Study Title:

Calcium Intake and Successful Weight Loss

Study Abstract

Background: The role of dairy calcium intake and serum vitamin D concentrations in weight loss is controversial.

Objective: The objective was to assess the association of dairy calcium intake and serum vitamin D with weight loss.

Design: We analyzed data from participants in the 2-y Dietary Intervention Randomized Controlled Trial (DIRECT) [n = 322; mean body mass index (BMI; in kg/m2): 31; mean age: 52 y]. A representative sample (n = 126) was followed for 6 mo for serum vitamin D changes.

Results: Baseline serum 25-hydroxyvitamin D [25(OH)D] concentrations decreased significantly across the tertiles of baseline BMI (25.6 ± 8.0, 24.1 ± 8.9, and 22.9 ± 6.8 ng/mL, respectively; P for trend = 0.02). Baseline concentrations of vitamin D and dairy calcium intake were not associated with subsequent weight loss. However, in repeated-measures models adjusted for age, sex, baseline BMI, total fat intake, and diet group assignment, higher 6-mo tertile levels of dairy calcium intake (median for tertiles: 156.5, 358.0, and 582.9 mg/d, respectively) and serum 25(OH)D (14.5, 21.2, and 30.2 ng/mL, respectively) were associated with increased weight loss across the 2-y intervention (–3.3, –3.5, and –5.3 kg, respectively, for dairy calcium; P = 0.043; –3.1, –3.8, and –5.6 kg, respectively, for vitamin D; P = 0.013). In a multivariate logistic regression adjusted simultaneously for age, sex, baseline BMI, total fat intake, diet group, vitamin D concentration, and dairy calcium, an increase of 1 SD in dairy calcium intake increased the likelihood of weight loss of >4.5 kg in the preceding 6 mo [odds ratio (OR): 1.45; P = 0.046]. A similar increase was seen for serum 25(OH)D at the 6-mo point (OR: 1.7; P = 0.009).

Conclusion: Our study suggests that both higher dairy calcium intake and increased serum vitamin D are related to greater diet-induced weight loss. This trial was registered at clinicaltrials.gov as NCT00160108.

From press release:

A new study conducted by Ben-Gurion University of the Negev (BGU) researchers reveals that higher dairy calcium intake and increased serum vitamin D are related to greater diet-induced weight loss.

Regardless of diet, researchers also found participants with the highest dairy calcium intake -- equal to 12 oz. of milk or other dairy products (580 mg of dairy calcium) -- lost about 12 pounds (6 kg.) at the end of the two years. In comparison, those with the lowest dairy calcium intake -- averaging about 150 mg dairy calcium, or about half of a glass -- only lost seven pounds on average. The study was published in the current issue of the American Journal of Clinical Nutrition.

Beyond calcium, the researchers also found that blood levels of vitamin D independently affected weight loss success. Vitamin D levels increased among those who lost more weight. The dietary intervention study also confirmed other research that overweight participants have lower blood levels of vitamin D.

More than 300 overweight men and women, aged 40 to 65, participated in the study evaluating low fat, Mediterranean or low-carb diets for two years. Dr. Danit Shahar, of BGU's S. Daniel Abraham Center for Health and Nutrition and the Faculty of Health Sciences, led the study. It was part of the Dietary Intervention Randomized Control Trial (DIRECT) conducted at the Nuclear Research Center in Israel.

According to Dr. Shahar, "It was known that over-weight people had lower levels of serum vitamin D but this is the first study that actually shows that serum Vitamin D increased among people who lost weight. This result lasted throughout the two years that the study was conducted, regardless of whether they were on a low-carb, low fat or Mediterranean diet."

Vitamin D increases calcium absorption in the bloodstream and in addition to sun exposure can be obtained from fortified milk, fatty fish and eggs. Americans generally consume less than the recommended daily requirement of Vitamin D which is found in four glasses of milk (400 international units).

Study Information

1.D. R. Shahar, D. Schwarzfuchs, D. Fraser, H. Vardi, J. Thiery, G. M. Fiedler, M. Bluher, M. Stumvoll, M. J. Stampfer, I. Shai.
Dairy calcium intake, serum vitamin D, and successful weight loss.
American Journal of Clinical Nutrition
2010 September
Ben-Gurion University of the Negev (BGU).

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