Why vitamin D may prevent H1N1

Source: Web exclusive: November 2009

Taking vitamin D supplements may help protect you from the H1N1 virus, a U.S.-based researcher says.

‘Vitamin D fights common seasonal influenza and H1N1 in several ways,’ says William Grant, founder of the Sunlight, Nutrition And Health Research Center in California. Primarily, research in the past few years has found that vitamin D helps you fight off the flu by supporting your immune system’s response to viruses.

A 2007 study on post-menopausal African-American women (who are naturally deficient in vitamin D) found that those who took 2,000 IU per day of vitamin D had a 90% reduced risk of contracting the seasonal flu over those who took a placebo.

Though there haven’t been any randomized tests conducted on H1N1, Grant says research shows vitamin D will also work in preventing the virus. ‘H1N1 is largely seasonal,’ he says, adding that ‘the five groups that are shown as having more adverse effects from H1N1 are known to be vitamin-D deficient: pregnant women, Aboriginal people, obese people, people with type-2 diabetes and children with neurological diseases.’

How do you know if you’re deficient in vitamin D? If you live in Canada during the winter, you probably are. ‘It’s impossible to make enough vitamin D in Canada from sun right now,” says Grant, who receives research funding from the Vitamin D Society in Canada and Bio-Tech-Pharmacal, a U.S.-based pharmaceutical manufacturer that produces vitamin D supplements. To boost your vitamin-D levels, he recommends taking a supplement of 1,000 IUs or more every day. ‘If you haven’t been taking vitamin D for a long time, take large doses’10,000 IU per day for several days’then go down to 2,000 to 4,000 IU per day throughout the flu season.’ (Most vitamin D supplements on the market have 1,000 IU per tablet, which is what the Canadian Cancer Society recommends as a daily dose.)

While Health Canada is currently reviewing the health benefits of vitamin-D supplementation, they still recommend that people ages one to 50 get their daily dose of 200 IU of the vitamin from drinking two 500 mL glasses of milk. People over 50 are advised to take a daily supplement of 400 IU and it is not recommended that people take more than 2,000 IU per day. Grant says that’s not enough to make a difference to your immune system.’400 IU doesn’t do anything,’ he says. ‘If you are out in the sun all day in the summer you can make at least 10,000 IU of vitamin D per day.’

Still confused? Talk to your doctor about their recommendations for your situation, and consider getting your vitamin D levels tested.

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