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Herbal Extract

Grapefruit Seed Extract

Also known as: GSE, Citrus paradisi seed extract, grapefruit seed powder

C
Evidence

Grapefruit seed extract is a citrus-derived compound marketed for antimicrobial and antioxidant properties, though human clinical evidence remains limited. Most research has been conducted in vitro or in animal models rather than controlled human trials.

Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.

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Primary uses

  • Antimicrobial support
  • Antioxidant support
  • Immune system support
  • Digestive health

How it works

  • Contains polyphenols and flavonoids with potential antimicrobial activity
  • May inhibit bacterial and fungal growth in laboratory settings
  • Theoretical antioxidant effects from citrus bioflavonoids

Dosage

Typical range
50-300 mg daily (varies widely; often 125-250 mg for powder)
Timing
With or without food; typically divided into 2-3 doses
With food
May be taken with or without food; some prefer with meals for tolerance
Duration
Typically used short-term (2-4 weeks) or cyclically; long-term safety data limited
Special populations
Pregnant/nursing women should consult provider; use cautiously in children

Forms

  • Powder· 70/100
  • Liquid extract· 70/100
  • Capsule· 70/100

Safety

Common side effects

  • Digestive upset (nausea, diarrhea)
  • Allergic reactions (rare)
  • Headache (uncommon)

Contraindications

  • History of citrus allergy or sensitivity
  • Concurrent use with medications sensitive to CYP3A4 inhibition (theoretical risk based on grapefruit juice literature, though GSE profile may differ)
  • Pregnancy and lactation (insufficient safety data)

Evidence notes

Most evidence comes from in vitro and animal studies. Human clinical trials are sparse and methodologically limited. Safety is generally regarded as good based on traditional use, but efficacy claims for specific health conditions lack robust RCT support.

Grade C: Mostly observational or small trials; mechanism is plausible but unproven at scale.

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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.