Reduction of Cholesterol and Other Cardiovascular Disease Risk Factors by Alternative Therapies

Paramjit S Tappia; Yan-Jun Xu; Naranjan S Dhalla


Clin Lipidology. 2013;8(3):345-359. 

In This Article

Cholesterol- & Glucose-lowering Effects of Herbs

Garlic Powder

Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. It is a staple in the Mediterranean region and is a frequently used seasoning in Asia, Africa and Europe. The cholesterol-lowering effects of garlic powder (allicor) have been examined in a number of clinical trials in patients with hypercholesterolemia, CHD, diabetes and other CVDs. In a double-blinded, placebo-controlled, randomized study conducted in 51 patients with CHD, it was found that a 12-month treatment with allicor resulted in a significant decrease of cardiovascular risk by 1.5-fold in men and by 1.3-fold in women. This reduction was attributed to a decrease in LDL-C by 32.9 mg/dl in men and by 27.3 mg/dl in women.[42] In another study, the lipid-lowering effects of time-released allicor tablets (600 mg daily) were investigated in a double-blinded, placebo-controlled, randomized study in 42 men aged 35–70 years with mild hypercholesterolemia. Allicor treatment resulted in a moderate, but statistically significant decrease in total cholesterol level after 8 and 12 weeks. Furthermore, total cholesterol in allicor-treated patients fell by 7.6% as compared with the level at randomization and was 11.5% lower than the placebo group. LDL-C fell by 11.8 and 13.8%, respectively. Also noteworthy was the increase in HDL-C by 11.5%.[43]

The effects of allicor on the risk of ischemic heart disease (IHD) in primary prophylaxis of CVDs have been examined. In a double-blind, placebo-controlled study involving 167 patients with hyperlipidemia free of IHD, it was found that a 12-month intervention resulted in a 10.7% reduction of a 10-year absolute risk to develop IHD and decreased a 10-year absolute risk of acute myocardial infarction and sudden death by 22.7% in men. In women, allicor prevented age-related cardiovascular risk. Among lipid parameters, the greatest fall was observed for total cholesterol and LDL-C in men by 27.9 and 22.5 mg/dl, and in women by 11.4 and 10.8 mg/dl, respectively.[44] The efficacy of allicor has also been examined in Type 2 diabetic subjects. It is well known that diabetes is associated with accelerated development of atherosclerosis. In a 4-week, double-blinded, placebo-controlled study in 60 Type 2 diabetic patients,[45] it was demonstrated that treatment with allicor resulted in improved metabolic control due to the lowering of fasting blood glucose, serum fructosamine and serum TG levels. The authors concluded that the benefits from garlic preparations may lead to the reduction of cardiovascular risk in diabetic patients. Since allicor is the remedy of natural origin, it is safe with respect to adverse effects.

On the other hand, in another study, the beneficial effects of garlic have been disputed.[46] In this parallel-design trial involving 192 adults with LDL-C values between 130 and 190 mg/dl, volunteers were randomized to receive raw garlic, powdered garlic supplement, aged garlic extract supplement or placebo 6 days/week for 6 months. None of the different garlic preparations exerted any effect on LDL-C, HDL-C, TGs or total cholesterol:HDL-C ratio.[46] While this would be contary to the benefits of garlic in the prevention of CVD, others have suggested that different results might have been produced by doses differing in type, bioavailability and duration, as well as by different outcome measures and analysis.[47] Indeed, attenuation of oxidized LDL levels have been reported by garlic extracts.[48] With respect to the safe use of garlic, it has been consumed for several thousand years without any adverse long-term effects, suggesting modest quantities of garlic, at worst, may produce minimal risks to normal individuals. Possible side effects include gastrointestinal discomfort, sweating, dizziness, allergic reactions, bleeding and menstrual irregularities.[49] Garlic may interact with warfarin, antiplatelets, saquinavir, antihypertensives, calcium channel blockers and quinone family of antibiotics such as ciprofloxacin and hypoglycemic drugs, as well as other medications.[50]


Fenugreek, Trigonella foenum-graecum, is cultivated worldwide and is a common ingredient in the Indian subcontinent cuisine. The hypoglycemic and hypolipidemic effects of fenugreek (T. foenumgraecum L.) are well documented in animal studies[51–55] and these observations have been translated to humans.[56–59] For example, in a clinical trial study with 24 Type 2 diabetic patients[56] supplemented with 10 g/day powdered fenugreek seeds mixed with yoghurt or soaked in hot water for 8 weeks, it was found that supplementation with fenugreek (seeds soaked in hot water) resulted in significant decreases in fasting blood glucose, TGs and VLDL cholesterol by 25, 30 and 30.6%, respectively. This study demonstrated that fenugreek seeds can be used as an adjuvant in the control of Type 2 diabetes in the hot water-soaked form. In another study,[57] 25 newly diagnosed patients with Type 2 diabetes (fasting glucose <200 mg/dl) were randomly divided into two groups. Group 1 received 1 g/day hydroalcoholic extract of fenugreek seeds and group 2 received usual care (dietary control and exercise) and placebo capsules for two months. In group 1, as compared with group 2, no differences in the fasting blood glucose and 2 h postglucose blood glucose levels were observed; however, the area under the curve of blood glucose as well as insulin was significantly lower. A decrease in the percentage of β-cell secretion in group 1 compared with group 2, as well as an increase in insulin sensitivity, were also observed. Furthermore, a decrease in serum TG and an increase in HDL-C was detected in group 1 compared with group 2. It was suggested that fenugreek seeds improve glycemic control and decrease insulin resistance and TG levels in mild Type 2 diabetic patients.[57]

The efficacy of defatted fenugreek seed powder has also been examined in Type 1 diabetic patients.[58] Isocaloric diets with and without defatted fenugreek seed powder (100 g), divided into two equal doses, was incorporated into the diet and served with lunch and dinner for 10 days. After a 10-day intervention period, it was found that the fenugreek diet significantly reduced fasting blood sugar and improved the glucose tolerance test. There was a 54% reduction in 24-h urinary glucose excretion. Serum total cholesterol, LDL and VLDL cholesterol, and TGs were also significantly reduced, but the HDL-C fraction remained unchanged. These results indicate the potential of fenugreek seeds in the management of diabetes. The effects of fenugreek on blood lipids, blood sugar and platelet aggregation in patients with coronary artery disease have also been reported.[59] In this study, fenugreek given in a dose of 2.5 g twice daily for 3 months to CAD patients and patients with Type 2 diabetes with or without CAD, decreased total cholesterol and TGs without affecting the HDL-C. When administered in the same daily dose to Type 2 diabetic patients (non-CAD), fenugreek significantly reduced blood sugar (fasting and postprandial). In severe Type 2 diabetes, blood sugar (both fasting and postprandial) was only slightly reduced, but was not significant. In addition, fenugreek did not affect platelet aggregation, fibrinolytic activity and fibrinogen. Fenugreek would appear to be safe for human use, although the benefit/risk profile of fenugreek is yet to be determined.

Curcumin & Ginger

Curcumin is the major curcuminoid of the Indian spice turmeric, which is a member of the ginger family (Zingiberaceae). The effect of curcumin on lipid level in patients with acute coronary syndrome (ACS) has been evaluated.[60] In this randomized, double-blind controlled trial, ACS patients received escalating doses (low dose: 15 mg three times a day; moderate dose: 30 mg three times a day; high dose: 60 mg three times a day) of curcumin. Only administration of low-dose curcumin demonstrated a trend of reduction in total cholesterol level and LDL-C level in ACS patients. On the other hand, postprandial plasma glucose and insulin in healthy subjects treated with Curcuma longa (turmeric) has been investigated.[61] It was found that ingestion of 6 g turmeric increased postprandial serum insulin levels, but did not appear to affect plasma glucose levels or glycemic index in healthy subjects. The results indicate that turmeric may have an effect on insulin secretion. The hypolipidemic effects of curcuminoids in obese patients in a double-blind, placebo-controlled, randomized crossover trial have also been examined.[62] In this preliminary study, patients (n = 30) were treated with curcuminoids (1 g/day for 30 days) or placebo. Interestingly, while serum TG levels were significantly reduced following curcumin supplementation, serum levels of total cholesterol, LDL-C, HDL-C and high-sensitivity CRP were not affected. These findings indicated that curcuminoid supplementation results in a significant reduction in serum TG concentrations, but does not have any influence on other lipid profile parameters. It is of note that, to date, more than 65 human clinical trials of curcumin, which include more than 1000 participants, have been completed and as many as 35 clinical trials are currently ongoing. Curcumin is now used as a supplement in several countries including the USA, India, Japan, China and South Africa.[63] It should be noted that curcumin has no severe toxicity except for minor gastrointestinal side effects, even up to a dosage of 8 g for 3 months.[64] While possible carcinogenic effects of curcumin has been suggested by some,[65–67] clinical studies in humans with high doses (2–12 g) of curcumin have demonstrated few side effects, with some subjects reporting mild nausea or diarrhea.[68] More recently, it has been documented that curcumin may potentially cause iron deficiency in susceptible patients.[69] However, further studies are required to establish the benefit/risk profile of curcumin.

Ginger is the rhizome of the plant Zingiber officinale and is regarded as a culinary ingredient and a medicine. The effect of ginger on lipid levels in patients with hyperlipidemia has also been evaluated.[70] In this double-blind, placebo-controlled clinical trial, patients were randomized to receive ginger capsules 3 g/day in three divided doses (n = 45) or placebo (lactose capsule 3 g/day in three divided doses; n = 40) for 45 days. There was a significant reduction in TG and LDL-C, and an increase in HDL-C levels in the ginger-treated group. These results demonstrated the lipid-lowering effects of ginger. With respect to the safe use of ginger, ginger is on the US FDA 'generally recognized as safe' list, although it does interact with some medications, including warfarin. Ginger is contraindicated in people suffering from gallstones, as it promotes the production of bile. There are also suggestions that ginger may affect blood pressure, clotting, heart rhythms and gastrointestinal discomfort.