In this article:
- Garlic contains allicin, an active ingredient that produces sulfur and imparts taste.
- Garlic bulbs contain vitamins and minerals such as vitamins B6, C, E, phosphorus, manganese, and calcium.
- Garlic may help lower the risk of cardiovascular disease by positively affecting blood pressure and cholesterol levels.
- Garlic should be stored in a dark and cool place with proper ventilation to prevent sprouting or mold.
- In some cases, garlic consumption may result in heartburn or an upset stomach.
Garlic, or Allium sativum, belongs to the onion genus and has been used medicinally since ancient times.
It originated in Asia but is a staple ingredient also in the Mediterranean region. It is thought that garlic was given to slaves in ancient Egypt to help increase their productivity for building pyramids. Garlic was also prescribed in the Codex Ebers for helping cure various ailments and improving circulation as well. (1)
Garlic has nutritional benefits similar to those of onions and leek. The root bulb of garlic is made of multiple cloves or bulblets of garlic and has a strong flavor and odor. This odor is imparted by sulfur compounds made from allicin, an active ingredient of garlic.
When the garlic is cut, chewed, or crushed, it releases an enzyme known as alliinase, which interacts with alliin to produce allicin. (2)
Therefore, the presence of alliin and alliinase is vital for the functions of garlic. Dried garlic preparations are often enteric-coated to prevent the degradation of the enzyme by stomach acid. Alliinase can also be deactivated by heat, due to which, cooked garlic is less potent.
Besides alliin, garlic also contains various other sulfur-containing active compounds, collectively known as thiosulfinates. These thiosulfinate compounds also provide health benefits.
Garlic bulbs can be used in many forms for cooking or medicinal purposes – dehydrated, fresh, and steam-distilled oil.
Types of Garlic
Garlic generally has two types: (28)
- Hardneck: The central stalks of this type of garlic are hard and woody, extending to the basal plate situated at the bottom of the bulb. This is considered closer to wild garlic.
- Softneck: This type of garlic has a non-woody pseudostem, which is made of overlapping leaf sheaths. This type gives rise to a flower stalk only under stressful environmental conditions. Softneck garlic is what is mostly available in grocery stores.
Other types of garlic include:
- Creole garlic: The garlic bulb is rosy or purplish, distinguishable from the intermittent rosy hues of the hardneck varieties. This type of garlic is uncommon and, therefore, not likely to be found in grocery stores.
- Black garlic: It is created with the help of high humidity, heat treatment, and especially prolonged aging. As the aging progresses up to several weeks and longer, the cloves of the garlic turn black. This variety of garlic is commonly popular in Japan, Korea, and Thailand.
- Elephant garlic: This variety of garlic, known as Allium ampeloprasum is related closer to leeks than to garlic itself. This garlic produces very large cloves.
Nutritional Value of Garlic
The sulfur compounds present in garlic account for its main health benefits. These include sulfoxides, thiosulfinates, diallyl sulfides and polysulfides, ajoenes, vinyldithiines, certain amino acids, and proteins.
Additionally, garlic contains vitamin B6, manganese, copper, vitamin C, calcium, phosphorus, zinc, folate, and selenium. (3)
Health Benefits of Garlic
Garlic can be considered a highly nutritious food with antioxidant and antimicrobial properties. It has been used since ancient times for the treatment and prevention of various ailments. These are some of the benefits of garlic.
1. May help in lowering cardiovascular disease risk
Multiple studies demonstrate a positive effect of garlic on the prevention of cardiovascular problems. (4) This is chiefly supplemented by garlic’s properties that help:
- Lower cholesterol levels
- Manage blood pressure
Garlic may be effectively used as an adjunct treatment for lowering lipid levels. (4)
A 2018 review study concluded that garlic possesses antihyperlipidemic properties as it helps reduce low-density lipoprotein cholesterol and total cholesterol levels in the body. However, it has little to no effect on the high-density cholesterol and triglycerides levels. (5)
A 2013 study demonstrated the efficacy of aged garlic extract in treating uncontrolled hypertension. Garlic could be considered as a tolerable and safe adjunct to conventional antihypertensive treatments. (6)
A random clinical trial conducted in 2016 demonstrated that the use of garlic and lemon juice for patients with hyperlipidemia helped improve their blood pressure, fibrinogen, and lipid levels. (7)(8)
Additionally, a review study analyzed garlic supplements in cardiovascular protection based on surrogate markers of atherosclerosis and reduction of risk factors such as total cholesterol and hypertension.
Although more large-scale studies are required for establishing their overall potential for cardioprotection, garlic supplements were found to be effective in managing blood pressure and cholesterol levels in additional studies. The supplements were found to be safe and tolerable and maybe potential complementary treatments. (9)(10)(11)(12)(13)
Note: Multiple studies suggest garlic may provide cardio health benefits, especially as a lipid-lowering and antihypertensive agent. However, it may be best suited as an adjunct therapy, and more studies are needed to establish its safety and correct dosage.
Other foods that are good for your cardiovascular health:
2. May aid in blood sugar regulation
The role of dietary factors in the prevention of metabolic disorders such as diabetes is well established. Garlic is one such food that may help and is now gaining popularity due to its prevalent over-the-counter use.
A review study conducted in 2019 concluded that garlic usage could help reduce glucose and lipid profile levels. Therefore, it could therapeutically be effective for patients with diabetes and cardiovascular disease. (14)
A 2011 study demonstrated that the use of garlic as an adjunct to standard antidiabetic treatment helped improve the glycemic control and antihyperlipidemic activity of the study participants. Hence, garlic could be utilized for the management of diabetes and hyperlipidemia. (15)(16)
Note: Many studies support the antihyperglycemic activity of garlic, but more large-scale human trials are needed to conclude its efficacy, safety, and usage.
3. May provide relief from colds and flu
Garlic has been shown to have antiviral and antimicrobial properties that may help alleviate the common cold. However, there is a lack of clinical trials that support the usage of garlic for curing and preventing the common cold.
A single trial suggested the use of garlic for lowering the chances of having a common cold. However, evidence on this claim is poor, and further research on its efficacy is warranted. (17)
In another study, supplementing the diet with aged garlic extracts was shown to enhance immune cell function. This, in turn, can help reduce the duration of the flu and colds, but more research is needed. (18)
- Everything You Need to Know About the Flu and How to Prevent It
- 7 Natural Expectorants to Relieve a Cough
Other Possible Health Benefits of Garlic
Garlic may also exhibit the following health benefits.
1. May protect against microbial infections
The antiviral, antibacterial, and antifungal properties of garlic have been extensively researched. However, most of these studies involve the use of garlic supplements, rather than its food form, and there is a lack of human trials.
It has been seen that fresh garlic extracts can help inhibit infectious pathogens. It can also improve the effectiveness of antibiotics against resistant strains. Therefore, this herb may aid in the treatment of infections caused by multidrug-resistant strains. (19)(20)
Note: More human-based studies are required before concluding its efficacy.
2. May improve bone health
Garlic is known to have antioxidant properties that help reduce oxidative stress.
As oxidative stress plays a significant role in the development of osteoporosis, the use of garlic tablets for its phytoestrogens and antioxidative effects can help lower oxidative stress indices in menopausal women with osteoporosis. (21)
Note: More studies are needed to support this claim.
3. May lower the risk of cancer
Cancer is a chief contributor to mortality, morbidity, and healthcare rates worldwide. Studies report the role of dietary supplements such as aged garlic in exhibiting anticancer effects. (22)
Allium vegetables and their components are found to affect all stages of carcinogenesis. Additionally, they influence multiple biological processes that can alter the risk of developing cancer. (23)
Note: Further studies are needed to obtain clearer evidence on the anticancer activity of garlic.
4. May prevent cognitive decline
Aged garlic extract may be a potential agent for the prevention of cognitive and learning memory deficits.
Note: It is vital to conduct further direct human studies to establish the relationship between cognitive decline and intake of aged garlic extract.
How is Garlic Used?
Garlic can be used in multiple forms, including:
Raw garlic cloves can be used for making oils and liquid extracts, and powdered forms can be made into tablets and capsules.
Selecting and Storing Garlic
Fresh garlic has a high concentration of active ingredients. Select bulbs that are plump looking and have tight skin. Avoid picking garlic with loose or frayed skin.
It should not be moldy, dried out, or sprouting. Do not pick bulbs that are visibly damaged and have soft or discolored patches or bruising.
For the storage of garlic, select a cool and dark place with proper ventilation to prevent sprouting and molding. You may either store them as whole bulbs or peel the individual cloves and keep them in an airtight container inside the refrigerator.
Properly stored, good-quality garlic can last for months.
How to Increase the Shelf-Life of Garlic
To store garlic for a long time, the bulbs must be properly selected. It is vital to avoid soft bulbs, as they can affect the whole batch.
After selecting the good-quality bulbs, cure the garlic under the sun for a few hours. This helps in drying the garlic, enabling long-term storage.
Re-examine the bulbs and remove the ones that are soft, damaged, or have sprouted.
Store the cloves in the crisper drawer in the refrigerator to avoid humidity. This keeps the garlic fresh for a few weeks, after which it may begin sprouting. Whole garlic bulbs should be stored at room temperature.
When kept outside, the garlic can sprout within a few days and, therefore, should be used quickly. However, sprouted garlic can be planted in a pot and allowed to grow.
Alternatively, you may deep-freeze the garlic cloves, although people frequently complain of the altered taste of frozen garlic.
You may also roast a batch of garlic without peeling the cloves. After roasting, cut the tips of the bulb and squeeze out the softer flesh. Store roasted garlic in an airtight container for up to a week in the fridge or for several months in the freezer.
Roasted garlic can be used to substitute fresh garlic in all recipes, although it has a mellow taste. Freshly roasted garlic may also be used as a topping for pizza or for spreading alongside butter.
Safety of Garlic
When ingested as a food or flavoring, garlic is generally safe for most adults. However, in some cases, garlic consumption may cause heartburn, allergic reactions, upset stomach, and odor, especially with raw garlic.
Pastes, mouthwash, and gels containing garlic can be used for up to 3 months safely. However, applying raw garlic to the skin can severely irritate and burn the skin.
While garlic is likely to be safe when taken in food amounts by pregnant women, its medicinal use can be harmful.
There is also a lack of information on the safety of its topical use in pregnant and breastfeeding women. Therefore, it is best to avoid its usage as a precautionary measure.
For children, the use of garlic as medicine for a short period is possibly safe. However, it is recommended to avoid feeding children large doses of garlic as it may be dangerous or fatal.
Before taking any supplement, including garlic, you should first consult your healthcare team, especially if you are taking medications.
Garlic is known to inhibit the action of some medications such as saquinavir, which is used for treating HIV. The effect of garlic on other drugs has not been well studied.
Garlic can act as a blood thinner similar to aspirin. It reduces the blood’s ability to clot and increases the chances of bleeding. Therefore, it should not be used when you are taking an anticoagulant such as warfarin.
Additionally, inform your healthcare provider of any garlic supplements you are taking well before any surgery or dental work. It is recommended to avoid garlic consumption at least 1 week before surgery.
Moreover, refrain from using garlic if you have a bleeding disorder.
Note: It is vital to inform your doctor about any integrative or complementary health practices you follow. This ensures safe care practice and coordination.
Can garlic be taken on an empty stomach?
It is believed that consuming garlic on an empty stomach helps in reaping its maximum benefits. However, it should be taken in moderation.
Eating large amounts of garlic, especially on an empty stomach, can cause flatulence, gastrointestinal problems, and an imbalance of the gut microflora.
Does garlic aid weight loss?
A few in vitro and animal studies support the use of garlic for weight loss. (26) However, dietary garlic is not sufficient, and an excess of garlic consumption may be harmful.
While the use of garlic oil for its anti-obesity effects has been tested in animal studies, there is a need for further studies to reach any conclusion. (27)
What are garlic leaves used for?
The flowers and leaves of garlic, found on the head, are occasionally used for consumption. They have a milder flavor in comparison to the bulbs and are often eaten while they are still tender and immature.
Garlic in Cooking
Garlic has been used as a flavoring agent for centuries. It has a strong flavor and also imparts a pungent odor to the food and also to the consumer. Hence, cooked garlic is recommended, as consuming raw garlic can leave a strong odor.
Garlic is often used for flavoring soups, salad dressings, stews, and spreads. While the cloves are popularly used, garlic leaves may also be added to various dishes.
Oriental cooking generally uses flowering scapes. You may also find garlic in the form of pickles or as a flavoring in salt and oil. Dehydrated forms are also available commercially.
Garlic Recipes to Try
You may try the following recipes that use garlic to create a tasty meal.
1. Parmesan and Garlic Potato Wedges
- 4 russet potatoes
- 1 tbsp vinegar (white or apple cider)
- 4 cups of water
- 1 tbsp salt
- ¼ cup butter
- 4 oz. parmesan cheese, shredded
- 4 garlic cloves, peeled and minced
- ¼ cup fresh parsley, chopped
- 1 tbsp lemon zest
- Chop the potatoes into large wedges and add them to a pot.
- Add vinegar, water, and one tbsp of salt to the pot.
- Boil the potatoes and allow them to simmer for 10 minutes.
- Drain the water and pat the potato wedges dry.
- Preheat the oven to 400°F.
- Place butter in tbsp sized pieces on the baking sheet.
- Put the baking sheet in the preheated oven to melt the butter.
- Sprinkle parmesan over the baking sheet in an even, thin layer.
- Add a layer of minced garlic.
- Place the potatoes over the garlic and cheese and bake for 45 minutes.
- Take parsley, lemon zest, pepper, and salt in a small bowl and mix.
- Put the wedges on a plate and sprinkle the spice mix on top.
2. Garlic Bread
- 3 heads garlic
- 2 tbsp olive oil
- 1 pound Italian bread loaf
- ½ cup butter
- 1 tbsp fresh parsley, chopped (optional)
- 2 tbsp parmesan cheese, grated (optional)
- Preheat the oven to 350°F.
- Cut the tops of the garlic heads to expose the tips of each clove.
- Place the garlic on a baking sheet.
- Drizzle olive oil on the garlic and bake for around 30 minutes, to soften the cloves.
- Squeeze out the cloves in a bowl.
- Add the butter, parsley, and parmesan cheese to the garlic and mix well.
- Set the oven to broil.
- Slice the bread horizontally and place the slices on the baking sheet, cut-side up.
- Spread the garlic mix on the exposed bread sides.
- Toast the bread for around 5 minutes.
Garlic is an excellent flavoring agent and is used in many dishes around the world.
There is significant evidence to consider garlic as a potential primary or adjuvant therapeutic agent in treating various disorders. However, these studies pose problems such as small sample size, methodological inadequacies, and lack of dosage determination. Thus, more standardized studies are required to establish the benefits of garlic. (28)
Before consuming garlic medicinally, it is best to get individualized guidance from your healthcare team.