Oranges are well known for their high concentration of vitamin C, but the citrus fruit also contains many other vitamins and nutrients. Oranges also contain vitamin A, many of the B vitamins, and vitamin E, making them a regular part of a healthy and balanced diet.
Vitamin A is an important nutrient for vision, and for healthy skin. However, it can be toxic in excessive quantities — an overdose can damage the skin, make bones weak or brittle, and induce fatigue and vomiting. Consult a physician before exceeding the U.S. recommended daily allowance of vitamin A.
Water-soluble B vitamins play important roles in cell metabolism. Among the B vitamins contained in oranges: vitamin B1, or thiamine, which helps the body process protein, fat, and carbohydrates; vitamin B2, or riboflavin, which converts carbohydrates into fuel and activates vitamin B6 and folic acid; vitamin B3, or niacin, processes alcohol, forms fats from carbohydrates, and regulates cholesterol; vitamin B5, or panthotenic acid, helps the body get energy from fats, synthesizes cholesterol, and helps activate adrenal glands; vitamin B9, or folate, helps the body to produce red blood cells; and vitamin B6, which regulates moods and mental processes by helping to form neurotransmitters, dopamine, hormones, melatonin, and serotonin.
Vitamin C is a water-soluble substance that acts as an antioxidant, and contributes to the general health of the body in various ways. In reducing the clumping of platelets and the stiffness of arteries, it can protect against certain types of heart disease. It also strengthens blood vessels and muscles by helping the body to produce collagen, and is a natural antihistamine. Vitamin C also contributes to healing, combats viruses, assists in liver bile formation, and detoxifies the body.
Vitamin E helps the body process glucose, and its antioxidant properties may protect against some types of cancer and heart disease. Vitamin E may also protect against toxins from air pollution, premenstrual syndrome, cataracts, skin damage due to ultraviolet radiation, diabetes, and certain neurological disorders. Because it boosts the activity level of the immune system, vitamin E has limited benefits for those suffering from rheumatoid arthritis and asthma.