Page 261 - Cosmetology

chemicals that are biologically active against free radicals. Polyphenol compounds, such as the catechins
found in green tea, also fit this profile. Soy extract’s increased use in anti-aging products is largely due to
studies showing that genistein (a component of soy) has a collagen-stimulating effect and that various
compounds in soy influence skin thickness and elasticity. Researchers have also looked at Bifidobacterium-
fermented soy milk extracts. On mouse skin and in human skin fibroblasts (lab cultured), this bacteria-
modified form of soy was shown to stimulate production of hyaluronic acid in skin. This was due to the
amount of genistein released during the fermentation process.

Studies performed on mouse skin have shown that topical application of soy milk and other soy compounds
has a protective effect against UVB light damage. It is theorized that these benefits will translate to human
skin as well, but conclusive evidence has not materialized yet.

There is no research showing that soy extract or soy oil has estrogenic effects when applied to skin, as it
can when taken orally. Some companies have asserted that soy can affect hair growth and lighten skin color
when applied topically. The single study citing this was done by Johnson & Johnson that sells products
claiming to have this effect.

soy isoflavones. See soy extract.

soy oil. Emollient oil similar to all nonfragrant plant oils. See natural moisturizing factors and soy extract.

soy protein. See soy extract.

soya sterol. One form of phytosterol. There is no research showing soy sterols to have estrogenic or
antioxidant benefit for skin. See phytosterol.

spearmint oil. Fragrant, volatile oil that can cause skin irritation and allergic reactions. See counter-irritant.

SPF. See sun protection factor.

spikenard. Plant that has antibacterial properties for skin.

Spilanthes acmella extract. Plant extract that can have antibacterial properties.

spinach extract. Can have antioxidant properties, but whether benefits can be realized when it is applied
topically on skin is not known.

Spiraea ulmaria. See meadowsweet extract.

spirulina. See algae.

squalane. See natural moisturizing factors and squalene.

squalene. Oil derived from shark liver or from plants and sebum. It is a natural component of skin and is
considered a good emollient that has antioxidant and immune-stimulating properties.

St. John’s wort. Contains several components that are toxic on skin in the presence of sunlight. St. John’s
wort’s association with improving depression when taken as an oral supplement is unrelated to its topical
impact on skin. However, it also has potent antioxidant properties.

star anise. See anise.

steapyrium chloride. Antistatic agent used in hair-care products.

stearalkonium chloride. Antistatic ingredient used in hair-care products to control flyaways and aid in
helping a brush or comb get through hair.

stearalkonium hectorite. Used as a suspending agent.

stearates. See stearic acid.

stearic acid. Fatty acid used as an emollient and as an agent to help keep other ingredients intact in a