It is closely related to onions, shallots and leeks.
It 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 (1).
Its use was well documented by all the major civilizations… including the Egyptians, Babylonians, Greeks, Romans and the Chinese (2).
This is what garlic looks like:
The entire “head” is called a garlic bulb, while each segment is called a clove. There are about 10-20 cloves in a single bulb, give or take.
We now know that most of the health effects are caused by one of the sulfur compounds formed when a garlic clove is chopped, crushed or chewed.
This compound is known as allicin, and is also responsible for the distinct garlic smell.
Allicin enters the body from the digestive tract and travels all over the body, where it exerts its potent biological effects (which we’ll get to in a bit).
Bottom Line:Garlic is a plant in the onion family, grown for its cooking properties and health effects. It is high in a sulfur compound called Allicin, which is believed to bring most of the health benefits.
2. Garlic Is Highly Nutritious, But Has Very Few Calories
Calorie for calorie, garlic is incredibly nutritious.
A 1 ounce (28 grams) serving of garlic contains (3):
For those with high cholesterol, garlic supplementation appears to reduce total and/or LDL cholesterol by about 10-15% (10, 11, 12).
Looking at LDL (the “bad”) and HDL (the “good”) cholesterol specifically, garlic appears to lower LDL but has no reliable effect on HDL (6, 7, 13, 14, 15).
Garlic does not appear to lower triglyceride levels, another known risk factor for heart disease (10, 12).
Bottom Line: Garlic supplementation seems to reduce total and LDL cholesterol, particularly in those who have high cholesterol. HDL cholesterol and triglycerides do not seem to be affected.
6. Garlic Contains Antioxidants That May Help Prevent Alzheimer’s Disease and Dementia
Oxidative damage from free radicals contributes to the aging process.
Garlic contains antioxidants that support the body’s protective mechanisms against oxidative damage (16) .
High doses of garlic supplements have been shown to increase antioxidant enzymes in humans (5, 17), as well as significantly reduce oxidative stress in those with high blood pressure (6).
The combined effects on reducing cholesterol and blood pressure, as well as the antioxidant properties, may help prevent common brain diseases like Alzheimer’s disease and dementia (17, 18).
Bottom Line: Garlic contains antioxidants that protect against cell damage and ageing. It may reduce the risk of Alzheimer’s disease and dementia.
7. Garlic May Help You Live Longer
Effects 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 disease is also an important factor, because these are common causes of death, especially in the elderly or people with dysfunctional immune systems.
Bottom Line: Garlic has known beneficial effects on common causes of chronic disease, so it makes perfect sense that it could help you live longer.
8. Athletic Performance Can be Improved With Garlic Supplementation
Garlic was one of the earliest “performance enhancing” substances.
It was traditionally used in ancient cultures to reduce fatigue and enhance the work capacity of labourers.
Most notably, it was administered to Olympic athletes in ancient Greece (19).
Rodent studies have shown that garlic helps with exercise performance, but very few human studies have been done.
Subjects with heart disease that took garlic oil for 6 weeks had a reduction in peak heart rate of 12% and improved their exercise capacity (20).
However, a study on nine competitive cyclists found no performance benefits (21).
Other studies suggest that exercise-induced fatigue may be reduced with garlic (2).
Bottom Line: Garlic can improve physical performance in lab animals and people with heart disease. Benefits in healthy people are not yet conclusive.
9. Eating Garlic Can Help Detoxify Heavy Metals in the Body
At high doses, the sulfur compounds in garlic have been shown to protect against organ damage from heavy metal toxicity.
A four week study in employees of a car battery plant (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 (22).
Three doses of garlic each day even outperformed the drug D-penicillamine in symptom reduction.
Bottom Line: Garlic was shown to significantly reduce lead toxicity and related symptoms in one study.
10. Garlic May Improve Bone Health
No human trials have measured the effects of garlic on bone loss.
However, rodent studies have shown that it can minimise bone loss by increasing estrogen in females (23, 24, 25, 26).
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 (27).
This suggests that this garlic may have beneficial effects on bone health in women.
Foods like garlic and onions have also been shown to have beneficial effects on osteoarthritis (28).
Bottom Line:Garlic appears to have some benefits for bone health by increasing estrogen levels in females, but more human studies are needed.