Friday, July 30, 2010

The Vitamin D Advantage

Wherever one looks these days, vitamin D is labeled as practically the Holy Grail of good health. But the natural source of vitamin D is from the sun, which causes a dilemma for us all. Too much sun can mean courting skin cancer, but not enough may cause a vitamin D deficiency.

Vitamin D deficiency is widespread in dark-skinned African Americans and anyone with similar skin tones. The reason is that melanin limits the amount of sunlight exposure penetrating the skin.

And not having enough vitamin D could raise your risk of developing several conditions including cardiovascular disease or osteoporosis, says Asha Thomas, M.D, the director of the Sinai Hospital Division of Endocrinology.

Think swallowing a daily multi-vitamin means you are covered? Think again.

“Multi-vitamins typically have 400 units of vitamin D,” Dr. Thomas says. “That might be appropriate if you already have normal levels of vitamin D. But we are finding most people are deficient. So many people are way too low.”

Only relatively recently did people even know what their vitamin D level was. “Physicians just recently started checking people’s,” says Dr. Thomas.

According to the National Center for Health Statistics, 36 percent of Americans are vitamin D deficient. Researchers believe that number could be double for African Americans. In fact, vitamin D deficiency has been called “the hidden epidemic” for darker-skinned people.

“There is a higher incidence of vitamin D deficiency in African Americans starting in puberty and older,” Dr. Thomas says. Reasons could be because it is the time young people stop playing outdoors or other lifestyle reasons, she says.

Getting your vitamin D from the sun or supplements is a personal choice and both will work. But check with your doctor to find out where you stand with vitamin D and how much sun to get or supplements to take.
-Sandra Crockett


mbarnes said...

Over two years ago the Canadian Cancer Society started recommending that everyone take vitamin D to prevent cancer. The data on vitamin D preventing cancer is as extensive as the data on smoking causing cancer. Take a look at it has all the information

Ken said...

Yes that sounds plausible - but it's wrong. The huge state of the art July 2010 study Common genetic determinants of vitamin D insufficiency: a genome-wide association study found that none of the genes they identified are linked with skin pigmentation.

Confirmation of that interpretation in an article Here :- ” the accompanying (Lancet) editorial points out, it is somewhat surprising that none of the genes identified are linked with skin pigmentation”

A systematic review of the association between common single nucleotide polymorphisms and 25-hydroxyvitamin D concentrations
"We speculate that recently identified U-shaped relationships between 25OHD concentrations and disease outcomes (i.e. increased risk at both high and low concentrations) may reflect a mixture of genotype-defined subgroups."

'Genetics to Blame for Vitamin D Deficiency?'
"Researchers conducted a genome-wide association study (Common genetic determinants of vitamin D insufficiency: a genome-wide association study) that involved almost 34,000 people of European descent from 15 different studies. They used radioimmunoassay and mass spectrometry to determine vitamin D concentrations and found that variants at three genetic sites, or "loci," were significantly associated with vitamin D concentrations. The presence of harmful alleles at three "loci" more than doubled the risk of Vitamin D insufficiency."

Maybe non-whites are the ones who benefit from doubling their vitamin D levels ? Nope - Vitamin D, Adiposity, and Calcified Atherosclerotic Plaque in African-Americans "positive associations exist between 25-hydroxyvitamin D and aorta and carotid artery CP in African-Americans"

Many people are naturally low in vitamin D, forcing vitamin D levels up by taking supplements can only do harm. If you think you can improve yor health by conforming to the advice of Holick or - God forbid - that of Hollis, Cannel & Co at the vitamin D 'Council' who recommend (>50ng/ml) then you are in for an unpleasant surprise.

Vitamin D and homeostasis

Mad dogs and ....