Many actions associated with herbal supplements may help prevent or potentially alleviate atherosclerosis. Herbs such as garlic and ginkgo appear to directly affect the hardened arteries by multiple mechanisms. Herbs such as psyllium, guggul, and fenugreek reduce cholesterol and other lipid levels in the blood¡ªknown risk factors for hardened arteries. A related group are herbs, including green tea, prevents the oxidation of cholesterol, an important step in protecting against atherosclerosis. Finally, there are herbs such as ginger and turmeric that reduce excessive stickiness of platelets, thereby reducing atherosclerosis.
Garlic has been shown to prevent atherosclerosis in a four-year double-blind trial. The preparation used, standardized for 0.6% allicin content, provided 900 mg of standardized garlic powder per day. The people in this trial were 50 to 80 years old, and the benefits were most notable in women. This trial points to the long-term benefits of garlic to both prevent and possibly slow the progression of atherosclerosis in people at risk.
Garlic has also lowered cholesterol levels in double-blind research, though more recently, some double-blind trials have not found garlic to be effective. Some of the negative trials have flaws in their design. Nonetheless, the relationship between garlic and cholesterol-lowering is somewhat unclear.
Garlic has also been shown to prevent excessive platelet adhesion in humans. Allicin, often considered the main active component of garlic, is not alone in this action. The constituent known as ajoene has also shown beneficial effects on platelets. Aged garlic extract, but not raw garlic, has been shown, to prevent oxidation of LDL cholesterol in humans, an event believed to be a significant factor in the development of atherosclerosis.
Ginkgo may reduce the risk of atherosclerosis by interfering with a chemical the body sometimes makes in excess, called platelet activating factor (PAF). PAF stimulates platelets to stick together too much; ginkgo stops this from happening. Ginkgo also increases blood circulation to the brain, arms, and legs.
Garlic and ginkgo also decrease excessive blood coagulation. Both have been shown in double-blind and other controlled trials to decrease the overactive coagulation of blood that may contribute to atherosclerosis.
Guggul has been less extensively studied, but double-blind evidence suggests it can significantly improve cholesterol and triglyceride levels in people. Numerous medicinal plants and plant compounds have demonstrated an ability to protect LDL cholesterol from being damaged by free radicals. Garlic, ginkgo, and guggul are of particular note in this regard. Garlic and ginkgo have been most convincingly shown to protect LDL cholesterol in humans.
Several other herbs have been shown in research to lower lipid levels. Of these, psyllium has the most consistent backing from multiple double-blind trials showing lower cholesterol and triglyceride levels. The evidence supporting the ability of fenugreek to lower lipid levels is not as convincing, coming from preliminary studies only.
Since oxidation of LDL cholesterol is thought to be important in causing or accelerating atherosclerosis, and green tea protects against oxidation, this herb may have a role in preventing atherosclerosis. However, while some studies show that green tea is an antioxidant in humans, others have not been able to confirm that it protects LDL cholesterol from damage. Much of the research documenting the health benefits of green tea is based on the amount of green tea typically drunk in Asian countries¡ªabout three cups per day (providing 240¨C320 mg of polyphenols).
The research on ginger¡¯s ability to reduce platelet stickiness indicates that 10 grams (approximately 1 heaping teaspoon) per day is the minimum necessary amount to be effective.Lower amounts of dry ginger, as well as various levels of fresh ginger, have not been shown to affect platelets.
Turmeric¡¯s active compound curcumin has shown potent anti-platelet activity in animal studies. It has also demonstrated this effect in preliminary human studies. In a similar vein, bilberry has been shown to prevent platelet aggregation115 as has peony. However, none of these three herbs has been documented to help atherosclerosis in human trials.
Butcher¡¯s broom and rosemary are not well studied as being circulatory stimulants but are traditionally reputed to have such an action that might impact atherosclerosis. While butcher¡¯s broom is useful for various diseases of veins, it also exerts effects that are protective for arteries.