Studies Indicate D May Boost Diet Efforts, Reduce Excess Fat

From: http://naturalmedicine.suite101.com/article.cfm/weight-loss-obesity-and-vitamin-d-levels
Mar 19, 2010 Laura Owens

Evidence suggest adequate levels of vitamin D may improve success with weight management programs and lower incidence of obesity in some.

Vitamin D continues to make headline news. Findings suggest adequate levels may break barriers with individuals battling excess weight.

Research reveals a relationship between vitamin D levels in the body, vitamin D intake, and body weight. While the exact relationship is not entirely understood, a growing body of evidence suggests an association between obesity/excess body weight and D levels exists.

In addition, the link is supported by the fact that obesity and low D are co-morbid (occur at the same time) with diseases such as: disease, hypertension, diabetes, osteoarthritis, osteoporosis, depression and even periodontal disease.

Vitamin D Levels Predict Weight Loss Success

In a 2010 study researchers found that adequate vitamin D levels in the body improves weight loss success with a diet program.
"Vitamin D deficiency is associated with obesity, but it is not clear if inadequate vitamin D causes obesity or the other way around," said the study's lead author, Shalamar Sibley, MD, MPH, an assistant professor of medicine at the University of Minnesota.
For the study, scientists measured circulating blood levels of vitamin D in 38 overweight men and women before and after the subjects followed a diet plan for 11 weeks consisting of 750 calories a day fewer than their estimated total needs. Subjects also had their fat distribution measured with DXA (bone densitometry) scans.

While the participants' vitamin D levels were lower than what many experts consider sufficient, the subjects' baseline, or pre-diet vitamin D levels predicted weight loss in a linear relationship. For every increase of 1 ng/mL in level of 25-hydroxycholecalciferol, the precursor form of vitamin D and a commonly used indicator of vitamin D status, subjects lost almost a half pound (0.196 kg) more on their calorie-restricted diet. For every 1-ng/mL increase in the active or "hormonal" form of vitamin D (1,25-dihydroxycholecalciferol), subjects lost nearly one-quarter pound (0.107 kg) more.
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In addition, subjects with higher baseline vitamin D levels (both the precursor and active forms) lost more abdominal fat. The implications of these findings, researchers believe, are promising. "Our results suggest the possibility that the addition of vitamin D to a reduced-calorie diet will lead to better weight loss," Sibley said.

Obesity and Vitamin D Levels

In another study out of the University of Madrid researchers found that excess body weight was associated with decreasing amounts of vitamin D. Scientists measured the body weight of 61 young, overweight/obese women and randomly assigned them to two different weight control programs: diet V, increased greens and vegetables, or diet C, increased cereals (some of which were enriched with vitamin D).

Taking into account only women with a vitamin D intake below expert-recommended levels, the women who were obese had a significantly lower average serum 25(OH)D concentration than those who weighed less. In addition, group C (increased cereals, some enriched with vitamin D) subjects lost more weight than the Group V subjects.

In another study out of Spain, researchers gathered the following data on 102 children ages nine to 13: height, body weight, body mass index (BMI), waist and hip measurements (to determine the quantity of visceral or abdominal fat), and the thickness of the tricipital and bicipital skinfold (to determine the quantity of subcutaneous fat). Scientists also analyzed the childrens' diet with a three-day weighed food record and their vitamin D intake as compared to recommended (expert) levels.

Results showed while there was no significant difference in body weight based on vitamin D intake, children who had insufficient levels of D in their body had higher weight, BMI, waist measurement and waist/height ratio than the children with adequate levels of D in their body.

In addition, results showed that children with a body weight, BMI, bicipital skinfold thickness, waist measurement and waist/height ratio above the 50th percentile for each variable were at a greater risk of having a low serum 25(OH)D concentration.

Obesity and Vitamin D Epidemic: Coincidence?

Dr. John Cannell, Director of the Vitamin D Council in his 2004 Newsletter article, "Obesity and Vitamin D," writes, "One third of Americans are obese. While much of that epidemic is surely due to playing Nintendo instead of baseball, or the consumption of soft drinks instead of water, does that explain it all? Is it a coincidence that the twin epidemics of obesity and vitamin D deficiency are occurring together?"

A growing body of research suggests more than a coincidence. While there are numerous alternative explanations for the findings notes Dr. Cannell, an overwhelming number of studies suggest a link. The following is an incomplete list, for the full list refer to Dr. Cannell's September 2004 newsletter.

* When aboriginal populations migrate from high altitude (more UV rays to convert to D in the skin) to low altitude, body fat increases.
* Higher calcium intake is consistently associated with lower body weight, as vitamin D significantly increases calcium absorption.
* The combination vitamin D and calcium reduced subsequent spontaneous food intake and increased the metabolism of fat.
* Genetic abnormalities of the vitamin D receptor (called VDR polymorphisms) are associated with body weight and fat mass. Patients with VDR polymorphisms have reduced vitamin D activity at their receptors.
* Blood parathyroid levels, which are elevated in vitamin D deficiency, predict obesity.
* Starting since 1981 studies have consistently shown that 25(OH)D levels are lower in obese subjects.
* Obesity is associated with early death, and low vitamin D levels are more likely in the winter. Scientists have known about and debated the cause of excess winter deaths for years
* Obese subjects obtain lower 25(OH)D levels when exposed to ultraviolet light or when they take supplemental vitamin D. Subjects appeared to deposit some of their vitamin D in their excessive fatty tissue which impaired their ability to raise their 25(OH)D levels.

Whether excess weight contributes to lower levels of vitamin D in the body or low vitamin D causes excess weight is still unclear. Research indicates however, a relationship exists. The implications for weight management and leveraging the effectiveness of a diet program are promising.

References

The Endocrine Society (2009, June 12), “Successful Weight Loss With Dieting Is Linked To Vitamin D Levels,” ScienceDaily. Retrieved March 18, 2010.
Ortega RM, López-Sobaler AM, Aparicio A, Bermejo LM, Rodríguez-Rodríguez E, Perea
JM, Andrés P, “Vitamin D status modification by two slightly hypocaloric diets in young overweight/obese women.” International Journal of Vitamin & Nutritional Research 2009 Mar;79(2):71-8.
Rodríguez-Rodríguez E, Navia-Lombán B, López-Sobaler AM, Ortega RM,
“Associations between abdominal fat and body mass index on vitamin D status in a group of Spanish schoolchildren,” European Journal of Clinical Nutrition, 2010 Mar 10.
Cannell, John, MD, The Vitamin D Council, “Obesity and Vitamin D,” The Vitamin D Newsletter, September 17, 2004.