Females aged 65 or more with low Vitamin D levels are more likely to gain weight than their counterparts with adequate levels, researchers from the Kaiser Permanente Center for Health Research in Portland, Oregon, reported in the Journal of Women's Health. The authors explained that their study, involving 4,659 elderly women (65+ years) who were monitored for 4.5 years, found a 2.1 lbs (1 kilogram) higher weight gain among those with low Vitamin D blood levels.

Study author Erin LeBlanc, MD, an endocrinologist, said:

"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. 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."

Some people need to increase their Vitamin D levels

Experts from the US Preventive Services Task Force said recently that postmenopausal females require greater vitamin D doses to prevent bone fractures. They added that, so far, there is not enough compelling evidence to recommend that younger people take supplements. The Endocrine Society, on the other hand, believes a considerable number of adults do need to take vitamin D supplements for bone health.

Association between weight gain and low Vitamin D levels

LeBlanc said:

"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. Since there are so many conflicting recommendations about taking Vitamin D for any reason, it's best if patients get advice from their own health care provider."

Most of the women in this study had not been attempting to lose weight, the authors explained. However, some of them did so as a natural result of aging.

Over the 4.5 year study period:
  • Approximately 60% of the women stayed within 5% of their starting weight
  • 27% lost over 5% of their body weight
  • 12% of them put on over 5% of their body weight
The Endocrine Society recommends a 30 ng/ml (nanograms per millimeter) of vitamin D blood level for good health.

Most of the women had insufficient Vitamin D levels

78% of the women in the study had less than 30 ng/ml. At the start of the study their average weight was 148.6 pounds, compared with 141.6 pounds for those with a vitamin D level of at least 30 ng/ml.

571 women gained weight during the study period. Those with low vitamin D levels gained 18.5 pounds, while the ones with adequate levels of vitamin D gained 16.4 pounds.

What is Vitamin D?

Vitamin D is a group of fat-soluble secosteroids. It is known as a steroid vitamin. Vitamin D encourages the absorption and metabolism of phosphorous and calcium. Exposing the skin to normal quantities of sunlight usually promotes enough vitamin D synthesis in the skin so that the person does not need supplements.

There are five forms of vitamin D, as far as we know - vitamins D1, D2, D3, D4, D5. The ones that matter to us are vitamins D2 (ergocalciferol) and D3 (cholecalciferol).

Humans get their vitamin D from:
  • Sun exposure
  • Food
  • Supplements
Vitamin D is biologically inert; it goes through two hydroxylation reactions to become active in the human body. Calcitriol (1,25-Dihydroxycholecalciferol) is its active form in the human body.

Calcitriol encourages the body's absorption of phosphorous and calcium from food in the intestines, as well as the reabsorption of calcium in the kidneys, which raises the flow of calcium in the bloodstream. Adequate calcium in the bloodstream is vital for bone health - it also prevents the development of overactive reflexes (hypocalcemic tetany). Calcitriol is also involved in maintaining many organ systems.

Click here to read about Vitamin D in more detail.


Calcium regulation
Calcium regulation. Vitamin D's role is shown in orange


Written by Christian Nordqvist