1. Garlic contains compounds with potent medicinal properties

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Garlic is a plant in the Allium (onion) family. It is closely related to onions, shallots, and leeks.

Each segment of a garlic bulb is called a clove. There are about 10–20 cloves in a single bulb, give or take.

Garlic grows in many parts of the world and is a popular ingredient in cooking, due to its strong smell and delicious taste.

However, throughout ancient history, the main use of garlic was for its health and medicinal properties (1Trusted Source).

Its use was well documented by many major civilizations, including the Egyptians, Babylonians, Greeks, Romans, and Chinese (1Trusted Source).

Scientists now know that most of garlic’s health benefits are caused by sulfur compounds formed when a garlic clove is chopped, crushed, or chewed.

Perhaps the most well-known compound is allicin. However, allicin is an unstable compound that is only briefly present in fresh garlic after it’s been cut or crushed (2Trusted Source).

Other compounds that may play a role in garlic’s health benefits include diallyl disulfide and s-allyl cysteine (3Trusted Source).

The sulfur compounds from garlic enter your body from the digestive tract. They then travel all over your body, exerting strong biological effects.

SUMMARYGarlic is a plant in the onion family that’s grown for its distinctive taste and health benefits. It contains sulfur compounds, which are believed to be responsible for some of those health benefits.

Calorie for calorie, garlic is incredibly nutritious.

A single clove (3 grams) of raw garlic contains (4Trusted Source):

• Manganese: 2% of the daily value (DV)
• Vitamin B6: 2% of the DV
• Vitamin C: 1% of the DV
• Selenium: 1% of the DV
• Fiber: 0.06 grams

This comes with 4.5 calories, 0.2 grams of protein, and 1 gram of carbs.

Garlic also contains trace amounts of various other nutrients.

SUMMARYGarlic is low in calories and rich in vitamin C, vitamin B6, and manganese. It also contains trace amounts of various other nutrients.

Garlic supplements are known to boost the function of the immune system.

A large, 12-week study found that a daily garlic supplement reduced the number of colds by 63% compared with a placebo (5Trusted Source).

The average length of cold symptoms was also reduced by 70%, from 5 days in the placebo group to just 1.5 days in the garlic group.

Another study found that a high dose of aged garlic extract (2.56 grams per day) reduced the number of days sick with cold or flu by 61% (6Trusted Source).

However, one review concluded that the evidence is insufficient and more research is needed (7Trusted Source).

Despite the lack of strong evidence, adding garlic to your diet may be worth trying if you often get colds.

SUMMARYGarlic supplements may help prevent and reduce the severity of illnesses like the flu and common cold, but more research needs to be done before any conclusions can be made.

Cardiovascular diseases like heart attack and stroke are responsible for more deaths than almost any other condition (8Trusted Source).

High blood pressure, or hypertension, is one of the most important factors that may lead to these diseases.

Human studies have found garlic supplements to have a significant impact on reducing blood pressure in people with high blood pressure (9Trusted Source, 10Trusted Source, 11Trusted Source).

In one study, 600–1,500 mg of aged garlic extract were just as effective as the drug Atenolol at reducing blood pressure over a 24-week period (12Trusted Source).

Supplement doses must be fairly high to have the desired effects. The amount needed is equivalent to about four cloves of garlic per day.

SUMMARYHigh doses of garlic appear to improve blood pressure for those with known high blood pressure (hypertension). In some instances, supplements may be as effective as regular medications.

Garlic can lower total and LDL (bad) cholesterol.

For those with high cholesterol, garlic supplements appear to reduce total and LDL cholesterol by about 10–15% (13Trusted Source, 14Trusted Source, 15Trusted Source).

Looking at LDL (bad) and HDL (good) cholesterol specifically, garlic appears to lower LDL but has no reliable effect on HDL (9Trusted Source, 10Trusted Source, 16Trusted Source, 17Trusted Source, 18Trusted Source).

High triglyceride levels are another known risk factor for heart disease, but garlic seems to have no significant effects on triglyceride levels (15Trusted Source).

SUMMARYGarlic supplements seem to reduce total and LDL (bad) cholesterol, particularly in those who have high cholesterol. HDL (good) cholesterol and triglycerides do not seem to be affected.

Oxidative damage from free radicals contributes to the aging process.

Garlic contains antioxidants that support the body’s protective mechanisms against oxidative damage (19Trusted Source).

High doses of garlic supplements have been shown to increase antioxidant enzymes in humans, as well as significantly reduce oxidative stress in people with high blood pressure (7Trusted Source, 9Trusted Source, 20Trusted Source).

The combined effects on reducing cholesterol and blood pressure, as well as the antioxidant properties, may reduce the risk of common brain conditions like Alzheimer’s disease and dementia (21Trusted Source, 22Trusted Source).

SUMMARYGarlic contains antioxidants that can help protect against cell damage and aging. It may reduce the risk of Alzheimer’s disease and dementia.

The potential effects of garlic on longevity are basically impossible to prove in humans.

But given the beneficial effects on important risk factors like blood pressure, it makes sense that garlic could help you live longer.

The fact that it can fight infectious diseases is also an important factor, because these are common causes of death, especially in the elderly or people with dysfunctional immune systems (23Trusted Source).

SUMMARYGarlic has known beneficial effects on common causes of chronic disease, so it makes sense that it could also help you live longer.

Garlic was one of the earliest “performance enhancing” substances.

It was traditionally used in ancient cultures to reduce fatigue and improve the work capacity of laborers.

Most notably, it was given to Olympic athletes in ancient Greece (1Trusted Source).

Rodent studies have shown that garlic helps with exercise performance, but very few human studies have been done (23Trusted Source).

In one small study, people with heart disease who took garlic oil for 6 weeks had a 12% reduction in peak heart rate and better exercise capacity (24Trusted Source).

However, a study on nine competitive cyclists found no performance benefits (25Trusted Source).

Other studies suggest that exercise-induced fatigue may be reduced with garlic (2Trusted Source).

SUMMARYGarlic may improve physical performance in lab animals and people with heart disease. The benefits for people without heart disease are not yet conclusive. Ultimately, more research is needed.

At high doses, the sulfur compounds in garlic have been shown to protect against organ damage from heavy metal toxicity.

A 4-week study in employees at a car battery plant (who had excessive exposure to lead) found that garlic reduced lead levels in the blood by 19%. It also reduced many clinical signs of toxicity, including headaches and blood pressure (26Trusted Source).

Three doses of garlic each day even outperformed the drug D-penicillamine in reducing symptoms.

SUMMARYGarlic was shown to significantly reduce lead toxicity and related symptoms in one study.

No human studies have measured the effects of garlic on bone loss.

However, rodent studies have shown that it can minimize bone loss by increasing estrogen in females (27Trusted Source, 28Trusted Source, 29Trusted Source, 30Trusted Source).

One study in menopausal women found that a daily dose of dry garlic extract (equal to 2 grams of raw garlic) significantly decreased a marker of estrogen deficiency (31Trusted Source).

This suggests that this supplement may have beneficial effects on bone health in women.

Foods like garlic and onions may also have beneficial effects on osteoarthritis (32Trusted Source).

SUMMARYGarlic appears to have some benefits for bone health by increasing estrogen levels in females, but more human studies are needed.

The last one is not a health benefit but is still important.

Garlic is very easy to include in your current diet. It complements most savory dishes, particularly soups and sauces. The strong taste of garlic can also add a punch to otherwise bland recipes.

Garlic comes in several forms, from whole cloves and smooth pastes to powders and supplements like garlic extract and garlic oil.

A common way to use garlic is to press a few cloves of fresh garlic with a garlic press, then mix it with extra virgin olive oil and a bit of salt. This works as a very simple and nutritious salad dressing.

Garlic side effects

However, keep in mind that there are some downsides to garlic, such as bad breath. There are also some people who are allergic to it.

If you have a bleeding disorder or are taking blood-thinning medications, talk with your doctor before increasing your garlic intake.

SUMMARYGarlic is delicious and easy to add to your diet. You can use it in savory dishes, soups, sauces, dressings, and more.