Reviewed: Dong H, Zhao Y, Zhao L, Lu F. The effects of berberine on blood lipids: a systemic review and meta-analysis of randomized controlled trials. Planta Med. 2013;79(6):437-446.
Hyperlipidemia is characterized by excess cholesterol and triglycerides (known collectively as lipids) in the blood. Hyperlipidemia increases the risk of stroke and heart attack. Berberine is an isoquinoline alkaloid isolated from several medicinal plants* and is used in China to treat hyperlipidemia and type 2 diabetes. The purpose of this meta-analysis was to evaluate the efficacy and long-term safety of berberine in the regulation of blood lipids.
The following electronic databases were searched from their establishment through April 2012: Medline®, EmbaseTM, the Cochrane Library, the China Hospital Knowledge Database (CHKD), the Wanfang database, and various databases of ongoing trials. There were no language restrictions, but the search was limited to clinical trials. The following search terms were used: berberine, lipids, human, Huang Lian Su, Xiao Bo Jian, Xue Zhi, and Zhi Xue. Huang Lian Su and Xiao Bo Jian are the names of a single chemical entity of berberine in Chinese. Xue Zhi and Zhi Xue mean “blood lipids” in Chinese. Reference lists from articles also were searched. Two independent reviewers selected articles. The inclusion criteria were (1) trials whose subjects consumed a berberine monopreparation alone or with other pharmaceutical agents for ≥ four weeks; (2) randomized controlled trials (RCTs) with either a parallel or crossover design; (3) trials in which berberine was used as the active treatment intervention; and (4) trials in which the data of berberine impact on blood lipid profiles — including triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL), and high-density lipoprotein cholesterol (HDL) — could be obtained from the study publication. Studies using berberine-containing herbs or extracts in lieu of berberine as a single chemical entity were excluded. Study quality was assessed using the Jadad scale. The effects of berberine intake on blood lipids were calculated as differences between the berberine group and the non-berberine control group.
Eleven studies, with a total of 874 patients, met the inclusion criteria and were incorporated into the meta-analysis. They were published between 2004 and 2012, and all studies originated in China (four written in English and seven in Chinese). The primary diagnoses for patients in the studies were type 2 diabetes (four studies), type 2 diabetes plus hyperlipidemia (one study), impaired glucose tolerance plus hyperlipidemia (one study), hyperlipidemia (two studies), hypercholesterolemia (two studies), and polycystic ovarian syndrome plus insulin resistance (one study). One of two berberine formulations were used for all of the studies — berberine chloride tablets (10 studies, manufacturer not reported) and berberine chloride liposome capsules (one study, manufacturer not reported). The dose and duration typically ranged from 0.9 g to 1.5 g for eight to 16 weeks, with one study using 0.6 g daily and one study having a duration of 52 weeks. Nine studies were of poor quality (Jadad score < three), and only two were of high quality.
The pooled results for the 11 studies show that the berberine groups, compared with the control groups, had statistically significant reductions of TC (P < 0.00001), TG (P < 0.00001), LDL (P < 0.00001), and HDL (P < 0.001). In a subgroup analysis, berberine plus the pharmaceutical statin drug simvastatin — compared with simvastatin alone (two pooled studies) — significantly improved TC (P=0.02), TG (P 0.02), LDL (P=0.02), but had no effect on HDL. The individual studies did not report whether the effect size was large enough to reduce the risk for coronary heart disease (CHD). The pooled data showed a 25 mg/dL reduction in LDL that is statistically significant compared to control. The authors argue that this level of reduction is clinically meaningful based on ATPIII (Adult Treatment Panel III) guidelines (i.e., CHD relative risk is reduced by 30% for every 30 mg/dL reduction in LDL). Pooled adverse effects in patients taking berberine included mild diarrhea, abdominal distention, bitter taste, and mild-to-moderate constipation; there was no significant difference with controls for the incidence of adverse effects. Three studies reduced the dose during the study due to gastrointestinal discomfort.
The authors conclude that berberine may be effective in controlling blood lipid levels. Repeated oral administration of 0.3 g berberine three times per day decreased the liver enzymes cytochrome P450(CYP)2D6, CYP2C9, and CYP3A4 activities in healthy subjects, and the doses used in three of the included studies were as great and in seven were higher; therefore, potential herb-drug interactions should be considered. The safety of berberine needs additional evaluation. An important limitation of this meta-analysis was that nearly all of the included data came from studies of relatively poor quality (nine studies out of 11), which limits the reliability of the conclusions of the meta-analysis. Also, the authors note that these studies, performed exclusively on subjects of Chinese ethnicity, might not be applicable to populations of other ethnic origins.
—Heather S. Oliff, PhD
*Berberine is found in the following medicinal plants: the roots of barberry (Berberis spp., Berberidaceae), goldthread (Coptis spp., Ranunculaceae), and goldenseal (Hydrastis canadensis, Ranunculaceae).