Supplements: a convincing solution to weight loss?
claims for weight loss, according to two UK experts, who reviewed
the evidence for a number of natural products including yerba mate,
chromium picolinate, ephedra and garcinia camboga.
While ephedra and other ephedrine-containing products do appear to be effective, such supplements have been associated with an increased risk of adverse events, and cannot be recommended for over-the-counter use, write Max H Pittler and Edzard Ernst from the Peninsula Medical School at the UK's Exeter and Plymouth universities.
Compliance with conventional weight-management programs is notoriously poor, and a plethora of over-the-counter slimming aids are sold with claims of effectiveness, they note. This is likely to increase as the numbers of obese continues to climb.
Last week the Food and Drug Administration (FDA) sent warning letters to 16 dietary supplement distributors said to be making false and misleading claims for weight loss products promoted over the internet.
Many of these products claim to block starch, carbohydrates and fat calories, while allowing consumers to lose weight without any changes in lifestyle. After reviewing the claims of the various products, FDA concluded that claims being made regarding these products are not supported by reliable scientific evidence.
"These products give unfounded hope to people who are attempting to lose weight. False and misleading claims have significant health consequences to individuals that may be overweight because these products do not produce the desired results," said acting FDA Commissioner Lester M. Crawford.
The researchers carried out literature searches to indentify randomized and double-blind trials on supplements studied for weight loss effects. They used five systematic reviews and meta-analyses and 25 additional trials on chitosan, chromium picolinate, Ephedra sinica, Garcinia cambogia, glucomannan, guar gum, hydroxy-methylbutyrate, plantago psyllium, pyruvate, yerba maté, and yohimbe.
"The reviewed studies provide some encouraging data but no evidence beyond a reasonable doubt that any specific dietary supplement is effective for reducing body weight. The only exceptions are E. sinica- and ephedrine-containing supplements, which have been associated with an increased risk of adverse events," conclude the authors in this month's American Journal of Clinical Nutrition (vol. 79, no 4, 529-536).
