Fundamentals of Food Technology

VITAMIN D

Vitamin D is otherwise known as ‘sunshine vitamin’ as it can be synthesized from sunlight by our body.
 
Functions

1. Vitamin D promotes the absorption of calcium and phosphorus from the small intestine
2. In the DNA vitamin D helps to form active calcium binding protein
3. It also maintains the concentration of calcium and phosphorus in the blood
4. Vitamin D helps the deposition of calcium phosphate in the bone. In rachitic children there may be delay in dentition and malformation of the teeth occurs
 
Deficiency

• Deficiency of vitamin D results in poor absorption of calcium and phosphorus from the intestine and excessive loss of them in the urine and faeces.
• Concentration of calcium in the plasma is diminished and it produces tetany which is characterized by hyperexcitability of the nervous system.
• This stimulates the parathyroid glands to decalcify bone calcium to raise the plasma calcium level.
• Deficiency of vitamin D leads to rickets in children and osteomalacia in adults
 
 
Rickets

• The name of Rickets is given to vitamin D deficiency after a famous English bone setter by EII. In mild deficiency of vitamin D, the symptoms shown are restlessness and irritability.
• Rickets is a disease of infancy and childhood. Calcium and phosphorus are not deposited enough to form strong bones and as a result the leg bones become bent and deformed.
 


Symptoms

• Small round unossified areas are developed near skull bones
• Projections are formed on the osteochondal junction of the ribs.
• It resembles a rosary and it is known as ‘rickets rosary’.
• The abdomen is distended and chest deformities like depression of ribs attached to diaphragm take place. This is known as Harrison’s sulcus and gives an appearance of ‘pigeon breast’.
• In a later stage, pelvic deformities, bow legs and/or knock knees develop.
• Nutritional rickets occur in infants and children of poor families. Premature infants are more susceptible to rickets
 
Osteomalacia

• Osteomalacia occurs among adults.
• It is often known as ‘adult rickets’. Osteomalacia is most common among women who live on a poor diet lacking in calcium and vitamin D. Pregnant women are more prone to this.
• It is mainly because of the increase in weight during pregnancy accompanied by the deficiency of vitamin D.
• It is again common among women who observe ‘purdah’.
• Repeated pregnancies and prolonged lactation further deplete calcium stores which results in osteomalacia.
• Pain, softening and tenderness in the bones and fractures are the common complaints of the patients of osteomalacia.
 
Sources

• Best sources: Fish liver oils, egg yolk, milk, butter, ghee and fortified foods
• Best natural source: Sun light
Requirements

• The daily requirements of vitamin D for infants, children, pregnant and nursing women have been estimates to be 400 IU (10µg) and for older children and adults about 200 IU (5µg).