Archive for May 2011

The Scoop on Sunscreen, Part 2

There is definitely a role for antioxidants in the area of sun protection. Ultraviolet rays create free radicals that cause photoaging of the skin. It has been demonstrated that the skin’s native antioxidant protection breaks down during excessive UV injury and aging (due to the fact that there are more free radicals created by the UV damage and cell metabolism than there are antioxidant molecules available in the skin). This allows free radicals to damage DNA, proteins, and lipids.

The photo-protective capability of antioxidants does not lie in their ability to reflect or absorb UV rays. Rather, they prevent the damage created by UV-generated free radicals. Antioxidants neutralize free radicals by donating one of their own electrons, ending the destructive cascade. The antioxidants themselves don’t become free radicals, because they are stable in either form due to their chemical behavior. They act as scavengers to prevent cell damage. Antioxidants that give up their electrons are not harmful, because they have the ability to accommodate the change in electrons without becoming reactive.

Under normal conditions, the antioxidant defense system within the body can easily handle free radicals that are produced. A free radical attack on a membrane usually damages a cell to the point that it must be removed by the immune system. Free radicals are commonly associated with an inflammatory response and are hypothesized to be greatest 24 hours after an insult. The immune system is the main body system that utilizes free radicals.

New methods to protect skin from photodamage are necessary, as sunscreens are under-used and have incomplete spectral protection. Skin naturally uses antioxidants to protect itself from photodamage. Vitamin C, Vitamin E, alpha lipoic acid, retinol, selenium, zinc, solymarin, soy, soflavones, and tea polyphenols may supplement sunscreen protection and provide additional photodamage repair when sunscreens fail. The incorporation of antioxidants into sunscreens provides added protection against the harmful effects of UV exposure and may provide reparative effects if/when sunscreens fail.

Antioxidants are manufactured in the body and can also be applied to the skin or extracted from ingested food. In other words, they create an increase in photoprotection when used in conjunc- tion with sunscreens.

There are other things that can be done in addition to wearing an effective sunscreen to protect against UVA/UVB rays. Particularly if you are reluctant to wear sunscreens, I would encourage you to wear protective clothing, find shade, avoid tanning beds, and get Vitamin D safely. Keep in mind that snow, ice, sand, glass and metal reflect UV rays. UV rays are able to penetrate water to a depth of about 30 inches. It is important to remember that fog and clouds only reduce UV intensity about 30 percent, and the sunscreen benefit of clothing is related to the thickness, type of fiber, weave, stretch, color and other factors. In fact, nylon stockings have an SPF of only 2-3.

Patients often inquire about window glass and sunglasses. UVB rays are blocked by glass, but UVA rays (the longer wavelength UV rays) pass through window glass and sunglasses and can damage the skin and eyes.

All the news is not bad. There have been advances. Environmental regulations have improved the thickness of the ozone layer. Clothing has been manufactured to provide sun protection, some chemically treated with sunscreen agents. Glass has been thickened, polarized and tinted to increase its sun protective properties. Many cosmetic products also contain pigment and sunscreen ingredients, which increase their sun protection ability to an SPF 3-15 based on the product.

Inorganic sunscreens—micronized zinc oxide and titanium dioxide—provide broad-spectrum protection with no concerns about toxicity. Emphasis on inorganic sunscreens and synergistic antioxidants may avoid concerns associated with organic sunscreens and may be particularly useful if you concerns about specific sunscreen ingredients.