The function of Vitamins:

Vitamins are essential to life. They contribute to good health by regulating metabolism and assisting the biochemical process that release energy from digested food. They are considered micronutrients because the body needs them in relatively small amounts compared with other nutrients such as carbohydrates, proteins, fats and water.

Enzymes are essential chemicals that are the foundation of human bodily functions. They are catalysts (activators) in the chemical reactions that are continually taking place within the body. Vitamins work with these enzymes as coenzymes, thereby allowing all the activity that occur within the body to happen quickly and accurately.

Of the major vitamins, some are water soluble and some are oil soluble. Water-soluble vitamins must be taken into body daily as they cannot be stored and are excreted within one to four days. These include vitamin C and the B-complex vitamins. Oil-soluable vitamins can be stored for longer periods of time in the body's fatty tissue and the liver. These include vitamins A, D, E and K. Both types of vitamins are needed by the body for proper functioning.

Balance and Synergy:

Taking vitamins and minerals in their proper balance is important to the proper functioning of all vitamins. Scientific research has proven that an excess of an isolated vitamin or mineral can produce the same symptoms a deficiency of that vitamin or mineral. For example, high does of isolated B vitamins are proven to cause depletion of other B vitamins. Zinc must also be taken in the proper amounts. When taken in excess, this mineral causes symptoms of zinc deficiency.

Synergy is the combination of two or more vitamins in order to create a stronger vitamin function. For example, in order for bioflavanoids to work properly (they prevent bruising and bleeding gums), they must be taken along with vitamin C.

In addition, there are certain substance that block the absorption and effects of vitamins. For example, because the absorption of vitamin C is greatly reduced while taking antibiotics, more supplementation is necessary at this time.

Vitamins and minerals should be taken with meals unless specified otherwise: oil-soluble vitamins should be taken before meals, and water-soluble ones should be taken between or after meals.

Vitamin A (Beta-Carotene):

This supplement prevents night-blindness and other problems as well as some some skin disorders such as acne. It enhance immunity, may heal gastrointestinal ulcers, protects against pollution and cancer formation, and needed for epithelial tissue maintenance and repair. It is important in the formation of bones and teethes, aids in fat storage, and protects against colds, influenza, and infections. Vitamin A acts as an antioxidant, which helps protect the cells against cancers and other diseases. This important vitamin also slows the aging process. Protein cannot be utilized by the body without this supplement.

When food containing beta-carotene is consumed, it is converted to vitamin A in the liver. No vitamin overdose can occur with beta-carotene, although the skin may turn slightly yellow-orange in color.

Source

Vitamin A can be found in fish liver, animal livers, and green and yellow fruits and vegetables. Foods that contains significant amounts include alfalfa, apricots, asparagus, beets, broccoli, cantaloupe, carrots, Swiss chard, dandelion greens, fish liver oil and liver, garlic, kale, mustard, papayas, parsley, peaches, red peppers, sweet potatoes, spinach, spirulina, pumpkin and yellow squash, turnip greens, and watercress.

Vitamin B Complex:

The B vitamins help to maintain healthy nerves, skin, eyes, hair, liver, and mouth, as well as muscle tone in the gastrointestinal tract. B-complex vitamins are coenzymes involved in energy production and may be useful for depression or anxiety. The B vitamins should always be taken together, but up to two to three times more of one
B vitamin than another can be taken for a particular disorder.

Vitamin B1 (Thiamin)-

Thiamin enhances circulation and assists in the producing of hydrochloric acid, blood formation, and carbohydrate metabolism. Thiamin affects energy, growth disorder, and learning capacity, and is needed for normal muscle tone of the intestines, stomach, and heart.

Source

Food sources of thiamin include dried beans, brown rice, egg yolks, fish, organ meats (liver), peanuts, peas, pork, poultry, rice bran, soybeans, wheat germ, and whole grains. Other sources are asparagus, beans, broccoli, Brussels sprouts, most nuts, oatmeal, plum, dried prunes, and raisins.

Vitamin B2 (Riboflavin)-

Riboflavin is necessary for read blood cell formation, antibody production, cell respiration, and growth. It alleviates eye fatigue and is important in the prevention and treatment of cataracts. It aids in the metabolism of carbohydrates, fats, and proteins. When used with vitamin A, it maintains and improves the mucous membranes in the digestive tract. riboflavin also facilitates oxygen use by the body tissues (skin, nails, hair), eliminates dandruff, and helps the uptake of iron and vitamin B6. Vitamin B2 is important during pregnancy because a lack of this vitamin may damage the fetus even though the mother may be unaware of a deficiency. B2 is needed for the metabolism of trytophan, which is converted to niacin in the body. Carpal tunnel syndrome may benefit from a treatment program that includes riboflavin and B6. Deficiency symptoms include cracks and sores at the corner of the mouth.

Source

Vitamin B2 is found in the following food products: beans, cheese, eggs, fish, meat, milk, poultry, spinach and yogurt. Other sources include asparagus, avocados, broccoli, Brussles sprouts, currants, and nuts.

Vitamin B3 (Niacin, Niacinamide, Nicotinic Acid)-

Vitamin B3 is needed for proper circulation and healthy skin. B3 aids in the functioning of the nervous system, in the metabolism of carbohydrates, fats, and proteins, and in the production of hydrochloric acid for the digestive system. Niacin lowers cholesterol and improves circulation. B3 is also effective in the treatment of schizophrenia and other mental illness.

Source

Niacin and niacinamide are found in beef, broccoli, carrots, cheese, corn flour, eggs, fish, milk, pork, potatoes, tomatoes, and whole wheat.

Vitamin B5 (Pantothenic Acid)-

Known as the "antistress" vitamin, pantothenic acid plays a role in the production of the adrenal hormones and formation of antibodies, aids
in vitamin utilization, and helps to convert fats, carbohydrates, and proteins into energy. This vitamin is needed to produce vital steroids and cortisone in the adrenal gland, and is an essential element of coenzymes A. It is required by all cells in the body and is concentrated in the organs. It is also needed for normal functioning 
of the gastrointestinal tract and may be helpful in treating depression and anxiety.

Source

The following food contains pantothenic acid: beans, beef, eggs, salt-water fish, mother's milk, pork, fresh vegetables, and whole wheat. 

Vitamin B6 (Pyridoxine)-

Pyridoxin is involved in more bodily functions than any other single nutrient. It affects both physical and mental health. It is beneficial if you suffer from water retention. It is necessary in the absorption of fats and protein. Pydoxine also aids in maintaining sodium and potassium balance, and promotes red blood cells formation. It is required by the nervous system, and is needed for normal brain function and for the synthesis of RNA and DNA (nucleic acid), which contains the genetic instructions for the reproduction of all cells and for normal cellular growth. It activates many enzymes and aids in B12 absorption, immune system function, and antibody production. Vitamin B6 has a role in cancer immunity and chemical called homocysteine, which attacks the heart muscle and allows the deposition of cholesterol around the heart muscle. B6 may also be useful in preventing oxalate kidney stones and acts as a mild diuretic.
It reduces the symptoms of premenstrual syndrome and is helpful in the treatment of allergies, arthritis, and asthma. Carpal tunnel syndrome is linked to a B6 deficiency.

Source
All foods contains small amounts of vitamin B6; however, the following foods have highest amounts: brewer's yeast. carrots, chicken, eggs, fish, meat, peas, spinach, sunflower seeds, walnuts, and wheat germ.Other sources not quite as rich in B6 include avocado, banana, bean, blackstrap molasses, brown rice and other whole grains, cabbage, and cantalouope.

Vitamin B12 (Cyanocobalamin)-

Vitamin B12 is needed to prevent anemia. It aids in cell formation and cellular longevity. This vitamin is also required for proper digestion, absorption of foods, protein synthesis, and metabolism of carbohydrates and fats. In addition, vitamin B12 prevents nerve damage, maintains fertility, and promotes normal growth and development.

A vitamin B12 deficiency can be caused by malabsorption, which is most common in the elderly and those with digestive disorder. Vegetarian are also more likely to have a B12 deficiency symptoms include abnormal gait, memory loss, hallucinations, eye disorders, anemia, and digestive disorder.

Source

The largest amounts of vitamin B12 are found in blue cheese, cheese, clams, eggs, herring, kidney, liver, mackerel, milk, seafood, and tofu. B12 is not found in vegetables; it is available only from animal sources.