Nutrition and the Skin
The skin is the largest organ in the body and protects us from losing water and protein, while providing a barrier against ultraviolet radiation and infection. The skin requires adequate nutrients, including enough water and protein, to maintain its function. Some nutrients are concentrated in the skin. People who eat a lot of carrots will notice that their skin turns an orange tone due to the concentration of beta-carotene in the skin. This beta-carotene can protect the skin from ultraviolet radiation.
Nutrition not only affects the day-to-day functioning of the skin, but also can influence the risk of developing various types of skin lesions, including age spots and acne. Studies have shown that the incidence of precancerous aging spots (called solar keratoses) can be reduced in individuals exposed to lots of sunlight by reducing the total fat in the diet.
Acne is a common condition associated with obesity, especially in women with increased male hormone levels, leading to oily skin and plugging of hair follicles. Acne is more common in individuals with obesity and diabetes than in the general population, but is a normal occurrence during puberty when male hormone levels are increasing in both teenage girls and boys.
The stratum corneum, or outer layer of the skin, is made up of 14 layers of dead cells shed by the living cells, which are found many layers below the surface of the skin. These dead cells can harbor bacteria, undergo oxidation and affect skin health. The deep living skin cell layers are also fed by the bloodstream so that nutrients can reach them from above and below. Some vitamins applied to the skin have been shown to increase nutrient levels more effectively than vitamins taken orally, but both contribute to the vitamin levels measured in skin cells. Vitamin A, beta-carotene, colorful antioxidants, green tea and fish oils in the diet have all been considered to have positive effects on skin health. A diet providing adequate protein, healthy fats and oils and antioxidants from colorful fruits and vegetables can help maintain healthy skin.
Recent studies in mice have indicated an interrelation between energy balance, diet, and the composition of the gut bacteria.
The Fitness Textbook will teach you the basic principles of human performance nutrition, including muscle metabolism and fuel utilization before, during and after exercise.