During the summer, the body can convert solar energy into ample amounts of vitamin D with just 10-15 minutes exposure daily to the sun. That's not possible during the winter months when the angle of the sun sinks lower into the southern hemisphere.
Dr. Lappe, who is a professor of medicine and holder of the Criss/Beirne Endowed Chair in the Creighton School of Nursing, goes on to say that if you live in North American at latitudes above the 37th parallel you may be getting little or no Vitamin D at all.
"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 said. "What that means is most of us are deficient in vitamin D this time of year." The amount of vitamin D you should take daily is a subject of great debate, Lappe notes.
While there may be a great deal of debate about how much vitamin D is needed for optimum health, there is little debate about how valuable Vitamin D is for human health. Without Vitamin D there would be no human life. Among a very long list of benefits associated with Vitamin D are prevention and treatment of : infections and inflammation, cancer prevention, depression and neurological disorders, cold and flu, diabetes, osteoporosis and tuberculosis.
Vitamin D is available from several sources besides the sun, although it`s difficult to take in adequate amounts of vitamin D by eating alone. While you can get some Vitamin D from the vitamin from food source, primarily fish oil and fish, taking supplemental Vitamin D may be necessary to get enough of this valuable vitamin. By far the most effective form of Vitamin D is Vitamin D3, the form found in nature.
The U.S. government`s recommended daily allowance is 200 IU until age 50, 400 IU for 50-70 year olds, and 600 IU after age 70. However, many medical experts believe those recommendations are way too low.
The Canadian Cancer Society recently recommended that people with light skin take 1,000 IU of the vitamin supplement during fall and winter, and that people with darker skin or limited exposure to sunlight take that amount throughout the year.
The society`s recommendation coincided with the publication of the Creighton research in June. The four-year study involving 1,179 Nebraska women showed a 60 percent decrease in the risk of developing canceer for those who took calcium supplements plus 1,100 IU of vitamin D3 daily.
On the other hand, Dr. John Cannell, of the prestigious Vitamin D Council, recommends 5000 units of Vitamin D3 daily for optimum health, and many in the field of natural health agree.
Note: due to concerns about Vitamin A toxicity, a growing number of health experts, including Dr. Cannell and Dr. Mercola are recommending against cod liver oil as a source of vitamin D3.
Sources for this article included:
The Vitamin D Council
The National Institute of Health
Medical News Today