After an alarming increase in the incidence of rickets, a crippling disease affecting children, researchers have recommended vitamin D supplements especially during the dark winter months.

Since humans need a crucial amount of vitamin D, besides sunlight and a diet that includes oily fish, egg yolk and liver, a daily supplement of at least of seven micrograms of the sunshine vitamin is essential.
Rickets was a common problem during the Industrial Revolution in England when a poor diet and a polluted atmosphere with very little sunlight coming through, affected children. It is disconcerting to note that an affluent lifestyle has led to the same problem today.
Source-Medindia