Grapefruit Seed Extract


Grapefruit seed is prepared in extract form from the seeds, pulp, and white membranes of grapefruits from grapefruit trees (Citrus paradisi). The grapefruit tree, first discovered on the Caribbean island of Barbados in the seventeenth century, was brought to Florida in 1823 for commercial cultivation. The plant was probably named grapefruit because its fruits grow in bunches or clusters. Grapefruit seed extract (GSE) is used as a broad spectrum, non-toxic, antimicrobial compound. The extract comes in two forms, liquid and powder.

GSE was developed by Dr. Jacob Harich, a physicist who was born in Yugoslavia in 1919 and educated in Germany. His education in nuclear physics was interrupted by Word War II. After witnessing the horror of war as a fighter pilot, Harich decided to devote the rest of his life to improving the human condition.

He then expanded his educational pursuits to include medicine, including gynecology and immunology. He came to the United States in 1957 to study at Long Island University in New York. As an immunologist, he was interested in studying natural substances that might help protect the body from undesirable microorganisms.

In 1963, he moved to Florida, the heart of grapefruit country, and began research on the use of grapefruit seeds as a biocide. By 1990, holistic health practitioners began to recommend the use of GSE to their patients. In 1995, Harich was invited to the Pasteur Institute of France, a leading AIDS research center.

Researchers at the Center have been investigating the potential of GSE as a prophylactic against the HIV virus as well as against some of the secondary infections associated with AIDS. He was also honored by farmers in Europe who use a powdered form of GSE in fish and poultry feed to control Salmonella and Escherichia coli. In 1996, Harich passed away.

General use

GSE is a broad spectrum bactericide, fungicide, antiviral, and antiparasitic compound. When used in vitro, GSE has been shown to be highly effective against a broad spectrum of bacteria, including Staphyloccus aureus, Streptococcus pyogenes, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Shigella dysenteriae, Legionella pneumoniae, Clostridium tetani, Diploccus pneumoniae, and many others. GSE also strongly inhibits many types of pathogenic fungi and yeast.

Examples of external uses of GSE include:
  • mouth and lips: mouthwash, mouth ulcers, thrush, bad breath, cracked lips, sunburned lips, and cold sores
  • teeth and gums: plaque, tooth decay, toothaches, tooth extraction, gingivitis, and toothbrush cleaner
  • nose and sinuses: sinusitis, runny nose (rhinitis), and nasal ulcer
  • throat: sore throat, tonsillitis, coughs, hoarseness, and laryngitis
  • ears: ear cleaning, earaches, and inflammation of the middle ear (otitis media) in conjunction with internal use
  • face: acne and shaving
  • scalp and hair: shampoo, dandruff, itching scalp, and head lice
  • skin: small cuts, skin abrasions, scratches, minor burns, rashes, dermatitis, psoriasis, shingles, eczema, nettle rash, insect bites and stings, tick and leech bites, leg ulcers, warts, and skin fungi
  • feet: athlete’s foot, sweaty feet, calluses, corns, blisters, nail fungi, and cuticular infections
  • vagina and genitals: vaginitis, yeast infections, vaginal parasites, feminine hygiene, and fungal and parasitic diseases in the male genital area
Grapefruit Seeds

Examples of internal uses include:


Grapefruit seeds and pulp contain a combination of bioflavonoids and polyphenolic compounds. The polyphenols are unstable but are chemically converted during the GSE synthesis process into more stable substances that belong to a class of compounds called quaternary ammonium compounds. The active quaternary ammonium compound in GSE believed to be responsible for its antimicrobial properties is a diphenol hydroxybenzene complex.

The antimicrobial activity appears to develop in the cytoplasmic membrane of the microorganisms. The active ingredients disorganize the cytoplasmic membrane so that the uptake of amino acids is prevented. At the same time there is a leakage of low molecular weight cellular contents through the cytoplasmic membrane. Studies have also shown that GSE inhibits cellular respiration.

The extract is prepared by grinding grapefruit seeds and pulp into a fine powder. The powder is dissolved into purified water and distilled to remove fiber and pectin. The distilled slurry is spray dried at low temperatures forming a concentrated grapefruit bioflavonoid powder.

This concentrated powder is dissolved in vegetable glycerin and heated. Food grade ammonium chloride and ascorbic acid are added. This mixture is heated under pressure where it undergoes catalytic conversion using natural catalysts, including hydrochloric acid and natural enzymes. The slurry is then cooled, filtered, and treated with ultraviolet light. Residual ammonium chloride in the final product is between 15 and 18%; residual ascorbic acid is between 25 and 35 mg/kg.

There is no residue of hydrochloric acid in the final product. In the United States, standardized GSE contains 60% grapefruit extract materials and 40% vegetable glycerin. A powdered form of GSE is also available that contains 50% grapefruit extract materials, 30% silicon dioxide, and 20% vegetable glycerine.

To treat infections, 15 drops in 8 oz of water is used. For diaper yeast infections and as a vaginal douche, 10–15 drops of grapefruit seed extract is used in 4 oz of water.


GSE has been shown to be non-toxic at levels many times greater than the recommended dosages. Even when taken daily, GSE seldom produces a significant allergic reaction. However, people who are allergic to citrus fruits should exercise caution in the use of GSE.

Citricidal®, the brand name of a GSE product in the United States containing 60% grapefruit seed extract in an aqueous, vegetable glycerine solution, has, in the United States, been labeled as GRAS (Generally Recognized as Safe) in the Code of Regulations. The Food and Drug Administration (FDA) has approved Citricidal® for cosmetic preparations. In addition, Citricidal® has also been approved by the FDA for the disinfection of foods.

Generally, GSE should never be used at full strength. GSE is extremely irritating to the eyes. If it gets into the eyes, a person should wash the eyes with large amounts of warm water and consult a physician, if necessary.

After an excessive ingestion of GSE, an individual should drink large amounts of water and take up to 3 tsp of psyllium husks (or up to 6 psyllium capsules). A doctor should be consulted, if necessary.

Side effects

Since GSE is quite acidic, if it is not properly diluted, it may further irritate already irritated tissues, such as a stomach or intestinal lining.


Over 75 different combination herbal preparations containing GSE are available, based on the assumption of Chinese herbal medicine that combinations of substances are more beneficial than single remedies. In addition, the antimicrobial properties of GSE make it an excellent preservative, thus enabling the herbs it accompanies to retain their potency.