Girls who consume more calcium tend to weigh less and have lower body fat than those with low calcium consumption, suggest new findings presented at the Experimental Biology 2003 meeting in San Diego last week.
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 all food intake 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, 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.
Also, it made very little difference if the calcium came solely from dairy products in the diet or from total calcium including supplementation.
The researchers report that even small amounts of calcium were associated with lower weight. An increase in one serving of dairy - a cup of milk or a thumb-sized piece of cheese, about 300mg of calcium - was associated with 0.9mm 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, said the researchers. Dr Novotny explained that as calcium intake increases, the body increases its ability to break down fat and decreases fat synthesis.
Others have however questioned Novotny's explanations. While the scientist says this study suggests that fairly small changes in calcium intake would have a positive effect, some say that the results could easily reflect a tendency towards healthy eating by those consuming more calcium.
Dairy companies on the other hand will be jumping at the findings, particularly in the light of growing obesity rates among children and adolescents in the developed world.