Regular Cola Intake May Reduce Bone Mineral Density in Women

by Laurie Barclay, News CME, 11 Oct 2006

Regular consumption of carbonated cola drinks may increase risk for low bone mineral density (BMD) in women, according to the results of the Framingham Osteoporosis Study reported in the October issue of the American Journal of Clinical Nutrition.

"Soft drink consumption may have adverse effects on bone mineral density (BMD), but studies have shown mixed results," write Katherine L. Tucker, MD, from Tufts University in Boston, Massachusetts, and colleagues. "In addition to displacing healthier beverages, colas contain caffeine and phosphoric acid (H3PO4), which may adversely affect bone."

Using dual-energy x-ray absorptiometry, the investigators measured BMD at the spine and at 3 hip sites in 1413 women and in 1125 men in the Framingham Osteoporosis Study. Dietary intake was evaluated with a food frequency questionnaire. Each BMD measure was regressed on the frequency of soft drink consumption after adjustment for body mass index, height, age, energy intake, physical activity score, smoking, alcohol use, total calcium intake, total vitamin D intake, caffeine from noncola sources, season of measurement, and, for women, menopausal status and estrogen use.

Cola intake was associated with lower BMD at each hip site in women but not in men (P < .001 - .05). However, it was not linked with lower BMD at the spine for women or men. Compared with those who consumed less than 1 serving of cola per month, those with daily cola intake had a mean BMD 3.7% lower at the femoral neck and 5.4% lower at Ward's area. These results were similar with diet cola and to a lesser extent with decaffeinated cola.

There were no significant relationships between noncola carbonated beverage consumption and BMD. Although total phosphorus intake was not significantly higher in daily cola consumers than in nonconsumers, the calcium-to-phosphorus ratios were lower.

Study limitations include possibly incomplete control of confounding.

"Intake of cola, but not of other carbonated soft drinks, is associated with low BMD in women," the authors write. "Additional research is needed to confirm these findings.... Unless additional evidence rules out an effect, women who are concerned about osteoporosis may want to avoid the regular use of cola beverages."

The United States Department of Agriculture and the National Institutes of Health supported this study. The authors have disclosed no relevant financial relationships.