Guggul, an extract from a tree resin, has potential lipid-lowering properties that have been studied in previous clinical trials. Guggulipid is marketed in the United States as a dietary supplement intended to lower cholesterol levels, or as part of a combination herbal product for “heart health,” weight loss, and arthritis. Szapary and colleagues conducted a randomized clinical trial comparing placebo with usual-dose and high-dose gug-gulipid to determine the safety of this supplement and its efficacy in reducing low-density lipoprotein (LDL) cholesterol levels.

Trial participants were at least 19 years of age and had primary hypercholesterolemia. Eligibility in the study required participants to have LDL levels of 130 to 200 mg per dL (3.36 to 5.17 mmol per L) and fasting triglyceride levels of less than 400 mg per dL (4.52 mmol per L). Participants were randomized to receive placebo, guggulipid in a standard dose (1,000 mg), or guggulipid in a high dose (2,000 mg), each taken three times daily with meals. Additional stratification according to baseline LDL levels was performed to determine whether guggulipid might have a different effect on patients with severe hypercholesterolemia. Patients maintained their usual dietary habits. Weight, vital signs, and lipid and blood chemistry analyses were performed at baseline and at weeks 4 and 8. Participants also were asked about any adverse events. The study's primary end point was percentage change from baseline in levels of LDL at eight weeks. Secondary end points included percentage changes in total cholesterol level, high-density lipoprotein (HDL) cholesterol level, very-low-density lipoprotein cholesterol level, and triglyceride level at four to eight weeks, and laboratory test results for electrolyte levels, renal function, and hepatic function.

Of the 103 eligible participants, 85 completed the study. There were no significant differences in demographic, dietary, or laboratory characteristics in the three randomized groups except for body mass index. After eight weeks, LDL levels decreased by 5 percent in the placebo group and increased by 4 percent in the standard-dose guggulipid group, and increased by 5 percent in the high-dose gug-gulipid group. The LDL levels were 9 to 10 percent higher in the treatment groups than in the placebo group, with no differences found between low-dose and high-dose groups. There was no difference in LDL levels in the groups stratified according to LDL cholesterol severity. There was a borderline significant trend toward reduced HDL levels in standard-dose and high-dose guggulipid groups at eight weeks, but only in the per-protocol analysis for the standard-dose group did this difference achieve statistical significance. This same analysis determined that patients with baseline LDL levels of 160 mg per dL (4.14 mmol per L) or higher had reductions of 14 and 10 percent in triglyceride levels in the standard-dose and high-dose guggulipid groups, respectively, compared with the placebo group.

This randomized, placebo-controlled study, which used a standardized guggulipid preparation, found that guggulipid did not lower cholesterol levels in patients eating a usual Western diet. It appeared to increase LDL levels compared with placebo. Some patients taking gug-gulipid, especially in the higher dosage, developed a hypersensitivity reaction.