UPDATE 2/20/13 A recent study reveals that not all Vitamin D supplements are created equal. Researchers studied bottles of randomly purchased D supplements and found potency ranging from 9% to 140%. Best bet: Pick supplements that have the seal of the U.S. Pharmacopeia (USP) to help ensure that your body gets the listed dose.
Another new study, slated for the March 2103 Journal of Clinical Endocrinology & Metabolism, suggests that while darker-skinned women tend to have lower levels of 25(OH)D, they appear to absorb and metabolize vitamin D in the same way as Caucasian women do and, according to a leading expert in the field, need not take larger doses of vitamin D as previously advised.
According to the National Institutes of Health, one in four people over age 60 may be deficient in vitamin D – not only because our bodies becomes less efficient at producing and processing dietary vitamin D as we age, but also because we spend too little time outdoors, especially during the winter months, and so we may not absorb enough of the ultraviolet rays that our bodies use to make the vitamin.
The result? Several recent research studies point to a host of potential health problems; Vitamin D, a fat-soluble vitamin, is essential as it aids calcium absorption to help us maintain strong bones; plays a role in cell growth and neuromuscular function; and combats inflammation, among other things.
5 Reasons You Should Mind Your D
- Less risk of heart disease A recent study from the University of Copenhagen adds to evidence that vitamin D may protect your heart. Researchers found that people with low blood levels of vitamin D had a higher risk of heart attack and cardiovascular disease compared to those with normal levels. The 2012 study involved more than 10,000 people and associated low serum vitamin D with a 40 percent higher risk of ischemic heart disease (insufficient blood supply to the heart from clogged arteries), a 64 percent greater chance of heart attack, and a 57 percent higher risk of early death.
- Lower diabetes risk Researchers at the University of California, San Diego School of Medicine have found a lower risk of developing type 1diabetes (insulin-dependent diabetes) among people with low blood levels of vitamin D compared to those with higher levels. The 2012 study suggests an optimal blood level of 25(OH)D of 50 ng/ml could cut the number of cases of type 1 diabetes in half; you’d need 4,000 IU a day to get to that level.
- Better brain health Vitamin D may help keep women’s brains sharp as they age, two according to studies from France published in 2012 by the Gerontological Society of America. One study analyzed four years of data from 6,200 French women over age 65 and found those with very low levels of vitamin D had higher odds of cognitive decline. The findings echo earlier research showing that people over 65 deficient in vitamin D are up to 60 percent more likely to experience cognitive decline.
- Fewer falls Past studies have linked disability and mobility problems in men and women with low levels of vitamin D. A 2012 Australian study found that people who spent more time outdoors during the months when the sun is stronger had greater ankle strengthand were more physically active; the study concluded that decreased ankle strength may predispose older people to winter falls.
- Better moods Vitamin D may help stave off depression. In a six-year study of 12,600 people, higher vitamin D levels were associated with a significant decrease in depression, especially among people with a prior history. Screening for vitamin D levels in depressed patients and screening for depression in people with low vitamin might be helpful, suggests a statement by the lead author of the report in the January 2012 Mayo Clinic Proceedings.
How Much Vitamin D Do We Need?
There’s some controversy here: In 2010 the Institute of Medicine set a recommended dietary allowance for vitamin D in food or supplements at a minimum 600 international units for adults 51 to 70 and 800 IU’s after age 70. Many endocrinologists argue that this RDA may not be high enough (the tolerable upper limit is 4,000 IU) while other experts say that excess dietary vitamin D can be toxic. (Some meds, including prednisone and possibly Cholestyramine, can hamper absorption of Vitamin D.)
What Are the Best Sources of Vitamin D?
Vitamin D is called the sunshine vitamin for good reason: we make D in the skin when ultraviolet light from the sun converts the hormone 7-dehydroxycholesterol so the body can synthesize it into active vitamin D3.
A few foods contain Vitamin D, among them fatty fish like salmon, along with fortified milk, orange juice and cereal, but it’s hard to get enough of it from food alone, and depending on how dark your skin is, the climate you live in and how much you avoid the sun, you might not get enough from the UV rays, either.
Depending on your age and health, your doctor may recommend supplements. But in many cases, sensible sun exposure and plenty of dietary vitamin D will provide what you need.