March 18, 2004
Ivanhoe Broadcast News
Vitamin D is a fat-soluble vitamin that can be found in food or made in the body after exposure to ultraviolet rays from the sun.
The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Without vitamin D, bones can become thin, brittle, soft, or misshapen.
New research shows vitamin D may be more valuable than once believed.
"Vitamin D affects a variety of other tissues and organs. Vitamin D deficiency may put people at risk for several different diseases,” said Kerry Burnstein, a researcher at the University of Miami.
A recent study showed women who take vitamin D supplements through multivitamins are 40 percent less likely to develop multiple sclerosis than women who do not take supplements.
"The number of cases of MS increases the farther you get from the equator. One hypothesis has been that sunlight exposure and high levels of vitamin D may reduce the risk of MS,” said Kassandra Munger, a researcher from the Harvard School of Public Health.
Study results show a higher intake of vitamin D supplements did reduce the risk of MS, but the benefit was not seen among women who only got their intake of vitamin D through food. Other studies have shown people with MS tend to have insufficient levels of vitamin D and that periods of low vitamin D occur before times of high disease activity.
Another study showed women with the highest levels of vitamin D intake
are about one-third less likely to develop rheumatoid arthritis than are
women with the lowest levels. Researchers from
the University of Alabama at Birmingham analyzed data from nearly 30,000 women and found both dietary and supplemental vitamin D intake were associated with a lower risk of RA.
High dietary intake - at least 290 IU a day, reduced risk by 28 percent and high supplemental intake, at least 400 IU a day, reduced risk by 34 percent.
"Immune cells can be regulated by vitamin D and since there appears to be an immune component to diseases such as multiple sclerosis and rheumatoid arthritis, the thought is that maybe vitamin D can protect,” Burnstein said.
Burnstein also said vitamin D deficiency is associated with higher rates of specific cancers.
"Vitamin D can inhibit the proliferation of cells so it can inhibit abnormal cell growth. It helps cells to mature and specialize and that can be helpful, especially in cancers. Vitamin D deficiency actually seems to put people at risk for the three major types of cancer: prostate, breast and colon cancer,” Burnstein said.
Vitamin D deficiency may put people at higher risk for Type 1 diabetes and high blood pressure, she said.
Experts recommend 400 IU of vitamin D a day, which is equivalent to 10 micrograms. That 400 IU a day recommendation is for adults under age 70. Children actually need less vitamin D and people over 70 should get slightly more at 600 IU a day.
People can get enough vitamin D with about 15 minutes of sunlight a day. However, that's not possible everywhere in the world. For example, the average amount of sunlight in Boston is insufficient to produce significant vitamin D synthesis in the skin from November through February.
Also, sunscreens with a sun protection factor (SPF) of 8 or greater
will block UV rays that produce vitamin D, but it is still important to
routinely use sunscreen whenever sun exposure is longer than 10 to 15 minutes.
Individuals with limited sun exposure should include sources of vitamin
D in their diet. Four cups of fortified skim milk a day will do the trick
as will fatty fish.
Copyright © 2004, Ivanhoe Broadcast News