According to the National Osteoporosis Foundation, approximately 55 percent of Americans, mostly women, are at risk of developing osteoporosis, a disease of porous and brittle bones that causes higher susceptibility to bone fractures. Now, Katherine Tucker, PhD, director of the Epidemiology and Dietary Assessment Program at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, and colleagues have reported findings in the American Journal of Clinical Nutrition that cola, a popular beverage for many Americans, may contribute to lower bone mineral density in older women, a condition which increases risk for osteoporosis.
Tucker, also a professor at the Friedman School of Nutrition Science and Policy at Tufts, and colleagues analyzed dietary questionnaires and bone mineral density measurements at the spine and three different hip sites of more than 2,500 people in the Framingham Osteoporosis Study whose average age was just below 60. In women, cola consumption was associated with lower bone mineral density at all three hip sites, regardless of factors such as age, menopausal status, total calcium and vitamin D intake, or use of cigarettes or alcohol.
However, cola consumption was not associated with lower bone mineral density for men at the hip sites, or the spine for either men or women. The results were similar for diet cola and, although weaker, for decaffeinated cola as well.
Men reported drinking an average of six carbonated drinks a week, with five being cola, and women reported consuming an average of five carbonated drinks a week, four of which were cola. Serving size was defined as one bottle, can or glass of cola. “The more cola that women drank, the lower their bone mineral density was,” says Tucker, who is corresponding author of the study. “However, we did not see an association with bone mineral density loss for women who drank carbonated beverages that were not cola.”
“Carbonated soft-drink consumption increased more than three-fold” between 1960 and 1990, cite the authors. They also note that more than 70 percent of the carbonated beverages consumed by people in the study were colas, all of which contain phosphoric acid, an ingredient that is not likely to be found in non-cola carbonated beverages.
Why the cola drinks might cause osteoporosis is unclear. Consumption of less calcium due to colas displacing milk or other foods might be to blame. Or the phosphorus in the form of phosphoric acid might create acidic conditions in the blood that mobilize calcium from the bones. Or perhaps women who drink colas eat less of some foods which are beneficial in other ways.
While previous studies have suggested that cola contributes to bone mineral density loss because it replaces milk in the diet, Tucker determined that women in the study who consumed higher amounts of cola did not have a lower intake of milk than women who consumed fewer colas. However, the authors did conclude that calcium intake from all sources, including non-dairy sources such as dark leafy greens or beans, was lower for women who drank the most cola. On average, women consumed 1,000 milligrams of calcium per day, and men consumed 800 milligrams per day, both lower than the daily recommended 1,200 daily milligrams for adults over age 50.
“Physiologically, a diet low in calcium and high in phosphorus may promote bone loss, tipping the balance of bone remodeling toward calcium loss from the bone. Although some studies have countered that the amount of phosphoric acid in cola is negligible compared to other dietary sources such as chicken or cheese,” Tucker says, “further controlled studies should be conducted to determine whether habitual cola drinkers may be adversely affecting their bone health by regularly consuming doses of phosphoric acid that do not contain calcium or another neutralizing ingredient.”
Sugary drinks are a bad idea because they displace healthier foods. You are better off drinking pure fruit juices that come with anthocyanins and other beneficial flavonoid compounds. Given a choice between empty calories and nutritionally richer foods you should opt for the latter.
If you want caffeine then your best bet is probably green tea or perhaps black tea. A recent study found that black tea reduces blood levels of the stress hormone cortisol after humans are exposed to stressful situations. Tea might also reduce the risk of colorectal cancer. Though the evidence for reduced cancer risk from tea is mixed. Tea cancer reduction success in animal models may be due to use of doses far higher than humans will get from drinking tea.
|Share |||Randall Parker, 2006 October 08 12:56 PM Aging Diet Studies|