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Good nutrition is essential for maintaining proper function of the body systems, including the skin, the largest organ. Most health experts recommend eating a balanced diet with a variety of healthful foods to keep skin healthy and glowing, as well as to prevent diseases such as cancer and heart disease. In addition, healthy eating habits may help prevent worsening of some skin conditions, such as psoriasis.

Many substances found in food affect the skin’s health. These include:

• Antioxidants. Chemicals that interact with other chemicals called free radicals, which can damage the skin and other cells. Vitamins A, C, E and beta carotene – as well as certain fruits and vegetables – have antioxidant properties. These are essential for skin health, help in wound healing and may also help protect skin cells against damage by free radicals. Free radicals are toxic molecules, which are naturally produced by oxygen, sunlight (ultraviolet radiation), smoking and pollution.
  
  Some studies have indicated that antioxidants may help slow down skin aging by ridding the body of free radicals. However, the evidence to support these claims remains mixed.
  
  
• Vitamin D. Consuming adequate amounts of vitamin D can aid in calcium absorption, bone formation and skin healing. Lack of vitamin D can lead to softening of the bones. Good sources of vitamin D include egg yolks, herring, sardines, tuna, salmon and fortified milk.
  
  Vitamin D is also naturally formed in the skin when it is exposed to direct sunlight. However, sun exposure should be limited to avoid the damaging effects of excessive ultraviolet radiation on the skin (e.g., skin cancer, wrinkles).
  
  Since the body requires calcium to benefit from vitamin D, foods that contain both nutrients (e.g., fortified milk, salmon) are especially beneficial. Many dietary supplements also contain both vitamin D and calcium.
  
  
• Vitamin A. This vitamin is essential for growth, vision and immune response. A lack of vitamin A can result in skin disorders. It can also cause the nails to split and break.  
  
  
• Fat. Some fat is necessary to maintain healthy skin, hair and nails. For instance, eating foods with omega-3-fatty acids (e.g., salmon, cod, bass, broccoli) can help protect against fungal and bacterial nail infections. However, reducing intake of foods high in certain types of fat and cholesterol can decrease the risk of weight gain and coronary heart disease.
  
  It is more important to reduce the type of fat (such as trans fats and saturated fats) than to reduce the amount of fat. Trans fats are unsaturated fatty acids (building blocks of dietary fats) formed when vegetable oils are processed and made more solid. They are found in fats labeled “partially hydrogenated.” Many margarines and foods in fast food restaurants are sources of trans fats. Saturated fats contain high levels of saturated fatty acids. They can be found in animal products such as cheese, butter and red meat. 
  
  
• Fiber. High fiber intake has been shown to substantially reduce the risk of coronary heart disease and stroke. Fiber is also associated with lower cholesterol levels and improved bowel function, which help promote healthy looking skin.
  
  
• Folate. A type of B vitamin important to the production of skin cells. Natural sources of folate include certain breakfast cereals, orange juice, peas, peanuts, beans and leafy green vegetables.
  
  
• Iron. Iron is essential to proper oxygen transport and regulation of cell growth, including skin cells. A deficiency of iron limits oxygen delivery to cells, causing fatigue, decreased immunity and pale skin. Thin, rigid or easily broken nails may also indicate a lack of iron. Sources of iron include liver, kidneys, red meat, poultry, eggs, peas, legumes, dried fruits and leafy green vegetables (e.g., kale).
  
  
• Protein. Protein helps prevent muscle tissue from breaking down and helps repair tissue that has been damaged, including skin tissue. Sources of protein include meat, fish, poultry, eggs, milk, cheese, dried beans and peas, peanut butter, nuts, bread and cereal.
  
  
• Zinc. Zinc plays a crucial role in promoting cell reproduction and the growth and repair of tissues. Brittle nails with white spots may indicate a deficiency in zinc. Sources of zinc include whole grains, poultry and seafood (particularly oysters).
  
  
• Alcohol. Drinking alcohol causes small blood vessels in the skin to widen (dilate), allowing more blood to flow close to the skin's surface. This results in a flushed appearance and a feeling of warmth, which may worsen skin conditions including acne, rosacea, psoriasis and certain types of ulcers (pressure sores). In addition, excessive consumption of alcohol can deplete the body of water and lead to dry skin.
  
  
• Caffeine. This stimulant and diuretic can be found in coffee, tea, soft drinks, chocolate and some over-the-counter drugs. Excessive consumption can contribute to dehydration, which can lead to sallow, dry skin.