Herbs for serum cholesterol reduction

Safety

Few adverse events or drug interactions were reported in clinical trials of any of the 11 herbs identified. Many are used extensively in traditional medicine and culinary practices around the world, which supports their relative safety.

However, the long-term safety for use as herbal medicinal products has not been established. Long-term exposure of large numbers of patients within a formal setting would be necessary to determine safety, although difficulties associated with all herbal medicinal products exist, such as the inability to identify active ingredients and the potential for adulteration and misbranded products. No direct or indirect evidence exists for herb-drug interactions for fenugreek, guggul, Asian ginseng, and milk thistle (Table 6).

Study limitations

Although differences in study design, methodological quality, statistical methods, and subject populations create problems with interpretation of these figures, they appear to compare favorably with studies of garlic; the most recent meta-analysis suggested an average effect size of 4% to 6%.⁶ Studies of conventional therapeutic options for hypercholesterolemia (eg, statins) have demonstrated reductions of 20% to 30% in serum cholesterol.²⁹

Several shortcomings of the review need to be addressed. First, although attempts were made to obtain data from unpublished trials by contacting authors and manufacturers, none were located. There is evidence to suggest that studies with significant positive results are more likely to be published,³⁰ and this may be more pronounced with unfamiliar herbal therapies.

Second, because much of this research has been conducted in India and China, our extensive search strategy may not have located all the published material.

Third, there were several weaknesses with the original trials; of the 25 randomized clinical trials of herbal medicinal products for serum cholesterol reduction identified, only 12 scored 3 or more points on the Jadad scale. The most frequent methodological flaws were conduct of single-blind or open studies and incomplete reporting of methods of randomization, blinding, and subject withdrawals.

Conclusions

Evidence suggests that physicians do not ask their patients about complementary and alternative therapies and that patients are reticent to discuss these treatments with their physicians.^{31- 34} Surveys indicate widespread use of complementary and alternative therapies among patients undergoing cardiac surgery.^1,2 Although no equivalent surveys have been conducted for patients with hypercholesterolemia, in light of the relatively large number of herbal medicinal products with potential lipid-lowering properties available, it seems prudent for physicians to explore this area in their clinical decision-making process.

In conclusion, although 11 herbal medicinal products were identified with potential hypo-cholesterolemic activity, the evidence supporting individual plants is limited. In addition to lowering cholesterol, several of the herbs may exert beneficial effects in cardiovascular disease by elevating HDL levels and inhibiting lipid oxidation. The safety profiles of the products in question seems to be encouraging. Further research is therefore warranted to establish the therapeutic value of these herbs in the treatment of hypercholesterolemia.

Acknowledgments

The authors thank Jongbae Park, Barbara Wider, and Francesca Borelli, Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, for translation of papers from Chinese, Italian, and French, to and Esther Prati, Pharmaton, Lugano, for assistance with locating relevant articles. JTC received a research fellowship from Pharmaton SA, Lugano, Switzerland.