Discover Vitamin D

Discover Vitamin D

Posted on 19. Apr, 2010 by in Heart Health, Nutrition

If you’ve been reading the news lately, you may have noticed new studies on vitamin D popping up all the time. Most of us know it’s essential for building strong bones, but research shows that this vitamin is crucial to so many more aspects of our health. But experts find that most of us aren’t getting enough, and call for an increase in the recommended dietary intake to protect against heart disease, cancer, and more.

What Is D?

A fat-soluble vitamin with properties of both a vitamin and a hormone, D is necessary for growth and is particularly important for normal development of bones and teeth in children. It’s required for the absorption and utilization of calcium and protects against muscle weakness. D enhances immunity and is necessary for normal thyroid function and blood clotting. There are several different forms of vitamin D. D2 (ergocalciferol) comes from food sources. D3 (cholecalciferol) is considered the natural and most active form of D. It’s synthesized in the skin in response to the sun’s ultraviolet (UV) rays and converted to a biologically active form, calcitriol, by the liver and kidneys. D5 is the synthetic form of vitamin D.

Heart Health

Vitamin D is necessary for regulating the heartbeat, and new research finds that it may also be involved in preventing coronary artery disease. In a study of more than 18,000 healthy men aged 40 to 75, investigators found that those deficient in D were at a greater risk for heart attack than men whose D levels were sufficient. This relationship remained significant even after adjusting for factors known to be associated with heart disease, including family history of heart attack, body mass index, alcohol consumption, physical activity, a history of diabetes, ethnicity, omega-3 levels, and triglyceride levels. “Vitamin D deficiency has been related to an increasing number of conditions and to total mortality,” says lead researcher Edward Giovannucci, MD, ScD. “These results further support an important role for vitamin D in myocardial infarction [heart attack] risk.”

D and Cancer

The link between vitamin D and cancer protection dates back nearly 70 years, and supportive evidence just keeps growing. New research suggests that D3 may link with a specific gene that releases an antioxidant enzyme to protect DNA from damage. When healthy prostate cells and prostate cancer cells were subjected to oxidative stress, researchers found that D induced the antioxidant enzyme in the healthy cells. “If you reduce DNA damage, you reduce the risk of cancer and aging,” says lead researcher Yi-Fen Lee, PhD. “Our findings reflect what we see in those studies [suggesting beneficial properties of D] and demonstrate that vitamin D not only can be used as a therapy for prostate cancer, it can prevent prostate cancer from happening.”

In a four-year study, researchers found that improving calcium and vitamin D status, but not calcium status alone, significantly reduced cancer risk in more than 1,000 postmenopausal women. However, the American Cancer Society critiqued the study, stating that cancer takes longer to develop than the four years of the clinical trial and that D was not proven to actually “prevent” cancer. “Frankly, I wouldn’t care whether vitamin D simply impaired the promotion of a latent cancer to one that could be diagnosed, or whether it prevented cancer entirely,” says Reinhold Vieth, PhD, a professor of nutritional sciences and pathobiology at the University of Toronto. “Either way I’d come out a winner with vitamin D.”

More on Healthy Bones

Calcium and vitamin D are the dynamic duo of bone health, and they may also help reduce the risk of stress fractures during exercise. In a study of more than 14,000 women in basic training, those who received daily calcium and vitamin D supplementation experienced 20 percent fewer stress fractures than their counterparts who did not receive supplements. Stress fractures are one of the most common overuse injuries seen in the U.S. military, and they’re more common in women. This injury is also a common problem for many athletes.

How Much Is Enough?

The adequate intake for vitamin D is currently 200 IU per day for children and adults up to 50, but studies show that most of us aren’t getting enough and experts call for an increase. A recent study at Boston Children’s Hospital found that, in a group of 380 healthy infants and toddlers, 40 percent had low blood levels of vitamin D and 12 percent of those were D deficient. Some experts recommend multiplying D levels by 10—from 200 IU to 2,000 IU—for children’s long-term health.

“Our research reveals that vitamin D, at doses equivalent to 2,000 IU a day, is not only safe for adolescents but it is actually necessary for achieving desirable vitamin D levels,” says researcher Ghada El-Haff Fuleihan, MD. A simple lab test can detect vitamin D levels. Talk to your doctor to determine whether you’re deficient and to establish your optimal amount.

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