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.”