What’s in that weight-loss supplement?
March 18, 2005
By Karen Collins
Many common ingredients pose potential health risks
Americans spend billions of dollars each year on weight-loss supplements.
Although we wouldn’t buy a car or a dinner without knowing
some details, many who purchase these supplements have no idea what
is in them, or what independent reports say about their safety and
effectiveness.
Even though the Food and Drug Administration has charged some companies
with using banned ingredients, and the Federal Trade Commission
has successfully prosecuted marketers who made illegal claims, the
same products, or copycat versions, still remain available.
Some weight loss supplements contain ingredients meant to suppress
the appetite. Caffeine and its herbal counterparts, guarana, bitter
orange and yerba maté, as well as ephedra (ma huang), fall
into this category. Animal studies suggest that they may slightly
suppress the appetite, but the limited human studies lasted only
a few months. All these ingredients are nervous system stimulants,
so they commonly produce side effects like headaches, insomnia,
elevated blood pressure and heart palpitations.
Deceptive labeling
Product labeling can be deceptive: Weight-loss supplements labeled
ephedra- or caffeine-free may contain other ingredients from the
list above, which may pose the same health risks. Although ephedra
(ma huang) has been banned by the FDA, you may still see it in some
supplements. In a summary of more than 50 trials, this substance
created a 2 to 3.6-fold increase in the risk of psychological, heart
and digestive system problems.
Supplement manufacturers claim other ingredients aid weight loss
by speeding up the metabolism. For example, EGCG, a phytochemical
found in green tea, is being studied for its potential to reduce
cancer risk. Some initial studies suggest it could slightly increase
the rate at which calories burn. Now it can be found in many weight-loss
supplements and “weight-loss vitamins.”
However, since there are only extremely short initial studies so
far, the body might adapt to EGCG, reducing its effect over time.
In addition, the weight loss benefit seen with EGCG amounts to about
60 to 70 calories a day. This small difference is more likely to
help prevent a gradual yearly weight gain than reverse excessive
weight gain. Third, the effect of EGCG appears to depend on the
dose. Supplements with amounts of 30 to 40 mg of EGCG, which is
commonly seen in these products, may not have the same effect as
a dose over 250 mg used in the studies.
Few significant effects
Supplements may also contain ingredients that manufacturers state
will block the absorption of fat or carbohydrates. Chitosan is a
common example, and a few preliminary studies made it appear promising.
However, several controlled studies found that chitosan had no significant
effect on fat absorption. In the most recent study, men would need
seven months to lose one pound of body fat. There was no fat loss
for women.
Another group of ingredients are said to increase the feeling of
fullness and decrease eating. Guar gum appears safe for this purpose,
but 11 well-controlled studies show it has no benefit for weight
loss. Psyllium can help control blood sugar and blood cholesterol,
but studies do not support its reputed ability to reduce eating
and assist weight loss.
There are more than 50 individual supplements and 125 combination
products now available for people who want to lose weight. Yet a
Harvard Medical School review of these products that set standards
for product quality, safety and effectiveness concluded that none
of them met all three standards.
Future research may identify some safe and effective ingredients
for weight loss, but for now it seems smarter to invest in walking
shoes, a gym membership, or healthier food instead.
Source:http://msnbc.msn.com
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