• Garlic has a high nutritional content for its size, with significant amounts of vitamin C, selenium, manganese, and iron. 
• There is also some evidence that consuming garlic may help strengthen the immune system, reduce risk for certain cancers, improve heart health, and even boost athletic performance. 
• To achieve these health benefits, you should consume no more than 1 to 2 cloves of fresh garlic each day. 
• This article was medically reviewed by Samantha Cassetty, MS, RD, nutrition and wellness expert with a private practice based in New York City.
• Visit Insider’s Health Reference library for more advice.

Garlic is an easy flavor addition to many types of meals. And beyond its widespread use for taste and seasoning, garlic can actually provide notable health benefits. 

Here are five benefits of garlic and how much you should add to your diet. 

Garlic is nutritious for its size 

One raw clove of garlic has roughly 14 calories, 0.57 grams of protein, and about three grams of carbohydrates (one slice of white bread has 34 grams of carbohydrates, for comparison.)

Though one raw clove of garlic is pretty small, there is actually a significant amount of the following vitamins and nutrients: 

• Vitamin C (2.81 mg)
• Selenium (1.28 mcg)
• Manganese (0.15 mg)
• Iron (0.15 mg)

One garlic clove packs a dense nutrient profile, but garlic’s small size means we’re not getting a large amount of nutrients from a single garlic clove. “The concentration is not as robust as we would think about, say eating a full salad,” says Tom Holland, MD, a physician scientist at Rush University Medical Center.

You shouldn’t add too much garlic to your diet, too quickly. “One to two cloves a day should be the maximum consumed by anyone,” says Tracey Brigman, a food and nutrition expert at the University of Georgia. Eating more than that may cause upset stomach, diarrhea, bloating, or bad breath. 

“If you opt for adding two cloves of garlic a day to your diet, you may also want to add fresh parsley, mint, or raw apples to your diet to help prevent the bad breath associated with garlic consumption,” Brigman says. 

Garlic may help boost your immune system

The flavorful bulbs at the end of the garlic plant are also rich with nutritious compounds called allicin and alliinase. In fact, the presence of allicin helps garlic boost the immune system. 

A 2015 review from the Journal of Immunology found that garlic fortifies the immune system by stimulating immune cells like macrophages, lymphocytes, and natural killer cells. Garlic may also help stave off colds and flu because of the plant’s antimicrobial and antibiotic properties, Brigman says, which would stop the growth of viruses, bacteria, and other unwanted organisms. 

However, Brigman notes that although some studies show a benefit, there is a lack of strong evidence that garlic supplements help prevent or reduce severity of the common cold and flu.

You should still wash your hands, avoid touching your face, stay hydrated, and practice other methods to prevent getting sick. Garlic probably won’t prevent sickness, but it may provide a little extra boost if you want to strengthen your immune system. 

Garlic may reduce the risk of certain cancers 

“[Garlic is] also a good source of phytochemicals, which help to provide protection from cell damage, lowering your risk for certain cancers,” says Brigman. 

Phytochemicals are compounds in vegetables and fruits associated with a reduced risk of chronic illness. There is some evidence that consuming phytochemicals through garlic can have anticarcinogenic effects and potentially lower risk for stomach and colorectal cancers. 

However, research in human subjects is lacking, and it’s not proven that garlic consumption can actually prevent or treat cancer. 

Garlic may improve heart health 

A 2019 study published in Experimental and Therapeutic Medicine found that consuming two capsules of garlic extract a day for two months can lower blood pressure and decrease arterial stiffness for people with hypertension. 

“Garlic seems to lead to overall protection for your heart,” Brigman says. 

In addition, a 2013 report suggested that garlic can reduce lipids in the blood, which means lower cholesterol and thus a lower risk for plaque build up in the cardiovascular system. 

The amount of garlic needed to achieve these heart healthy effects differ among individuals. However, looking at the research available on the subject, it’s best to consume about four fresh cloves of garlic per week, says Puja Agarwal, PhD, a nutrition epidemiologist at Rush University Medical Center. 

Garlic may allow you to exercise longer 

Historically, Ancient Greek athletes ate garlic before an event to improve their performance. That’s because garlic releases nitric oxide, a compound that relaxes blood vessels and lowers blood pressure. This compound is often released while running to supply more oxygen to working muscles. 

Some animal studies in rats and mice have also found that garlic can improve athletic endurance, finds a 2007 from Molecular Nutrition Food Research. However, Brigman notes the inconclusive data in human subjects means we can’t draw definitive conclusions. 

Takeaways 

Brigman says to opt for whole garlic rather than the pre-minced version in jars, as you will get the most health and medicine benefits from raw garlic.

This is because the alicin in garlic, which contributes to many of its health benefits, is most potent briefly after it has been chopped, crushed, or chewed. In fact, the amount of allicin in garlic cloves peaks 10 minutes after chopping and is destroyed by temperatures over 140 degrees Fahrenheit. 

“If you want to add garlic to hot meals, then add it when your food is almost finished cooking to limit the destruction of allicin,” Brigman says. 

Allicin can also be consumed in supplemental forms, such as in pills, but the most benefit comes from raw garlic, Brigman says. This may be due to the fact that garlic supplements do not have regulated manufacturing standards and may actually contain little to no allicin.