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Medical Author:

Betty Kovacs, MS, RD

Betty Kovacs, MS, RD

Betty is a Registered Dietitian who earned her B.S. degree in Food and Nutrition from Marymount College of Fordham University and her M.S. degree in Clinical Nutrition from New York University. She is the Co-Director and Director of nutrition for the New York Obesity Research Center Weight Loss Program.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Vitamins

Vitamins are needed in small quantities to perform invaluable functions. They are required for normal function, growth, and maintenance of body tissues. Without a sufficient quantity of any vitamin, a deficiency will occur with a subsequent decline in health. Fortunately, a balanced diet is often sufficient enough to meet your needs.

Vitamins fall into two classes: fat-soluble and water-soluble. Their solubility will determine how the vitamin is absorbed and transported by the bloodstream, whether or not it can be stored in the body, and how easily it can be lost from the body. Requirements for each of the vitamins are based on age, gender, pregnancy, and lactation. You can find them at http://www.iom.edu/Object.File/Master/7/296/webtablevitamins.pdf.

The fat-soluble vitamins are A, D, E, and K. Adequate absorption of these vitamins is dependent on efficient fat intake and absorption. Except for vitamin K, fat-soluble vitamins are not easily excreted from the body, so they can be toxic at excessive levels. The only way to reach toxic levels would be through taking supplements, not through your diet. This is another case when balance is the key, and excessive amounts can cause harm.

Vitamin A is abundant in our food supply, so there is little risk of a deficiency. It is needed for regulation of the immune system, vision, reproduction, bone growth, cell division, and cell differentiation. A deficiency will result in night blindness and a decreased immune system, resulting in a decrease in the ability to fight infections. This can occur from an inadequate diet, chronic diarrhea, and an excess intake of alcohol. Dietary sources of vitamin A include

• whole eggs,



• milk,



• liver,



• fortified cereals,



• sweet potatoes,



• cooked spinach,



• fresh mango,



• cooked acorn squash,



• cooked kale,



• cooked broccoli, and



• margarine.

Vitamin D is supplied by our diet and sunlight. Exposure to ultraviolet (UV) rays from the sun can trigger the production of vitamin D in our body. The amount of sun needed will depend on your skin color, age, the time of the day, season, and geographic location. Experts have recommended that you expose your hands, face, and arms two to three times a week for about 10 to 15 minutes without sunscreen.

Vitamin D is needed for healthy bones by maintaining normal blood levels of calcium and phosphorus and for maintenance of a healthy immune system. A deficiency in children can result in rickets, and a deficiency in adults can cause osteomalacia. An inadequate diet, limited exposure to sunlight, and malabsorption can cause the deficiency. Dietary sources of vitamin D are

• cod liver oil,



• baked herring,



• salmon,



• canned tuna in oil,



• sardines in oil,



• milk,



• fortified cereals, and



• whole eggs.

Vitamin E has been shown to have a wide array of health benefits, including prevention of stroke, diabetes, cancer, heart disease, arthritis, cataracts and improved immune function. With all of the functions that vitamin E has, a deficiency of it can result in numerous health problems. Fortunately, vitamin E deficiencies are rare in this country. Impairment in your ability to absorb fat would put you at risk for a deficiency, so it's important to have your doctor monitor your levels. Dietary sources of vitamin E are

• almonds,



• sunflower seeds,



• sunflower oil,



• wheat germ,



• peanut butter,



• avocado,



• hazelnuts,



• broccoli, and



• kiwi.

Vitamin K is probably most well-known by those who take blood-thinning medications. Vitamin K plays a crucial role in blood clotting and needs to be monitored when taking these medications. Without vitamin K, your blood would not clot, so it is essential for everyone. Vitamin K is also needed for bone proteins. Some vitamin K can be made in the intestines. When people take antibiotics that kill the beneficial and harmful bacteria in the intestines, it puts them at risk for a vitamin K deficiency. Dietary sources of vitamin K include

• kale,



• spinach,



• turnip greens,



• collards,



• Swiss chard,



• parsley,



• mustard greens, and



• Brussels sprouts.

The water-soluble vitamins are B and C. Their solubility means that they can leech into water that they are washed, stored, and cooked in and can be excreted in the urine. They are associated with some of the most well-known deficiency diseases. When consumed in adequate amounts, they play an essential role in our health.

There are numerous B vitamins. Each one of them facilitates energy release in every cell, so a deficiency affects the entire body. Fortunately, deficiencies are rare when a diet is well balanced. These are the various B vitamins:

• Thiamin: Also known as vitamin B1, thiamin is involved in nervous-system and muscle functioning, the flow of electrolytes in and out of nerve and muscle cells, carbohydrate metabolism, and the production of hydrochloric acid. Very little thiamin is stored in the body, so depletion can occur in a little as 14 days. Chronic alcohol intake and an inadequate diet can lead to a thiamin deficiency. Beriberi is the deficiency disease for thiamin. Sources of thiamin are pork chops, sunflower seeds, green peas, baked potatoes, and enriched and whole grain cereals and pastas.



• Riboflavin: This B vitamin also plays a role in energy metabolism. It has similar function and sources as thiamin, so a deficiency in one usually means a deficiency in the other. Additional sources of riboflavin are milk and milk products and beef liver.



• Niacin: Along with its role in energy metabolism, niacin is also responsible for the synthesis and breakdown of fatty acids. Pellagra is the deficiency disease for niacin. Because the primary source of niacin is dairy products, poultry, fish, lean meats, nuts, and eggs, deficiencies can be found among the poor as well as in alcoholics.



• Folate: This vitamin became a mandatory addition to certain foods due to its role in producing and maintaining new cells. The folate fortification project was implemented for the protection of developing fetuses. A folate deficiency in a woman who is pregnant can cause neural tube defects that result in malformations of the spine (spina bifida), skull, and brain (anencephaly). Since the fortification of foods with folate began, the incidence of these defects has declined. Dietary sources of folate are fortified cereals, beef liver, pinto beans, lentils, spinach, asparagus, avocados, and broccoli.



• Vitamin B12: Like folate, vitamin B12 is needed for producing and maintaining new cells. It is also needed to maintain the sheaths that surround and protect nerve fibers. An inadequate amount of B12 causes pernicious anemia. Signs of vitamin B12 deficiency are fatigue, weakness, constipation, loss of appetite, weight loss, and numbness and tingling in the hands and feet. An excess intake of folate can mask the symptoms of B12 deficiency, so it's important to have your levels checked by a blood test, especially if you consume a vegetarian diet. Vitamin B12 is found in animal products like trout, salmon, beef, and dairy foods. There are fortified cereals that provide B12 as well.

Vitamin C is needed to form collagen in bones, cartilage, muscle, and blood vessels, and aids in the absorption of iron. Vitamin C deficiency was discovered in sailors more than 200 years ago. This deficiency, later called scurvy, was killing sailors who stayed out on the sea for long voyages. Initial symptoms of scurvy in adults may include loss of appetite, diarrhea, shortness of breath, weakness, and fever, followed by irritability, depression, leg pain, pseudoparalysis, swelling over long bones of the body, anemia, paleness, poor wound healing, corkscrew hair, dry eyes, skin thickening (hyperkeratosis), and bleeding (particularly gum bleeding, bleeding behind the eyes causing prominence, bleeding at the joints of the ribs and sternum causing discoloration under the skin of the chest, skin bruising, or blood in the urine or stool). Scurvy can now be prevented with an adequate diet. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits such as oranges, limes, and lemons.