Most children suffer from vitamin D deficiency

Levels of 25-hydroxyvitamin D (25(OH)D) are deficient or insufficient in most children, reports a recent study. Aside from vitamin D intake, time spent outdoors and higher exposure to UV radiation seem to be effective methods of improving 25(OH)D status.

Drawing from a previous multicentre study, the researchers measured 25(OH)D levels in serum samples of 2,171 children (totalling 3,606 measurements), who were found to have a mean 25(OH)D level of 45.2 nmol/L.

Using globally accepted reference standards, 63 percent of children were deemed to have deficient levels of 25(OH)D (<50 nmol/L); meanwhile, 33 percent had insufficient levels (50 to <75 nmol/L). Only 3 percent had levels at or above 75 nmol/L and were classified as having sufficient 25(OH)D. Of note, children had a very low mean intake of vitamin D, at only 1.7 µg/day.

Mixed effects logistic regression analysis was then performed to identify correlates of 25(OH)D status and showed that vitamin D intake indeed contributed to 25(OH)D sufficiency, such that each additional 1-µg/day intake led to a 12-percent higher likelihood of achieving non-deficiency (odds ratio [OR], 1.12, 95 percent confidence interval [CI], 0.89–1.41).

A similar effect was reported for time spent outdoors, with each additional hour per day resulting in a 21-percent better chance of achieving a non-deficient vs deficient 25(OH)D status (OR, 1.21, 95 percent CI, 1.12–1.31). Such an interaction might be partially explained by UV radiation exposure.

“As cloud-modified vitamin-D UV dose and outdoor time were the most important determinants of vitamin D status, measures to expand the time spent outdoors by promoting outdoor activities in settings like kindergartens and schools should be implemented,” the researchers said.

“This would also help to prevent overweight and obesity which additionally affect serum 25(OH)D concentrations, although potential adverse effects of sunlight exposure like skin cancer need to be taken into account during outdoor time,” they added.