Cosmeceutical Critique: SeleniumDr. Leslie Baumann
Volume 33, Issue 10, Page 28 (October 2002)
With the trend toward a more natural health care approach, many patients are drawn to beauty formulas and regimens that contain natural elements, such as selenium.
An essential trace element found in the human body, selenium is said to have anticarcinogenic, anti-inflammatory, antioxidant, and therefore antiaging properties. Water, soil, and plant foods are the major sources of selenium in most countries. It is also found in foods such as cereals and cereal products, meat, fish, Brazil nuts, shellfish, and dairy products. Its toxicologic properties and essential nutritional role were first discovered in livestock in the late 1950s and in humans in 1973.
Epidemiologic studies indicate an association between selenium deficiency and carcinogenesis, fatal cardiomyopathy (Keshan disease), and cardiovascular disease; selenium limits oxidation of LDL cholesterol and carcinogenesis (Altern. Ther. Health Med. 2:59-62, 1996).
Selenium also affects thyroid function, because it is essential for the synthesis of active thyroid hormone.
Currently, only one reductive metabolic pathway of selenium is well characterized in biologic systems. Selenium is the vital antioxidant required to form glutathione peroxidase, one of our most important natural antioxidant defenses.
This essential antioxidant enzyme protects membranes from oxidative deterioration, a function that it shares with vitamin E. In fact, studies have concluded that vitamin E and selenium are synergistic (Ann. Biol. Clin. [Paris] 54:181-87, 1996).
Efficient removal of superoxide free radicals by the selenium–glutathione peroxidase couple maintains the integrity of membranes, reduces the risk of cancer, boosts the immune system, and slows the aging process. This action is what causes some to believe that selenium has an impact on carcinogenesis. Several studies have linked low levels of selenium to an increase in the incidence of prostate cancer (J. Natl. Cancer Inst. 90:1219-24, 1998).
Further, the incidence of nonmelanoma skin cancer is significantly higher in areas of the United States with low soil selenium levels. A multicenter trial, however, concluded that supplementation with 200 ?g of selenium daily did not affect the recurrence of these nonmelanoma skin cancers but significantly reduced the total morbidity and mortality from other cancers, including lung, colorectal, and prostate cancer (JAMA 277:880-81, 1997).
Selenium also contains anti-inflammatory properties that prevent the production of inflammatory cytokines. One study showed that after damage to the skin from UV exposure, inflammatory cytokines inhibit the immune response, thus increasing the number of damaged skin cells (J. Invest. Dermatol. 110:653, 1998). These inflammatory cytokines also lead to the formation of wrinkles and premature aging of the skin.
Further, selenium enhances both the humoral and cellular immunity, increasing the host response to infection (Clin. Exp. Dermatol. 25:631-36, 2000).
As a result of these antioxidant, anti-inflammatory, and anticarcinogenic properties, selenium has been added to topical skin care products as well as natural spring water vaporizers for the skin. Another form of selenium, selenium sulfide, is a common additive in antidandruff shampoos because of its antimicrobial effect on tinea capitis and the yeast Pityrosporum ovale.
The current Recommended Daily Allowance of oral selenium is 55 ?g for both men and women. However, researchers are currently looking at daily doses as high as 400 ?g. It must be noted that selenium toxicity, or selenosis, exists. High doses of selenium are neurotoxic and can cause hair loss, nail loss, and dermatitis, as well as gastrointestinal upset.
Despite advertising claims, most available topical formulations contain very low concentrations of selenium, which are not well absorbed by the skin. Formulated as selenium sulfide, selenium does not penetrate the skin. However, cutaneous selenium absorption can be achieved with L-selenomethionine.
Recent animal and human studies have found that when taken orally or applied topically in the form of L-selnomethionine, selenium demonstrated protection against both daily and excessive UV damage. Treated patients also experienced decreased skin inflammation and pigmentation, and there was a delay in the onset and a decrease in the incidence of skin cancer (J. Invest. Dermatol. 106.1086-89,1996; Nutr. Cancer 17:123-37, 1992).
In a more recent study, researchers at the University of Edinburgh (Scotland) concluded that oral selenium had significant protective effects against UV radiation–induced damage to skin cells. The researchers did not examine topical selenium (Clin. Exp. Dermatol. 25:631-36, 2000).
While studies outside of dermatology suggest that oral selenium has nutritional benefits and is an anticarcinogenic and anti-inflammatory agent, the dermatologic benefits are still being investigated. Although these early studies of the effects of both oral and topical selenium are promising, more double-blind, placebo-controlled trials are needed to support selenium as an adjunct to the antiaging product market.
DR. LESLIE S. BAUMANN is director of cosmetic dermatology at the University of Miami. Dr. Monica Halem, a research fellow at the university, contributed to this column. To respond to the column, or to suggest topics for future columns, write to Dr. Baumann at our editorial offices or via e-mail to email@example.com.
© 2002 International Medical News Group. Published by Elsevier Inc. All rights reserved.