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Vitamin D Deficiency in ChildrenPediatricians have begun to look harder at Vitamin D levels in children because this vitamin, once thought to be primarily involved in calcium absorption, is now being shown to have significant implications for a variety of health conditions which manifest in later life.(1) And while parents and doctors have assumed that children took in enough Vitamin D from sunshine exposure, supplemented foods, or vitamin supplements, a recent study has found that 12% of American infants and toddlers are deficient in vitamin D, and another 28% are at risk for it.(2)
Parents may want to discuss this issue with their pediatrician at their child's next well visit.
Vitamin D's primary role is helping the body absorb and use calcium to build strong bones. But recent research has been showing it also has a potential impact on the development of some chronic diseases including heart disease, high blood pressure, diabetes mellitus, inflammatory and autoimmune diseases and cancer.3Although the mechanism is unclear, evidence is mounting that maintaining adequate vitamin D levels through childhood may decrease the development of a variety of chronic conditions of adulthood or may help the body fend off the onset of some chronic diseases.(1)
We take in vitamin D through our diet and from being exposed to the sun. Liver, fatty fish such as salmon, and egg yolks are all good sources of vitamin D. Many foods, especially milk, are fortified with D. Vitamin D is also synthesized in the skin, a process stimulated by the action of the sun's ultraviolet light on the skin. Poor diet or insufficient sun exposure can both lead to deficiencies, particularly when one source — diet or sun exposure — is not able to compensate for the other.
Recent research has made doctors aware that more infants, young children and adolescents are D deficient than was previously realized, even though they show no outward symptoms of deficiency.2 Some D deficient children have even shown x-ray evidence of thinning of the bone. While the significance or even permanence of this x-ray finding is uncertain, the concern is that the density that bones develop during childhood can influence the risk for osteoporosis in later life.(2)(5)(6)
Breast-Fed Babies Need Vitamin DThe exact blood level values of vitamin D that define normality at different ages and the amount of vitamin D recommended for supplementation are both areas of active study. But there is consensus that babies that are breast-fed are at high risk for low D because breast milk is a poor source of this nutrient. The American Academy of Pediatrics recommends that all breast-fed infants receive vitamin D supplements.(7)(8)
Children whose dietary habits replace Vitamin D supplemented milk with juice, which generally is a poor source of D, are also at risk for deficiency.(2) Decreased sun exposure, such as in northern latitudes and during cold seasons, or among dark skinned patients, can also contribute to vitamin D deficiency in some populations.(7)
Numerous studies have also documented low vitamin D levels in adolescents both in Europe and the United States, and while the reasons are unclear, it is possible that the sedentary and indoor adolescent life style may result in both decreased sun exposure and poor intake of foods supplemented with vitamin D.(4)
Take a Supplement or the Sun?A review in the American Journal of Public Health estimates the daily sun exposure needed to maintain a normal vitamin D level at only 15 minutes in summer and 20 minutes in early fall or late spring for people in the U.S. or at a similar latitude. But this assumes clear skies and exposure of arms, shoulders and back. The exposure length is doubled for African Americans.(3)
During November to March in the northeast and midatlantic regions and other areas north of 37 degrees latitude, it is not possible to obtain sufficient vitamin D from sun exposure.
Because exposure to ultraviolet radiation is associated with development of skin cancer, it is better for sun-sensitive or fair skinned people or those taking photosensitizing medications to take oral vitamin D supplements rather than the sun.3 Similarly, the Academies of Pediatrics and Dermatology both advocate using oral supplementation rather than increased sunlight exposure to increase vitamin D levels in children, particularly in very young children who are very vulnerable to damage from UV light.(8)
What Parents Should DoBecause excess vitamin D and excessive sun exposure have serious health consequences, parents and patients should not add supplements or increase their children's exposure to sunlight without clear medical guidance. Too much vitamin D causes excessively high levels of calcium with symptoms that include weakness, headache, sleepiness, constipation, nausea, bone pain and kidney stones.
Nutrition and disease prevention counseling is an important part of any visit to your pediatrician. Even though measuring Vitamin D levels in the blood is not recommended as part of routine health screening, and bone x-rays are not typically obtained on asymptomatic children, parents should consider discussing their children's risk for low vitamin D by reviewing their diet and sun exposure and asking what changes they should make to treat this easily preventable deficiency which has long term consequences.
The picture regarding vitamin D is a work in progress, but evidence is accumulating and doctors are able to make informed recommendations based on current and constantly updated information. So, next time you and your children make a visit to the pediatrician's office, ask your physician about vitamin D.
January 1, 2008
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