Drinking skimmed milk fortified with three grams of CLA (Tonalin, Cognis) led to significant body fat mass reductions among 30 health men and women over 12 weeks, compared to the same amount of people drinking a placebo milk.
The study adds to an ever-growing body of science supporting the potential of CLA for weight management and weight loss, a category of already estimated to be worth $7bn worldwide.
"These findings are especially exciting in light of the weight management platform that has evolved in the dairy industry based on mounting scientific evidence," said David Cai, senior scientist, Cognis Nutrition & Health.
"Dairy products are excellent carriers for CLA, considering taste, colour, texture, processing and product development issues.
Formulators will find CLA to be a health-enhancing ingredient that can be added to a dairy product without adversely affecting the sensory characteristics of the product," he added.
Published recently in the British Journal of Nutrition , the randomised, double-blind, placebo-controlled intervention trial showed that 12-weeks of supplementation with the CLA-rich milk led to significant reductions in fat mass in the trunk (torso) area of the body.
University of Barcelona researchers recruited 60 overweight and obese men and women (body mass index between 25 and 35 kg per sq. m), aged between 35 and 65, and randomly assigned them to a daily intake of 500 ml skimmed milk fortified with 3 grams of CLA, or a placebo milk.
The researchers, led by Amalia Lafuente, report that consumption of the CLA-rich milk was associated with a significant three per cent reduction of body fat mass in overweight subjects, while no significant fat loss was found in the obese volunteers or in either group taking the placebo.
The lack of effect in obese subjects may be due to a relatively short study period, stated the researchers.
A longer study would detect if CLA could affect body fat changes in this group, they said.
Moreover, no adverse effects or clinical changes were reported by the researchers, supporting the apparent safety of the ingredient.
In contrast, a previous study reported greater body fat mass (BFM) reduction of up to nine per cent after 12 months' supplementation with Tonalin CLA ( Journal of Nutrition, Vol. 135, pp.
778-784).
However, Lafuente pointed out: "If the Gaullier study results are extrapolated to those of our shorter study (12 weeks), they coincide with the three per cent BFM reduction we observed.
Our data indicate that CLA supplementation may be a useful approach to reducing fat mass, which is a prominent cardiovascular risk factor."
Lafuente and co-workers wrote that it was unclear by which mechanisms CLA could affect body composition, stating that in vitro and in vivo studies have suggested several possibilities, including the inhibition of certain enzymes associated with fat accumulation, modification of signaling pathways linked to leptin expression, and the prevention of triacylglyceride accumulation in fat cells.
"These findings have considerable significance for Tonalin CLA, indicating that the ingredient can work as well in a functional food product - a dairy matrix, for example - as it does in a food supplement," said Dr. Doris Bell, leader of Cognis' global research program on Tonalin CLA.
"The study also re-confirms that the longer term consumption of Tonalin CLA is effective, safe and, importantly, does not negatively affect blood lipids or glucose levels.
"This had been an area of interest for some authorities in the past, but any potential concerns are now entirely dispelled by the overwhelming evidence of 18 clinical studies.
"Pending Novel Food approval, there are clearly huge opportunities for functional food manufacturers to join supplement producers in marketing successful products for healthy fat loss featuring Tonalin CLA," she concluded.
The study was supported by Corporacion Alimentaria Penasanta, the Spanish Ministry of Health, Institute Carlos III, and DURSI GRC2005SGR00039.
Source: British Journal of Nutrition Published on-line ahead of print, doi: 10.1017/S0007114507750882 "Effects of milk supplementation with conjugated linoleic acid (isomers cis-9, trans-11 and trans-10, cis-12) on body composition and metabolic syndrome components" Authors: N. Laso, E. Brugue, J. Vidal, E. Ros, J.A. Arnaiz, X. Carne, S. Vidal, S. Mas, R. Deulofeu and A. Lafuente