Taking calcium supplements might help fight middle-aged spread in women, according to a new study by Public Health Sciences Division researchers. The study shows that of 5,341 women in their 50s, those who took at least 500 milligrams of calcium supplements daily gained 4 pounds less over 10 years than women who didn't use supplements. The researchers did not see the same effect from calcium-rich foods or in men. The study, led by University of Washington graduate student Alejandro Gonzalez, is the largest analysis of calcium use and weight change to date. The findings appeared in the July issue of the Journal of the American Dietetic Association.
Supplements and weight loss
"This study suggests that calcium supplements may have a small beneficial influence on reducing weight gain, particularly among women approaching midlife," said Gonzalez, noting that more evidence from randomized clinical trials is needed before calcium supplements can be recommended specifically for weight loss.
The researchers investigated weight change among 10,591 men and women over an 8- to 12-year period from age 45 to age 53 to 57 in relation to calcium intake. The women who took more than 500 milligrams of calcium as supplements gained 11.2 pounds over 10 years compared to 15.2 pounds for those who didn't take the supplements. The scientists adjusted for energy intake and physical activity — the two main components of weight change — as well as smoking and education, but the results held.
Participants came from a subsample of the Vitamins and Lifestyle (VITAL) study, led by PHS epidemiologist Dr. Emily White, Gonzalez's adviser. VITAL recruited a high number of supplement users and collected detailed information on supplement use over a 10-year period to study vitamin and mineral supplementation and cancer risk.
Previous studies suggested calcium has an effect on controlling weight, but results have been inconsistent.
"We expected to refute the hypothesis that calcium plays a role in regulating weight. We thought it had been overhyped, particularly by the dairy industry," White said. "I think we were both somewhat surprised."
Scientists aren't exactly sure how calcium might exert such effects, but some studies show that low calcium intake boosts the amount of calcium contained within cells, which in turn switches on genes involved in fat storage. "When you decrease calcium, the cells hold more fat," Gonzalez said.
Still, Gonzalez points out that calcium pills aren't a magic bullet for slimming down. "People who took more calcium gained less weight, but everybody still put on pounds," he said.
Gonzalez, who completed the research for his master's degree in nutrition, has worked at the Center since 2002. He is currently completing his doctorate before beginning medical school at the UW in the fall. Co-author White is a professor of Epidemiology and associate dean of research at the UW School of Public Health and Community Medicine. Drs. Alan Kristal and Alyson Littman of PHS also contributed to this National Cancer Institute-funded study.
The final word on calcium's effect on weight is expected next year from the Women's Health Initiative (WHI) Calcium/Vitamin D Supplementation Trial. The WHI study — coordinated by the Hutchinson Center, which houses one of its clinical centers — involved more than 36,000 postmenopausal women who took 1,000 mg of calcium (and vitamin D) or a placebo daily for seven to 11 years. "The WHI results will be the definitive answer," White said.
The work of the Vitamins and Lifestyle (VITAL) study continues. For this study of 77,700 Washington state residents age 50 to 76, detailed information was collected over a 10-year period on the use of 38 supplements, diet, non-steroidal anti-inflammatory drug use, anthropometrics, exercise, health history and cancer-risk factors. More than 54,000 participants also provided DNA, which constitutes the sixth largest DNA specimen bank in the United States, for future genetic studies.
Researchers continue to follow-up the cohort for cancer and other outcomes. The study data and specimens are also available as a resource for additional studies by scientists at the Hutchinson Center and elsewhere.
"VITAL is alive and well and looking for additional studies to utilize this resource," said Dr. Emily White, VITAL's principal investigator.