Garlic contains compounds like allicin that may help fight colds and the flu by boosting the immune system.
Garlic has been used for centuries as food and as a natural treatment remedy.
In fact, eating garlic may provide a wide variety of health benefits, such as reducing the risk of heart disease, improving cognitive health, enhancing immune function, and decreasing the risk of certain types of cancer.
Keep reading to learn more about how garlic may be particularly protective against the common cold and the flu.
Garlic contains compounds that could help boost the immune system to fight germs that can cause the common cold and the flu.
In particular, whole garlic contains a compound called alliin. When garlic is crushed, minced, chopped, or chewed, alliin turns into allicin (with a “c”), which accounts for up to 80% of garlic’s bioactive compounds.
Allicin contains sulfur, which gives garlic its distinctive smell and taste. But, allicin is unstable, so it quickly converts to other sulfur-containing compounds thought to give garlic its medicinal properties.
These compounds can 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.
Garlic has shown promise as a treatment for preventing viral infections that can cause the common cold and the flu.
Studies have shown that garlic may reduce the risk of becoming sick and how long you stay sick. It may also reduce the severity of symptoms.
For instance, a 2021 review found that garlic was as effective as several types of vaccines at preventing or reducing the severity of influenza. Garlic reduced the risk of contracting the flu by around two-thirds compared to a placebo.
It may help protect against several types of viruses, including:
- influenza B
- HIV (type 1)
- herpes simplex virus (HSV-1 and HSV-2)
- vesicular stomatitis virus
- coxsackievirus
- gammaretrovirus
Despite these findings, it’s important to note that garlic should not be used as a replacement for vaccinations in the prevention of the flu. There are no guidelines about how much garlic and how often you need to consume it to experience any possible benefits.
The way garlic is processed or prepared can change its health benefits.
The enzyme alliinase, which converts alliin into the beneficial allicin, only works under certain conditions. It may also be deactivated by heat.
For instance, a
However, the researchers noted that crushing garlic and allowing it to stand for 10 minutes before cooking can help prevent the loss of its medicinal properties. Increasing the amount of garlic used may also compensate for the loss of health benefits caused by cooking.
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.
Another way to increase your garlic intake is by taking a garlic supplement.
But it’s important to note that garlic supplements are not regulated by the Food and Drug Administration (FDA), so the allicin content and quality can vary, and so can the potential health benefits.
Powdered garlic
Powdered garlic is made from fresh garlic that has been sliced and dried. It doesn’t 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.
It’s unclear how much allicin can be derived from powdered garlic supplements. This varies greatly depending on the brand and preparation.
Aged garlic extract
When raw garlic has been sliced and stored in 15% to 20% ethanol for over 1.5 years, it becomes an aged garlic extract.
This type of supplement doesn’t contain allicin, but it retains the medical properties of garlic. Many of the studies showing benefits against colds and the flu used aged garlic extract.
Garlic oil
Garlic oil is also an effective supplement. It’s typically prepared using steam distillation and taken in capsules. This type of oil is distinct from garlic-flavored oil used for cooking, which is made by infusing raw garlic into cooking oils.
In 1989, homemade garlic oil was linked with several cases of botulism, a rare but severe infection caused by the toxin Clostridium botulinum. If you’re going to make your own, make sure to use proper preservation methods.
There’s no established effective dosage of raw garlic or garlic supplements.
A 2020 review investigating the possible health benefits of garlic extract for viral infections like the flu found a wide range of supplements and daily doses, including:
- Garlic extract capsule: 300 to 600 milligrams (mg) taken for 150 days, and 2.56 g for 90 days
- Garlic oil: 50 mg
- Garlic extract: 50 mg per kilogram (kg) of bodyweight per day, for 10 days
A 2017 study also found that
Before taking a garlic supplement, carefully read and follow the instructions on the packaging label to prevent any complications. If you’re unsure about garlic supplements, speak with a healthcare professional.
One of the
To help prevent the common cold and the flu, it’s important to:
- regularly wash your hands in warm water
- avoid sharing objects with someone who has a viral infection
- avoid touching your eyes and mouth
- stay regularly active and eat a balanced diet
Other ways to
- eating a balanced diet of vegetables, fruits, lean proteins, whole grains, dairy, and nuts
- quitting smoking, if you smoke
- limiting your alcohol consumption, if you drink
taking a probiotic to promote a healthy gut, enhance immune response, and reduce the risk of infection
A healthcare professional could provide further recommendations for boosting your immune system and preventing viral infections like the cold and flu.
Studies suggest that garlic may help fight colds and the flu. It may reduce your risk of developing an illness and help you recover faster.
To maximize these benefits, it’s best to consume raw garlic or aged garlic extract.
Garlic is both tasty and nutritious, and there are many excellent reasons to include it in your diet.