best way."

Scientists first reported more than 60 years ago that there is a connection between vitamin D and a lowered cancer risk. But until now the human evidence has been mostly observational, meaning researchers looked at how much of the vitamin people consumed and then counted up the cancers.

In the new study, 1,179 healthy, post-menopausal women aged 55 and older who were free of known cancers for at least 10 years before entering the study were randomly assigned to take daily dosages of 1,400 to 1,500 milligrams of calcium supplement alone, the supplemental calcium plus 1,100 IU of vitamin D, or placebos.

Over four years of follow-up, 50 women were diagnosed with non-skin cancers, 13 in the first year and 37 later.

Compared with the placebo group, the relative risk of developing cancer during the study was 60% lower in the calcium-plus-vitamin D group, and about 47% lower in the calcium-only group.

But when they did a second analysis and took out the women diagnosed with cancer in the first year of the study, thinking those cancers probably already existed at the beginning of the study, the results were even stronger, with the calcium-and-vitamin D group showing a 77% relative cancer-risk reduction.

However, calcium alone didn't have a significant effect.

The calcium was included in the study because researchers initially set out to investigate the link between calcium, vitamin D and bone health. The cancer findings were a fortunate by-product.

The cancer society isn't making a recommendation for vitamin D supplements for children, because research so far has focused on adults.

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