vitamin

Fresh fruit and vegetables contain many of the essential dietary minerals and vitamins that we require to stay healthy.

Any of various chemically-unrelated organic (carbon-containing) compounds that are necessary in small quantities for the normal functioning of the mammalian body. Many act as coenzymes, small molecules that enable enzymes to function effectively. Vitamins must be supplied by the diet because the body generally cannot make them. Deficiency of a vitamin may lead to a metabolic disorder (‘deficiency disease’), which can be remedied by sufficient intake of the vitamin. Vitamins are generally classified as water-soluble (B and C) or fat-soluble (A, D, E, and K).

Vitamin A (retinol) is found in milk, cheese, butter, eggs, liver, kidney, oily fish (such as herring), and cod liver oil. However, the chemical carotene (found in most plants) can be converted to vitamin A in the human body. This vitamin is needed to make a chemical used by rod cells in the retina of the eye that respond in dim light. Shortage of this vitamin results in poor vision, especially at night.

Vitamin D is found in the greatest amounts in fish, but is present in tiny amounts in milk, cheese, butter, eggs, and liver. However, it can be made in the human skin when it is exposed to sunlight and this is sufficient for most people. It is needed to maintain bone in the body. Without the vitamin, bones are weak and can bend (rickets). Young children, pregnant women, and women breastfeeding a baby need much more than most other people. People who are housebound and do not get into the sun may become short of this vitamin.

Most people have balanced diets and so a real need to obtain extra vitamins from tablets is not common. Some vitamins are poisonous in high doses and there have been cases of people dying as a result of taking excessive amounts of vitamin pills.

Scurvy Scurvy is a disease which is the result of vitamin C deficiency. Vitamin C is found in fresh fruit and vegetables, but is generally destroyed during cooking. Scurvy was first observed around 3,500 years ago. However, in Western Europe it was not until the 1600s that it was discovered how to stop sailors suffering scurvy on long voyages. On such voyages, once the fresh fruit and vegetables had run out sailors would suffer and eventually die from scurvy. It was found that if they were given fresh sprouting cereals or citrus fruit juices this would prevent or cure scurvy.

History of vitamin research The idea of scurvy as a deficiency disease, however, caused by the absence of a specific substance, emerged later. In the 1890s a Dutch doctor, Christiaan Eijkman, discovered that he could cure hens suffering from a condition like beriberi by feeding them on whole grain, rather than polished, rice. In 1912 Casimir Funk, a Polish-born biochemist, had proposed the existence of what he called ‘vitamines’ (vital amines), but it was not fully established until about 1915 that several deficiency diseases were preventable and curable by extracts from certain foods.

By then it was known that two groups of substances were involved, one group being water-soluble and present, for example, in yeast, rice-polishings, and wheat-germ, and the other group being fat-soluble and present in egg yolk, butter, and fish-liver oils. The water-soluble substance, known to be effective against beriberi, was named vitamin B. The fat-soluble vitamin complex was at first called vitamin A. As a result of analytical techniques these have been subsequently separated into their various components, and others have been discovered.