Grapefruit: Benefits, Dosage, Contraindications

Updated on 19 March 2025

Grapefruit originates from Southeast Asia and became popular in Europe in the 18th century. It is the result of a natural cross between the sweet orange and the pomelo. Grapefruit seed extract (GSE) is a concentrate obtained from the seeds and white membranes of the fruit, renowned for its many therapeutic properties. Grapefruit is rich in vitamin C, flavonoids (notably naringin), and antioxidants, giving it its health benefits. GSE also contains polyphenols, known for their powerful antimicrobial properties. Grapefruit possesses antioxidant properties, primarily due to the flavonoids it contains. Grapefruit seed extract is recognized for its effectiveness against a wide spectrum of bacteria, viruses, and fungi, including resistant pathogens. The vitamin C in the fruit boosts the immune system and strengthens the body's ability to fight infections. GSE is used in drops or capsules to prevent and treat various digestive, skin, and ENT infections. In external use, it is effective against fungal infections and skin irritations.

Other name(s)

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Scientific name(s)

Citrus paradisii

Family or group:

Plants

Active ingredients:

Naringin

Neohesperidin

Bioflavonoids

Apigenin

Indications

Rating methodology

EFSA approval.

Several clinical trials (> 2) randomized controlled with double blind, including a significant number of patients (>100) with consistently positive outcomes for the indication.

Several clinical trials (> 2) randomized controlled with double blind, and including a significant number of patients (>100) with positive outcomes for the indication.

One or more randomized studies or multiple cohorts or epidemiological studies with positive outcomes for the indication.

Clinical studies exist but are uncontrolled, with conclusions that may be positive or contradictory.

Lack of clinical studies to date that can demonstrate the indication.

Oral Infections
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Grapefruit seed extract (GSE) is sometimes used as a supplement in treating oral infections thanks to its antibacterial and antifungal properties. It can reduce bacterial growth responsible for gingivitis and bad breath. As a mouthwash (diluted), it acts as a natural antiseptic, limiting inflammation and improving oral hygiene. However, robust clinical studies are lacking to confirm its effectiveness for these indications, and its use does not replace conventional treatments.

Posologie

Oral route: seeds

grapefruit seed extract

Fungal Infections
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Grapefruit seed extract (GSE) is known for its antifungal properties, particularly against Candida albicans and Aspergillus niger, responsible for skin fungal infections. Used in diluted local application, it may relieve superficial infections such as athlete’s foot by inhibiting fungal growth.

Posologie

Topical route: seeds

grapefruit seed extract

Properties

Antimicrobial

GSE is particularly appreciated for its antibacterial, antiviral, and antifungal properties. Its flavonoids, such as naringin and hesperidin, act by destroying the membranes of pathogenic microorganisms, inhibiting their reproduction. Studies show its effectiveness against Escherichia coli, Candida albicans, Staphylococcus aureus, and even some enveloped viruses. Unlike synthetic antibiotics, GSE preserves beneficial intestinal flora while eliminating pathogens.

Usages associés

Oral Infections, Fungal Infections

Grapefruit Seed Extract as a Natural Derived Antibacterial Substance against Multidrug-Resistant Bacteria
Anti-Biofilm Activity of Grapefruit Seed Extract against Staphylococcus aureus and Escherichia coli

Safety dosage

Adult: 10 drops - 15 drops

Grapefruit seed extract (GSE) is generally used in liquid solution or capsules. For an adult, the standard dosage is 10 to 15 drops diluted in a glass of water, 2 to 3 times a day, for a period of 7 to 15 days. For external use, GSE is diluted in water or vegetable oil before being applied to the skin to treat fungal infections or irritations. The concentration varies according to needs, but a dilution of 5 drops for 50 ml is often recommended for safe application.

Interactions

Médicaments

Cytochrome P450 3A4: strong interaction

Grapefruit and grapefruit seed extract (GSE) are well-known for their potential interactions with certain medications. These interactions are mainly due to the inhibition of hepatic enzymes, notably CYP3A4, which plays a key role in the metabolism of many drugs. This inhibition can lead to increased plasma concentrations of the concerned drugs, thus amplifying their effects and risks of side effects. The most concerned drug classes include statins, immunosuppressants, calcium channel blockers (for hypertension), and certain anxiolytics. Even in small quantities, grapefruit can prolong the half-life of drugs or alter their elimination.

Precautions

Pregnant woman: use with caution

The use of GSE is not formally contraindicated, but it is advised to seek medical advice before consuming.

Nursing woman: use with caution