What Is the Connection between Garlic and Cholesterol?

Garlic has been used for a few millennia to enhance the flavor of food and promote a healthy life. Allium sativum, garlic's formal name, is reportedly effective in as many as 200 health-related applications. Until recently, scientists presumed a preventative connection between garlic and cholesterol levels — at least the bad kind of cholesterol. It's still widely believed that garlic helps the body prevent heart disease by introducing more good cholesterol, called high-density lipoproteins (HDL), and inhibiting the amount of bad cholesterol, or low-density lipoproteins (LDL). Recent research, however, casts a shadow over garlic's use as an exclusive treatment to lower already-dangerous LDL levels.

A natural blood thinner, like aspirin, garlic is also a powerful antioxidant that's reputedly effective in battling a range of maladies, from yeast infections and colds to certain cancers and cholesterol. These characteristics combine to remove free radicals more efficiently from the bloodstream. Scientists long have believed this gives plaque-forming LDLs less of an opportunity to be oxygenated and form blockages in the arteries. When plaque builds up, it can worsen into atherosclerosis, the precursor to many heart attacks and strokes. The National Heart, Lung and Blood Institute (NHLBI) recommends that a person's LDL level be below 100, measured in milligrams per deciliter.

Garlic and cholesterol are also connected in that garlic is suspected to increase levels of HDLs, which are too large to latch to arterial passages. Instead, scientists believe they help carry LDLs and other harmful elements out of the circulatory system. The NHLBI states a healthy HDL level is 60 mg/dL. In all, a person's total cholesterol intake shouldn't exceed 200 mg/dL.

New studies on the connection between garlic and cholesterol may lead to new beliefs about its efficacy in lessening LDL levels. A February 2007 study by researchers at the University of Stanford points out the limitations of garlic in battling bad cholesterol. Three groups of about 50 people, each exhibiting high levels of LDLs, were given a different type of supplement daily for six months: One group got a placebo, and the others got powdered, aged or raw garlic. None of the groups showed a marked change in LDL levels.

Since the study focused on people whose LDL levels were already considered too high, researchers noted that this didn't mean that garlic didn't have a preventative effect on plaque creation and heart disease. It merely stressed that people with LDL levels that are already too high may need other treatments and dietary supplementation to improve their conditions. After the study was published, medical authorities called for more specific studies of the connection between garlic and cholesterol levels.