Women drinking cola regularly are at risk of developing
osteoporosis, a disease of porous and brittle bones that causes
higher susceptibility to bone fractures.
Cola consumption may contribute to lower bone mineral density in
older women, a condition which increases risk for osteoporosis.
Tucker, 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.
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."
Tucker stresses that as with any epidemiological study, the
results should be taken with caution. "We are not certain why women
who drank more cola also had lower bone mineral density,"says
Tucker. Although adjustment for fruit juice intake did not change
results, women in the study who drank a considerable amount of cola
not only consumed less calcium, but less fruit juice as well.
Previous studies have also shown that low fruit and vegetable
intake may affect bone mineral density.
The message from experts is clear that overall nutritional
choices can affect bone health, but "there is no concrete evidence
that an occasional cola will harm the bones," says Tucker.
"However, women concerned about osteoporosis may want to steer away
from frequent consumption of cola until further studies are
conducted."
(China Daily October 8, 2006)