garlic supplement

Garlic (Allium sativum) is a cultivated bulb with a long history of use in both food and traditional health practices. It is sold as a supplement in several forms, including fresh and aged garlic preparations, powders, oils, and extracts, which can differ in their content of garlic's characteristic sulfur compounds. According to NCCIH, garlic is cultivated worldwide and ancient writings from Egypt, Greece, and India describe its use for a variety of health problems.

The evidence is limited and the benefits, where seen, are small. NCCIH states that garlic supplements "may reduce levels of total cholesterol and low-density lipoprotein (LDL) cholesterol to a small extent in people who have high blood cholesterol levels." Limited evidence suggests they "may reduce blood pressure to a small extent" in people with high blood pressure, and "may reduce blood sugar to a small extent in people with diabetes." For cancer, NCCIH says consuming garlic does not seem to reduce the risk of stomach cancer and that its effect on colorectal cancer risk is uncertain. Evidence for immune or cold-related benefits is weak: NCCIH notes a 2022 review identified only two studies suggesting a possible benefit, both small and with research weaknesses. Garlic supplements are not a substitute for prescribed treatments such as cholesterol-lowering, blood-pressure, or diabetes medications.

There is no established standard dose. Products vary widely by form (for example, aged extract, powder, or oil) and in their content of active sulfur compounds, so they are not interchangeable. NCCIH notes that garlic taken orally has been used safely in research studies that lasted as long as 7 years. Talk with your health care providers before starting a garlic supplement, particularly if you have a medical condition, take medications, or are pregnant or breastfeeding.

Garlic taken orally is generally considered safe and, per NCCIH, has been used safely in studies lasting as long as 7 years. NCCIH cautions that fresh raw garlic used topically (on the skin) may not be safe and can cause severe skin irritation and chemical burns. Garlic may not be safe during pregnancy or breastfeeding when taken orally in amounts greater than those found in foods. Because garlic supplements may increase the risk of bleeding, tell your health care providers if you take garlic, especially before any surgery.

According to NCCIH, side effects of garlic consumed orally include breath and body odor, abdominal pain, flatulence (gas), and nausea. Some people have allergic reactions to garlic.

NCCIH cautions that garlic supplements may increase the risk of bleeding. This is especially important if you are going to have surgery or if you take medicines that may also affect bleeding, such as anticoagulants (blood thinners) or aspirin. Tell all of your health care providers about any garlic supplements you take so they can check for possible interactions. (Garlic may interact with additional medications not covered by NCCIH's overview; check with a pharmacist about your specific drugs.)