Vitamins are organic nutrients that are vital for good health and normal functioning of all the cells, tissues and processes of the body. It's important to eat a balanced diet that contains a wide variety of foods to get all of the vitamins you need. The symptoms of a vitamin deficiency depend on what areas of the body the vitamin affects. There are many different vitamins, and you should consult your doctor if you're concerned about a deficiency.
Vitamin D allows the bones to absorb calcium, which is necessary for their growth and strength. There are two forms of the vitamin. Vitamin D-2 is found in egg yolks, fatty fish, fortified milk and liver. Vitamin D-3 is made by the body when the skin is exposed to sunlight. Symptoms of a lack of vitamin D include bone fractures and softening of the bones. The RDA for vitamin D is 400 IU, although some nutrition experts now recommend 800 to 1,000 IU. A lack of vitamin D may increase the risk of macular degeneration in the eyes, breast and prostate cancers, diabetes and high blood pressure.
Vitamin A is essential for eyesight. You can get vitamin A in foods such as green, red and yellow vegetables, brightly colored fruits, liver, dairy products, fish liver oil and eggs. Symptoms of a vitamin A deficiency include night blindness, damage to the eyes, vision loss, dry and scaly skin, respiratory infections and other signs of decreased immune system function. The RDA is 2,333 IU for women and 3,000 IU for men. Too much vitamin A can be toxic.
Vitamin B-12 is vital for the neurological system and the production of blood cells. Animal products, including eggs, meat, dairy products and fish, especially clams and fatty fish, are the only natural sources of the vitamin. It's also added to some cereals. A lack of vitamin B-12 is characterized by abnormal walking in the elderly, memory loss, instability, depression, confusion, decreased reflexes, decreased hearing and abnormal growth in children. Permanent neurological damage can result. The RDA of vitamin B-12 for adults is 2.4 mcg.
Vitamin C is protects the cells from damage, and is necessary for the production of collagen, an essential protein found in bones, tendons, ligaments and cartilage. A lack of vitamin C causes a condition called scurvy, which has symptoms of fatigue, weakness, pale skin, sunken eyes, inflamed gums, muscle pain, poor appetite, easy bruising, diarrhea, fever, aching joints, irritability and shortness of breath. You can get this vital nutrient from fruits and vegetables, especially citrus fruits, papayas, bell peppers, hot chili peppers, potatoes, broccoli, leafy greens and sweet potatoes. The RDA for vitamin C is 75 mg for women and 90 mg for men.
Vitamin B-1, or thiamine, is necessary for the production of red blood cells, for converting blood sugar into energy and for the normal metabolic functions of the heart, nerves and muscles. A lack of vitamin B-1 causes beriberi. There are two forms of the disorder, which mainly affect alcoholics. Wet beriberi affects the cardiovascular system, and symptoms include shortness of breath during activity and during sleep, a fast heart rate and swelling of the lower legs. Dry beriberi affects the nervous system and is characterized by confusion, difficulty walking, vomiting, difficulty speaking, and tingling, pain and loss of sensation in the hands and feet. The RDA for vitamin B-1 is approximately 1.1 mg. You can get this vitamin from pork, fortified cereals, nuts, oatmeal, sunflower seeds and cauliflower.