Garlic has been used since millennia for flavoring foods and as medicines. Hippocrates recommended it for treating fatigue, parasites and respiratory problems. Many health benefits are attributed to garlic, such as reducing high blood pressure and cholesterol, preventing heart attacks and certain cancers. How true are these claims? Dr. Raghavendra Rao looks at some facts.

Colorectal Cancer (CRC) and Colon Adenomas: A meta-analysis study in the Journal of Nutrition (2007) showed that garlic has a protective effect against colon adenomas. In one study, there was a 29% reduction in the incidence of colon adenomas. Animal studies also showed a protective influence against CRC. The US Food and Drug administration noted that there was very limited evidence for the protective quality of garlic against CRC and suggested further studies.

High Cholesterol and Low-Density-Lipoproteins (LDL): In a Stanford study (2007), 192 adults with moderate high cholesterol and LDL were given raw garlic, powdered garlic, aged garlic and a placebo, about 4 grams per day, 6 days a week for 6 months. The researchers found that there was no statistically significant effect on cholesterol or LDL levels. Currently, garlic is not recommended for reducing high cholesterol.

High Blood Pressure (BP): Garlic is consumed for lowering BP by many individuals. A meta-analysis published in 2008 showed that garlic consumption lowered the BP in people with high and normal blood pressures.

In one study on 47 hypertensive individuals, garlic lowered the systolic BP by 12 mm of mercury and the diastolic by 9 mm, as compared to a placebo. Stabler SN, Tejani AM and others in 2012 did another meta-analysis and noted a reduction in systolic and diastolic pressures. The reductions were within the known daily variations. The authors concluded that there was insufficient evidence to consume garlic for reducing high blood pressure.

Heart Attacks: Garlic prevents platelet aggregation in a test tube. It has antioxidants. Both these qualities should help in preventing cardiovascular accidents. However, the studies done so far are inconclusive. This is because most studies had small numbers of participants and different garlic preparations were given to them.

Other Claims: Many websites tout other benefits of garlic. They claim that it prevents hair loss, cures acne, fungal infections, prevents colds, helps psoriasis heal, keeps away mosquitos, and heals cold sores. There are no solid scientific studies to prove these statements.

Side Effects: Garlic is safe to take in small quantities when added to food items. If consumed too much, it can cause bad breath, body odor, stomach irritation and pain, gas, nausea, vomiting and loose stools. There is not enough data on nursing mothers regarding its safety to newborns. Garlic may prolong bleeding, so use caution when you are taking medicines to prevent clotting.

Whether medically effective or not, garlic has a unique flavor and adds zest to many dishes. If you like it, enjoy it.