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New Research To Plug Gaps In Calcium For Weight Loss Knowledge

The dairy industry has been eagerly promoting trials showing that the calcium in milk products can prevent obesity but several gaps in the evidence mean that dietary guidelines based on this effect are a long way off, say scientists.

Numerous studies in the last three years have investigated the link between dietary calcium and obesity, with some demonstrating an inverse relationship - the higher an individual’s calcium intake, the lower the body weight.

Most recently, researchers at the University of Tennessee showed that high-calcium intake could significantly enhance weight and fat loss in obese people already following a low-calorie regime.

But while the growing body of research suggests that calcium could be a valuable tool against the rapidly rising cases of obesity, scientists have not yet uncovered the mechanism behind this effect.

“There are still numerous gaps in our knowledge, such as how the mineral effects body weight and whether it is quantitatively important,” says Arne Astrup, head of the Institute of Human Nutrition at the Royal Veterinary and Agricultural University in Denmark.

One hypothesis for the mechanism, from Michael Zemel, a nutritionist at the University of Tennessee, suggests that it has to do with the actions of vitamin D. Data appear to show that the active form of vitamin D, called calcitriol, causes fat cells to create more fat. Calcitriol levels are raised with lower intake of calcium. Therefore, fat cells produce more fat on low calcium diets. By contrast, high-calcium diets suppress calcitriol and, as a consequence, promote the burning of fat.

But Astrup cautioned, “For this to be included in dietary guidelines, we need very solid evidence but we are only just beginning to get there. It is certainly premature to tell people that they can slim on a dairy-rich diet.” In fact, he added, “calcium is the headline, rather than dairy”.