Natural Foods Merchandiser
Secret shopper: If I'm in the sun a lot, do I need a vitamin D supplement?

Secret shopper: If I'm in the sun a lot, do I need a vitamin D supplement?

Each month, NFM’s secret shopper heads incognito into a natural products store with a question. The employee’s answer—and our expert’s evaluation of the response—is reported here. Our aim: to help you improve your store’s customer service.

STORE: Large natural foods chain in the Washington, D.C. area

NFM: If I’m in the sun a lot, do I still need a vitamin D supplement?

Store: No. Well, how many hours of sun are you getting a day? If you’re getting two hours of sun per day, then that should be plenty. Yeah, at least that’s what I’ve heard, two hours of sun per day is all you need.

NFM: OK. Do you know if that varies by region? Like, say, is it different if I were in Maine versus Florida?

Store: No, sun is sun. It doesn’t matter where you are. It has something to do with the UVA rays or something. I mean, if you think you need a supplement, we have them right here. It definitely won’t hurt you to take them.

Comment: David A. Mark, Ph.D., consultant on labeling and marketing health claims

This employee needs a refresher course in vitamin D. First, it is ultraviolet B rays that lead to the production of vitamin D in the skin.

In the spring, summer and fall, 15 minutes of sun exposure on arms and legs will suffice for a fair-skinned person. A dark-skinned person will need at least twice that. The ability to make vitamin D decreases with age and obesity, so for some individuals, more than one hour per day is needed.

Sun is not sun. Further north, because the sun’s angle is greater, less UVB penetrates the atmosphere. This is the same in the winter, early morning or late afternoon. Many outdoor exercisers are surprised to find out that they have low vitamin D levels, because their exposure to the sun is at the wrong time of day. Sunscreen with an SPF of 8 or higher will block more than 95 percent of UVB rays.

Finally, the employee missed a safety issue with vitamin D. The Food and Drug Administration currently sets the safe upper limit at 2,000 IU per day. This may be increased by late 2010. Some manufacturers are anticipating the revision and are now marketing products with 5,000 IU dosage.

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