The epidemiological study by researchers from the University of Sao Paulo adds to the on-going debate of the role of calcium, mainly from dairy products, in weight loss. The topic is a source of controversy with both camps able to quote research that supports their side and undermines the other.
Over 300m adults are obese worldwide, according to latest statistics from the WHO and the International Obesity Task Force. About one-quarter of the US adult population is said to be obese, with rates in Western Europe on the rise, although not yet at similar levels.
However, the researchers, led by Milena Baptista Bueno, concede that their study does not prove causality that calcium intakes are responsible for weight loss, but that higher calcium intake may be purely indicative of a healthy lifestyle.
“In the present study, higher mean calcium intakes were also observed among women with normal weight who were non-smokers, practiced physical activity, and had higher educational levels,” wrote Baptista Bueno.
“Together, these facts could indicate a better lifestyle and socioeconomic level and, hence, better access to health care, which in part would account for the weight loss.”
The researchers recruited 1,459 adults aged between 20 and 59 to take part in the study. Almost 30 per cent of the participants were overweight, while 13 per cent were obese. Questionnaires were used to assess physical activity levels and lifestyle factors, while food consumption was assessed using 24-hour dietary recalls.
Baptista Bueno and co-workers report that the average calcium intake for the whole population was 448.6 mg per day.
They calculated that people with the lowest average intakes (less than 264.9 mg per day) were 24 per cent more likely to be overweight, compared to people who consumed at least 593.7 mg per day.
The researchers suggested that two mechanisms may be behind the effects of calcium on body weight. The first was an effect on certain hormones that play a role in fat build-up, while “the second proposed mechanism is that increased dietary calcium seems to bind more fatty acids in the intestines, thereby inhibiting fat absorption,” they stated.
“Our data support that further clinical research on the effects of calcium on fat metabolism must be pursued with prospective randomized clinical trials,” concluded Baptista Bueno and co-workers.
Dairy calcium is not the whole picture
This would agree with statements by Dr. Michael Zemel from the University of Tennessee. At the Paris Anti-Obesity Therapies 2006 conference he said that dairy can help reduce body fat and that calcium only accounts for about 40 per cent of the effect.
But Dr Zemel told attendees at the Paris Anti-Obesity Therapies congress in 2006, that dairy can help reduce body fat and that calcium only accounts for about 40 per cent of the effect.
"The anti-obesity effect of dietary calcium is supported by cellular mechanistic studies, animal studies, human epidemiological studies and clinical trials," said Zemel.
"This works for milk, yoghurt and cheese," said Zemel, but also pointed out that cheese, having a significantly higher fat content, was an interesting issue.
Source: NutritionPublished online ahead of print 21 July 2008, doi:10.1016/j.nut.2008.05.020“Dietary calcium intake and overweight: An epidemiologic view”Authors: M. Baptista Bueno, C.L. Galvao, L.A. Martini, R.M. Fisberg