Weight-Loss Supplements: Do They
Work?
January 26, 2005
By Karen Pallarito
Now that the holiday cookies are history, you've resolved
to get fit and trim. Perhaps you've even considered
taking over-the-counter dietary supplements to help
you reach your weight-loss goals.
Drugstores, nutrition shops and Web sites offer a plethora
of supplements and combination products that claim to
help burn fat, block fat absorption, modulate carbohydrate
metabolism, boost energy expenditure, suppress appetite,
flush out excess water weight and control cravings--all
good outcomes to an eager dieter.
So what's the harm in grabbing a bottle?
"There's a tremendous appeal for a magic pill
to help lose
weight--manufacturers of weight-loss pills appeal
to that, I think," said Dr. Robert Saper, director
of integrative medicine in the Department of Family
Medicine at Boston University Medical Center.
But in a review of the scientific evidence, published
in the Nov. 1, 2004, issue of American Family Physician,
Saper suggested there's no miracle pill on the market.
In fact, some of the supplements out there may be dangerous
or might interact with prescription medications that
people are taking, he said.
"There's very few of them that show benefit for
what people are taking them for," agreed Dr. Gary
A. Green, a clinical professor in the Division of Sports
Medicine at the University of California, Los Angeles.
Steven Dentali, vice president of scientific and technical
affairs at the American Herbal Products Association,
offers a somewhat more upbeat assessment: "I would
say there is some preliminary evidence that some of
these ingredients can be useful in combination with
diet and exercise."
Dietary supplements have quite a following among many
Americans. Overall, 7% of adults use over-the-counter
weight-loss supplements, according to a five-state survey
reported in 2001 in the Journal of the American Medical
Association. The use of nonprescription weight-loss
products is particularly common among young obese women--28.4%
reported taking them.
One recent success story is that of former Playboy
"Playmate of the Year" Anna Nicole Smith.
The 37-year-old actress and model dropped 69 pounds
in eight months using a formulation of TRIMSPA, a popular
brand-name product, the supplement maker's Web site
claims.
But do you know what you're getting when you buy brand-name
dietary supplements, including TRIMSPA, Xenedrine, and
Hydroxycut, or individual herbal products?
The Natural Medicines Comprehensive Database, a source
for evidence-based information on natural brand-name
products and ingredients, lists more than 50 individual
supplements and 125 proprietary products, according
to Saper, who examined individual ingredients found
in several commercial products.
Chromium, for example, is a popular weight-loss supplement
found in many products, but its efficacy and long-term
safety are uncertain, he said. Guar gum, derived from
the Indian cluster bean, appears to be ineffective for
weight loss. Chitosan, derived from shellfish, is another
one to avoid, Saper said. "I discount chitosan
because, although it's safe, its role as a 'fat blocker'
is not well-substantiated," he explained.
Glucomannan, a plant fiber, may be helpful for modest
weight loss, he said, but the data are insufficient
to support a definitive conclusion.
Overall, the amount of well-designed research to substantiate
the effectiveness of many individual herbs for weight
loss is sparse, Saper said. Even greater questions exist
as to the safety and effectiveness of combination products
and the potential for harmful interactions among different
ingredients, he noted.
Dietary aids containing the herbal supplement ephedra
were extremely popular until the U.S. Food and Drug
Administration banned their sale in April 2004 due to
reports of deaths. Ephedrine, the active ingredient,
is a stimulant known to increase metabolic rate, heat
production and the risk of heatstroke.
Dangerous supplements still remain available on store
shelves and Web sites, Consumers Union warns. The public
advocacy group's Consumer Reports magazine last May
published a list of the "dirty dozen"--12
supplement ingredients that have been linked either
to serious adverse effects or to a strong theoretical
risk. The list included bitter orange, a common dietary
supplement that contains a compound called synerphrine,
which carries risks similar to ephedrine, Saper said.
Critics of the dietary supplement industry want Congress
to put some teeth into federal regulations. Under the
Dietary Supplement Health and Education Act of 1994,
manufacturers of dietary supplements are not required
to provide evidence of safety or effectiveness. The
burden rests on the FDA to prove that a product is either
unsafe or ineffective.
"As long as they don't claim to treat any specific
disease or condition they can basically make any claims
that they want," Green said.
For its part, the herbal products association has expressed
support for a mandatory adverse-events reporting system
for dietary supplements.
Until there's better data, motivated dieters would
be better off talking to their physicians about proven
weight-loss strategies, such as diet and exercise, according
to Saper.
But Dentali believes herbal products can play a role
in a sensible weight-loss strategy. Switching from soda
to green tea, for example, may provide some health benefits,
"and you're not sucking down those sodas."
Source:www.forbes.com
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