Vitamin D deficiency associated with pediatric obesity

Researchers studying healthy children and children with a spectrum of cutaneous and extracutaneous diseases, were unable to detect significant differences between vitamin D status and having atopic dermatitis or its severity. But they did find children with atopic dermatitis were less likely to be sufficient in vitamin D in the studied disease groups. They also found the strongest associations with vitamin D status in the total population of children studied were related to body mass index and race.

More than half of pediatric patients, in general, have low serum 25-hydroxy vitamin D, making vitamin D deficiency one of the most common nutritional deficiencies among children. Thresholds for deficiency have been defined as less than 20 ng/mL; for insufficiency are 20.0 to 29.9 ng/mL; and for sufficiency 30.0 ng/mL and higher, according to Endocrine Society. These thresholds suggest many healthy children are vitamin D deficient, even if they don’t have decreased bone mineral density or are not at high risk for rickets, according to the study.

Vitamin D’s impact on atopic dermatitis also remains controversial, despite a growing interest in using vitamin D supplementation in pediatric atopic dermatitis patients. Both high and low vitamin D levels have been shown in previous studies to be atopic dermatitis risk factors. Yet another study showed no notable difference in vitamin D status between atopic dermatitis patients and healthy adult controls, but did find atopic dermatitis improved substantially with vitamin D supplementation, the authors report.

In this retrospective chart review of 665 patients seen at the Cardinal Glennon Children’s Hospital in St. Louis, Mo., researchers included children, ages newborn to 21 years, who had at least on serum 25-hydroxyvitamin D level result taken between October 2009 and 2013.

They categorized subjects as healthy or chronically ill. Children with illnesses were grouped into one of four organ-specific disease groups - those with atopic dermatitis representing skin disease; kidney diseases; gastrointestinal system illnesses; or cystic fibrosis. The 91 with atopic dermatitis represented 14 percent of the total.

Average vitamin D levels were lowest in atopic dermatitis patients, at 22.24 ng/mL. Comparatively, averages were 24.54 ng/mL in the healthy cohort; 26.44 ng/mL in the renal group; 26.29 ng/mL in the gastrointestinal cohort; and 31.06 ng/mL among those with cystic fibrosis, which was the group least likely to have vitamin D deficient patients.

Only 15 percent of pediatric atopic dermatitis patients studied had sufficient vitamin D levels, which was the lowest for vitamin D adequacy among all groups. Vitamin D status, however, was not significantly associated with atopic disease severity. In the atopic dermatitis group with mild disease, 56 percent of children were vitamin D deficient; nearly a third were insufficient and 13 percent were sufficient. Among those with moderate skin disease, 38 percent were deficient; 43 percent insufficient and 19 percent sufficient. And among those with severe atopic dermatitis, 46 percent were deficient, 48 percent insufficient and 11 percent sufficient.

THE FINDINGS

The impact of vitamin D status was most prominent when the researchers looked at the children’s body mass index, or BMI, with deficiency being associated with overweight and obesity and sufficiency with being underweight. The second biggest impact was with race. African American children were significantly more likely than Caucasians to have vitamin D deficiency. African American children have greater skin pigmentation, which limits ultraviolet B penetration. They also have a higher prevalence of lactose intolerance, which could impact their dietary D absorption, the authors suggest.

Other variables, including gender and seasonal variation, did not appear to impact vitamin D levels.

Limitations of the study include that it was conducted in a single center and was non-blinded, which could limit the findings’ generalizability, the authors write.

The findings of a very high prevalence of vitamin D deficiency and insufficiency among children with dark skin, as well as those with high BMIs, calls for a possible need to redefine the normal serum vitamin D range in these populations, especially when considering the risks to bone health and other comorbidities, according to the authors.

REFERENCES

Darji K, Tobin C, Bryan ZT, et al. “Vitamin D Deficiency and Atopic Dermatitis: Consider Disease, Race, and Body Mass,”Skinmed. 2017 Dec 1;15(6).