Vitamin D helps the body control calcium and phosphate levels. If the blood levels of these minerals become too low, the body may produce hormones that cause calcium and phosphate to be released from the bones. This leads to weak and soft bones.
Vitamin D is absorbed from food or produced by the skin when exposed to sunlight. Lack of vitamin D production by the skin may occur in people who:
- Live in climates with little exposure to sunlight
- Must stay indoors
- Work indoors during the daylight hours
You may not get enough vitamin D from your diet if you:
- Are lactose intolerant (have trouble digesting milk products)
- Do not drink milk products
- Follow a vegetarian diet
Infants who are breastfed only may develop vitamin D deficiency. Human breast milk does not supply the proper amount of vitamin D. This can be a particular problem for darker-skinned children in winter months (when there are lower levels of sunlight).
Not getting enough calcium and phosphorous in your diet can also lead to rickets. Rickets caused by a lack of these minerals in diet is rare in developed countries, because calcium and phosphorous are found in milk and green vegetables.
Your genes may increase your risk of rickets. Hereditary rickets is a form of the disease that is passed down through families. It occurs when the kidneys are unable to hold onto the mineral phosphate. Rickets may also be caused by kidney disorders that involve renal tubular acidosis.
Disorders that reduce the digestion or absorption of fats will make it more difficult for vitamin D to be absorbed into the body.
Occasionally, rickets may occur in children who have disorders of the liver, or who cannot convert vitamin D to its active form.
Rickets is rare in the United States. It is most likely to occur in children during periods of rapid growth, when the body needs high levels of calcium and phosphate. Rickets may be seen in children ages 6 - 24 months. It is uncommon in newborns.