Regular consumption of caffeinated carbonated beverages may result in bone loss

Consumption of carbonated beverages has been associated with increased risk of bone fracture both earlier and later in life, yet the contributions of the individual components of these beverages to calcium loss is unclear. The per capita consumption of carbonated beverages has risen dramatically, making them the preferred beverage of women 20-40 years old, many of whom already have an inadequate daily intake of calcium. In an article in this month’s American Journal of Clinical Nutrition, Heaney and Rafferty investigated the effect of caffeinated and noncaffeinated beverages on urinary calcium excretion in a group of 30 women with an average age of 31 years. The subjects habitually drank from two to seven 12-ounce cans of carbonated beverages daily; 27 drank predominantly colas.

Four types of beverages were evaluated. One caffeinated and 1 non-caffeinated beverage contained citric acid as an acidulant, and 2 cola-type beverages were either caffeinated or non-caffeinated and contained phosphoric acid as an acidulant. Milk and water were also tested as control beverages. Small but significant increases in urinary calcium excretion resulted from consumption of the 2 caffeinated beverages, whereas the 2 non-caffeinated beverages had no effect. No calcium loss was due to either phosphoric or citric acid acidulation. Phosphoric or citric acid acidulation had no effect on calcium loss.

Though the caffeine in the drinks was primarily responsible for excess calcium excretion, previous studies of the effect of caffeine have shown a compensatory drop in calcium excretion over the 24-hour period following ingestion. The fact that the small calcium loss from carbonated beverages was offset by reduced excretion later in the day, and the habituation of the subjects to frequent consumption, lead the authors to conclude that the main cause of calcium loss from carbonated beverages was their lack of the nutrients needed for bone health. Carbonated beverages displace milk in the diet, eliminating a major source of bone-building calcium.

Heaney, Robert P. and Karen Rafferty. Carbonated beverages and urinary calcium excretion. Am J. Clin Nutr 2001;74:343-7.

This media release is provided by The American Society for Clinical Nutrition to provide current information on nutrition-related research. This information should not be construed as medical advice. If you have a medical concern, consult your doctor. To see the complete text of this article, please go to:

http://faseb.org/ajcn/September/12185-Heaney.pdf

For more information, please contact: rheaney@creighton.edu

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