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Hydroxycitric Acid
Natural Health, April, 1999 by Winifred Yu
SOME EXPERTS CLAIM THIS SUPPLEMENT CAN HELP YOU LOSE WEIGHT.
WHAT IT IS Hydroxycitric acid (HCA) is an extract made from the dried rind of the fruit grown on the Asian tree Garcinia cambogia.
HEALING CLAIMS HCA is said to inhibit the body's ability to make fat. It is also believed to be an appetite suppressant as well as an energy booster.
HOW IT WORKS HCA appears to inhibit the function of ATP citrate lyase, the enzyme that converts excess glucose into fat. This enables the body to burn glucose for fuel before it's stored as fat. HCA also decreases the production of malonyl CoA, the second compound involved in the body's synthesis of fat. This slows the formation of lipids--fat precursors--and enables the body to metabolize fat more efficiently.
HCA may also boost basal metabolic rate (BMR), the minimum amount of energy required for a resting body to stay alive. This has implications for dieters since to conserve needed fuel a person's BMR tends to decline when they're on a low-calorie diet. As a result, weight loss often slows. But HCA helps maintain the body's BMR so the body continues to burn calories and lose weight.
No one is certain how HCA works to suppress appetite. John Lowenstein, Ph.D., a professor of biochemistry at Brandeis University in Waltham, Mass., says that HCA's inhibition of ATP citrate lyase may lower levels of acetylcholine, a neurotransmitter involved in appetite control. Other researchers suggest that HCA may initially increase production of the polysaccharide glycogen slightly. Higher glycogen levels signal satiety, reducing appetite.
THE EVIDENCE A study published in the International Journal of Obesity in 1996 points to HCA's ability to maintain BMR. Researchers found that humans on a 1,200 calorie diet who took 1.3 g of HCA a day lost an average of 14 pounds during a two-month period. Those who were on the same diet but took a placebo lost an average of eight pounds.
A study published in the American Journal of Clinical Nutrition found that rats fed HCA gained 80 percent less weight than rats who were not fed HCA. And a study published in the International Journal of Obesity found that rats fed HCA ate less food, gained less weight, and expended an average of 13 percent more energy than rats in a control group not taking HCA.
SKEPTICISM Some experts are wary of HCA's effects on weight loss. Larry S. Hobbs, author of The New Diet Pills (Pragmatic Press, 1995), questions the reliability of studies that support HCA's weight-loss claims. He claims that rats are more efficient at converting glucose to fat than humans, which would enhance HCA's effects. As for the human studies, Hobbs notes that subjects were often using HCA along with a restricted diet, which alone would promote weight loss, so it's unclear whether the weight loss is due to the HCA or the diet.
Dallas Clouatre, Ph.D., co-author of The Diet and Health Effects of HCA (Keats Publishing, 1994), supports the use of HCA for weight loss. But he adds that because the studies used a more potent sodium-based HCA supplement than the calcium-based form available on the market, the dosages tested in studies won't work for most overweight people.
A study published in the Journal of the American Medical Association (JAMA) in November 1998 found that subjects who used HCA showed no more weight loss than those given a placebo. (A spokesperson at Sabinsa Corporation in Piscataway, N. J., a manufacturer that makes an HCA supplement called Citrin, challenged the JAMA findings by saying the subjects were fed a high-fiber diet, which prevents HCA absorption by flushing it out of the body.)
SAFETY Studies have shown that 4 g daily of HCA taken for four weeks produce no adverse effects. No studies of HCA's safety have been done using larger doses or testing over longer periods of time. However, Clouatre has found that an HCA dose of more than 10 g daily may prevent essential minerals from being absorbed by the body. And because HCA is an acid, more than 10 g may also cause gastrointestinal upsets.
It is not known whether artificially elevating the body's BMR, essentially a starvation survival mechanism, is harmful.
Winifred Yu is a freelance writer in Albany, N.Y.
COPYRIGHT 1999 Weider Publications
COPYRIGHT 2008 Gale, Cengage Learning
Natural Health, April, 1999 by Winifred Yu
SOME EXPERTS CLAIM THIS SUPPLEMENT CAN HELP YOU LOSE WEIGHT.
WHAT IT IS Hydroxycitric acid (HCA) is an extract made from the dried rind of the fruit grown on the Asian tree Garcinia cambogia.
HEALING CLAIMS HCA is said to inhibit the body's ability to make fat. It is also believed to be an appetite suppressant as well as an energy booster.
HOW IT WORKS HCA appears to inhibit the function of ATP citrate lyase, the enzyme that converts excess glucose into fat. This enables the body to burn glucose for fuel before it's stored as fat. HCA also decreases the production of malonyl CoA, the second compound involved in the body's synthesis of fat. This slows the formation of lipids--fat precursors--and enables the body to metabolize fat more efficiently.
HCA may also boost basal metabolic rate (BMR), the minimum amount of energy required for a resting body to stay alive. This has implications for dieters since to conserve needed fuel a person's BMR tends to decline when they're on a low-calorie diet. As a result, weight loss often slows. But HCA helps maintain the body's BMR so the body continues to burn calories and lose weight.
No one is certain how HCA works to suppress appetite. John Lowenstein, Ph.D., a professor of biochemistry at Brandeis University in Waltham, Mass., says that HCA's inhibition of ATP citrate lyase may lower levels of acetylcholine, a neurotransmitter involved in appetite control. Other researchers suggest that HCA may initially increase production of the polysaccharide glycogen slightly. Higher glycogen levels signal satiety, reducing appetite.
THE EVIDENCE A study published in the International Journal of Obesity in 1996 points to HCA's ability to maintain BMR. Researchers found that humans on a 1,200 calorie diet who took 1.3 g of HCA a day lost an average of 14 pounds during a two-month period. Those who were on the same diet but took a placebo lost an average of eight pounds.
A study published in the American Journal of Clinical Nutrition found that rats fed HCA gained 80 percent less weight than rats who were not fed HCA. And a study published in the International Journal of Obesity found that rats fed HCA ate less food, gained less weight, and expended an average of 13 percent more energy than rats in a control group not taking HCA.
SKEPTICISM Some experts are wary of HCA's effects on weight loss. Larry S. Hobbs, author of The New Diet Pills (Pragmatic Press, 1995), questions the reliability of studies that support HCA's weight-loss claims. He claims that rats are more efficient at converting glucose to fat than humans, which would enhance HCA's effects. As for the human studies, Hobbs notes that subjects were often using HCA along with a restricted diet, which alone would promote weight loss, so it's unclear whether the weight loss is due to the HCA or the diet.
Dallas Clouatre, Ph.D., co-author of The Diet and Health Effects of HCA (Keats Publishing, 1994), supports the use of HCA for weight loss. But he adds that because the studies used a more potent sodium-based HCA supplement than the calcium-based form available on the market, the dosages tested in studies won't work for most overweight people.
A study published in the Journal of the American Medical Association (JAMA) in November 1998 found that subjects who used HCA showed no more weight loss than those given a placebo. (A spokesperson at Sabinsa Corporation in Piscataway, N. J., a manufacturer that makes an HCA supplement called Citrin, challenged the JAMA findings by saying the subjects were fed a high-fiber diet, which prevents HCA absorption by flushing it out of the body.)
SAFETY Studies have shown that 4 g daily of HCA taken for four weeks produce no adverse effects. No studies of HCA's safety have been done using larger doses or testing over longer periods of time. However, Clouatre has found that an HCA dose of more than 10 g daily may prevent essential minerals from being absorbed by the body. And because HCA is an acid, more than 10 g may also cause gastrointestinal upsets.
It is not known whether artificially elevating the body's BMR, essentially a starvation survival mechanism, is harmful.
Winifred Yu is a freelance writer in Albany, N.Y.
COPYRIGHT 1999 Weider Publications
COPYRIGHT 2008 Gale, Cengage Learning
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