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Secret Side Effects of Eating Garlic, Says Science

These are helpful things to know before cooking your next pasta dinner.
FACT CHECKED BY Kiersten Hickman

Garlic is pretty powerful. The medicinal use of this small but mighty food can be traced all the way back to as early as 1500 B.C. by the Ancient Egyptians for things like headaches, bug bites, and heart issues. And now in the modern-day, we love eating garlic for a number of reasons—especially for the flavors it adds to our favorite pasta recipe.

We can consume garlic in many forms. There is, of course, the fresh clove of garlic to chop up and put in your alfredo sauce. But we can also use garlic powder tablets, garlic oil, and aged garlic extract, which is garlic that undergoes an aging process to produce a very potent extraction.

When it comes to garlic, we wanted to find all of the possible effects, including the good, the bad, and the ugly. Here are the secret side effects of eating garlic you may not have known about. Plus, don't miss The #1 Best Juice to Drink Every Day, Says Science.

You might feel bloated


Garlic is high in a type of carbohydrate called fructan. These carbs can also be found in foods like wheat, rye, onions, asparagus, grapefruit, watermelon, black beans, and cashews. According to Lori Chung RD, via the Ohio State University Wexner Medical Center, people often misdiagnose themselves with gluten intolerance when they may in fact have an intolerance to fructans.

Symptoms of fructan intolerance are very similar to gluten intolerance and include things like bloating, stomach pain, cramps, and excess gas. If you often experience similar gastrointestinal issues after eating garlic, you may want to be careful!

According to Current Gastroenterology Reports, a FODMAP diet may be helpful for those with a possible fructan intolerance, although more research still needs to be done to determine the effectiveness of this. It has also been shown that cooking your garlic can help alleviate some of the possible digestive discomforts.

You might get heartburn

three cloves of roasted garlic on table

Gastroesophageal Reflux Disease (GERD), is a very common issue among adults that causes excess acid reflux in the esophagus. This creates a lot of pain, nausea, and heartburn.

If you have GERD or are easily susceptible to heartburn, you may want to be careful with how much garlic you consume. Our bodies have a lower esophageal sphincter (LES), which is a group of muscles that prevents stomach acid from traveling back up to the esophagus. According to Primary Care, garlic can weaken the "tone" of these LES muscles and cause more heartburn, especially for those with GERD or related struggles.

You might strengthen your immune system

garlic in bowl unpeeled

Garlic can potentially help us strengthen our immune system. According to the Journal of Immunology Research, garlic can improve our immunity by stimulating various types of cells in our body that are directly linked to our immune system function. This report emphasized that more human studies still need to be done on this topic, but the current findings are very promising.

Another study from Clinical Nutrition found that aged garlic extract can have a positive result on immunity as well. This study gave 60 participants a daily dose of aged garlic extract and another group of 60 participants a placebo. After the trial period, it was found that the group taking the extract reported much less severe cold/flu symptoms, as well as less time actually being sick.

30 Best Immune-Boosting Foods

You might be able to use it as an anti-fungal

crushing garlic with a knife
Marina Kliets/Shutterstock

Garlic has been known to contain certain antimicrobial properties, which is basically how you might describe something that kills or destroys a certain organism. "Antimicrobial" is an umbrella term that includes things like antibacterial and anti-fungal.

A report from the Ulster Medical Journal found that garlic has properties that can help fight off nine out of the 24 common bacterial infections mentioned in the report, as well as one of the 10 fungi listed: candida parapsilosis. This is a common species of candida (or yeast) that can sometimes lead to yeast infections if there is too much of it.

Garlic may be a helpful anti-fungal agent, but it is recommended as an addition to other types of anti-fungal medicine and shouldn't necessarily be used on its own until more research has been done.

You might improve your cognitive function

garlic oil

Some research has found that garlic can have a positive effect on our cognitive function. According to the Journal of Nutrition, aged garlic extract has been known to lower our chances of cognitive decline while helping to improve our memory and retention.

A report found in Experimental and Therapeutic Medicine also found that garlic extract might be able to fight off certain cancers, heart disease, and help prevent dementia because of its unique antioxidant properties.

For a sharper mind, here are the 30 Best & Worst Foods For Your Brain.

You might lower your blood pressure

garlic supplements

Garlic has also been known to have properties that can actually lower our blood pressure levels over time. According to a report on garlic consumption by the Nutrition Journal, consuming fresh cloves of garlic or garlic products can have positive effects on lowering our blood pressure.

In a report published by Dove Medical Press, it was found that one of the main factors in lowering blood pressure with garlic is based on the polysulfides found in their makeup. These polysulfides help to regulate what is known as the "redox signaling pathways" in our body, which are the ways in which our cells get important messages about things that need repair or protection. This includes maintaining our body's blood pressure levels.

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Samantha Boesch
Samantha was born and raised in Orlando, Florida and now works as a writer in Brooklyn, NY. Read more about Samantha