Dairy weight-loss claims get Paris Anti-Obesity boost
massive fillip at the Paris Anti-Obesity Therapies congress, but
natural product-based dietary supplements don't help weight loss
said experts.
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.
"Paris Anti-Obesity Therapies 2006 aims to launch discussion between the different actors involved in the fight against obesity," explained Dr Marvin Edeas, chairman of the organising committee.
From a food and nutrition perspective, dairy and calcium intake and weight-loss took centre stage with a presentation by Dr Michael Zemel from the University of Tennessee.
The role of dairy products, and in particular calcium, in weight loss is a source of controversy with both camps able to quote research that supports their side and undermines the other. But Dr Zemel told attendees at the Pasteur Institute in Paris, 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.
This was supported by Riita Korpela and colleagues from the University of Helsinki who presented a poster with findings of an animal study of the effects of a high calcium diet with whey protein isolates on weight gain during a high fat diet. Interestingly, calcium supplements alone (in the form of calcium carbonate) did not reduce weight or fat tissue gain.
The congress, organised by the International Society of Antioxidant in Nutrition and Health and attended by over 200 people, also looked at dietary supplements and body weight reduction with an invited presentation by Dr Edzard Ernst from the Universities of Exeter and Plymouth in the UK.
Dr Ernst showed the results of his various meta-analyses and systematic reviews for a wide-range of dietary supplements currently marketed as promoting weight loss, including ephedra, chitosan, guar gum and chromium picolinate.
"Except for Ephedra sinica, and other ephedrine-containing dietary supplements, the weight of the evidence was not convincing enough to suggest effectiveness. However, the intake of E sinica and ephedrine is associated with an increase risk of adverse effects," said Ernst.
The two-day congress included a presentation by Dr Marvin Edeas, who is also the president of the French Society of Antioxidants, entitled, "The potential use of natural antioxidants in the treatment of obesity." Dr Edeas told the attendees that obesity is associated with a higher production of free radicals and lower levels of antioxidant defences, while weight loss is associated with a "significant increase in plasma antioxidant levels."
However, classic antioxidants like vitamin E and beta-carotene have been shown in clinical trials to have no significant benefit for obesity-related disease, said Edeas.
"An explanation may be that classic antioxidants act only as scavengers on a subset of already formed oxidants, particularly lipid peroxidation products. They also work in a stoichiometric, rather than a catalytic manner," said Edeas, meaning that once a molecule of, say, vitamin E was used it was not regenerated, but lost as an antioxidant.
When pressed on which antioxidants, if any, could be a candidate to benefit obese people, Dr Edeas suggested polyphenols.
Dr Zemel also chaired a round table discussion on the policies, strategies and initiatives of big food industries to fight against obesity. Participation of multinational food companies had been scheduled but no invited representative from the companies were present, leaving the academics to discuss what the policies should be.
Dr Frank Turek from Northwestern University asked why the big food companies weren't present, and called for the food industry to stop "advertising to young children what you know is unhealthy and high in energy."
The seven-man discussion panel agreed that the policies should be multiple, and suggested reducing portion sizes, making the 'healthier choice the easier choice' for consumers, and starting to change eating habits in schools.
