Vitamin are a group of substances essential for normal metabolism, growth and development, and regulation of cell function. Vitamins work together with enzymes, co-factors (substances that assist enzymes), and other substances necessary for healthy life.
There are 13 vitamins essential for bodily functions and these can be divided into two categories: fat-soluble vitamins and water-soluble vitamins. Fat-soluble vitamins include vitamins A, D, E and K. The water-soluble vitamins are thiamine, niacin, folate, vitamin B12, pantothenic acid and biotin and vitamin C. All vitamins can be obtained from food while vitamins D and K can be synthesized by the body.
As most individuals with eating disorders do not get adequate amounts of these essential nutrients from the foods they eat, it is important to include a vitamin supplement in your daily routine. While most multi-vitamins will provide sufficient quantities of each of the 13 essential vitamins, I highly recommend pre-natal vitamins as they are generally of a higher quality and contain more of the trace nutrients that others may not provide. They do tend to be a bit more expensive than other multi-vitamins but they are well worth the additional cost.
Vitamin A is a fat-soluble vitamin which helps form and maintain healthy teeth, skeletal and soft tissue, mucous membranes and skin. It is also known as retinol because it generates the pigments in the retina. Vitamin A also promotes good vision, especially in dim light. It may also be required for reproduction and breast-feeding.
Beta-carotene, the precursor to vitamin A, has antioxidant properties which are known to quench free radicals, which are unstable substances that can react with and damage cells, tissues and organs. Free radicals are believed to be associated with many of the degenerative changes seen with aging. However, it is not yet known whether antioxidants can prevent these changes and studies have been conflicting. For example, one study found increased cancer risk in smokers who took high doses of beta carotene.
As with many other vitamins, a certain amount of Vitamin A is necessary, but too much is toxic. If you don't get enough Vitamin A, you are more susceptible to infectious diseases and vision problems. However, large doses of Vitamin A can be toxic. Large doses can also cause abnormal foetal development in pregnant women.
Increased amounts of beta-carotene can turn the colour of skin to yellow or orange. The skin colour returns to normal once the increased intake of beta-carotene is reduced.
Vitamin D is a fat-soluble vitamin that promotes the body's absorption of calcium, which is essential for the normal development of healthy teeth and bones. It also helps maintain adequate blood levels of the minerals calcium and phosphorus.
A vitamin D deficiency leads to soft bones or rickets while large doses of vitamin D can result in increased calcium absorption from the intestinal tract, and possibly also to increased calcium resorption from the bones, leading to elevated levels of calcium in the blood. This can lead to abnormal calcium deposition in soft tissues, such as the heart and lungs, reducing their ability to function.
Vitamin D is also known as the "sunshine vitamin" because the body manufactures the vitamin after being exposed to sunshine. Ten to 15 minutes of sunshine 3 times weekly is adequate to produce the body's requirement of vitamin D.
Vitamin E is a fat-soluble vitamin. It acts as an antioxidant that protects body tissue from damage caused by unstable substances called free radicals. Free radicals can harm cells, tissues, and organs, and they are believed to be one of the causes of the degenerative processes seen in aging. Vitamin E is also important in the formation of red blood cells and it helps the body to use vitamin K.
The benefit of vitamin E supplementation in cancer, heart disease, dementia, liver disease, and stroke are still not known. It is likely that a protective effect will be found for coronary artery disease.
There is no known dietary deficiency of vitamin E.
Vitamin K is a fat-soluble vitamin that plays an important role in blood clotting. 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 deficiency is very rare and occurs when there is an inability to absorb the vitamin from the intestinal tract. Vitamin K deficiency can also occur after prolonged treatment with oral antibiotics. Individuals with vitamin K deficiency usually have an increased propensity to bruising and bleeding.
Thiamine is one of the B vitamins, a group of water-soluble vitamins that participate in many of the chemical reactions in the body. Thiamine (vitamin B1) helps the body cells convert carbohydrates into energy. It is also essential for the functioning of the heart, muscles, and nervous system.
A deficiency of thiamine can cause
weakness, fatigue, psychosis, and nerve damage. Thiamine deficiency in the U.S.
and is most often seen in alcoholics, because heavy drinking limits the ability
of the body to absorb this vitamin from foods. Since few alcoholics consume
higher than normal amounts of thiamine to make up for the difference, they
become deficient and may develop the disease called beriberi.
In severe deficiency, brain damage can occur. One type is called Korsakoff
syndrome (confusion and loss of short-term memory); the other is Wernicke's
disease (eye disturbances, unsteady gait, and confusion). Either or both of
these conditions can occur in the same person.
There is no known toxicity associated with thiamine.
Niacin is a water-soluble vitamin necessary for many aspects of health, growth, and reproduction. It is part of the vitamin B complex. Niacin assists in the functioning of the digestive system, skin, and nerves. It is also important for the conversion of food to energy.
A deficiency of niacin causes pellagra.
The symptoms include inflamed skin, digestive problems, and mental impairment.
Large doses of niacin can cause liver damage, peptic ulcers, and skin rashes.
Even normal doses can be associated with skin flushing. It can be prescribed as
a treatment for elevated total cholesterol and other types of lipid disorders,
but it should only be used with medical supervision due to its potential for
severe side effects.
Folic acid (folate) is a water-soluble
vitamin in the B-complex group. It works along with vitamin B12 and vitamin C to
help the body digest and utilize proteins and to synthesize new proteins when
they are needed. It is necessary for the production of red blood cells and for
the synthesis of DNA (which controls heredity and is used to guide the cell in
its daily activities). Folic acid also helps with tissue growth and cell
function. In addition, it helps to increase appetite when needed and stimulates
the formation of digestive acids.
Synthetic folic acid supplements may be used in the treatment of disorders
associated with folic acid deficiency and may also be part of the recommended
treatment for certain menstrual problems and leg ulcers.
Most people in the United States have
an adequate dietary intake of folic acid because it is plentiful in the food
supply. However, pregnant women often require additional supplementation as
prescribed by a health care provider. Adequate folic acid is important for
pregnant women because it has been shown to prevent some kinds of birth defects,
including neural tube defects such as spina bifida. Many foods are now fortified
with folic acid to help prevent these kinds of birth defects.
Women in their childbearing years should make an effort to consume foods that
are good sources of folic acid. Studies published by the Centers for Disease
Control and Prevention (CDC) suggest that women who receive supplements of folic
acid BEFORE CONCEPTION may reduce the risk for neural tube defects by 50%. Women
who plan to become pregnant may want to discuss taking a multivitamin with their
health care provider if they are not already doing so.
Folic acid deficiency may cause poor growth, greying hair, inflammation of the tongue (glossitis), mouth ulcers, peptic ulcer, and diarrhoea. It may also lead to certain types of anaemia. Toxicity from excessive folic acid intake does not normally occur, as folic acid is water soluble and regularly excreted by the body.
Vitamin B12 is a water-soluble vitamin that is part of the vitamin B complex. Like the other B vitamins, it is important for metabolism. It helps in the formation of red blood cells and in the maintenance of the central nervous system.
Because vitamin B12 comes primarily from animal products, people who follow a strict vegetarian diet and do not consume eggs or dairy products may require vitamin B12 supplements. (Non-animal sources of vitamin B12 exist but are highly variable in their B12 content, and are therefore unreliable sources.)
The human body stores several years' worth of vitamin B12, so nutritional deficiency of this vitamin is extremely rare. However, deficiency can result from being unable to use vitamin B12. Inability to absorb vitamin B12 from the intestinal tract can be caused by a disease known as pernicious anaemia. Additionally, strict vegetarians or vegans who are not taking in proper amounts of B12 by way of supplements are also prone to a deficiency state. Low levels of B12 can cause anaemia as well as numbness or tingling in the extremities and other neurologic symptoms such as weakness and loss of balance.
Pantothenic acid and biotin are water-soluble vitamins, which means that they cannot be stored by the body and must be replenished every day. They are used for the breakdown and utilization by the body of food and are part of the B vitamin complex.
Pantothenic acid is essential for the
metabolism of food. It is essential in the synthesis of hormones and
cholesterol. Cholesterol is needed by the body for the proper functioning of its
cells' membranes, particularly in the brain.
Biotin is essential for the metabolism of proteins and carbohydrates (like the
other B vitamins), and in the synthesis of hormones and cholesterol.
There are no known deficiencies of either pantothenic acid or biotin. Large doses of pantothenic acid do not produce symptoms other than (possibly) diarrhoea. There are no known toxic symptoms associated with biotin.
Vitamin C is a water-soluble vitamin that is necessary for normal growth and development. It promotes healthy teeth and gums, helps in the absorption of iron, aids in the maintenance of normal connective tissue, and promotes wound healing. It also helps the body's immune system.
Vitamin C should be consumed every day, since it is not a fat-soluble vitamin and cannot be stored for later use.
There has been much debate regarding the use of vitamin C in
cancer and heart disease prevention. Although the evidence is mixed regarding a
definitive benefit of vitamin C in this regard, it is still encouraged that
individuals maintain adequate intake. On the other hand, the majority of current
evidence does not support vitamin C's role in the prevention or treatment of the
common cold.
Vitamin C is an antioxidant, which means that it quenches free radicals that can
damage organs, tissues, and cells. Free radicals are believed to be one of the
causes of the degenerative changes seen with aging, but it is not yet known
whether consumption of additional antioxidants like vitamin C can help.
A deficiency of vitamin C causes the disease scurvy, which is
rare in the United States.
Toxicity does not normally occur, since vitamin C is water soluble and is
regularly excreted by the body. Recent studies have shown, however, that
excessive doses of vitamin C (many times more than the recommended amount) can
lead to toxicity. The most common manifestations of vitamin C toxicity are
kidney stones, and in very rare circumstances, anaemia (caused by interference
with vitamin B12 absorption).