By David Crocker

Vitamin D supplementation seems all the rage these days. Do we really need to take it? How much is necessary? How much is too much? What is this nutrient, and what can it do for us?

Vitamin D is often considered a vitamin, but in fact, isn’t a vitamin at all, but rather a fat-soluble secosteroid or hormone. One of vitamin D’s main functions is to help our bodies absorb calcium and phosphorus properly. This is essential for strong bones and teeth.

Children who don’t get enough vitamin D often develop rickets or other skeletal deformities, as well as malformed teeth. Adults who don’t get sufficient amounts may suffer from osteomalacia, or bone softening. For this reason, vitamin D is used for preventing falls and fractures in folks at risk for osteoporosis.

Vitamin D may help arm the immune system, preventing autoimmune diseases, and help prevent cancers, say scientists from the university of Colorado Denver School of Medicine, Massachusetts General Hospital and Children’s Hospital Boston.

It may reduce risk for developing multiple sclerosis, and play a key role in helping the brain to keep working well, in later life. Vitamin D has been shown to reduce the risk of developing rheumatoid arthritis in women. Also, higher intake of vitamin D has been associated with a reduced risk of breast cancer in women.

One form of vitamin D known as calcitrol or calcipotriene can be applied directly to the skin for a particular type of psoriasis.

Now we know some of the great stuff vitamin D can do for us, but how much do we actually need, how much should we take, and how much is unsafe? First of all, five forms of vitamin D have been discovered, D1, D2, D3, D4, and D5, but D2 (ergocalciferol), and D3 (cholecalciferol) seem to be most important to humans.

We obtain vitamin D, three different ways. First, it comes through our diet, from sources like salmon, mackerel, tuna, sardines, or cod liver oil (the richest dietary source). Small amounts are added to most dairy products. The second source is from dietary supplements, and third, from exposure to sunlight.

That’s right. Vitamin D3 (sometimes called the sunshine vitamin) is synthesized in our skin when 7-dehydrochlesterol (which is a cholesterol precursor) reacts with ultraviolet light. In fact, several studies show fewer incidents of autoimmune disease and multiple sclerosis in those who live closest to the equator.

It takes very little sun exposure to produce vitamin D. For some, that means as little as five minutes, twice a week. Or, if you’re already tan or have darker skin, it may take 15-20 minutes, and if you’re black, it takes six times the sun exposure to produce vitamin D.

If you’re going to use supplementation, I recommend 600iu daily of vitamin D3 for ages 1-65. For those 66 and older, 800iu. For those who are vitamin D deficient, upper limits can be as high as 10,000iu, but only under a doctor’s recommendation, and direct supervision.

Remember vitamin D is fat soluble, and it’s stored in the liver, so levels can accumulate and reach toxic levels. Too much vitamin D can also cause a condition called hypercalcemia, where blood calcium levels rise too high. This can cause renal failure as well as damage to organs. Also, when taking vitamin D, ask your doctor to monitor your status if you are living with any chronic liver or kidney disorder.

Diet or exercise question? Email me at dwcrocker77@gmail.com or visit fitness4yourlife.org. David Crocker of Landrum has been a nutritionist and personal trainer for 28 years. He served as strength director of the Spartanburg Y.M.C.A., head strength coach for USC-Spartanburg baseball team, the S.C state champion girl’s gymnastic team and the Converse College equestrian team. He served as a water safety consultant to the United States Marine Corps, lead trainer to L.H. Fields modeling agency, and taught four semesters at USC-Union. David was also a regular guest of the Pam Stone radio show.