Grapefruit seed extract (GSE) or citrus seed extract is a supplement made from the seeds and pulp of grapefruit.

It’s rich in essential oils and antioxidants and has a variety of potential health benefits.

However, some claims about its benefits are exaggerated, and there are some risks to be aware of.

This article reviews the 6 main benefits of supplementing with grapefruit seed extract, as well as the myths and dangers associated with its use.

Grapefruit Seed Extract

Grapefruit seed extract has several health benefits when taken as a supplement.

1. Contains Powerful Antimicrobials

Grapefruit seed extract contains potent compounds that can kill more than 60 types of bacteria and yeasts (1, 2).

Test-tube studies have shown that it can even be as effective as some commonly prescribed topical antifungal and antibacterial medications, such as nystatin (1).

GSE kills bacteria by breaking down their outer membranes, causing them to burst open after just 15 minutes of exposure (3).

It kills yeast cells by causing apoptosis, a process in which cells self-destruct (4).

However, most of the studies on grapefruit seed extract have been test-tube studies, so it’s unknown whether they would have the same effects when taken as a supplement.

2. Packs Antioxidants

Grapefruit seed extract contains many powerful antioxidants that can protect your body from oxidative damage caused by free radicals.

Oxidative damage has been linked to many chronic illnesses, including heart disease and diabetes (5, 6).

Studies on grapefruit seeds and grapefruit seed extracts have found that both are rich in essential oils, vitamin E, flavonoids and polyphenols — all of which act as antioxidants in your body (7, 8, 9).

The polyphenol naringin is found in very high concentrations in grapefruit seeds. In fact, it’s what gives grapefruit its bitter taste (10, 11).

Naringin has strong antioxidant abilities and has been found to protect tissues against radiation damage in mice (12).

However, more research is needed to understand the potential benefits of antioxidants from grapefruit seed extract in humans.

3. May Protect Against Stomach Damage

Animal studies have found that grapefruit seed extract can protect the stomach from damage caused by alcohol and stress (13, 14).

It appears to protect the stomach lining from ulcers and other lesions by increasing blood flow to the area and preventing damage caused by free radicals (14).

GSE is also capable of killing the bacterium H. pylori, which is believed to be one of the major causes of stomach inflammation and ulcers (15).

While grapefruit seed extract appears to be beneficial in animals and test-tube studies, human research is lacking. More studies are needed before recommendations can be made.

4. May Help Treat Urinary Tract Infections

Since grapefruit seed extract is so effective at killing bacteria, researchers have begun to investigate whether it can treat infections in humans.

One very small study found that eating six grapefruit seeds every eight hours for two weeks effectively treated urinary tract infections in some people (16).

It’s hypothesized that the antioxidants and antimicrobial compounds in grapefruit seeds can help your body fight off infectious bacteria growing inside your urinary tract.

However, more research is needed to determine whether GSE supplements can be routinely used to treat infections in humans.

5. May Reduce Your Risk of Heart Disease

High cholesterol, obesity and diabetes are some of the major risk factors for heart disease.

Some animal research suggests that grapefruit seed extract supplements can improve these risk factors and thus reduce the chances of developing heart disease.

Rats given GSE daily for 31 days had significantly lower blood sugar and cholesterol levels and weighed less than rats not receiving the supplement (17).

One study even found that GSE was as effective as the drug metformin in reducing blood sugar levels in rats with diabetes (18).

However, there is currently no research on whether grapefruit seed extract has similar effects in humans.

6. May Protect Against Damage Caused by Restricted Blood Flow

All cells in your body require a steady flow of blood to receive oxygen and nutrients and carry away waste.

When blood flow is restricted, such as in cases of blood clots or stroke, cells in the affected area become damaged and may die.

Some studies suggest that grapefruit seed extract supplements can help reduce the severity of this type of damage.

Giving rats GSE 30 minutes before cutting off blood flow to an organ significantly reduced damage and inflammation in the area after blood flow was restored (19, 20).

Researchers believe GSE is protective due to its powerful antioxidants and its ability to increase blood flow to tissues.

However, more research is needed to understand how grapefruit seed extract may be used in the management or prevention of these types of injuries in humans.

Summary Test-tube and animal studies suggest that grapefruit seed extract can fight infections, reduce the risk of heart disease and protect against oxidative stress and tissue damage, but human research is lacking.

While there are many potential benefits to supplementing with grapefruit seed extract, there are also some myths surrounding its use.

It Can Treat Almost Any Infection

One of the most common myths about grapefruit seed extract is that it can cure almost any infection, including yeast overgrowth in your gut, opportunistic infections that develop in people with AIDS and even acne.

Most of these claims are based on studies showing that GSE can kill a wide variety of bacteria and yeasts inside a test tube.

However, no studies have linked GSE in supplement form to treating these infections.

To date, there is no peer-reviewed research to support many of these claims, although some may be published in the future.

It’s a Completely Natural Supplement

Many people believe that grapefruit seed extract is a completely safe and natural supplement.

While it’s possible to make simple alcohol extracts from grapefruit seeds, many commercial products are actually highly processed.

Companies often make their extracts by mixing grapefruit seed and pulp powder with glycerin (a thick sweet liquid made from fats) and heating it with ammonium chloride and vitamin C.

Hydrochloric acid and natural enzymes are added, and the final product is cooled and sold as commercial grapefruit seed extract (1).

You can contact individual supplement companies to learn more about how they produce or source their grapefruit seed extract and whether they test for purity.

Summary There is not enough research to support the claims that grapefruit seed extract supplements can cure infections in humans. Moreover, most commercially available grapefruit seed extracts are highly processed.

Grapefruit seed extract may have some benefits, but there are also certain dangers to be aware of.

Potential Contaminants

Since grapefruit seed extracts are sold as supplements, they’re not regulated for quality and purity.

Several studies have found that many commercial GSE supplements are contaminated with synthetic antimicrobial compounds, including benzethonium chloride and triclosan, as well as preservatives like methylparabens (21, 22, 23, 24).

Some researchers believe that these synthetic compounds are responsible for the antimicrobial effects of commercial grapefruit seed extracts, but more research is needed (25).

Possible Interactions With Certain Medications

Since grapefruit seed extract supplements have not been extensively studied in humans, research on their potential side effects or interactions with certain medications is lacking.

However, supplements that are contaminated with benzethonium chloride may interfere with your liver’s ability to process and excrete certain medications, potentially increasing their effects.

For example, one study found that GSE supplements increased the effects of the blood-thinning drug warfarin and caused excessive bleeding (26).

It’s important to consult with your doctor or pharmacist before starting any new supplements, including GSE.

Summary Grapefruit seed extract supplements can be contaminated with synthetic antimicrobials, which may interfere with certain medications.

Grapefruit seed extract (GSE) is promoted for various health benefits, such as fighting infections or protecting against tissue damage, oxidative stress and even heart disease.

However, human research to support these claims is lacking.

What’s more, many GSE supplements are highly processed and may interact with certain medications.

If you’re interested in trying grapefruit seed extract supplements, be sure to look for high-quality products and always check with your doctor first.