Benefits of Garlic
“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.
Modern science has recently confirmed many of these beneficial health effects.
Here are 11 health benefits of garlic that are supported by human research.
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 (1).
Its use was well documented by many major civilizations, including the Egyptians, Babylonians, Greeks, Romans and Chinese (2).
Scientists now know that most of its health benefits are caused by sulfur compounds formed when a garlic clove is chopped, crushed or chewed.
Perhaps the most famous of those is known as allicin. However, allicin is an unstable compound that is only briefly present in fresh garlic after it’s been cut or crushed (3).
Other compounds that may play a role in garlic’s health benefits include diallyl disulfide and s-allyl cysteine (4).
The sulfur compounds from garlic enter the body from the digestive tract and travel all over the body, where it exerts its potent biological effects.
SUMMARY Garlic 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 bring some of the health benefits.
Calorie for calorie, garlic is incredibly nutritious.
One clove (3 grams) of raw garlic contains (5):
- 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
- Decent amounts of calcium, copper, potassium, phosphorus, iron and vitamin B1
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. In fact, it contains a little bit of almost everything you need.
SUMMARY Garlic 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.
One large, 12-week study found that a daily garlic supplement reduced the number of colds by 63% compared to a placebo (6).
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% (7).
However, one review concluded that the evidence is insufficient and more research is needed (8).
Despite the lack of strong evidence, adding garlic to your diet may be worth trying if you often get colds.
SUMMARY Garlic supplements help 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, 600–1,500 mg of aged garlic extract was just as effective as the drug Atenolol at reducing blood pressure over a 24-week period (12).
Supplement doses must be fairly high to have the desired effects. The amount needed is equivalent to about four cloves of garlic per day.
SUMMARY High 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 cholesterol.
SUMMARY Garlic supplements seem to reduce total and LDL cholesterol, particularly in those who have high cholesterol. HDL cholesterol and triglycerides do not seem to be affected.
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 (19).
SUMMARY Garlic contains antioxidants that 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 disease is also an important factor, because these are common causes of death, especially in the elderly or people with dysfunctional immune systems.
SUMMARY Garlic 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 enhance the work capacity of laborers.
Most notably, it was given to Olympic athletes in ancient Greece (1).
Rodent studies have shown that garlic helps with exercise performance, but very few human studies have been done.
People with heart disease who took garlic oil for 6 weeks had a 12% reduction in peak heart rate and better exercise capacity (23).
However, a study on nine competitive cyclists found no performance benefits (24).
Other studies suggest that exercise-induced fatigue may be reduced with garlic (2).
SUMMARY Garlic may 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 (25).
Three doses of garlic each day even outperformed the drug D-penicillamine in reducing symptoms.
SUMMARY Garlic 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.
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 (31).
SUMMARY 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 is still important.
Garlic is very easy (and delicious) 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.
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 to your doctor before increasing your garlic intake.
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 a healthy and super satisfying dressing.
SUMMARY Garlic is delicious and easy to add to your diet. You can use it in savory dishes, soups, sauces, dressings and more.
For thousands of years, garlic was believed to have medicinal properties.
Science has now confirmed it.
Black garlic is raw garlic that people have fermented under controlled high-temperature, high-humidity conditions for several weeks (1).
In addition to having black cloves, black garlic has a milder flavor and a more delicate, sticky consistency than raw garlic (1).
Black garlic also offers a number of health benefits that may outweigh those of raw garlic, which hasn’t been aged.
This article reviews 6 of the potential health benefits black garlic may offer.
- 1. Contains more antioxidants
The fermentation process causes black garlic to contain substantially more antioxidants than raw garlic (2).
One 2014 study found that the total antioxidant activity increased significantly in black garlic during aging. In the study, garlic reached its peak antioxidant content at 21 days of fermentation (5).
As a result of the fermentation process, black garlic contains more antioxidant compounds than raw garlic. Antioxidants have protective effects against cell damage and disease.
- 2. May help regulate blood sugar
In a 2019 study in rats fed a diet high in fat and sugar, treatment with an extract of black garlic resulted in metabolic improvements such as lowered cholesterol, decreased inflammation and appetite regulation (8).
An older 2009 study in rats with diabetes found that the antioxidant activity of black garlic could help protect against complications that often result from high blood sugar (9).
In another animal study from 2019, researchers fed rats a diet high in fat. Rats that consumed black garlic experienced significantly lower levels of glucose and insulin in their blood compared with those that didn’t consume it (10).
The antioxidant activity of black garlic fermented using the bacteria Lactobacillus bulgaricusmay even help prevent the development of gestational diabetes, according to one study including 226 women at risk of the condition (11).
It’s important to note that some of these results were from animal studies and that scientists need to do more studies of the effects of black garlic on diabetes and blood sugar levels in humans.
Studies have shown black garlic may help regulate blood sugar, reduce the risk of gestational diabetes, and even prevent damage from uncontrolled diabetes. Scientists need to do more research on these effects in humans, however.
- 3. May reduce the risk of heart disease
Studies have shown that black garlic may reduce indicators of heart disease, including levels in the blood of total cholesterol, LDL (bad) cholesterol, and triglycerides. It may also increase HDL (good) cholesterol (12).
One animal study compared the effects of raw and black garlic in rats recovering from heart damage due to ischemia — lack of blood flow to the heart.
Researchers found that both raw and black garlic helped open up circulation to protect the heart from damage (13).
Another animal study found that black garlic extract helped reduce total blood fats, triglycerides, and total cholesterol in rats fed a diet high in fat. Elevated levels of these usually indicate an increased risk of heart disease (14).
In a different animal study, black garlic lowered high triglycerides and cholesterol levels, reducing the risk of heart disease (15).
A different study gave 60 people with elevated cholesterol 6 grams of either aged black garlic extract or a placebo daily for 12 weeks. Black garlic increased HDL (good) cholesterol and reduced potential heart disease markers (16).
One study gave participants with coronary heart disease 20 grams of black garlic extract daily for 6 months. Those who consumed it experienced increased antioxidant levels and improved indicators of heart health compared with those who took a placebo (17).
However, more robust studies including humans are needed in this area.
Black garlic may help reduce certain markers of heart disease, like triglycerides and LDL (bad) cholesterol. It may also increase HDL (good) cholesterol for some people
- 4. Compounds in black garlic may protect brain health
Black garlic may help prevent inflammation that can impair memory and worsen brain function over time.
One rat study found that black garlic could reduce brain inflammation caused by beta amyloid and even improve short term memory (19).
In another study, researchers induced oxidative stress in the brains of rats. Giving the rats black garlic extract prevented this oxidative stress from causing memory impairment (20).
Black garlic may contain compounds that help protect the brain from memory loss and degenerative diseases, like Alzheimer’s. However, scientists need to do more research on these potential effects in humans.
- 5. May have anticancer properties
Several studies indicate a positive effect of black garlic in fighting cancer cells.
In a test tube study in the blood of 21 volunteers, black garlic extract showed stronger immune-stimulating, antioxidant, and anticancer activities than raw garlic extract (21).
In fact, the researchers found that the black garlic extract solution was toxic to lung, breast, stomach, and liver cancer cells within 72 hours (21).
Other test tube studies have found that black garlic caused cancer cells to start dying off in human colon and stomach cancers, as well as leukemia. It also reduced the growth of these cancer cells (22, 23, 24).
In one review of 25 studies, researchers found that aged garlic showed probable beneficial effects against cancer in most of the human, animal, and test tube studies the review examined (25).
This research is preliminary, and scientists need to do more research on the potential cancer fighting properties of black garlic.
Black garlic has shown stronger immune boosting, antioxidant, and anticancer activities than raw garlic in a number of cancer-related studies.
- 6. Black garlic may help protect your liver
Black garlic may help protect the liver from damage that can come from its constant exposure to chemicals, medications, alcohol, and germs.
Rat studies have found that black garlic exerts protective effects in the event of a liver injury, preventing further liver damage (26).
Black garlic may also be helpful in more chronic conditions. For instance, one animal study found that black garlic improved liver function in the case of chronic alcohol-induced liver damage, likely through its antioxidant activity (27).
Another study in rats with liver damage found that aged black garlic decreased ALT and AST, two chemicals in the blood that indicate liver damage (1).
Black garlic may have a preventive effect on the liver, protecting it from damage that can result from injury, everyday chemical exposure, or even chronic alcohol use.Potential downsides
Neither raw nor black garlic appear to come with major side effects. However, raw garlic has a couple of downsides that black garlic may share.
Eating raw garlic in large amounts may increase the risk of bleeding. Because of this, people on blood thinning medications may also want to avoid black garlic in large amounts (28).
That said, one study examined the effects of aged garlic extract on blood clotting among people taking blood thinning medication and found it posed no serious risk (29).
Still, it’s best to speak with a healthcare professional to determine whether black garlic is safe and appropriate for you.
Additionally, people who experience an allergic reaction after consuming raw garlic should also avoid black garlic (30).
Avoid black garlic if you have an allergy to raw garlic. You may also want to avoid it in large amounts if you take blood thinning medications. If you are concerned about taking black garlic, speak with your healthcare provider.How to add it to your diet
While you may be more familiar with raw garlic, black garlic can be a delicious addition to your diet.
Its sweet flavor and gelatinous consistency work well with a few dishes.
Here are some of the ways you can use black garlic:
- Add it with soy sauce to make a flavorful stir fry.
- Use it to season soups.
- Mash it into cheese dip or cream cheese.
- Blend it with mayo or hummus.
- Thinly slice cloves and add them to salads or pasta dishes.
- Use them as a topper for pizza.
- Blend them with olive oil to make a simple salad dressing.
You may also find that you enjoy eating black garlic on its own since it’s milder than raw garlic.
Black garlic has a milder, sweeter flavor compared to that of raw garlic. You can add it to pastas, soups, or stir fries; blend it into oils; or mix it into dips and sauces.Bottom line:
Black garlic is raw garlic that has been fermented under controlled conditions for several weeks. This changes its color and flavor.
This process also significantly increases the antioxidant activities of the garlic. In fact, antioxidants in black garlic are likely the reason for its potential benefits for the heart, liver, blood sugar, and brain, as well as its potential anticancer properties.
Black garlic doesn’t appear to have major side effects, but you should avoid it in large amounts if you take blood-thinning medications or have a garlic allergy.Pros and Cons Eating Raw Garlic
Garlic is a popular ingredient enjoyed for both its unique flavor and powerful health benefits.
However, garlic is usually sautéed, roasted, or baked before being added to recipes.
For this reason, many people are unsure whether raw garlic is safe to consume.
This article takes a closer look at whether you can eat raw garlic, along with the potential benefits and downsides of doing so.Can you eat raw garlic?
In most recipes, garlic is typically cooked or used in powdered form.
Cooking garlic alters its taste and texture, making it softer, milder, and creamier and giving it a more subtle flavor and aroma.
However, it can also be enjoyed raw rather than cooked.
Although raw garlic tends to have a stronger, more pungent flavor, it can be consumed safely and makes a great addition to many dishes.
In fact, raw garlic is often added to dips, dressings, and sauces like aioli or pesto.
What’s more, raw garlic may even retain more beneficial compounds than cooked garlic and improve several aspects of your health.
Although raw garlic has a stronger, more pungent flavor than cooked garlic, it’s safe to consume and can be added to various recipes.Health benefits of raw garlic
Garlic is a great source of allicin, a sulfur-containing compound associated with many health benefits (1).
Allicin, which is responsible for the distinct taste and smell of garlic, is produced when fresh garlic is crushed or chopped (1).
Therefore, while consuming cooked garlic can be beneficial, opting for raw garlic instead may help maximize its nutritional value.
Here are a few of the potential health benefits of raw garlic:
- Improves immunity. Several studies show that garlic may help decrease inflammation and boost immune function, which may be due to its content of antioxidants and sulfur-containing compounds like allicin (4, 5).
- Supports heart health. Some research suggests that garlic may help lower blood pressure and decrease cholesterol levels to support heart health (6).
- Stabilizes blood sugar levels. Garlic may help reduce fasting blood sugar levels and improve blood sugar management, which may be beneficial for managing type 2 diabetes (7, 8).
- Protects brain health. Although research in humans is limited, animal studies show that consuming high amounts of fresh garlic or aged garlic extract could improve memory and support brain health (9, 10, 11).
Raw garlic retains higher amounts of allicin, a beneficial sulfur-containing compound. Garlic has been shown to improve immunity, stabilize blood sugar levels, and support heart and brain health.Potential downsides of eating raw garlic
Although raw garlic may be associated with several health benefits, there are a few potential drawbacks to consider.
First, raw garlic has a much stronger taste and smell than cooked garlic, which some people may find unappetizing.
Additionally, those with gastroesophageal reflux disease (GERD) are often advised to limit their consumption of garlic to prevent heartburn.
Garlic may also increase the risk of bleeding by preventing the formation of blood clots.
While enjoying raw garlic in moderation is unlikely to cause any issues for most healthy adults, people taking blood thinners should check with their doctor before consuming large amounts of garlic or using garlic supplements (13).
Garlic could trigger heartburn and irritate the digestive tract. It may also increase the risk of bleeding, especially if consumed in large amounts or used in supplement form.How much should you eat?
In supplement form, doses of up to 3,600 mg of aged garlic extract have also been shown to be effective (13).
Be sure to talk to your doctor before using garlic supplements, especially if you have any underlying health conditions or are taking medications.
Consider reducing your intake or discontinuing consumption if you notice any negative side effects after eating raw garlic.
Eating 1–2 cloves of raw garlic per day may be beneficial. In supplement form, doses of up to 3,600 mg of aged garlic extract per day have been shown to be effective.Bottom line:
Although raw garlic has a stronger flavor and more pungent smell than cooked garlic, it’s safe to consume.
Raw garlic also retains more allicin, which is the sulfur-containing compound responsible for many of garlic’s beneficial health effects.
For best results, aim for around 1–2 cloves per day and reduce your intake if you experience any side effects, such as heartburn, acid reflux, or increased bleeding.How Garlic Fights Colds and Flu
Garlic has been used for centuries as both a food ingredient and a medicine.
In fact, eating garlic can provide a wide variety of health benefits (1).
This article explains how garlic is particularly protective against the common cold and the flu.Garlic Can Boost Immune Function
Whole garlic contains a compound called alliin. When garlic is crushed or chewed, this compound turns into allicin (with a c), the main active ingredient in garlic (7).
Allicin contains sulfur, which gives garlic its distinctive smell and taste (8).
However, allicin is unstable, so it quickly converts to other sulphur-containing compounds thought to give garlic its medicinal properties (5).
These compounds have been shown to boost the disease-fighting response of some types of white blood cells in the body when they encounter viruses, such as the viruses that cause the common cold or flu (5, 9).Bottom line:
Garlic can be crushed, chewed or sliced to produce allicin, which is thought to give garlic its immune-boosting properties.Can Garlic Help Prevent Colds and The Flu?
Garlic has shown promise as a treatment for preventing colds and the flu.
One study gave 146 healthy volunteers either garlic supplements or a placebo for three months. The garlic group had a 63% lower risk of getting a cold, and their colds were also 70% shorter (11).
Another study found that colds were on average 61% shorter for subjects who ate 2.56 grams of aged garlic extract per day, compared to a placebo group. Their colds were also less severe (9).
If you often get sick with a cold or flu, eating garlic can help reduce your symptoms or prevent your illness entirely.
However, a review of the evidence found that many of the studies investigating the effects of garlic on the common cold were of poor quality (12).
It’s also unknown if you need to take garlic constantly, or if it also works as a short-term treatment when you start getting sick.Bottom Line:
Regularly eating garlic may help prevent the common cold or the flu. If you do get sick, eating garlic can reduce the severity of your symptoms and help you recover faster.How to Maximize the Benefits of Garlic
The way garlic is processed or prepared can really change its health benefits.
The enzyme alliinase, which converts alliin into the beneficial allicin, only works under certain conditions. It can also be deactivated by heat.
However, it was noted that crushing garlic and allowing it to stand for 10 minutes before cooking can help prevent the loss of its medicinal properties.
The researchers also stated that the loss of health benefits due to cooking could be compensated for by increasing the amount of garlic used.
Here are a few ways to maximize the health benefits of garlic:
- Crush or slice all your garlic before you eat it. This increases the allicin content.
- Before you cook with your crushed garlic, let it stand for 10 minutes.
- Use a lot of garlic — more than one clove per meal, if you can.
Ensure whole garlic is crushed, chewed or sliced before it’s eaten. Let crushed garlic stand for 10 minutes before you cook it.Garlic Supplements
Another easy way to increase your garlic intake is by taking a supplement.
However, be cautious, as there are no regulated standards for garlic supplements.
That means the allicin content and quality can vary, and so can the health benefits.Powdered Garlic
Powdered garlic is made from fresh garlic that has been sliced and dried. It does not contain allicin, but is said to have allicin potential.
Powdered garlic is processed at low temperatures, and then put inside capsules to protect it from stomach acid.
This helps the enzyme alliinase survive the harsh environment of the stomach so that it can convert alliin to the beneficial allicin in the intestine.
When raw garlic has been sliced and stored in 15–20% ethanol for over 1.5 years, it becomes aged garlic extract.
This type of supplement does not contain allicin, but it does retain the medical properties of garlic. Many of the studies showing benefits against colds and the flu used aged garlic extract (2, 9, 17).Garlic Oil
Garlic oil is also an effective supplement and is made by infusing raw garlic into cooking oils. You can add it directly to your meals or take it in capsules.
However, it’s worth noting that animal studies have shown that garlic oil can be toxic to rats at higher doses and in certain conditions (18).
Common types of garlic supplements include powdered garlic, aged garlic extract and garlic oil. Aged garlic extract may be the best type.How Much Garlic Should You Eat Per Day?
The minimum effective dose for raw garlic is one segment (clove) eaten two to three times per day.
You can also take an aged garlic supplement. In that case, a normal dose is 600 to 1,200 mg per day.
High intakes of garlic supplements can be toxic, so don’t exceed the dosage recommendations.Bottom Line:
You can get a benefit from garlic by eating 2-3 garlic cloves per day. Supplement doses range from 600 to 1,200 mg per day.Other Tips to Boost Immune Function
Here are 5 more ways to boost immune function and help you avoid colds and the flu:
- Take a probiotic: Probiotics can promote a healthy gut, enhance your immune system and reduce your risk of infection (22, 23, 24, 25).
- Eat a healthy, balanced diet:Your whole diet is important. Getting a balance of important nutrients will make sure your immune system stays in good shape.
- Don’t smoke:Cigarette smoke can weaken your immune system and make you more prone to infection (26, 27, 28).
- Avoid excess alcohol:Excess alcohol is thought to damage your immune system and make you more susceptible to infections (29, 30, 31).
- Take a zinc supplement:Take zinc lozenges or syrup within 24 hours of the start of a cold, as this may reduce the duration of the cold (32).
A healthy diet and lifestyle are essential for keeping your immune system in good shape.Take Home Message
Studies show that garlic can help fight colds and the flu. It can reduce your chances of catching an illness, and help you recover faster.
To maximize these benefits, it is best to consume raw garlic or aged garlic extract.
At the end of the day, garlic is both tasty and super healthy. Then there are many other great reasons to include it in your diet.Reference:
Written by Joe Leech, MS on June 28, 2018
Written by Helen West, RD— Updated on March 17, 201
Photo Credit: Michael Pierce