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Vitamins

Definition

Vitamins are organic compounds that are necessary to sustain life. Vitamins cannot be made by the body and must be obtained from food or supplements.

Description

Vitamins play a crucial role in a variety of bodily functions and influence the health of nearly every organ in the body. Vitamins stimulate the chemical reactions responsible for converting food into energy, growth, digestion, elimination, wound healing and resistance to disease. Without Vitamins, many bodily processes necessary for sustaining life would occur very slowly or cease completely. Vitamin deficiencies can result in specific nutritional disorders such as scurvy and beriberi and general health problems.

There are some medical conditions that can result in vitamin deficiencies. Coeliac disease and regional enteritis can prevent the absorption of Vitamins. Other conditions which may cause vitamin deficiencies include; prolonged intestinal infection, fever and/or diarrhoea, pancreatic disease, liver disease, burns, severe wounds, surgery, cancer, AIDS and kidney disease. Certain genetic health conditions and lifestyle factors may increase the need for the intake of certain Vitamins. These include: alcoholism (increases the body's demand for B group Vitamins), pregnancy (demands optimum levels of folic acid), smoking (increases the body's demand for vitamin C) and pernicious anaemia that may require vitamin B12 supplementation.

Women who are considering becoming pregnant or who are already pregnant should take a folic acid supplement (B vitamin) every day to prevent neural tube defects. The recommended daily dosage is 500 mcg or 0.5 mg of folic acid.

Fat-Soluble Vitamins

Fat soluble Vitamins include Vitamins A, D, E and K and are found in the fatty or oily part of both vegetable and animal foods. With an excessive intake, it is possible for toxic levels of fat-soluble Vitamins to build-up in the body. Vitamin A, for example, can cause birth defects if more than the recommended dose is taken over a period of time. This is because, unlike water-soluble Vitamins, the fat-soluble type can be stored in body tissues. For this reason, to maintain health, foods high in fat-soluble Vitamins may be consumed less frequently than those high in water-soluble Vitamins.

Water-Soluble Vitamins

Water soluble Vitamins include vitamin C and the B group Vitamins. Water-soluble Vitamins are excreted in the urine and not stored in the body so it is important to include vegetables and fruits regularly in the diet. Water-soluble Vitamins are less heat-stable than the fat-soluble variety and are more likely to be lost during cooking and processing. Thus, people with a diet that is high in processed and highly cooked foods may not be consuming enough vitamin C or B group vitamins to maintain good health.

Vitamin A - Functions

  • Healthy eyes - particularly for vision in dim light.
  • Slows down the production of keratin. Excess keratin production can cause skin problems such as acne and psoriasis.
  • Enhances the production of antibodies that fight infections.
  • Antioxidant activity that prevents cell damage and premature ageing by destroying free radicals.
  • Wound healing.
  • Formation of sperm and maintenance of placenta and foetal development.

Food Sources

Liver, fish-liver oils, eggs, full-cream dairy products, dark-green vegetables, deep-yellow coloured fruits and vegetables.

B Group Vitamins - Functions

  • Healthy nervous system - protects against anxiety, stress, nervous tension.
  • Healthy skin, bones, hair and muscles.
  • Healthy intestinal and bowel function.
  • B group vitamins can be depleted by chronic, excessive alcohol consumption.

Food Sources

Complete B group vitamins found in brewer's yeast, liver, the germ and bran of cereal grains, beans, peas, nuts, milk and leafy green vegetables.

Vitamin C - Functions

  • Production of collagen.
  • Breakdown of cholesterol and production of bile (assists in the breakdown and absorption of fats).
  • Production of hormones.
  • Antioxidant. May protect against cataracts, infection, premature ageing, cancer and heart disease by destroying free radicals

Food Sources

Citrus fruits such as oranges, lemons, limes, grapefruits etc. Rosehips, acerola cherries, berries, melons, tomatoes, broccoli, green and red peppers, dark green leafy vegetables etc.

Vitamin D - Functions

  • Important for the absorption of calcium.
  • Strong teeth and bones.
  • Prevention of bone disease such as osteoporosis, rickets and osteomalacia.
  • Controls immune responses - prescribed in some cases of autoimmune disease such as lupus.

Food Sources

Milk, fatty fish (Salmon, mackerel), cod liver oil, fish liver oil, some breads and cereals and egg yolks.

Vitamin E - Functions

  • Antioxidant.
  • Maintenance of healthy nervous system.
  • Necessary for normal production of red blood cells.
  • Healthy reproductive system.
  • May help to reduce the risk of atherosclerosis and stroke.

Food Sources

Vegetable and seed oils (soybean, safflower, sunflower and corn oils etc), nuts and seeds, whole grains and wheat germ.

NOTE : Two types of Vitamin E are available as nutritional supplements. Naturally occurring Vitamin E (commonly known as d-alpha-tocopherol) is maintained in the human blood circulation. Synthetic Vitamin E (commonly known as dl-alpha-tocopherol) is not maintained in the human blood circulation and is often a cheaper but less effective vitamin supplement.

Vitamin K - Functions

  • Essential for creating the proteins involved in blood clotting.
  • Improves bone strength by increasing the mineral content of bones.
  • May be prescribed for excessive bleeding caused by Vitamin K deficiency; prevention of bleeding in newborn babies; and for gastrointestinal problems that decrease the absorption of Vitamin K e.g cystic fibrosis, sprue, Crohn's disease, colitis etc.

Food Sources

Broccoli, Brussels sprouts, cabbage, cauliflower, kale, spinach, soybeans, lettuce, pork, liver, egg yolk, safflower, canola, olive and soybean oils, alfalfa, blackstrap molasses, yoghurt.

Medical Use

Always consult your Health Care Professional to advise you on dosages and any possible interactions. Vitamin supplements are not an equivalent substitute for a proper balanced diet.

Dosage

The maintenance dose refers to the daily amount required of a Vitamin to prevent deficiencies and maintain health. The therapeutic dose is the dose required to boost the body's immune system and the mechanisms involved with healing and recovery. Therapeutic doses of Vitamins A, C and E, for example, may help to prevent the common cold and improve recovery time.

Notes

Fat soluble Vitamins A, D, E and K are available as dry or water soluble supplements for people who cannot tolerate the intake of dietary fat. Always store Vitamins in a cool, dry and dark place to maintain nutritional value.

Sustained Release

Sustained or time-release Vitamins are designed to slowly dissolve and be absorbed by the body. The theory is that a greater therapeutic effect may occur when blood levels of this type of Vitamin are kept at a stable level. The added benefits of Vitamins produced in a sustained-release state have not yet been scientifically validated.

Enteric Coating

Both Vitamin capsules and tablets can be enterically coated. This means that the supplement is coated with an organic substance that protects it from attack by stomach juices. The coating helps the tablet or capsule to pass beyond the stomach and into the small intestine before releasing its contents. Nutrients are most effectively absorbed from the small intestine, however, there is the chance that an enterically coated tablet or capsule may pass through the digestive tract without being properly digested.

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