The first large study to look at total calcium consumption in adolescents found that girls who consumed more calcium weighed less and had lower body fat. The findings were presented at the Experimental Biology 2003 meeting in San Diego, as part of the American Society for Nutritional Sciences program.
Dr. Rachel Novotny, and colleagues at the University of Hawaii at Manoa and Kaiser Permanente Clinical Research Center in Honolulu, studied 321 white, Asian, and mixed ethnicity girls aged nine to 14 years (average age 11.5 years). The girls were enrolled in the health plans of Kaiser Permanente Honolulu Clinic during 2000 and 2001.
For three days, each girl recorded everything she ate and drank and any calcium or multivitamin supplements she took. A researcher recorded the girl’s weight and the amount of fat at the iliac, just above the hipbone near the belly button. This skin fold thickness is a measure of abdominal fat.
As expected, girls who consumed more total calories and exercised less were heavier and had more body fat. However, when the researchers compared groups of girls at comparable age, height, level of maturation, calorie intake and exercise level, they found that girls who consumed more calcium on average weighed less than similar girls who consumed less calcium. It made very little difference if the calcium came solely from dairy products in the diet or from total calcium including supplementation.
It didn’t take much calcium to make a difference. An increase in one serving of diary — a cup of milk or a thumb-sized piece of cheese, about 300 mg of calcium — was associated with 0.9 mm lower skin fold (about half an inch) and 1.9 pounds in lower weight. A similar increase in total calcium intake from all sources, including supplementation, was associated with a 0.9mm lower skin fold and a 2.1 pound lower weight.
These findings are consistent with other studies in 30 and 60 year old women, as well as preschool children. They can be explained, says Dr. Novotny, by the fact that as calcium intake increases, the body increases its ability to break down fat and decreases fat synthesis.
Dr. Novotny believes these are significant findings, because 15 percent of all children and teens in the United States are considered obese. High body fat contributes to many common diseases such as high blood pressure, heart disease, cancer and diabetes. While caloric intake and physical activity remain imperative for maintaining weight and body fat during adolescence, Dr. Novotny says this study suggests that fairly small changes in calcium intake would have a positive effect.