Although the condition of deformed bones had been known for centuries, it was not until 1922, that the cause of rickets was discovered. Many investigators noted that a poor environment, consisting a poor hygiene, a lack of sunshine and exercise and often city dwelling was associated with the incidence of rickets. In 1924 cod-liver oil was recommended as a remedy for rickets.
Vitamin D helps in metabolism and absorption of calcium and phosphorus which are essential components for the development of bones. It also helps in eruption of teeth.
Effects of Deficiency of Vitamin D
It is the disease caused due to the deficiency of Vitamin D. This is a disease of early properly with the growth. They become pliable and distorted, which results in such deformities as pigeon chest, enlarged wrists and ankles, and bow-legs or knock-knees.
The leg bones are not strong enough to support the weight and body of the child while learning to walk. Profused dieting and restlessness are early symptoms of rickets in infants. Growth may not be slow at first because of natural increase of bones in length. But a prolonged deficiency of Vitamin D results into stunted growth and deformities occur at later stage.
Prolonged deficiency of dietary calcium and vitamin D or sunlight may result in osteomalacia- sometimes called adult rickets. This condition is characterized by poor calcification of the bones. The bones become soft, so that they become flexible, leading to deformation of limbs, spine, thighs or pelvis. These bone-changes are usually accompanied by rheumatic pain and exhaustion.
Sources of Vitamin D
Natural foods are poor sources of Vitamin D except that small amounts of it are present in egg yolk, liver, fish.
Fish liver oils provide the most important source of this vitamin and should be included daily in the diets of growing children and pregnant and lactating mothers.
Although ultraviolet rays of sunlight help in the synthesis of vitamin D but one cannot always depend on it as dust, Smoke, fog, particularly the clothing and ordinary window glasses act as barriers to prevent rays form reaching the skin.
The formation vitamin D by the action of sunlight depends on many factors such as length and intensity of exposure to sunlight and the colour of skin. Heavily pigmented skins prevent ultra-violet rays from reaching deeper layer of skin and the adequate synthesis of the steroid hormone is either totally stopped or retarded.
This vitamin is stable to heat as well as oxidation.