Dairy and Vitamin D Independently Linked to Weight Loss

Summary
A great deal of controversy exists regarding the exact role that calcium from dairy products plays in weight loss. This study was conducted to look into the possible association among calcium intake via dairy products, serum vitamin D and weight loss. Calcium intake from dairy products and vitamin D concentration in blood was assessed for two years in participants who were trying to lose weight. The results of this study “suggests that both higher dairy calcium intake and increased serum vitamin D are related to greater diet-induced weight loss.”

Introduction
There have been studies with conflicting results regarding weight loss with dairy food products intake. Some studies report that ingestion of dairy products leads to weight loss while others show no such benefits. Vitamin D in blood is known to improve absorption of calcium in one’s diet. It is acknowledged that increased vitamin D concentration in the body is related to a lower “Body Mass Index” (BMI); but the reason for this has not been found yet. Also, there have been no studies that look into vitamin D concentration in the blood, calcium intake and weight loss. This study was done as an attempt to explore such a link.

Methodology

  • This study was conducted over a two-year period between July 2005 and June 2007. The criteria for participation were that the subjects (a) were aged between 41 and 65 years and had a BMI>27 or (b) had type 2 diabetes or heart disease.
  • The subjects received one of three different diets – low fat, low carbohydrate or a Mediterranean diet. Dairy product intake was not supervised.
  • Using food-related questionnaires, the daily diet of the participants was analyzed.
  • Vitamin D in blood was measured through blood tests in all participants.

Results

  • It was noted that with rising BMI, the vitamin D concentration in blood decreased.
  • Over two years, higher levels of dietary calcium intake and higher vitamin D quantities were linked with greater weight loss.
  • Dairy calcium ingestion of 156.5, 358.0 and 582.9 mg/d was associated with weight reduction of -3.3, -3.5 and -5.3 kg respectively over the duration of the study.
  • Similarly blood vitamin D levels of 14.5, 21.2 and 30.2 ng/ml were linked with weight reduction of -3.1, -3.8 and -5.6 kg respectively over the duration of the study.

Next steps/shortcomings
Authors of this study admit that assignment of the study subjects to the various diets was not random. In an ideal study this should have been so. Also, the diet-related questionnaires were self-reported and there could be human errors in the results. The researchers suggest that the actual link between vitamin D levels and dairy calcium ingestion still remains unexplained and further studies are needed to clarify this link.

Conclusion
At baseline levels, dairy calcium and vitamin D intake did not have any effect on weight loss in the participants of the study.  When increasing the intake amount, the results of this study “suggest that both higher consumption of dairy calcium and increased serum vitamin D are independently associated with successful weight loss.” The researchers nevertheless warn that the results should be interpreted with caution since some studies have shown that dairy may have negatively impact prostate and breast cancer.

For More Information:
Dairy Calcium Intake, Serum Vitamin D and Successful Weight Loss
Publication Journal: The American Journal of Clinical Nutrition, September 2010
By Danit R. Shahar; Dan Schwarzfuchs; Ben-Gurion University of the Negev, Beer-Sheva, Israel

*FYI Living Lab Reports Are Summaries of the Original Research.
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