"Let food be thy medicine, and medicine be thy food."
Those are famous words from the ancient Greek physician Hippocrates, often called the father of Western medicine.
He actually used to prescribe garlic to treat a variety of medical conditions.
Well... modern science has recently confirmed many of these beneficial health effects.
Here are 11 health benefits of garlic that are supported by human research studies.
Garlic is a plant in the Allium (onion) family.
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.
Its use was well documented by all the major civilizations... including the Egyptians, Babylonians, Greeks, Romans and the Chinese (2).
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.
Calorie for calorie, garlic is incredibly nutritious.
A 1 ounce (28 grams) serving of garlic contains (3):
- Manganese: 23% of the RDA
- Vitamin B6: 17% of the RDA
- Vitamin C: 15% of the RDA
- Selenium: 6% of the RDA
- Fiber: 0.6 gram
- Decent amounts of calcium, copper, potassium, phosphorus, iron and vitamin B1
Garlic also contains trace amounts of various other nutrients. In fact, it contains a little bit of almost everything we need.
This is coming with 42 calories, with 1.8 grams of protein and 9 grams of carbs.
Bottom Line: Garlic is low in calories and very rich in Vitamin C, Vitamin B6 and Manganese. It also contains trace amounts of various other nutrients.
Garlic supplementation is known to boost the function of the immune system.
One large 12-week study found that a daily garlic supplement reduced the number of colds by 63% compared with placebo (4).
The average length of cold symptoms was also reduced by 70%, from 5 days in placebo to just 1.5 days in the garlic group.
Another study found that a high dose of garlic extract (2.56 grams per day) can reduce the number of days sick with cold or flu by 61% (5).
If you often get colds, then adding garlic to your diet could be incredibly helpful.
Bottom Line: Garlic supplementation helps to prevent and reduce the severity of common illnesses like the flu and common cold.
Cardiovascular diseases like heart attacks and strokes are the world's biggest killers.
High blood pressure, or hypertension, is one of the most important drivers of these diseases.
In one study, aged garlic extract at doses of 600-1,500 mg was just as effective as the drug Atenolol at reducing blood pressure over a 24 week period (9).
Supplement doses must be fairly high to have these desired effects. The amount of allicin needed is equivalent to about four cloves of garlic per day.
Bottom Line: High doses of garlic appear to improve blood pressure of those with known high blood pressure (hypertension). In some instances, supplementation can be as effective as regular medications.
Garlic can lower total and LDL cholesterol.
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.
Oxidative damage from free radicals contributes to the aging process.
Garlic contains antioxidants that support the body's protective mechanisms against oxidative damage (16) .
Bottom Line: Garlic contains antioxidants that protect against cell damage and ageing. It may reduce the risk of Alzheimer's disease and dementia.
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.
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.
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.
No human trials have measured the effects of garlic on bone loss.
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.
The last one is not a health benefit, but still important.
It is the fact that it is very easy (and delicious) to include garlic 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.
The minimum effective dose for therapeutic effects is one clove eaten with meals, two or three times a day.
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, then talk to your doctor before increasing your garlic consumption.
The active compound allicin only forms when garlic is crushed or cleaved when it is raw. If you cook it before crushing it, then it won't have the same health effects.
Therefore, the best way to consume garlic is raw, or to crush and cut it and leave it out for a while before you add it to your recipes.
My favorite way to use garlic is to press a few cloves of fresh garlic with a garlic press, then mix with extra virgin olive oil and a bit of salt. This a healthy and super satisfying dressing.