The forgotten benefits of vitamin D...

Getting optimal amounts of vitamin D may have a positive influence on blood sugar levels, possibly reducing the risk of developing insulin resistance.

According to some reports, up to 25% of the adult population in America are resistant to insulin to some degree.

Normally, the carbohydrate in the food you eat is eventually broken down into glucose (also known as blood sugar). Glucose, in turn, triggers the release of the hormone insulin.

Insulin helps to move nutrients from the blood into the cells of your body. However, in someone with insulin resistance, muscle cells are not able to deal with glucose properly.

In the new study, published in the American Journal of Clinical Nutrition, vitamin D status (as determined by blood levels of 25-hydroxyvitamin D) was assessed in a group of healthy young volunteers. Insulin resistance was also measured. Lower blood levels of vitamin D were associated with a greater degree of insulin resistance.

But it's important to remember that association does not mean causation.

There is research, for example, to show that people who eat breakfast are less likely to suffer from obesity or diabetes.

But is it eating breakfast that's solely responsible for this?

People who eat breakfast may be more likely to engage in other healthy behaviors, such as eating more fruit and vegetables. Maybe people who don't eat breakfast are less likely to exercise, or more likely to consume a diet high in sugar or trans-fatty acids.

In other words, levels of vitamin D in the blood may simply be a marker for one or more nutrients in the diet which also aid blood sugar control.

That said, vitamin D deficiency is far more common than most people realize. The vitamin is present in only a few foods, such as cod liver oil, oily fish (including salmon, mackerel, and sardines), and fortified dairy products and breakfast cereals.

Most of the vitamin D in the human body is manufactured in the skin after exposure to ultraviolet light from the sun. People who do not receive adequate amounts of sun exposure are at risk of developing vitamin D deficiency.

According to Dr. Michael Holick, author of The UV Advantage, and a well-known authority on skin, UV light, and disease, the health benefits of moderate sunlight exposure include stronger bones, less depression, a boost in vitamin D levels (especially in Northern climates) — even an increased resistance to prostate and breast cancers!

Those with dark skin and elderly people have a reduced ability to produce vitamin D in response to sunlight exposure.

For people who are unable to obtain sunlight exposure, vitamin D supplementation may be worthwhile. The amount recommended by most doctors ranges from 400 to 1,000 IU per day. Although excessive doses of vitamin D can be toxic, recent research suggests that long-term use of 1,000 IU per day is safe.

Reference
Chiu, K.C., Chu, A., Go, V.L., & Saad, M.F. (2004). Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. American Journal of Clinical Nutrition, 79, 820-825