Vitamin D: Your Bodys Best Friend?

Vitamin D may help prevent or better manage depression, diabetes, some cancers, cardiovascular disease

/ Author:  / Reviewed by: Joseph V. Madia, MD

Quick: What supplement helps build bone mass, may help prevent esophageal cancer, wards off obesity-induced endometrial cancer, improves mood and possibly contributes to a strong, healthy heart?

If you answered vitamin D, you get an "A."

In a recent onslaught of research, vitamin D, which is produced in the skin of vertebrates after exposure to ultraviolet B light from the sun, is proving to be a kind of wonder supplement, good for what ails you -- from the doldrums to better cardiovascular health. The nutrient is also found in some foods, including fortified milk, canned tuna in oil, salmon and fortified cereal.

"Vitamin D has widespread benefits for our health and certain chronic diseases in particular," said Sue Penckofer, PhD, RN, of Loyola University Chicago Marcella Niehoff School of Nursing (MNSON), who helped lead a study looking at how the nutrient improves mood and health levels in winter months when sunlight exposure is scarce. The Loyola study found that the vitamin improves mood during cold weather months when days are short and more time is spent indoors.

The university research members now plan to look at the nutrient's role in improving mood and blood-sugar levels for women with type 2 diabetes.

"There is evidence to suggest that vitamin D supplementation may decrease insulin resistance," said Dr. Penckofer. "If we can stabilize insulin levels, we may be able to simply and cost effectively improve blood sugar control and reduce symptoms of depression for these women."

Still not ready to catch some rays (around 10 minutes in mid-day sun should suffice) or take a vitamin D supplement? Try this on for size: Inadequate levels of vitamin D have been shown to increase risk of stroke, heart disease and death -- even among people who've never had heart disease.

An Intermountain Medical Center research team followed 27,686 patients age 50 and older with no prior history of cardiovascular disease for more than a year and divided participants into three vitamin D categories: normal (more than 30 ng/ml), low (15 to 30 ng/ml) or very low (less than 15 ng/ml). Researchers found those with very low levels of vitamin D were 77 percent more likely to die, 45 percent more likely to develop coronary artery disease and 78 percent were more likely to have a stroke than patients with normal vitamin D levels.

"This was a unique study because the association between vitamin D deficiency and cardiovascular disease has not been well-established," said Brent Muhlestein, M.D., director of cardiovascular research of the Heart Institute at Intermountain Medical Center and one of the study authors. "Its conclusions about how we can prevent disease and provide treatment may ultimately help us save more lives."

Another recent study from the University of California, Davis, found that 30 percent of test subjects with metabolic syndrome had insufficient levels of vitamin D, while only 8 percent of those in a healthy group had the same deficiency. (Metabolic syndrome encompasses a number of factors, including high blood pressure, obesity and/or higher than normal blood-sugar levels, which predispose patients to heart disease and diabetes.)  

By contrast, researchers at the University of California, San Diego, found no independent link between serum levels of vitamin D and cardiovascular mortality. Their study suggests further research may be needed to draw conclusive evidence regarding vitamin D's effects on cardiovascular health.

"Prior published literature in community-dwelling adults suggests an increased risk of cardiovascular mortality only in individuals with vitamin D levels lower than levels observed here," said lead investigator Simerjot K. Jassal, MD, Division of General Internal Medicine and Geriatrics, Department of Medicine at UCSD. "Our null results may mean that only larger disruptions in levels of (vitamin D) contribute to cardiovascular mortality."

Vitamin D and Cancer

Researchers at the Georgetown Lombardi Comprehensive Cancer Center suggest adding vitamin D supplements to a daily health regimen may help fend off obesity-related endometrial disease. According to a recent study, 25 percent of obese mice fed a vitamin D-supplemented diet developed endometrial cancer, while 67 percent of obese mice not treated with the diet developed cancer. Researchers said vitamin D offered no protective effects for normal-weight mice, however.

Meanwhile, researchers at Case Western Reserve University School of Medicine are looking at the role vitamin D may play in preventing esophageal cancer in patients with Barrett's esophagus (a change in the lining of the esophagus that often acts as a precursor to esophageal cancer). According to principal investigator Linda Cummings, MD, vitamin D is also being studied for its possible role reducing the risks of several types of cancer, including those of the colon, breast and prostate.

Vitamin D and Healthy Bones

Did you know that by the time teenage girls graduate high school, they will have developed most of their bone mass? That's why a diet high in vitamin D and its good friend calcium is essential for growing girls (and boys).

Teenage girls need about 1,300 milligrams (mg) of calcium every day. (You can do the math: One cup of low-fat or fat-free milk has about 300 mg.) Calcium is also found in other foods, too, including fortified orange juice and yogurt.

But here's the kicker: Calcium can't do its job strengthening bones without its dependable pal, vitamin D. Teenage girls need about 200 international units of vitamin D a day to help absorption of the calcium.

So, what are you waiting for? Get some sun (not too much, though -- sun can also cause damage and deadly skin cancers), have some tuna for dinner, or head down to your local health food store for some vitamin D supplements. Your heart, mind, esophagus and bones will thank you!

Review Date: 
December 21, 2010