Researchers have launched the world’s first large, definitive clinical trial to find out if vitamin D supplements can stave off type 2 diabetes in people at high risk for the disease.
About 20 US medical centers are participating in the National Institutes of Health-funded trial, known as the D2d study, which will include some 2,500 volunteers with pre-diabetes, a problem affecting 79 million Americans.
“Without an effective intervention, about 10 percent of people with pre-diabetes will progress to type 2 diabetes each year,” reports Anatassios Pittas, MD, co-director of the Diabetes Center at Tufts Medical Center, who has received a grant of more than $40 million over five years from the NIH as part of the D2d study.
In the double-blinded clinical study, pre-diabetic participants ages 30 and older will be randomly assigned to take 4,000 international units (IU) of vitamin D3 or a placebo. Their health will be tracked for about four years.
MyAchingKnees Comment: While I think Vitamin D in a necessary supplement and a daily dose in the several thousand of IU's is required, I don't think these studies involving single nutrients do a lot of good since they do not consider nor evaluate the necessary and synergistic effect of taking all the required nutrients for the bodies immune system to optimally function.......still I am glad someone thinks that daily doses of more than the RDA recommended 400 IU are necessary.
New strategies are urgently needed to halt the diabetes epidemic, which now affects nearly 26 million Americans—with about 1.9 million new cases diagnosed each year, according to the American Diabetes Association. Rates have been rising in tandem with the obesity epidemic.
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“There’s a lot of hype about potential benefits of vitamin D—which is one of the most popular supplements with sales of $425 million a year in 2009—but not enough good scientific evidence to support a recommendation for or against taking it for diabetes prevention,” adds Dr. Pittas.
However, there are strong signals that the inexpensive vitamin—available for as little as 7 cents per pill—might be helpful. For example, Dr. Pittas and colleagues reported in a 2012 study that pre-diabetic patients with the most vitamin D in their blood had lower risk for progressing to type 2 diabetes, even when lifestyle interventions known to cut the threat, such as weight loss, exercising more, and eating a better diet were taken into account.
Ample amounts of the sunshine vitamin are linked to dramatic drops in risk for both type 1 and 2 diabetes. Compared to people with the most vitamin D in their blood, those with the least are 50 percent more likely to develop type 2 diabetes, according to a meta-analysis of 16 studies published earlier this year in Clinical Chemistry.
High levels of vitamin D have an even more potent effect on risk for type 1 diabetes (an autoimmune disease). A 2012 study found that people with vitamin D levels of 17 nanograms or less per milliliter of blood had more than triple the risk for type 1 versus those with levels above 40.
While these and other studies show a strong correlation between vitamin D and lower diabetes risk, they don’t establish causation. In other words, there is no proof that the sunshine vitamin prevents diabetes.
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What’s the Link Between Vitamin D and Diabetes Risk?
“For type 2 diabetes to develop, people have to have two problems: their bodies become resistant to insulin and the beta cells in their pancreas don’t produce enough insulin to keep up with demand,” says Dr. Pittas.
“There is some preliminary evidence that vitamin D may improve both problems,” adds Dr. Pittas. “Another intriguing discovery is that the beta cells in the pancreas that make insulin have the ability to activate vitamin D locally, which is not the case with most other tissues in the body.”
These discoveries offer a plausible biological mechanism by which vitamin D may fight diabetes, continues Dr. Pittas, who has been researching links with both forms of the disease for more than a decade. “I became intrigued with this association after learning that rates of type 1 diabetes rise as you move further from the equator.”
This geographic pattern also holds true for other autoimmune conditions, leading many researchers to hypothesize that sunshine, which sparks the body to produce vitamin D, may be protective.
However, there could also be other reasons, cautions Dr. Pittas. “For example, people who live close to the equator tend to have a healthier lifestyle than those in northern countries where people exercise less and eat a Western diet.”
Should You Take Vitamin D to Prevent Diabetes?
Since it’s not yet known if high doses of vitamin D, such as those used in the study, protect against diabetes, Dr. Pittas recommends sticking to the RDA of vitamin D (600 IU for people ages one to 70, and 800 IU for those over 70), unless your healthcare provider recommends higher doses.
Also discuss being checked for vitamin D deficiency, which is very common among Americans, especially in the winter, points out Amy Doneen, ARNP, medical director of the Heart Attack & Stroke Prevention Center in Spokane, Washington.
“Although a cause-and-effect relationship with diabetes hasn’t been established, optimizing your vitamin D levels if they’re low appears to be particularly beneficial if you have insulin resistance, the root cause of both type 2 diabetes and many heart attacks,” adds Doneen.
The best dietary sources for vitamin D include oily fish like salmon and mackerel, beef liver, egg yolks, and fortified dairy products.
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