Vitamin D – often called the sunshine-and-seafood vitamin – is unlike its companion micronutrients.
It's the only essential nutrient that exerts broad, hormone-like effects throughout the body, making a critical difference in virtually every organ and metabolic function.
So perhaps it should come as little surprise that a new study links vitamin D “insufficiency” to added weight gain.
The study focused on older women, and found that four out of five (80 percent) had insufficient levels of vitamin D … a finding with serious implications for bone health.
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 rank as the richest source, with a single 3.5 ounce serving surpassing the US RDA of 600 IU by about 15 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.
According to lead author Erin LeBlanc, M.D., “Nearly 80 percent of women in our study had insufficient levels of vitamin D. A primary source of this important vitamin is sunlight, and as modern societies move indoors, continuous vitamin D insufficiency may be contributing to chronic weight gain.” (KP 2012)
The finding of a widespread lack of vitamin D was bad enough, but the researchers also found that women who lacked vitamin D gained more weight than those with blood levels deemed sufficient.
Dr. LeBlanc called that weight-gain finding unprecedented: “This is one of the first studies to show that women with low levels of vitamin D gain more weight, and although it was only two pounds, over time that can add up.” (KP 2012)
Study links vitamin D lack to gradual weight gain
The study was conducted by researchers from the Kaiser Permanente Center for Health Research, the University of Minnesota, the University of Pittsburgh, and the University of Maryland (Leblanc ES et al. 2012).
The team recruited 4,659 women aged 65 and older, measured their vitamin D blood levels, and tracked their weight over a period of 4.5 years.
Vitamin D supplements called necessary for many adults
Recently, a panel of primary care experts – the US Preventive Services Task Force (USPSTF) – said healthy postmenopausal women may need higher doses of the vitamin to prevent fractures.
Although the USPSTF said there isn't enough evidence to recommend vitamin D supplements for younger people, The Endocrine Society – a group with much more expertise in the body's hormone system (which includes vitamin D) – concluded that many adults do need vitamin D supplements to keep their bones healthy.
They found that the women with insufficient levels of vitamin D gained about two pounds more than those with adequate levels.
She made a key point about the limitations of epidemiological studies like theirs: “Our study only shows an association between insufficient levels of Vitamin D and weight gain, we would need to do more studies before recommending supplements to keep people from gaining weight.” (KP 2012)
Details of the study
Dr. LeBlanc noted that their study was conducted among older women who, for the most part, were not trying to lose weight … though some of them lost weight as a natural result of aging.
About 60 percent of the 4,659 women in the study remained at a stable weight (within five percent of their starting weight) over the 4.5 year study period.
A bit more than one-quarter (27 percent) lost more than five percent of their body weight, and 12 percent gained more than five percent of their body weight.
Most women in the study (78 percent) had less vitamin D in their blood than the level defined as sufficient by The Endocrine Society panel of experts who set clinical guidelines on Vitamin D deficiency: namely, 30 nanograms per millimeter (ng/ml).
These women had higher weight to begin with: 148.6 pounds compared with 141.6 pounds for women whose vitamin D levels were 30 ng/ml or higher.
Among the 571 women who gained weight, those with insufficient vitamin D levels gained more weight – an average of 18.5 pounds over 4.5 years – than women who had sufficient vitamin D, who gained an average of 16.4 pounds over the same period.
This study is part of a larger project called the Study of Osteoporotic Fractures that has been ongoing for more than two decades, which is supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging.
Kaiser Permanente Center for Health Research (KP). Low Vitamin D Levels Linked to Weight Gain in Some Older Women. June 25, 2012. Accessed at http://www.kpchr.org/research/public/News.aspx?NewsID=73
Leblanc ES, Rizzo JH, Pedula KL, Ensrud KE, Cauley J, Hochberg M, Hillier For The Study Of Osteoporotic Fractures TA. Associations Between 25-Hydroxyvitamin D and Weight Gain in Elderly Women. J Womens Health (Larchmt). 2012 Jun 25. [Epub ahead of print]