New research appears to absolve the soft drinks industry from responsibility for the low calcium intake among US adolescents but it suggests that creative and effective ways of increasing levels of the mineral, such as through fortified milks, should be encouraged.
The study, by researchers at the Center for Food and Nutrition Policy (CFNP) at Virginia Tech and fully funded by the National Soft Drink Association, demonstrated that while calcium intake among adolescents is inadequate, it has been at the same level since the 1970s.
Previous studies have proposed that increasing consumption of sodas and sugary drinks is triggering both obesity and deficiencies in essential vitamins and minerals, by replacing milk drinking.
Dr Maureen Storey and colleagues assessed diet and beverage choices of boys and girls in four age groups: two to three year olds, four to eight year olds, nine to 13 year olds, and 14 to 18 year olds. The data used in the study were from the US Department of Agriculture's (USDA) Continuing Survey of Food Intake by Individuals from (CSFII) 1994-96 and 1998.
They report that soft drink consumption by teens is actually far less than is perceived. Adolescent girls (14 to 18 years of age) on average drink about one 12-ounce can of soda a day, and pre-adolescent girls (nine to 13 years of age) drink about three-fourths of a 12-ounce can each day.
Consumption of diet carbonated soft drinks is low even among teen girls, who consume an average of only 59 grams, or less than two-tenths of a 12-ounce can, per day, write the researchers in the February issue of the Journal of the American College of Nutrition (vol 23, no 1, 18-33).
"Many people have the mistaken impression that adolescent girls are drinking inordinate amounts of soft drinks," Storey said. "However, it is wrong to suggest that girls are consuming gallons of soda pop when the amount they are drinking, about one can a day, is not excessive if they are physically active."
According to the study, Caucasian teenage boys (14 to 18 years old) come closest to meeting the recommended adequate intake for calcium for their age group, getting about 95 per cent. However, this group is the most avid consumer of carbonated soft drinks, drinking nearly two 12-ounce cans a day. In general, younger boys and girls (two to three year olds and four to eight years olds) exceed their recommended adequate intake for calcium, but African-American boys and girls in both age groups have significantly lower intakes for calcium than do Caucasian boys and girls.
The study also found that although milk and milk products have the strongest association with calcium intake, soft drink consumption was not linked to decreased calcium intake.
"This is most likely because milk and soft drinks are not close dietary substitutes. Rather, the data suggest that when trade-offs occur, it is more likely to be between carbonated soft drinks, fruit drinks and ades," Storey said.
Milk consumption among adolescent girls remains low, with this group falling far below recommended dietary levels of calcium consumption.
To increase calcium consumption among adolescent girls, the study suggests educational and promotional efforts to encourage milk consumption, use of calcium-fortified beverages and foods, and calcium supplements if consumption of dairy products or other calcium-rich foods remains inadequate.