Feb. 4, 2000 (Atlanta) -- Psyllium fiber, in combination with a low-fat diet, lowers cholesterol significantly more than a low-fat diet alone, according to a report in the February issue of the American Journal of Clinical Nutrition. Experts say regular intake of psyllium fiber helps lower the risk of heart disease.
Researchers reviewed 19 studies of men and women with mildly to moderately high cholesterol. In each study, participants received 10.2 grams per day of either psyllium fiber, provided as Metamucil, or placebo. But beforehand, subjects followed the American Heart Association Step I diet for eight weeks or more.
In an analysis that combined study results, the data showed that psyllium fiber lowered total cholesterol an extra 4% and LDL ("bad") cholesterol an extra 7% over the placebo.
Additionally, psyllium fiber did not significantly affect HDL ("good") cholesterol or triglycerides. Though older adults showed greater reductions, the treatment effect was consistent between sexes and there were no clinically significant effects on vital signs and nutritional status.
The researchers also reviewed the data on the safety of psyllium consumption and found that the adverse events were similar to placebo; symptoms involving digestive problems were reported in both groups.
"Regular intake of psyllium fiber is a safe and effective way to lower serum cholesterol," says James Anderson, MD, an endocrinologist at the VA Medical Center and professor of medicine at the University of Kentucky, in Lexington. "And a 5% reduction in serum cholesterol translates to a 15% reduction in the risk of heart disease." Anderson tells WebMD that a low-fat diet may not always be enough.
"The National Cholesterol Education Program (NCEP) estimates that 30% of Americans have undesirably high cholesterol levels," says Anderson. "And although a low-fat diet is the primary intervention, diet alone may not be enough for the 7% with coronary artery disease or severely high cholesterol." Anderson tells WebMD that the NCEP recommends stepwise reductions in dietary fat and cholesterol, reserving drug therapy for those who don't respond.
"The NCEP recommends that fat should not exceed 30% of total calories and saturated fat should not exceed 10%," says Cindy Moore, MS, RD, the director of nutritional therapy at the Cleveland Clinic and spokesperson for the American Dietetic Association.
"But rather than focusing on foods to avoid, we should focus on food substitutions and portion control. That means more servings of fruits, vegetables, and whole grains," says Moore. "At the same time, it means fewer servings of meats and high-fat dairy products. It's also possible to get psyllium from dietary sources like oats and dried peas and beans." Moore tells WebMD that questions about psyllium fiber remain, and the researchers agree.
"In a recent study, a greater response in LDL cholesterol was observed in men," says Anderson. "And in previous studies, older adults showed greater reductions. Clearly, additional research is needed to clarify the effects of psyllium in population subgroups."
Anderson tells WebMD that psyllium is a natural source of fiber that has been used as a laxative for over 60 years. Though its mechanism of action is unclear, data suggest that it lowers serum cholesterol by increasing bile acid, decreasing absorption of fat and cholesterol, and inhibiting production of cholesterol by the liver. Two years ago, the FDA authorized manufacturers and distributors to claim that foods containing 1.7 grams of psyllium per serving reduce the risk of heart disease.
The study was funded in part by the Proctor & Gamble Company, maker of Metamucil.
- A review of several studies shows that psyllium fiber in addition to a low-fat diet can help lower cholesterol levels.
- The results showed the psyllium group lowered their total cholesterol an extra 4%.
- Older participants seemed to show the most benefit, although effects were consistent between men and women.