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Checking in on vitamin D intake recommendations

July 26th, 2010

Jane Brody has a piece in today’s New York Times on vitamin D needs — nothing particularly new, but summing up the trend of the last few years to believe that insufficient vitamin D in modern sun-phobic societies is behind a whole range of chronic diseases, and noting that current recommended intakes are far below the levels some experts believe are necessary:

The current recommended intake of vitamin D, established by the Institute of Medicine, is 200 I.U. a day from birth to age 50 (including pregnant women); 400 for adults aged 50 to 70; and 600 for those older than 70. While a revision upward of these amounts is in the works, most experts expect it will err on the low side. Dr. Holick, among others, recommends a daily supplement of 1,000 to 2,000 units for all sun-deprived individuals, pregnant and lactating women, and adults older than 50.

With that in mind, it’s worth pointing out the press release from Osteoporosis Canada that I noticed last week, announcing a revision of their recommended vitamin D intake:

The new guidelines recommend daily supplements of 400 to 1000 IU for adults under age 50 without osteoporosis or conditions affecting vitamin D absorption. For adults over 50, supplements of between 800 and 2000 IU are recommended. For people who need added supplementation to reach optimal vitamin D levels, doses up to the current “tolerable upper intake level” (2000 IU) are safely taken without medical supervision.

I’m still a little gun-shy about the very broad claims made by vitamin D advocates, but the evidence is strong enough that D is the only supplement I’ve taken (albeit sporadically) over the past few years. The bottle I have right now is 400 IU per pill — maybe I need to ramp that up, or at least take it every day during the winter.

  1. July 27th, 2010 at 05:26 | #1

    My acupuncturist swears by the high dose recommendations for vitamin D. He says that all adults need 2000 I.U. per day or more here in the Pacific NW. We can go for a month with little or no sun during the winter/spring. Seems easy enough to get 2000 I.U. a day and I’ve had no side effects. Of course running in the summer sun with my shirt off for an hour would be even better way to get it. I’m curious what the latest research has to say about the subject. Thanks for posting.

  2. July 27th, 2010 at 09:15 | #2

    25(OH)D testing will confirm the extent of your current vitamin D deficiency

    Bear in mind humans only have enough spare vitamin d to store in tissues above 40ng/ml 100nmol/l and it’s only above 60ng/ml 150nmol/l that adequate amounts of D3 pass to the baby in human breast milk.

    If you think human breast milk should be a complete food for babies then that natural level should be your aim irrespective of your gender. The problem for all athletes is that vitamin D is a fat soluble vitamin and as sweat contains body oils these draw vitamin D to the surface of the skin where UVA exposure converts D3 to suprasterols the body doesn’t use. So cyclists, marathon runners, or any outdoor physical activity that induces sweating leads to vitamin D degradation.Ideally, to acquire maximun amounts of D3 from sunlight, you need to lay naked in the midday sun (peak UVB content) without burning and then cover that skin with clothing to prevent further (UVA) exposure. In practice taking an effective amount of vitamin D3 DAILY is the safest option although there are other benefits from being in full spectrum bright light (melatonin/Circadian rhythm) that should not be overlooked.

  3. alex
    July 30th, 2010 at 17:56 | #3

    [This is an interesting comment from "Lere" that I accidentally deleted while purging spam:]

    You’re initial sceptical reaction was right. 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 ….

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