GABA. GABA (gamma aminobutyric acid/gamma amino-butyric acid) is an amino acid synthesized in the brain that acts as a neurotransmitter inhibitor and is associated with reducing the incidence of seizures and depression (Sources: Advances in Experimental Medicines and Biology, 2004, volume 548, pages 92–103; and Archives of General Psychiatry, July 2004, pages 705–713). Cosmetics companies include GABA in products and then claim that topical application relaxes muscles, thus sparing consumers from going through Botox injections. However, GABA has not been proven to relax muscles and reduce the appearance of wrinkles or expression lines when applied topically. Cosmetics companies are hoping that consumers will associate the topical application of products containing GABA with its internal function of controlling the manner in which nerve impulses fire. There is no substantiated research proving GABA works in this manner when applied topically, and if it did, it would be cause for alarm. Because if GABA worked as stated and you applied it to your entire face, what’s to stop it from affecting the muscles around your mouth, jaw, or neck? If it really relaxed muscles upon application, consumers would see more skin sagging, not to mention problems controlling the (relaxed) muscles in your fingers (assuming they come in contact with the product).

Lastly, the whole nonsense of using GABA in cosmetic products is refuted by the fact that GABA does not work alone to exert its effect internally on nerves. It requires many other substances (substances that are not present in the skin-care products containing GABA) for it to prevent nerves from being triggered and causing muscles to relax (Sources: http://www.emedicine.com; www.naturaldatabase.com).

galactoarabinan. Polysaccharide extracted from the western larch tree. See polysaccharide.

galbanum. Fragrant substance that, because of its resin and volatile oil content, can be extremely irritating and sensitizing on abraded skin. There is no research showing it has any benefit on skin.

gamma linolenic acid (GLA). Fatty acid used in cosmetics as an emollient, antioxidant, and cell regulator. GLA is considered to promote healthy skin growth and is an anti-inflammatory agent. GLA is found in black currant oil or seeds, evening primrose oil, and borage oil (Source: Biochemical and Biophysical Research Communications, March 17, 1998, pages 414–420). However, there is no research showing GLA to be effective in the treatment of wrinkles (Sources: British Journal of Dermatology, April 1999, pages 685–688; and Dermatology, 2000, volume 201, number 3, pages 191–195). When taken orally, GLA has been shown to have some anticancer properties, but there is no research showing that that effect translates to skin. See fatty acid.

Ganoderma lucidum extract. Mushroom stem extract. There is no research showing it to be effective when used topically on skin (Source: http://www.naturaldatabase.com), although it does have antioxidant properties (Source: Journal of Agricultural and Food Chemistry, October 2002, pages 6072–6077).

Gardenia florida extract. Flower extract used in cosmetics to impart fragrance; also functions as an antioxidant (Source: Natural Product Research, February 2007, pages 121–125). There is limited research proving its benefit for skin, and its fragrance component may be irritating, thus canceling out the antioxidant benefit.

gelatin. Protein obtained from plants or animals and used in cosmetics as a thickening agent.

Gellidiela acerosa extract. Extract derived from a type of algae. See algae.

Gentiana lutea (Gentian) root extract. Active part of the gentian plant, constituents of which are anti-inflammatory and antibacterial (Sources: http://www.naturaldatabase.com; and Phytomedicine, February 2007, epublication).

geranium extract. Extract that can have potent antioxidant properties (Source: Phytomedicine, June 2000, pages 221–229).

geranium oil. Fragrant oil that can have antimicrobial properties but also can be a skin sensitizer or irritant (Sources: Contact Dermatitis, June 2001, pages 344–346; and Journal of Applied Microbiology, February 2000, pages 308–316).

Geranium pretense. Geranium plant. See geranium extract and geranium oil.

Germaben II. Trade name for diazolidinyl urea. See diazolidinyl urea.

ginger extract. Extract from a plant in the Zingiberacae family that has research showing it has anti-inflammatory and anti-carcinogenic activity when taken orally (Sources: Carcinogenesis, May 2002, pages 795–802; and Food and Chemical Toxicology, August 2002, pages 1091–1097). However, topically it can be a skin irritant (Source: IFA—International Federation of Aromatherapists, http://www.int-fed-aromatherapy.co.uk).

ginger oil. See ginger extract.

Ginkgo biloba leaf extract. Research shows this potent antioxidant helps improve blood flow. It is often used in anti-cellulite products because of its relation to circulation. However, there is no research showing that improved circulation affects cellulite (Sources: Medical Hypotheses, March 2006, pages 1152–1156; Journal of Burn Care and Rehabilitation, November–December 2005, pages 515–524; Journal of Pharmaceutical and Biomedical Analysis, February 2005, pages 287–295; and Planta Medica, November 2004, pages 1052–1057).

ginseng. Herb in the family Araliaceae, native to Asia. A small number of studies carried out on animals have shown that ginseng may have anti-tumor, anti-cancer, and wound-healing properties (Sources: Journal of Korean Medical Science, December 2001, Supplemental, pages 38–41; and Cancer Letter, March 2000, pages 41–48), although there is also research showing that it can stimulate the growth of breast cancer cells (Source: Menopause, March–April 2002, pages 145–150). There is also in vitro research showing it can stimulate collagen production (Source: Journal of Ethnopharmacology, January 2007, pages 29–34). There is no evidence indicating that it has any benefit or risk when applied topically in skin-care products.

GLA. See gamma linolenic acid.

glabridin. Main ingredient in licorice extract. It has anti-inflammatory properties. There is research showing it to be effective in reducing skin discolorations (Source: Pigment Cell Research, December 1998, pages 355–361).

gluconolactone. See polyhydroxy acid.

glucose. Monosaccharide that has water-binding properties for skin. See mucopolysaccharide and water-binding agent.

glucose tyrosinate. See tyrosine.

glutamic acid. Amino acid derived from wheat gluten. It can have water-binding properties for skin. There is no research showing glutamic acid has any special properties when used in topical cosmetic formulations. See amino acid.

glutamine. Can help improve the barrier function of skin (Source: Journal of Biological Chemistry, July 1998, pages 1763–1770). See amino acid.

glutathione. Potent antioxidant (Source: Free Radical Research, March 2002, pages 329–340). See antioxidant.

glycereth-26. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glycereth-26 phosphate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glycereth-6 laurate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glycerin. Also called glycerol; it is present in all natural lipids (fats), whether animal or vegetable. It can be derived from natural substances by hydrolysis of fats and by fermentation of sugars. It can also be synthetically manufactured. For some time it was thought that too much glycerin in a moisturizer could pull water out of the skin instead of drawing it into the skin, but that theory now seems to be completely unfounded. What appears to be true is that glycerin shores up the skin’s natural protection by filling in the area known as the intercellular matrix and by attracting just the right amount of water to maintain the skin’s homeostasis. There is also research indicating that the presence of glycerin in the intercellular layer helps other skin lipids do their jobs better (Sources: American Journal of Contact Dermatitis, September 2000, pages 165–169; and Acta Dermato-Venereologica, November 1999, pages 418–421). See intercellular matrix and natural moisturizing factor (NMF).

glycerine. See glycerin.

glycerol. See glycerin.

glycerol monostearate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glycerol triacetate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glycerol trioleate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl cocoate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl dipalmitate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl distearate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl ester. Large group of ingredients that are composed of fats and oils. At room temperature, the fats are usually solid and the oils are generally liquid. Some tropical oils are liquids in their sites of origin and become solids in cooler or different applications. These multitudinous fats and oils are used in cosmetics as emollients and lubricants as well as water-binding and thickening agents.

glyceryl isopalmitate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl isostearate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl myristate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl oleate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl palmitate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glyceryl stearate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

glycine. See amino acid.

Glycine soja oil. Oil derived from wild soybeans; it has emollient properties. See natural moisturizing factor (NMF).

glycogen. Polysaccharide that has water-binding properties for skin. See polysaccharide.

glycol stearate. Used as an emollient and thickening agent. See glyceryl ester.

glycolic acid. See AHA.

glycolipid. Type of lipid composed of sugar (monosaccharide) and fat (lipid) that forms an important component of cell membranes and ceramides. Glycolipids coat cell walls, forming a barrier that holds skin and water content in place. See ceramides, lipid, and mucopolysaccharide.

glycoproteins. Cell-to-cell communicating ingredients created when a protein links with a carbohydrate. Glycoproteins play a critical role in the body in relation to how various systems recover from internal and external stresses. They also are fundamentally involved in cellular repair, among other functions. However, there is no evidence that they can affect wrinkles in any way when applied topically (Sources: http://www.glycoscience.com; http://www.anatomyatlases.org; and The Journal of Immunology, November 1, 2000, pages 5295–5303, and September 1991, pages 1614–1620). In addition, when glycoproteins are combined with saccharides they form substances that compose the skin’s intercellular matrix. This matrix keeps skin cells and the skin’s structure intact, with glycoprotein derivatives such as polysaccharides and glycosaminoglycans such as hyaluronic acid. See mucopolysaccharide, natural moisturizing factor (NMF), and protein.

glycosaminoglycans. Also known as mucopolysaccharides; these are a fundamental component of skin tissue, and are essentially a group of complex proteins. Chondroitin sulfate and hyaluronic acid are part of this ingredient group. See chondroitin sulfate, hyaluronic acid, mucopolysaccharide, and natural moisturizing factor (NMF).

glycosphingolipid. See glycolipid and natural moisturizing factor (NMF).

glycyrrhetic acid. Extract from licorice that has anti-inflammatory properties (Sources: American Journal of Respiratory and Cellular Molecular Biology, November 1998, pages 836–841; and Planta Medica, August 1996, pages 326–328). See licorice extract.

Glycyrrhiza glabra. Licorice plant. See glycyrrhetic acid and licorice extract.

gold. Relatively common allergen that can induce dermatitis about the face and eyelids (Source: Cutis, May 2000, pages 323–326). There is no research showing it has any benefit when applied topically to skin.

goldenseal. A plant that may have antibacterial or antiviral properties when taken orally. There is no evidence that such an effect occurs when applied topically on skin; however, it can be a skin irritant.

gotu kola. See Centella asiatica.

grape seed extract. Contains proanthocyanidins, which are very potent antioxidants, helpful for diminishing the sun’s damaging effects and lessening free-radical damage (Sources: Current Pharmaceutical Biotechnology, June 2001, pages 187–200; and Toxicology, August 2000, pages 187–197). It has also been shown to have wound-healing properties (Source: Free Radical Biology and Medicine, July 2001, pages 38–42). There is no difference in the antioxidant potential among different types of grapes (Source: Journal of Agricultural Food Chemistry, April 2000, pages 1076–1080).

grape seed oil. Emollient oil that also has good antioxidant properties. See grape seed extract and linoleic acid.

grapefruit oil. Citrus oil whose volatile components (chiefly substances known as furocoumarins) are irritating to skin. Topical application of grapefruit oil may cause contact dermatitis or a phototoxic reaction when skin is exposed to sunlight (Source: http://www.naturaldatabase.com).

green tea. Significant amounts of research have established that tea, including black, green, and white tea, has many intriguing health benefits. Dozens of studies point to tea’s potent antioxidant as well as anticarcinogenic properties. However, a good deal of this research is on animal models, which do not directly relate to effects on human skin (Source: Skin Pharmacology and Applied Skin Physiology, 2001, pages 69–76). There is only limited information about tea’s effect on skin (Source: Photodermatology, Photoimmunology, and Photomedicine, February 2007, pages 48–56).

The Journal of Photochemistry and Photobiology (December 31, 2001) stated that the polyphenols “are the active ingredients in green tea and possess antioxidant, anti-inflammatory and anticarcinogenic properties. Studies conducted by our group on human skin have demonstrated that green tea polyphenols (GTP) prevent ultraviolet (UV)-B…-induced immune suppression and skin cancer induction.” Green tea and the other teas (e.g., white tea, which is what green tea begins as) show a good deal of promise for skin, but they are not the miracle that cosmetics and health food companies make them out to be. As the Annual Review of Pharmacology and Toxicology (January 2002, pages 25–54) put it, “Tea has received a great deal of attention because tea polyphenols are strong antioxidants, and tea preparations have inhibitory activity against tumorigenesis. The bioavailability and biotransformation of tea polyphenols, however, are key factors limiting these activities in vivo [in humans]. Epidemiological studies … have not yielded clear conclusions concerning the protective effects of tea consumption against cancer formation in humans.”

Most researchers agree that tea (black, green, or white) has potent anti-inflammatory properties and that it is a potent antioxidant. Current research also indicates that epigallocatechin-3-gallate (EGCG), an extract of tea, can prevent collagen breakdown and reduce UV damage to skin (Source: Journal of Dermatological Science, December 2005, pages 195–204).

guaiac wood. Used as a fragrant extract in cosmetics; it is a potent skin irritant.

Guaiacum officinale. See guaiac wood.

guar gum. Plant-derived thickening agent.

guarana. Herb that contains two and a half times more caffeine than coffee. It can have constricting properties on skin and can therefore be a skin irritant. See caffeine and Paullinia cupana seed extract.

gums. Substances that have water-binding properties, but that are used primarily as thickening agents in cosmetics. Some gums have a sticky feel and are used as film-forming agents in hairsprays, while others can constrict skin and have irritancy potential. Natural thickeners such as acacia, tragacanth, and locust bean are types of gums.