More Vitamin D – Interview with Michael Holick

I just read a very engaging article about vitamin D (and that is saying a lot, I find most nutrition articles to be drowse-inducing). It is an interview with one of the world’s foremost vitamin D experts, Michael Holick. It is free on the web here.

A quick summary of the main points:

– 30 to 80% of the US population is vitamin D deficient.
– Vitamin D can protect against cancers, autoimmune diseases, infections, and bone problems.
– If you live north of Atlanta, your skin can’t make vitamin D from November through March.
– Both children and adults need 1,000 IU a day to keep their vitamin D levels above 30 ng/ml (about 75 nmol/L), which is the most healthy level.
– You need massive amounts of vitamin D to overdose. 5,000 IU per day, indefinitely, is probably safe.
– Vitamin D2 is as effective as D3.
– The sun is the most efficient way to receive vitamin D and may have important health benefits beyond vitamin D production.

For sun exposure, Dr. Holick says:

“I typically recommend people go out for a period of time—depending on the time of the year, the time of day, the latitude, and the degree of skin pigmentation—if you know you’re going to get a mild sunburn after 30 minutes, I typically recommend about 10, no more than 15, minutes of arms and legs exposure, or if you’re in a bathing suit, abdomen and back exposure as well, 2 to 3 times a week. Always wear sun protection on your face because that’s the most sun-damaged area and it’s only about 9% of your body surface, so it doesn’t provide you with that much vitamin D. Go out, enjoy yourself, get some sensible sun exposure, then put sunscreen on if you plan to stay out for a longer period of time. People with a higher degree skin pigmentation, such as African Americans, are walking around with an SPF of 8 to 15. That’s why they need to be exposed for much longer periods of time and why people of color are at especially high risk of having vitamin D deficiency.”

13 Responses to “More Vitamin D – Interview with Michael Holick”

  1. Vitamin D Interview | Says:

    […] might therefore consider taking a Vitamin D supplement, even if you already take a multivitamin. Link. Spread the […]

  2. Rita Says:

    Why did this apparently excellent article appear in an “alternative” journal? Is there something dodgy about it?
    It’s so difficult to sort out the sheep from the goats in these matters!

  3. Jack Norris RD Says:

    Alternative medicine typically seeks nutritional or natural ways to prevent or treat disease, so it doesn’t surprise me that they would have an interest in vitamin D and sunshine. Given that Dr. Holick has had many papers published in scientific journals, I would not be concerned about the above interview appearing in an alternative magazine.

  4. Rita Says:

    This report appeared in a journal – it does not invalidate the vitamin D research, but it does make one wonder about the emphases – see also the photo in the original article. I should point out that I have not checked out this journal, nor read the complete story, to do which one must subscribe:

    The Scientist Daily
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    by Alison McCook


    Vitamin D expert loses post
    Email: Alison McCook –
    News from The Scientist 2004, 5(1):20040416-02

    Published 16 April 2004


    Michael Holick, a dermatologist at Boston University, was recently asked to resign from school’s department of dermatology because of a book in which he describes the importance of sunlight in boosting vitamin D levels and his ties to the indoor tanning industry.

  5. Ava Odoemena Says:

    Now while I don’t like the “” at all for pushing vitamin D3 over D2 with unscientific arguments, the “Don Quichote” running that site has some background info to why Holick was sacked, it’s nevertheless its drawbacks a good site for everybody interested in Vitamin D. If you can bare the subliminal antivegan slant.

    BTW, my Vitamin D strategy is to grow delicatessen-mushrooms at home (easy to learn) and drying these in the summer sun. Exposure to appropiate sunlight shortly after harvest will boost the Vitamin D content of the mushrooms dramatically (they also tan:-)), and in dried form they last into winter to be added into stews or ground to a flour to be the base of tasty sauces.

    Sadly, many people find this very cheap and effective method too “odd” or “complicated” even though it would probably work with shrooms from the grocer; fending for themselves is just not something they were socialized with. Apart from sunlight though here in Europe this would form the only alternative for vegans, given that supplemental Vitamin D2 has vanished off the market thanks to that one infamous study. I’ve recently seen D2 400IU, but even 1600IU a day which I took before the mushroom idea would just raise my bloodlevels to a mere 42 nmol/L (the nmol/L is the more widespread parameter in Europe).

  6. A-Z tentang Tulang, Vitamin D, dan Calcium « VEGETARIAN HEALTH Says:

    […] on vitamin D compiled from an interview from leading vitamin D researcher Dr. Michael Holick, click here. But don’t forget to return to this page to read about calcium […]

  7. Rose Hackett Says:

    What type of Vitamin D supplemented in the Silk Soy Milk product. Synthetic D2
    is not fully absorbable and D3 is more absorbable from the gastrointesrinal tract.
    Rose Hackett

  8. Jack Norris RD Says:

    Vitamin D2 and D3 are both absorbed at the same rate. But vitamin D2 does not stay in your system for much more than 3 days, so you need to eat it regularly. You can read more here.

  9. China Says:

    Thanks for the info on Vit D. I am fair skinned & have been avoiding the sun for years. Last spring I was tested for Vit D and was very low.
    I am currently on therapeutic dosage of Vit D – even needed an injection. Point: if you are extremely low on Vit D, sunshine alone won’t correct it, you’ll need a therapeutic intervention. Particularly important if you have dark skin or live in a Northern latitude.

    And do get checked for B-12 as well, if you are vegan.

  10. Philip Barr Says:

    The IOM article release today is puzzling. I have not yet read it. I am aware that most vitamin D in food is added to the food. IOM reports we can get it from our nutrition. Well I consider my supplements part of my nutrition, including vitamin D. The above production from mushrooms appears to be an exception, and a very intriguing one.

    I wonder what Dr. Holick’s response to the IOM article is?

  11. Rita Says:
    Is this referring to the IOM article?

  12. Jack Norris RD Says:



  13. Kathleen M Says:

    A recent study in parrots indicated that supplementing their diet with D3 plus giving them sunshine (UVB rays) daily increased bone density and calcium absorption. D2 is not effective in birds at all FYI. I like the idea of approaching D level normalcy through sunlight and supplements.

    D3 is OK I think as it doesn’t involve killing the animal from whence the oil is derived — if it’s sheep or dog hair that the lanolin is taken from. I don’t go for slaughtering fish for supplementation in humans and cod liver oil has too much vit A in it to be effective for low D treatment.

    I add 1,000 IU to my diet Nov to Mar each year. My blood isn’t high or very low, so I will probably stick with that and add another 1,000 IU daily any time it dips under 30 ng/ml of 25 (OH) D. My Mom insisted everyone go “outdoors” for an hour every day and my dermatologist seems to go for that OK as I live about 35 degrees north. (Summer use some sunscreen if need be after 20 min or so.)

    Oil on the skin increases D absorption I think–it’s then a shiny surface.

    Even the monks in India that live in caves meditating, come out once a day after or for lunch to get some sun for an hour. I also think sleeping enough increases absorption of everything – I am in bed with the lights out by 8pm nightly and feel great and keep well. We hardly have any “dark” hours in the world anymore, and darkness matters too!!! Best, Kathleen M

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