There’s nothing like a little garlic to punch up a stir-fry, roast chicken, or pasta dish, but for centuries it has been purported to add some oomph to your health, too.

Ancient civilizations used garlic to treat asthma, digestive disorders, heart disease, infections, respiratory disorders, tumors, and even intestinal worms. Today, claims for the health benefits of garlic include lower blood pressure and cholesterol, an anti-inflammatory effect, a reduced risk of cancer, and a stronger immune system.

While many of these claims are overblown, there is evidence of some health benefits. Here is what you should know about this pungent allium, and how to reap its benefits. 

What Makes Garlic Special

Garlic’s odoriferous flavor comes from sulfur compounds made from allicin, an active ingredient once thought to be responsible for the health benefits of garlic. But it has as many as 40 other compounds, and “any number or combination of them may be responsible for its healthfulness,” says Matthew Budoff, M.D., a professor of medicine at the Los Angeles Biomedical Research Institute who studies the effects of garlic on cardiovascular health.

Most of the studies on the health benefits of garlic used garlic supplements because they provide a consistent dose, though others used garlic powder, garlic oil, and a Japanese method of preparing garlic that involved kneading and pulverizing crushed garlic together with egg yolk.

Budoff says the strongest evidence for the health claims suggests that garlic may help the heart, with data overall showing about a 10 percent reduction in cholesterol and a three to eight point drop in blood pressure.

“That isn’t quite as good as cholesterol or blood pressure pills," he says, "but it’s certainly a nice effect.”

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A review of studies published in the journal Neurological Research in March, for instance, concluded that garlic and some of its various preparations (such as garlic extract or powder) could be a helpful side therapy for those already being treated for cardiovascular disease, high blood pressure, and diabetes; and potentially may even reduce the risk of heart attack and stroke. 

Another study published in 2017 involving an analysis of nine clinical trials with a total of 768 patients with type 2 diabetes found that those who took 50 to 1,500 mg of a garlic supplement each day for two or three months had significant reductions in their fasting blood glucose levels.

And in an earlier, smaller study of 55 people with metabolic syndrome—a group of risk factors, such as excess stomach fat or high blood pressure, that raise the risk of heart disease—published in the Journal of Nutrition, Budoff and his colleagues found that those who took a daily garlic supplement for a year had slower plaque buildup from coronary artery disease than those who took a placebo. 

A Hint of Caution

But many studies showing a cardiovascular benefit, though rigorous, are small, and not every study shows that garlic is beneficial. There has even been concern that garlic supplements may be harmful for some people with heart disease.

A research review published in the Journal of the American College of Cardiology found that garlic (along with green tea, ginkgo, ginseng, and hawthorn) can interfere with the efficacy of some heart medications or increase their side effects.

For example, too much garlic can pose a bleeding risk for people on anticoagulants such as warfarin (Coumadin, Panwarfin) or a prescribed aspirin regimen. It may also make some other drugs less effective, such as saquinavir, a drug used to treat HIV infection, according to the National Institutes of Health.

The authors of the review also noted that garlic (and other herbal supplements) has “limited evidence of benefit,” meaning it might help but more research is needed.

The research is even weaker for garlic’s ability to fight bacteria, ward off colds, boost the immune system, or reduce the risk of certain cancers, such as stomach or colon cancer.

“There’s a lot of purported benefits of these medicines [garlic supplements],” says Budoff at the Los Angeles Biomedical Research Institute. “I’m more comfortable with the research on the cardiovascular benefits of garlic, and I’m less comfortable with it curing the common cold, acting as an antiviral, or other therapies.” 

Garlic in Your Dinner

Perhaps for these reasons, experts say the best way to get your garlic is from the fresh clove, although there can be a few “side effects” from eating it fresh. Garlic breath is probably the worst of it, but some people do suffer from indigestion after eating fresh garlic.

A less stinky and easier-on-the-stomach alternative may be black garlic, which is "aged" under intense heat and humidity for 10 days, turning the bulbs black and purportedly giving the allium a sweeter, more sour taste with a jelly-like consistency. This aging process rids the garlic of its pungent, irritating properties, but the benefits remain. 

Garlic is an essential part of the Mediterranean diet, "which has been shown to have the best long-term outcomes of any diet we know of,” says Budoff. Studies have linked this way of eating—which emphasizes produce, legumes, grains, and healthy oils, with small amounts of fish and meat—to a better quality of life, a lower risk of chronic disease, and better brain health in older adults.

“I use garlic in a lot of recipes,” says Ellen Klosz, a Consumer Reports nutritionist. “You can use it to spice up a healthy dish without having to add any salt. Just make sure to use fresh garlic instead of garlic salt, which will boost the sodium levels.”

How to Get the Most Out of Garlic

Choose the freshest bulbs. Look for plump bulbs with tight skin that isn’t frayed, loose, dried out, or moldy. Sprouting, too, is a sign of age. The fresher the garlic, the higher the concentration of its active ingredients, Budoff explains. Though garlic can keep for months, he says it’s best to eat it within a week. “If you go longer than that," he says, "you can end up with something that’s deactivated.” 

Store it right. Keep garlic in a cool, dark place with good ventilation to prevent it from getting moldy or from sprouting.

Chop it for your health. Chopping, slicing, or smashing garlic triggers an enzyme reaction that increases its healthful compounds. Heat prevents this reaction, so let garlic sit on the cutting board for at least 10 minutes before cooking.

Minimize garlic breath. The smell of garlic can stay on your breath and be excreted by the lungs for a day or two after you eat it. A study published in the Journal of Food Science in 2016 suggests that munching on raw mint leaves, apples, or lettuce after a garlicky meal can help by neutralizing the sulfur compounds in garlic responsible for its odor.