Page 227 - Cosmetology

Kigelia africana extract. Extract of an African plant commonly known as the sausage tree. The African lore
about this extract is that it can firm breast tissue, but there is no supporting research for this myth, or that
indicates this plant has any other benefit for skin.

kinetin. The trade name for kinetin is N6-furfuryladenine. It is a plant hormone responsible for cell division.
As a "natural" skin-care ingredient it is primarily being promoted as having been clinically proven to reduce
the signs of aging, improve sun damage, reduce surfaced capillaries, and offer many other skin benefits of
particular interest to aging baby boomers. There is a good deal of research on kinetin when it comes to
plants or in test tubes (in vitro), with cells, or even on flies, but there is no published research on kinetin's
topical effect, either on animal or human skin (Source: Dermatologic Clinics, October 2000, pages 609–615).

However, there are two unpublished clinical studies responsible for much of the attention kinetin is getting.
Both were sponsored by Senetek, the company licensing the use of kinetin. On a closer look, according to
MedFaq.com (a now-defunct Internet source that evaluated the legitimacy of medical research), the data are
far less convincing than Senetek would want you to know. These studies, paid for by Senetek, were both
done by Dr. Jerry L. McCullough, professor of dermatology, University of California, Irvine. According to
MedFaq, "The first study was well-designed—there was a control group and [it was done] double-blind….
After 24 weeks, a good response was noted in 30% of the subjects treated with kinetin… [but] there was no
statistically significant difference between the people taking kinetin and the people just getting the placebo."
Another study was then performed that did not use a placebo control group, but in which everyone was
using a product that contained some amount of kinetin. Not surprisingly, in this protocol the results for skin
were much better. "Essentially all of the subjects reported improvement after 24 weeks…" regardless of how
much kinetin the product contained. As MedFaq states, "This outcome could also have a variety of causes
unrelated to kinetin: It could reflect an improvement over time, a change across seasons, the subjects'
enthusiasm, or it could have been caused by the cream or lotion the kinetin is in. In the first study, all of the
subjects followed 'a standard skin care regimen consisting of a gentle-skin cleanser and daily use of
sunscreen.' If that regimen was followed in the second experiment, it too might explain the improvement."

kiwi fruit extract. As a food, kiwi has significant antioxidant properties that may even be greater than those
of vitamin C. Whether that benefit translates to its use on skin has not been demonstrated. The acid
component of the kiwi can be a skin irritant.

Kniphofia uvaria nectar. Derived from the plant also known as red hot poker or torch lily. There is no
research showing this to have any benefit for skin.

Ko ken. See kudzu root.

kojic acid. By-product in the fermentation process of malting rice for use in the manufacture of sake, the
Japanese rice wine. There is definitely convincing research, both in vitro and in vivo, and also in animal
studies, showing that kojic acid is effective for inhibiting melanin production. Both glycolic acid and kojic
acid, as well as glycolic acid with hydroquinone are highly effective in reducing the pigment in melasma
patients. So why aren't there more products available containing kojic acid? Kojic acid is an extremely
unstable ingredient in cosmetic formulations. Upon exposure to air or sunlight it turns a strange shade of
brown and loses its efficacy. Many cosmetics companies use kojic dipalmitate as an alternative because it is
far more stable in formulations. However, there is no research showing that kojic dipalmitate is as effective
as kojic acid, though it is a good antioxidant. There is a small amount of research showing kojic acid to be a
skin irritant.

kola nut. One of the major components of the kola nut is caffeine, which can be a skin irritant. However,
kola nut also has a primary amine content that can form nitrosamines, which are potential carcinogens.

konjac powder. A dietary fiber that is highly absorbent, but not more so than other food substances
(cornstarch for example) or nonfood substances (like talc, magnesium, or other minerals). If you have
problems with breakouts, any oil-absorbing substance can be helpful for skin; however, adding absorbents
in the form of food ingredients can increase the bacteria content in skin.

Krameria triandra extract. Derived from the plant commonly known as rhatany, it has a high tannin content
and skin-constricting properties, making it a potential skin irritant. However, it also has antioxidant
properties.

kudzu root. Source of isoflavone, genistein, and daidzein, all plant estrogens. It can be a potent antioxidant.