Writing in the journal PLOS One, researchers from the Department of Clinical Nutrition at Harbin Children's Hospital, China , stated previous studies showed that the incidence of RRTIs among children in northern China ranged from 17.8% to 18.7% in 2011.
They point out that numerous studies have focused on identifying the association between inadequate concentrations of vitamins A, D, and E and the incidence of RRTIs in Chinese children, but that the results have been contentious.
“No evidence is available to prove these hypotheses.Therefore, the roles of vitamins A, D, and E in children with RTIs and RRTIs should be clarified,” they wrote.
In their study, 1200 children aged 0.5–14 years were selected via a face-to-face survey in Harbin, China.
Among the participants, 600 children with RRTIs comprised the symptomatic group (RRTI group), whereas 600 healthy children were used as controls.
Blood samples were collected to measure serum levels of vitamins.
Significant deficiency
They found that serum levels of vitamins A and E were significantly lower in the RRTI group than the control group.
“The conditional logistic regression model and the receiver-operating characteristic curve showed that the insufficiency or deficiency of vitamins A, D, and E was positively correlated with RRTI occurrence (p < 0.05),” they added.
“The incidence of insufficiency or deficiency for vitamins A, E, and D was 24.33%, 8.17%, and 19.33% in the control group but increased to 63.00%, 33.83%, and 56.50% in the RRTI group, respectively.”
The researchers believe the study demonstrated that lower serum levels of vitamins A, D, and E are associated with RRTIs, but were unable to judge if it caused repeated illness or was a response of it.
“Vitamins may be associated with RRTIs by promoting immune system function, thereby increasing the resistance to RRTIs,” they added.
“However, this retrospective study cannot conclude the role of these vitamins in RRTIs because we cannot determine whether the vitamin levels influenced the occurrence of RRTIs or vice versa.”
The researchers concluded, a prospective study should be conducted to confirm the role of vitamins in RRTIs.
“In addition, the effects of a single dose or a combination of these vitamins on patients with RRTIs might be of interest,” they stated.
Source: Plos One
http://dx.doi.org/10.1371/journal.pone.0167689
“Low Serum Levels of Vitamins A, D, and E Are Associated with Recurrent Respiratory Tract Infections in Children Living in Northern China: A Case Control Study”
Authors: Yanping Chen, et al.