Vitamins

Definition

Vitamins are a group of substances essential for normal cell function, growth and development.

There are 13 essential vitamins. That means they are needed for the body to function. They are:

• Vitamin A
• Vitamin C
• Vitamin D
• Vitamin E
• Vitamin K
• Vitamin B1 (thiamine)
• Vitamin B2 (riboflavin)
• Vitamin B3 (niacin)
• Pantothenic acid
• Biotin
• Vitamin B6
• Vitamin B12
• Folate (folic acid)

Vitamins are grouped into two categories:

• Fat-soluble vitamins are stored in the body's fatty tissue.
• Water-soluble vitamins must be used by the body right away. Any left over water-soluble vitamins leave the body through the urine. Vitamin B12 is the only water-soluble vitamin that can be stored in the liver for many years.

Function

Each vitamin has specific functions. You can develop health problems (deficiency disease) if you do not get enough of a particular vitamin.

Vitamin A helps form and maintain healthy teeth, bones, soft tissue, mucous membranes, and skin.

Vitamin B6 is also called pyridoxine. The more protein you eat, the more vitamin B6 is needed to help the body use protein. Vitamin B6 helps form red blood cells and maintain brain function, among other things.

Vitamin B12, like the other B vitamins, is important for metabolism. It also helps form red blood cells and maintain the central nervous system.

Vitamin C, also called ascorbic acid, is an antioxidant that promotes healthy teeth and gums. It helps the body absorb iron and maintain healthy tissue. It also promotes wound healing.

Vitamin D is also known as the "sunshine vitamin," since it is made by the body after being in the sun. Ten to 15 minutes of sunshine 3 times a week is enough to produce the body's requirement of vitamin D. However, many people living in sunny climates still do not make enough vitamin D and need more from their diet or supplements. Vitamin D helps the body absorb calcium, which you need for the normal development and maintenance of healthy teeth and bones. It also helps maintain proper blood levels of calcium and phosphorus.

Vitamin E is an antioxidant also known as tocopherol. It plays a role in the formation of red blood cells and helps the body use vitamin K.

Vitamin K is not listed among the essential vitamins, but without it blood would not stick together (coagulate). Some studies suggest that it helps promote strong bones in the elderly.

Biotin is essential for the metabolism of proteins and carbohydrates, and in the production of hormones and cholesterol.

Niacin is a B vitamin that helps maintain healthy skin and nerves. It is also has cholesterol-lowering effects.

Folate works with vitamin B12 to help form red blood cells. It is necessary for the production of DNA, which controls tissue growth and cell function. Any woman who is pregnant should be sure to get enough folate. Low levels of folate are linked to birth defects such as spina bifida. Many foods are now fortified with folic acid.

Pantothenic acid is essential for the metabolism of food. It is also plays a role in the production of hormones and cholesterol.

Riboflavin (B2) works with the other B vitamins. It is important for body growth and the production of red blood cells.

Thiamine (B1) helps the body cells change carbohydrates into energy. It is also essential for heart function and healthy nerve cells.

Food Sources

FAT-SOLUBLE VITAMINS

Vitamin A:

• Eggs
• Meat
• Milk
• Cheese
• Cream
• Liver
• Kidney
• Cod
• Halibut fish oil

Vitamin D:

• Cheese
• Butter
• Margarine
• Cream
• Fortified milk
• Fish
• Oysters
• Cereals

Vitamin E:

• Wheat germ
• Corn
• Nuts
• Seeds
• Olives
• Spinach and other green leafy vegetables
• Asparagus
• Vegetable oils and products made from vegetable oils, such as margarine

Vitamin K:

• Cabbage
• Cauliflower
• Spinach
• Soybeans
• Cereals

WATER-SOLUBLE VITAMINS

Folate:

• Green, leafy vegetables
• Fortified foods

Niacin (B3):

• Dairy products
• Poultry
• Fish
• Lean meats
• Nuts
• Eggs
• Legumes
• Enriched breads and cereals

Pantothenic acid and biotin

• Eggs
• Fish
• Dairy products
• Whole-grain cereals
• Legumes
• Yeast
• Broccoli and other vegetables in the cabbage family
• White and sweet potatoes
• Lean beef

Thiamine (B1):

• Fortified breads, cereals, and pasta
• Whole grains
• Lean meats
• Fish
• Dried beans
• Peas
• Soybeans
• Dairy products
• Fruits and vegetables

Vitamin B12:

• Meat
• Eggs
• Poultry
• Shellfish
• Milk and milk products

Vitamin C (ascorbic acid)

• Citrus fruits and juices
• Strawberries
• Tomatoes
• Broccoli
• Turnip and other greens
• Sweet and white potatoes
• Cantaloupe

Most other fruits and vegetables contain some vitamin C; fish and milk contain small amounts.

Side Effects

Many people think that if some is good, a lot is better. This is not always the case. High doses of certain vitamins can be poisonous. Ask your doctor what is best for you.

Recommendations

The Food and Nutrition Board at the Institute of Medicine establish recommended dietary allowances (RDAs) for vitamins. The recommendations reflect how much of each nutrient you should receive on a daily basis, based on the known nutritional needs of practically all healthy people.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid.

Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy).

References

Hamrick I, Counts SH. Vitamin and mineral supplements. Wellness and Prevention. December 2008:35(4);729-747.

Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 237.

Anderson RA. Prescribing antioxidants. In: Rakel D, ed. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 103.

• Vitamin A Benefit

  Vitamin A, also known as retinol, is essential to the formation of visual purple in the retina, which allows vision in dim light. Beta carotene, the precursor to vitamin A found in vegetables, has antioxidant properties, which means it protects cells from the daily toxic damage of oxidation.

• Vitamin A Source

  Like most vitamins, vitamin A may be obtained in the recommended amount with a well-balanced diet, including some enriched or fortified foods.

• Vitamin B6

  Vitamin B6 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. The body cannot store them. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet.

• Benefits of Vitamin B6

  Pyridoxine, or vitamin B6, boosts the manufacture of antibodies to support the immune system. Large doses of B6 can cause numbness and neurological problems.

• Sources of Vitamin B6

  
  Like most vitamins, vitamin B6 may be obtained in the recommended amount with a well-balanced diet, including some enriched or fortified foods.

• Vitamin B12

  Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the body through the urine.
  Typically, water-soluble vitamins can not be stored by the body. Vitamin B12 is special, because the body can store it for years in the liver.

• Vitamin B12

  Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the body through the urine..

• Vitamin C

  Vitamin C is a water-soluble vitamin that is necessary for normal growth and development.
  Water-soluble vitamins dissolve in water. The body cannot store them. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet.

• Benefits of Vitamin C

  Ascorbic acid, or vitamin C, aids in many functions of the body, including the absorption of iron. Large doses of C do not usually cause toxicity because, as a water-soluble vitamin, it is simply excreted in the urine. People who tend to form kidney stones may find their condition aggravated by vitamin C supplementation or megadosing.

• Vitamin C Deficit

  A deficiency of Vitamin C may lead to a condition called Scurvy, characterized by weakness, anemia, bruising, bleeding gums and loose teeth.

• Vitamin D

  Too much vitamin D can make the intestines absorb too much calcium. This may cause high levels of calcium in the blood. High blood calcium can lead to calcium deposits in soft tissues such as the heart and lungs. This can reduce their ability to function.

• Sources of Vitamin D

  Like most vitamins, vitamin D may be obtained in the recommended amount with a well-balanced diet, including some enriched or fortified foods. In addition, the body manufactures vitamin D when exposed to sunshine, and it is recommended people get 10 to 15 minutes of sunshine 3 times a week.

• Benefits of Vitamin D

  Vitamin D promotes retention and absorption of calcium and phosphorus, primarily in the bones. Too much vitamin D may have the opposite effect of taking calcium from the bones and depositing it in the heart or lungs, reducing their function.

• Deficit of Vitamin D

  Because vitamin D is essential for the body's utilization of calcium, a deficiency may result in severe loss of calcium and consequently a softening and weakening of bones.

• Vitamin E

  Vitamin E is an antioxidant that protects body tissue from damage caused by unstable substances called free radicals. Free radicals can harm cells, tissues, and organs. They are believed to play a role in certain conditions associated with aging.

• Vitamin K

  Vitamin K is known as the clotting vitamin, because without it blood would not clot. Some studies indicate that it helps in maintaining strong bones in the elderly.

• Vitamin K

  Vitamin K is known as the clotting vitamin, because without it blood would not clot. Some studies indicate that it helps in maintaining strong bones in the elderly.

• Riboflavin

  Riboflavin (vitamin B2) works with the other B vitamins. It is important for body growth and red blood cell production and helps in releasing energy from carbohydrates.