OBJECTIVES To determine the effect of modifiable dietary intake variables (current vitamin D supplementation and daily cow's milk intake) on 25-hydroxyvitamin D level in early childhood and to evaluate the relationship between these modifiable dietary factors and other largely nonmodifiable determinants of vitamin D status including skin pigmentation and season. DESIGN Cross-sectional study. SETTING Primary care pediatric and family medicine practices participating in the TARGet Kids! practice-based research network in Toronto, Ontario, Canada. PARTICIPANTS From December 2008 to June 2011, healthy children 1 to 5 years of age were recruited during a routine physician's visit. INTERVENTIONS Survey, anthropometric measurements, and laboratory data were collected. A multivariable linear regression model was developed to examine the independent effects of vitamin D supplementation and daily volume of cow's milk on 25-hydroxyvitamin D level. MAIN OUTCOME MEASURES 25-Hydroxyvitamin D level. RESULTS Blood was obtained in 1898 children. Two modifiable dietary intake variables, vitamin D supplementation and cow's milk, increased 25-hydroxyvitamin D level by 3.4 ng/mL (95% CI, 2-4 ng/mL) and 1.6 ng/mL per 250-mL cup per day (95% CI, 1-2 ng/mL), respectively. Two nonmodifiable variables reflecting cutaneous vitamin D synthesis (skin pigmentation and season) were also strongly associated with 25-hydroxyvitamin D status but accounted for a much smaller proportion of the explained variation in 25-hydroxyvitamin D level. The effect of vitamin D supplementation and milk intake on 25-hydroxyvitamin D level appeared similar regardless of skin pigmentation or season. CONCLUSION Two modifiable dietary intake variables (vitamin D supplementation and cow's milk intake) are the most important determinants of 25-hydroxyvitamin D status in early childhood.
Rickets caused by poor nutrition was widespread in Norway at the beginning of this century. Today it is a very rare disease among Norwegian children. During the last 20 years, however, it has become quite common among immigrant children who have come from developing countries to live in Norway. This is probably due to a combination of different factors such as maternal vitamin D deficiency, lack of vitamin D supplementation, long-lasting breast feeding, latitude (therefore little sunshine in winter) and lack of exposure to sunshine during the summer. The paper reviews the disease, with a special emphasis on clinical findings, diagnosis, treatment and prevention.
The Centers for Disease Control and Prevention's latest data show markedly high prevalence rates of severe vitamin D deficiency among Americans of all ages. Because of the numerous negative health consequences associated with vitamin D deficiency, we must consider all potential causes including insufficient exposure to the sun's ultraviolet B radiation. This article presents data from the National Weather Service that documents how few days in Minnesota offer the opportunity to make vitamin D. Thus, even Minnesotans who spend a significant amount of time outdoors and consider themselves to have sufficient sun exposure may still be at risk for vitamin D deficiency. This is especially true for the elderly, those with high melanin content in their skin, and those with a higher body mass index, all of whom require significantly more sun to achieve adequate levels of vitamin D. Given the lack of sufficient ultraviolet B radiation people in Minnesota get from the sun between October and April, measurement of vitamin D status is required for rational replenishment and maintenance dosing. The goal of replenishment should be at least 32 ng/mL and, ideally, more than 50 ng/mL.