HEALTH UPDATES

Let Food Be They Medicine

Dietary intake of viatmin C and essential fatty acids affects skin aging

A recent study published in the American Journal of Clinical Nutrition found that women who consumed higher levels of vitamin C and linoleic acid and lower intakes of fats and carbohydrates had younger-looking skin. This study was the first of its kind to look at the relationship between dietary intake of certain nutrients and the effect on skin-aging and appearance in middle aged women.

Skin aging is greatly influenced by several factors including genetics, environment (e.g., sun exposure) and lifestyle (e.g., diet and smoking). Skin aging affects both the function and the appearance of the skin. Signs of skin aging include fine lines, wrinkles, hyperpigmentation, thinning skin (atrophy) and broken blood vessels. These dermal changes have been noted by a number of studies that investigated the relationship between nutrient intake and skin health or photoprotection.

In the present study, the nutritional intake of over 4,000 women between the ages of 40-74 years was observed. Nutritional intake was based on the first National Health and Nutrition Examination Survey or NHANES I. NHANES is conducted about every 4 years by the National Center for Health Statistics and examines the health and nutrition habits of the U.S. population. Since its inception in 1959, eight surveys have been conducted involving over 130,000 people. NHANES I was conducted during 1971-1974 and involved over 30,000 individuals aged 1-74 years.

In addition to examining nutritional intake, clinical examinations of the skin were conducted by dermatologists. Skin-aging was defined as a wrinkled appearance, dryness associated with aging (senile dryness) and thinning skin (skin atrophy). Each patient was also classified by their lifetime exposure to sunlight (low, moderate, high) and physical activity (very active, moderately active, quite inactive). Lifestyle factors such as cigarette smoking – which is known to prematurely age the skin – were also examined.

In reviewing the demographic data, a wrinkled appearance, skin dryness and thinning skin was associated with white women over 65 years of age; women who had a lower level of education and income; and women who consumed fewer calories, were moderately active or had high sunlight exposure.

In reviewing the dietary data, women with a wrinkled appearance had significantly lower intakes of protein, total dietary cholesterol, phosphorous, potassium, vitamin A and vitamin C. Women with dry skin associated with aging had significantly lower intakes of linoleic acid (the fat found in Omega-3 supplements like flax seed oil) and vitamin C than women without dry skin. Women with thinning skin had significantly lower linoleic acid intake than women without these changes. These differences were independent of factors known to affect skin aging such as exposure to sunlight.

One of the reasons why a higher level of vitamin C intake may be associated with a better skin-aging appearance is due to the antioxidant activity of this nutrient. Another explanation may lie in the photo-protective effect of vitamin C on the skin, which has been documented in a number of well-designed studies.

Although the study was based on the dietary habits of women from over 30 years ago, the information is relevant because the eating habits of Americans have declined during the past decade. Today, most women do not consume the recommended number of servings of fruits, vegetables, nuts, seeds and fish. Based on this most recent research, consuming more of these foods is not only good for women’s health but can positively influence the aging of their skin.

Source:
American Journal of Clinical Nutrition, 2007; 86:1225-31