Grapefruit seed extract (GSE), also known as citrus seed extract, is a liquid extract derived from the

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

pulp Pulp may refer to: * Pulp (fruit), the inner flesh of fruit Engineering * Dissolving pulp, highly purified cellulose used in fibre and film manufacture * Pulp (paper), the fibrous material used to make paper * Molded pulp, a packaging material ...

, and white membranes of grapefruit. GSE is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with

glycerin Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

. Commercially available GSEs sold to consumers are made from the seed, pulp, and glycerin blended together. GSE is sold as a dietary supplement and is used in

cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...

Grapefruit history

The grapefruit is a subtropical

citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

grown for its

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

which was originally named the "

forbidden fruit Forbidden fruit is a name given to the fruit growing in the Garden of Eden which God commands mankind not to eat. In the biblical story, Adam and Eve eat the fruit from the tree of the knowledge of good and evil and are exiled from Eden. As a ...

" of

Barbados Barbados is an island country in the Lesser Antilles of the West Indies, in the Caribbean region of the Americas, and the most easterly of the Caribbean Islands. It occupies an area of and has a population of about 287,000 (2019 estimate) ...

. The fruit was first documented in 1750 by Rev. Griffith Hughes when describing specimens from Barbados.Michael Quinion
World Wide Words: Questions & Answers; Grapefruit
2009. All parts of the fruit can be used. The fruit is mainly consumed for its tangy

juice Juice is a drink made from the extraction or pressing of the natural liquid contained in fruit and vegetables. It can also refer to liquids that are flavored with concentrate or other biological food sources, such as meat or seafood, such as ...

. The peel can be processed into

aromatherapy Aromatherapy is based on the usage of aromatic materials including essential oils and other aroma compounds, with claims for improving psychological and physical well-being. It is offered as a complementary therapy or as a form of alternative ...

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...

s and is also a source of dietary fiber. The seed and pulp, as byproducts of the juice industry, are retrieved for GSE processing or sold as cattle feed.

Efficacy

Despite

claims Claim may refer to: * Claim (legal) * Claim of Right Act 1689 * Claims-based identity * Claim (philosophy) * Land claim * A ''main contention'', see conclusion of law * Patent claim * The assertion of a proposition; see Douglas N. Walton * A righ ...

that GSE has

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

effects, there is no scientific evidence that GSE has such properties. Some evidence indicates that the suspected antimicrobial activity of GSE was due to the contamination or adulteration of commercial GSE preparations with synthetic antimicrobials or

preservatives A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...

. These chemicals were not present in grapefruit seed extracts prepared in the

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physic ...

, and GSE preparations without the contaminants were found to possess no detectable antimicrobial effect. Although citrus seed extract is sold in health food markets, there is no good evidence for any antimicrobial activity.

Phytochemicals

Analysis shows the phytochemicals of the seed extract and pulp are

flavonoids Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

, ascorbic acid (

vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) ...

tocopherol Tocopherols (; TCP) are a class of organic chemical compounds (more precisely, various methylated phenols), many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rat ...

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...

limonoid Limonoids are phytochemicals of the triterpenoid class which are abundant in sweet or sour-scented citrus fruit and other plants of the families Cucurbitaceae, Rutaceae, and Meliaceae. Certain limonoids are antifeedants such as azadirachtin from ...

s, sterols, and

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed ...

Preparations

GSE is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with glycerin. Commercially available GSE is made from the seed, pulp, glycerin, and synthetic preservatives all blended together.

Health claims and safety concerns

Although various health claims for using GSE are marketed in the dietary supplement industry, there is no scientific evidence from high-quality

clinical research Clinical research is a branch of healthcare science that determines the safety and effectiveness ( efficacy) of medications, devices, diagnostic products and treatment regimens intended for human use. These may be used for prevention, treatm ...

that it has any health effects, as of 2018. Phytochemicals in grapefruit seeds, particularly furanocoumarins and flavonoids, may cause adverse effects on health resulting from

grapefruit–drug interactions Some fruit juices and fruits can interact with numerous drugs, in many cases causing adverse effects. The effect is most studied with grapefruit and grapefruit juice, but similar effects have been observed with certain other citrus fruits. The ...

that influence the intended therapeutic effects of some 85 prescription drugs. The main safety concern about GSE is inhibition of the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...

, which controls liver metabolism of drugs; consequently, its inhibition by GSE unpredictably increases the blood concentrations of prescribed drugs.

References

{{reflist, 30em Dietary supplements Grapefruit Seeds