Baby, it’s not only cold outside, but your main source of vitamin D may have gone away too.
As the daylight hours grow shorter, the sun’s warm rays aren’t the only thing your body may be missing, warns Creighton University researcher Joan Lappe, Ph.D., internationally known for her NIH-funded research on vitamin D supplementation.
If you live in North American at latitudes above the 37th parallel – Omaha is near the 41st parallel - you probably are not getting enough vitamin D, says Lappe, a professor of medicine and holder of the Criss/Beirne Endowed Chair in the Creighton School of Nursing.
The sun rays are our primary natural source of vitamin D, which recent studies have shown may be even more important to our overall health than previously thought.
Adequate vitamin D intake is now believed to play a role in helping to prevent a number of chronic diseases, including osteoporosis, diabetes, high blood pressure and more. In addition, it is likely that vitamin D boosts the immune system and helps to prevent colds and flu that are so prevalent during the winter months, Lappe said.
Lappe’s own research has shown that vitamin D, when taken in combination with calcium supplements, can prevent all types of cancer in post-menopausal women and stress fractures (overuse injuries) in young, athletic women.
So when can you get your vitamin D naturally from the sun?
During the summer, the human body can convert solar energy into ample amounts of vitamin D with just 10-15 minutes of daily exposure to the sun. However, this time of year we cannot make our own vitamin D.
“From October until the end of March, the angle of the sun is such that, in much of North America, no vitamin D is available from that source,” Lappe says. “What that means is that many of us are deficient in vitamin D this time of year.”
While you can get the vitamin from fish oil and a few fortified foods, it’s difficult to take in adequate amounts of vitamin D by diet alone. Lappe recommends taking vitamin D3 – the same form of the vitamin that humans make from exposure to the sun.
The amount of vitamin D you should take daily is a subject of great debate, Lappe notes.
In November 2010, the National Academy of Science’s Institute of Medicine increased by 50 percent its recommended daily allowance (RDA) of vitamin D from 400 IU to 600 IU and doubled the tolerable upper limit from 2,000 IU to 4,000 IU. Also, the RDA for adults over 71 years old increased to 800 IU daily.
However, many vitamin D experts believe the new recommendations are still too low.
“Generally, medical experts consider it safe to take to take between 1,000 IU and 2,000 IU of vitamin D supplements daily,” Lappe said.