Garlic is an herb studied extensively for its possible health benefits. Its effects on hyperlipidemia, a condition of elevated fats, has shown conflicting results. While some research supports garlic's positive effects on lowering fats in the blood, other research disputes these findings.
Hyperlipidemia
Hyperlipidemia is a catch-all term for elevated fats in the blood, which can refer to elevated cholesterol, cholesterol esters, phospholipids or triglycerides. When cholesterol is elevated in isolation, it's called hypercholesterolemia, generically termed "high cholesterol." Cholesterol is carried by different lipoproteins throughout the blood. Low-density lipoprotein, or LDL, is considered bad cholesterol, bringing cholesterol to the tissues, while high-density lipoprotein, or HDL, is considered good cholesterol because it helps remove cholesterol. High cholesterol and high triglyceride levels are often associated with and are considered risk factors for heart disease. When more than one type of fat is elevated, hyperlipidemia is present.
Supporting Research
A 2011 study in "Food and Chemical Toxicology" found garlic given to rats significantly reduced total cholesterol, LDL cholesterol and triglyceride levels compared to rats who weren't given garlic. Rats who were fed a standard diet and a diet high in lipids both showed benefit from garlic intake. A 1990 study in the "British Journal of Clinical Practice" found garlic given to patients with mild high blood pressure lowered blood pressure as well as cholesterol and triglyceride levels after 8 to 12 weeks of treatment.
Dissenting Research
A study in the 1998 "Archives of Internal Medicine" found that garlic powder tablets proved ineffective in lowering cholesterol in a 12-week study. The study notes that previous research showing garlic tablets' positive effects on lowering cholesterol were inaccurate because of inadequate quality control. A 2007 study in the same journal found that neither raw garlic or garlic supplements helped lower LDL cholesterol in patients with moderately high cholesterol. Medline Plus categorizes garlic as possibly ineffective for lowering cholesterol and triglycerides, discounting the poor quality-controlled studies that have shown garlic's positive effects.
Considerations
Garlic's effects on hyperlipidemia may be insignficant, but its effects on other conditions that can increase the risk for heart disease can't be discounted. Garlic powder is possibly effective for lowering blood pressure in patients with normal and elevated levels, notes Medline Plus. High blood pressure is a risk factor for heart disease, as is hyperlipidemia. Artherosclerosis, a condition where the arteries become hardened and inflexible, also increases the risk for heart disease, but garlic seems to also have beneficial effects.
References
- American Heart Association: Hyperlipidemia
- "Food and Chemical Toxicology": Effect of Garlic on Liver Phosphatidate Phosphohydrolase and Plasma Lipid Levels in Hyperlipidemic Rats; E. Heidarian, et al.; May 2011
- "British Journal of Clinical Practice": Hypertension and Hyperlipidaemia: Garlic Helps in Mild Cases; W. Auer, et al.; August 1990
- "Archives of Internal Medicine": Garlic Powder And Plasma Lipids And Lipoproteins: A Multicenter, Randomized, Placebo-Controlled Trial; JL Issacsohn, et al.; June 1998
- "Archives of Internal Medicine": Effect of Raw Garlic vs. Commercial Garlic Supplements on Plasma Lipid Concentrations in Adults With Moderate Hypercholesterolemia: A Randomized Clinical Trial; C. Gardener, et al; February 2007
- Medline Plus: Garlic
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