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Linoleic Acid Also Protective, Study Suggests
By Salynn Boyles
WebMD Health News
Reviewed by Louise Chang, MD
Oct. 8, 2007 -- An orange a day may keep the wrinkles away.
In one of the first studies to examine the impact of nutrients from foods rather than supplements on skin aging, researchers reported that people who ate plenty of vitamin C-rich foods had fewer wrinkles than people whose diets contained little of the vitamin.
Diets rich in the omega-6 fatty acid linoleic acid were also associated with less skin aging from dryness and thinning, while higher-fat diets and those higher in carbohydrates were associated with more wrinkling.
Sunflower and safflower oils and many nuts are high in linoleic acid. Byproducts of linoleic acid are plentiful in salmon and other fatty fish.
The findings are far from conclusive, but they do suggest that when it comes to skin aging, you truly are what you eat.
"Our findings add evidence to a predominately supplement and topical application-based hypothesis that what we eat affects our skin-aging appearance," nutritional epidemiologist Maeve C. Cosgrove and colleagues write in the October issue of The American Journal of Clinical Nutrition.
Expert Isn't So Sure
But a dermatologist and skin-aging expert who spoke to WebMD remains skeptical.
Susan H. Weinkle, MD, who is a visiting clinical professor of dermatology at the University of South Florida, says it is difficult, if not impossible, to prove that specific foods affect wrinkling one way or another.
"Skin aging, especially facial aging, is remarkably multifactorial. It involves many things including genetics, ultraviolet light exposure, and lifestyle," she says.
The study was designed and carried out by researchers from Unilever, distributor of some 400 food, home cleaning, and personal care products.
The researchers analyzed data from a comprehensive health study conducted in the United States between 1971 and 1974, known as NHANES I. Their analysis included 4,025 women between the ages of 40 and 74 who had extensive dermatologic exams designed to evaluate skin wrinkling and other aspects of skin aging.
The women also completed a 24-hour recall survey listing all the foods they ate in a particular day.
Eating a diet low in vitamin C appeared to be a risk factor for wrinkling and aging-related skin dryness.
This makes sense, the researchers say, because vitamin C is an antioxidant that has been shown to play a role in the synthesis of collagen, the protein that helps keep skin elastic.
Higher dietary intake of linoleic acid was associated with a reduced risk of age-related dryness and thinning of the skin.
After digestion, linoleic acid is converted to DHA and EPA -- two fatty acids.
While the role of linoleic acid in skin aging has not been directly studied, the researchers note that several studies have suggested that DHA and EPA found in fish oil can protect against skin aging.
Weinkle says the dermatologic benefits of eating that much fish or any fish at all have yet to be proven.
"Again, this is very difficult to measure," she says.
So what can help keep skin looking young for as long as possible? Good genes play a big role, but so does protecting the skin from damage. Weinkle suggests:
- Stay hydrated. "We know that when people are dehydrated wrinkles are much
more noticeable," she says.
- Religious use of a good sunscreen. She recommends
looking for a sunscreen that has the words "stabilized UVA blockage" on its
- Don't smoke or stop smoking if you do.
- Use a good face cream to keep skin from losing precious moisture.
SOURCES: Cosgrove, M.C. American Journal of Clinical Nutrition, October 2007; vol 86: pp 1225-1231. Maeve C. Cosgrove, nutritional epidemiologist, corporate research, Unilever Colworth Park, Bedford, England. Susan Weinkle, MD, visiting clinical professor of dermatology, University of South Florida, Miami; spokeswoman, American Academy of Dermatology.
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