Study is first to link low vitamin D blood levels to increased fat within muscle tissue… a known factor in reduced strength and overall health
by Craig Weatherby

Last year, we reported the results of two studies suggesting that low blood levels of vitamin D reduce muscle power in adolescent girls.
Conversely, the results indicated that that higher vitamin D levels make girls stronger.    

 For more on those investigations, see “Vitamin D Seen to Strengthen Girls.”   

Fish fit the vitamin D bill; Sockeye salmon stand out
In addition to getting vitamin D from supplements, certain fish rank among the very few substantial food sources of vitamin D, far outranking milk and other D-fortified foods.

Among fish, wild Sockeye Salmon may be the richest source of all, with a single 3.5 ounce serving surpassing the US RDA of 400 IU by about 70 percent:

Vitamin D per 3.5 ounce serving*

Sockeye Salmon—687 IU
Albacore Tuna—544 IU
Silver Salmon—430 IU
King Salmon—236 IU
Sardines—222 IU
Sablefish—169 IU
Halibut—162 IU

*For our full test results, click here.
As well as being linked to cancer, osteoporosis, diabetes, cardiovascular disease, and autoimmune disorders, low blood levels of vitamin D are associated with being fatter and weaker. 

An alarming study published last March found that more than half of the 90 participating teenage girls and young women from sunny southern California lacked sufficient vitamin D in their blood (29 ng/ml or less), while nearly one in four had serious deficiencies (less than 20 ng/ml). That study also linked low levels of vitamin D to increased visceral (abdominal) fat in the young women (Kremer R et al. 2009).

That study also linked low levels of vitamin D to increased visceral (abdominal) fat in the young women (Kremer R et al. 2009).
Now, a new analysis from that study is the first to show a clear link between vitamin D levels and the accumulation of fat in muscle tissuea factor in muscle strength and overall health. 
New study links low vitamin D to fattier, weaker muscles
As the U.S.-Canadian team wrote, “We found that vitamin D insufficiency is associated with increased fat infiltration in muscle in healthy young women” (Gilsanz V et al. 2010).
Scientists have known for years that vitamin D is essential for muscle strength. Studies in the elderly have shown bedridden patients quickly gain strength when given vitamin D.
The study results are especially surprising, because study subjects – 90 healthy young women living in California, 16 to 22 years oldcould logically be expected to benefit from ample exposure to sunshinethe trigger that causes the body to produce vitamin D.
As co-author Richard Kremer, M.D. of McGill University said about the new study, “...we found an inverse relationship between vitamin D and muscle fat. The lower the levels of vitamin D, the more fat [we found] in subjects' muscles” (MUHC 2010).
While these results support the wisdom of ensuring adequate vitamin D intake from foods and supplements, Dr. Kremer noted that their findings cannot prove a cause-effect relationship between low vitamin levels and increased muscle fat:
“We don't yet know whether vitamin D supplementation would actually result in less accumulation of fat in the muscles or increase muscle strength” (MUHC 2010).
Among other sources, the study was funded by grants from the National Institutes of Health, the U.S. Department of the Army, the Canadian Institutes of Health Research (CIHR), and the Natural Sciences and Engineering Research Council of Canada.
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