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Botanical name(s):

Allium sativum. Family: Liliaceae

General description

Garlic consists of fresh or dried bulbs of the botanical plant Allium sativum. It’s cultivated worldwide. The bulb or clove is the part of the plant that’s used most often. But sometimes garlic oil is used. Garlic is best stored hung in plaits in a dry place.

Garlic contains alliin. When this is ground, it makes the strong-smelling, potent antibacterial agent allicin. Garlic may have antibacterial features. It’s also said to protect against atherosclerosis and stroke. This is because it keeps platelets from coming together. It also decreases high blood pressure and cholesterol.

Medically valid uses

Garlic decreases the ability of blood platelets to form clots. 

Some animal studies suggest that garlic may improve insulin release in people with diabetes. But there is no evidence to support this effect in humans. 

Other studies show that garlic may improve the elasticity of the aorta. It may also keep atherosclerotic plaque from forming.

There is some support that garlic can slightly lower cholesterol levels. However, recent research done by the National Center for Complementary and Alternative Medicine found that garlic had no effect on cholesterol.

Some research shows that taking garlic by mouth can modestly reduce blood pressure. This effect was seen in people with high blood pressure. It was also seen in people with normal blood pressure.

Unsubstantiated claims

Please note that this section reports on claims that have not yet been substantiated through studies.

Garlic contains allicin. This is a strong antibiotic. It’s released when cloves are crushed or chewed. Garlic has been used as an antiseptic, antibacterial, and antifungal agent. It’s said to help the body resist or destroy viruses and other microorganisms. It does this by boosting the immune system.

Garlic is also claimed to fight infections. It may also build up strength. Garlic may also have laxative properties.

Garlic may also help treat these issues:

  • Chronic bronchitis

  • Respiratory catarrh

  • Recurrent colds and respiratory infections

  • Chronic earaches

  • Sore throat

  • Sinus problems

  • Flu

  • Yeast infections

  • Intestinal worms

Dosing format

Garlic is available fresh or dried in oral capsule form. (The enteric-coated capsules are easiest for the body to absorb.) It also comes as an extract and as odorless supplements. The quality of commercial forms of garlic varies a lot.

Be sure to use garlic exactly as directed on the label.

Side effects, toxicity, and interactions

Garlic has a strong taste and odor. Raw garlic can cause stomach upset in some people. Odorless garlic supplements get rid of the offending taste and odor. They may also reduce stomach upset.

Some people are allergic to garlic. When taken in large amounts, garlic may cause side effects. These include causing stomach ulcers and anemia.

Garlic can interact with certain medicines. Using forms of it that contain allicin for a long time may decrease how well saquinavir works. If you’re taking this medicine, talk to your healthcare provider before using garlic.

Online Medical Reviewer: Poulson, Brittany, RD, CDE
Online Medical Reviewer: Wilkins, Joanna, R.D., C.D.
Last Review Date: 8/1/2016