ASK IT
Bright winter sun offers weak source of vitamin D
January 7, 2010
The You Docs
Q. My doctor prescribed 50,000 IU of vitamin D per week to help prevent bone loss. Is it possible to get or absorb some of that vitamin D from the sun through a window? (I've heard you can get a sunburn that way.)
A. Only about 5 per cent of the UVB rays you need for vitamin production penetrate window glass. UVB light can be scattered by air pollution and even absorbed by ozone, so it's a rare commodity at the best of times, which would be peak summer, at high noon, in the south. If you live north of about 30 degrees latitude – for instance, Austin, Tex., or Jacksonville, Fla. – you'd need at least 38 hours of sun exposure during a summer week. You can always eat more fatty fish (6 ounces will get you the 1,000 IU we recommend as a daily dose). And fortified foods, such as milk and cereal, add some but it's generally difficult to eat enough.
You need vitamin D, but 50,000 IU is a hefty dose, usually given to people who are deficient.
If you haven't been tested for D levels, ask your doctor to check your blood levels. You may not need to take such a hefty dose as 50,000 IU, and it may have some toxicity at very high doses.
For more You Docs advice, see their website www.realage.com.
Toronto Star
Featured Sponsored Listings