What Is Allicin?

Allicin is a compound that may help ease inflammation and block free radicals that harm cells and tissues in your body. The compound is one of the main active components of garlic and what gives it its distinct taste and scent.

Alliin is a chemical found in fresh garlic. An enzyme called alliinase is activated when the clove is chopped or crushed. This enzyme converts alliin into allicin.

Pure allicin only remains stable in freshly crushed or cut garlic for a short time. But letting garlic sit for 10 minutes after crushing or cutting it may help boost levels.

This article will discuss the possible health benefits of allicin, risks and side effects, and how to use it.

Health Benefits

Allicin may help guard against health issues like heart disease and cancer.

It may also protect against blood vessel damage by helping to lower your:

• Blood sugar 
• Blood pressure 
• Cholesterol

Some studies have also found that allicin may help your muscles recover faster after you work out. And the compound is thought to support immune health by warding off agents that cause illness, such as viruses and fungi.

Many studies have shown that the allicin in garlic may support health in various ways.

Support Blood Vessel Health

Studies have shown that the allicin in garlic supports blood vessel health.

It may help improve blood pressure (BP) control and keep the blood vessel disease known as atherosclerosis at bay.

A review of 39 randomized controlled trials (RCTs) found that regular use of compounds in garlic lowered people's cholesterol levels by about 8%.

It also helped lower the “bad fats” within your blood when taken for at least two months.

Tests showed that adults in the study had lower:

• Low-density lipoprotein (LDL)
• Total cholesterol

A more recent review of studies also supports these findings. The results of eight of nine reviews found a marked decrease in total cholesterol.

Lower Blood Pressure

Research suggests that allicin may help lower blood pressure and keep it within a healthy range. 

In adults with high blood pressure who took garlic supplements, the mean systolic blood pressure (SBP, the top number in a BP reading) was around six points lower compared to people who took a placebo (sugar pill). Their diastolic blood pressure (DBP, the bottom number) was almost nine points lower.

A double-blind randomized controlled trial published in 2021 backed up these results. Adults with nonalcoholic fatty liver disease (NAFLD) in the study received either a placebo or two tablets with 400 milligrams (mg) of garlic daily for 15 weeks.

Those who took the supplements had a nearly eight-point decrease in SBP and more than a five-point decrease in DBP at the end of the trial.

Protect Against Cancer

n 1990, the National Cancer Institute praised garlic for its ability to guard against cancer. Since then, multiple studies have shown that allicin and other active garlic compounds may shield against some cancers and keep cancer cells from spreading.

Research has explored its role against cancers of the:

• Breast
• Colon
• Liver
• Head and neck
• Ovaries
• Pancreas
• Prostate
• Skin

Possible Side Effects

Few side effects and health risks have been tied to allicin use. But be sure to talk with your doctor about how it may fit into your care plan before adding it to your regimen.

Discuss how the compound can impact your health or interact with any drugs and health aids you take such as:

• Drugs, both prescribed and over-the-counter (OTC)
• Dietary supplements
• Herbal remedies
• Essential oils

Allicin supplements have a few risks you should be aware of.

Digestive Issues

The compound may cause issues such as:

• Belching
• Gas
• Nausea
• Diarrhea
• Heartburn

Taking it with food may help limit or prevent these problems. 

Bleeding

Allicin may raise the risk of bleeding. That is because this and other garlic compounds help keep blood clots from forming. 

Be sure to talk with your doctor if you also take a blood thinner such as warfarin and other herbal and OTC aids that can thin your blood such as:

• Aspirin
• Gingko biloba
• Vitamin E

If you are due to have surgery or another procedure, your doctor may recommend that you avoid garlic and products with its compounds for some time beforehand.

Drug Interactions and Precautions

If you have blood pressure or blood sugar issues and take medicines to manage these, be sure to talk with your doctor before you try allicin. Using allicin at the same time may cause your blood pressure or blood sugar to drop too low.

It is not known whether it is safe to take the compound for:

• Pregnant women
• Nursing mothers
• Children

Dosage and Preparation

Allicin products are sold in pill or tablet form and may have garlic or allicin on the label. They may also come in powder, oil, or extract form.

There is no standard dose for the compound. The dose can vary based on your health needs and the specific product. In general, it's best to follow the instructions on the label.

A single garlic clove has about 5 mg to 18 mg of allicin. The doses most often used in studies range between 300 mg and 1,500 mg.

Higher daily doses are often divided into multiple doses taken throughout the day. Breaking up doses may also help limit some of the digestive side effects.

Be sure to talk with your doctor about the dose that’s right for you.

What to Look For

Stomach acids can dissolve tablets and garlic enzymes before they have the chance to work.

A 2018 review of garlic and allicin supplements found that tablets with enteric coating were not more bioavailable (able to be used and absorbed by the body) than those without it.

The study also found that allicin derived from garlic powder supplements was as bioavailable as those from equivalent amounts of crushed raw garlic when taken with a meal.

Supplements aren't regulated by the Food and Drug Administration, so their quality and potency can vary.

Be sure the product has been certified by one or more of these agencies:

• Consumer Labs
• U.S. Pharmacopeia Convention
• NSF International

Summary

Allicin is one of the main active compounds derived from garlic. It may help prevent certain cancers and may help lower blood sugar, cholesterol, and blood pressure. It may help your muscles recover after a workout and protect against infections.

Allicin supplements have few risks. It might cause some stomach upset and increase the risk of bleeding. Its safety isn't known for children or for pregnant or breastfeeding women.

If you're interested in trying allicin supplements, talk with your doctor or pharmacist first about whether they're safe and likely to be beneficial for you.