Popular supplements don't help in weight loss

London, July 14, 2010:

Popular slimming supplements sold in pharmacies and health food shops are not likely to facilitate weight loss beyond the placebo effect.

Two studies have found they were no more effective than the fake supplements they were compared with.

"There are scores of slimming supplements out there claiming weight-loss effects through all sorts of mechanisms of action," said Thomas Ellrott.

Ellrott, who heads the Institute for Nutrition and Psychology, University of Göttingen Medical School, Germany, led one of the studies.

"The market for these is huge, but unlike for regulated drugs, effectiveness does not have to be proven for these to be sold," said Ellrott.

Ellrott's group tested nine popular supplements against placebo pills in a randomised controlled trial, according to a release of the Institute for Nutrition and Psychology.

The supplements included L-Carnitine, polyglucosamine, cabbage powder, guarana seed powder, bean extract, Konjac extract, fibre pills, sodium alginate formulations and selected plant extracts.

The researchers bought the supplements from German pharmacies, changed the packaging and product names to make them look neutral and rewrote the information leaflet inserts to eliminate the product name from the text.

They then gave 189 obese or overweight middle-aged consumers packages of either fake pills or of one of the supplements, each week for eight weeks, in doses recommended by the manufacturers.

Average weight loss was between one kg and two kg across seven of the products, depending on the supplement, and was 1.2 kg in the group getting the placebo pills.

No statistically significant difference in weight loss was found for any of those products when compared with the placebo. These findings were presented at the International Congress on Obesity, Stockholm, Sweden.

In a second study, Igho Onakpoya of Peninsula Medical School at the Universities of Exeter and Plymouth, Britain, conducted the first systematic review of all existing systematic reviews of clinical trials on weight loss supplements.

The analysis summarises the state of evidence from reviews of studies involving nine popular slimming supplements, including chromium picolinate, Ephedra, bitter orange, conjugated linoleic acid (CLA), calcium, guar gum, glucomannan, chitosan and green tea.

"We found no evidence that any of these food supplements studied is an adequate treatment for reducing body weight," Onakpoya said.

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