Rickets used to be a relatively common nutritionally related disorder. Rickets is the softening of bones, most commonly in children, caused by a lack of vitamin D. This softening can lead to bone deformity (the classic bow legs) and fractures.
Rickets arises most commonly from severe malnutrition.
Vitamin D is required for appropriate absorption of calcium from the intestines, and so without vitamin D, calcium is not absorbed and calcium deficiency arises, despite the presence of it in the diet.
The skin can create vitamin D in the presence of direct sunlight, and occupations, whereby a person does not go outside much, wears sunscreen, has dark skin, or lives in parts of the world with low light levels, vitamin D deficiency, is more common.
In the first half of the 20th century, vitamin D was added to margarine and various other foods which had the effect of all but eliminating rickets from the developed world.
However, recent studies have shown that even though rickets may not manifest, vitamin D deficiency can be present leading to a number of serious health disorder in the long term. Thus the current advice is that some adults and many children should increase their vitamin D levels through either dietary supplements or by paying closer attention to their diet.
Foods that contain vitamin D include butter, eggs, fish liver oils, margarine, fortified milk and juice, and oily fishes such as tuna, herring, and salmon.