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PSYLLIUM, GARLIC FOR LOWERING CHOLESTEROL CAN SERVE AS "ADJUNCTS" TO DIET

This article was originally published in The Tan Sheet

Executive Summary

PSYLLIUM, GARLIC FOR LOWERING CHOLESTEROL CAN SERVE AS "ADJUNCTS" TO DIET modification, Thomas Pearson, MD/PhD, and Rajesh Patel, Columbia University, suggested in an editorial in the Oct. 1 issue of The Annals of Internal Medicine. Commenting on two positive studies of psyllium and garlic for reducing cholesterol that appear in the same issue of the medical journal, the editorial writers cautioned that the "new findings may be used indiscriminately by patients instead of in a medically directed program." "For the person with a high-risk cholesterol level, [garlic and psyllium supplements] can probably serve useful purposes as part of an overall dietary modification program," the editorial states. "Our concern is that their use will delay or replace the initiation of such a program, with the patient depending on these agents instead of on comprehensive medical care." The "main message to consumers," according to Pearson and Patesh, "should be subtraction of dietary fat, as advised by physicians and nutritionists, rather than substitution or supplementation." The editorial writers suggested that further studies are necessary to determine "the exact modes of action" of psyllium and garlic as well to find out whether possible interaction "with other cholesterol-decreasing drugs needs to be described." While the results of the two studies were significant, the editorial writers pointed out that dietary therapy reduced cholesterol levels by more than 10%, a figure higher than any reduction found in the two studies. In a study of psyllium's effect on cholesterol sponsored by Metamucil manufacturer Procter & Gamble, Dennis Sprecher, MD, University of Cincinnati, et al. found that supplementation of 5.1 g psyllium daily reduced total cholesterol levels by 4.5% on average and low-density lipoprotein (LDL) cholesterol levels by 5.8% overall. However, the investigators noted that the "small but significant" reduction was dependent on fat intake in the subject's diet. For psyllium recipients with high-fat diets (more than 40% of total caloric intake), total cholesterol and LDL cholesterol levels decreased 5.8% and 7.2%, respectively; for psyllium recipients with low-fat (less than 27% of total caloric intake) diets, the levels dropped 4.2% and 6.4%, respectively, Sprecher et al. reported. The double-blind, placebo-controlled, 16-week parallel trial was conducted at two centers at the University of Cincinnati and the Washington University School of Medicine. The study enrolled 37 participants in the high-fat program and 81 participants in the low-fat program. The participants were "healthy men and women," aged 21 to 70, who suffered from primary hypercholesterolemia (serum cholesterol >220 mg/dL). Following an eight-week "dietary lead-in phase," participants were given either Metamucil or placebo for an eight-week treatment period. Using the National Cholesterol Education Program's (NCEP) LDL cholesterol classification system, Sprecher et al. determined that "regardless of dietary regimen," 37.8% of all psyllium recipients moved towards lower risk groups, compared with 18.6% of the control group. Sprecher et al. speculated that "soluble fiber may physically entrap bile acids, resulting in increased fecal loss similar to that seen with the bile acid sequestrants" used as cholesterol- lowering drugs. The investigators added that psyllium therapy in combination with diet modification "should reduce the number of hypercholesterolemic patients who are placed on drug therapy and reduce the doses when drug therapy is required." "It is very likely that modifications in dietary cholesterol can explain only a small part, at best, of the LDL cholesterol changes observed with psyllium supplementation," Sprecher et al. said. "We have established that persons on a low-fat diet have a greater tendency to reach NCEP goals when they also receive psyllium." Furthermore, they maintained that "for particularly responsive persons," psyllium therapy alone may be adequate to lower levels. In a meta-analysis of five garlic supplementation articles, Stephen Warshafsky, MD, New York Medical College, et al. found that garlic supplementation could reduce subjects' total serum cholesterol levels "by about 9%" in a "conservative" estimate. The studies reviewed by Warshafsky et al. were limited to trials that met several conditions: at least 75% of participants had cholesterol above 200 mg/DL; there was a placebo control; and the study generated "enough data to compute effect size." Of the 28 studies found in the MEDLINE database, five were selected for review, three of which were conducted in Germany, one in Thailand, and one in the U.S. The studies ranged from 8 to 24 weeks. Three studies used Lichtwer Pharma's Kwai tablets, one used Wakunaga's Kyolic aqueous extract, and another used spray-dried garlic powder. "Meta-analysis of homogeneous trials estimated a net cholesterol decrease attributable to garlic of .59 mmol/L (95% CI, .44 to .74)," or approximately "one half to one clove per day," Warshafsky et al. said. However, the investigators found it was "difficult to establish" a dose-response relationship. A total of 410 subjects were enrolled in the trials, 185 men and 255 women. Of those, 365 completed the trials, 184 of whom were randomly assigned to the garlic group and 181 to the control. All five trials measured both total serum cholesterol and triglyceride level, Warshafsky et al. reported. "None of the trials placed any dietary restrictions on participants," they also noted. Nevertheless, "patients treated with garlic consistently showed a greater decrease in total cholesterol levels compared with placebo . . . The best available evidence suggests that garlic, in an amount approximating one half to one clove of garlic per day, decreased total serum cholesterol levels by about 9% in the groups of patients studied," Warshafsky et al. stated. However, "the quality of the included trials were not optimal," the investigators acknowledged. The effect sizes "were determined not to be homogeneous across all five studies" and dietary intake including "exogenous garlic ingestion", was not recorded. "Although we detected a significant hypocholesterolemic effect, the overall quality of the included studies weakens the validity of our findings," Warshafsky et al. concluded.
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