Study Examines Vitamin Products for Sun-Damaged Skin

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It’s that time of the year when sun worshippers take to the beaches and lounge chairs, exposing themselves to the risk of sun-damaged skin. A new study reviews the use of skin care products that contain vitamins and which claim to slow or reverse the impact of sun damage on the skin.

Although the best way to avoid the damaging and aging effects of ultraviolet (UV) radiation on the skin is to greatly limit your exposure to the sun and tanning beds, many people still choose to seek a tan or are exposed to UV rays because of their work. Numerous manufacturers produce skin care products containing vitamins which they claim can fight the effects of photoaging. But how true are these claims?

Dermatologist Jenny Kim, MD, PhD, FAAD, associate professor in dermatology, department of medicine at the University of California, Los Angles, David Geffen School of Medicine, and her colleagues reviewed the literature to determine the potential impact of skin care products containing vitamins A, C, E, and B3 on sun-damaged skin and photoaging.

Retinols and carotenoids are the two most common forms of vitamin A studied regarding photoaging. The researchers concluded that large clinical trials are still needed to explore the photoprotective benefits of carotenoids, but they may be helpful in preventing UV-induced collagen breakdown. Prescription retinoid products have scientific data to support their use for treating photoaged skin, but there is less evidence to support the effectiveness of over-the-counter retinoid products in improving photoaged skin.

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“We cannot assume that all retinoids are equal in their ability to fight photoaging,” said Dr. Kim. “Patients should consult their dermatologist before using any topical retinoid, as side effects can occur when used with other topical products.” She also noted that there is little evidence to support the use of oral retinoids to treat photoaging.

Vitamin C is a potent antioxidant, which theoretically means it could reverse the damage caused by UV radiation, but few clinically controlled studies support this idea. One challenge presented by topical formulas that contain vitamin C, also known as ascorbic acid, is that the body must convert the ascorbic acid to L-ascorbic acid. Dr. Kim notes that “many of the stabilized, commercially available forms have not been examined to determine whether this conversion is possible.” Therefore consumers may not be getting any benefit from a skin care product that contains vitamin C.

Another antioxidant, vitamin E, is available in many topical skin care products, but there is no data to support claims that it improves skin wrinkling, texture, or discoloration. Vitamin E has been studied more as a means to protect the skin before exposure to the sun than as an agent to reduce photoaging. Dr. Kim noted that although combining vitamins E and C in an oral supplement may provide some photoprotection, too much oral vitamin E can be harmful. In fact, two studies suggest high intake may increase the risk of basal cell carcinoma.

Lastly, clinical trials using topical vitamin B3 (niacinamide) have demonstrated that the vitamin has the ability to reduce dark spots on the skin. In a 2005 study that involved the application of 5% niacinamide to one side of the face twice daily for 12 weeks, the women in the study experienced significant reductions in redness, wrinkles, and yellowing, and improved skin elasticity. Dr. Kim notes, however, that larger clinical trials are needed to verify the role of vitamin B3 in the treatment of photoaging.

Dr. Kim’s message to consumers who are concerned about sun-damaged skin is to practice proper protection against the sun and to maintain a healthy diet that includes the recommended daily supply of vitamins. When it comes to buying topical agents to treat sun-damaged skin, Dr. Kim warns that “consumers should understand from our study that skin care products with vitamins may not provide clinically meaningful improvement.”

SOURCES:
American Academy of Dermatology
Bissett DL et al. Dermatologic Surgery 2005 Jul; 31(7 Pt 2): 860-65
Zussman J, Ahdout J, Kim J. Journal of the American Academy of Dermatology 2010 Feb 26.

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