Publication:

Zinc deficiency as a key risk factor for pneumonia in early childhood: a hospital-based case-control study

Background Pneumonia remains the leading infectious cause of under-five mortality globally. Zinc deficiency impairs immune function and is prevalent among children in low- and middle-income countries. This study examined the association between serum zinc status and pneumonia in hospitalised children aged 6-59 months at a tertiary care centre in Kerala, India.

Methods A prospective hospital-based case-control study was conducted from May 2023 to November 2024. Thirty children with WHO-defined pneumonia (cases) were compared with 30 age- and sex-matched healthy controls. Serum zinc was measured by atomic absorption spectrometry. Zinc deficiency was defined per IZiNCG criteria as <65 µg/dl. Logistic regression estimated the odds of pneumonia per 1 µg/dl decrease in serum zinc.

Results Mean serum zinc was significantly lower in cases than controls (54.0±11.6 µg/dl versus 76.8±13.6 µg/dl; mean difference 22.8 µg/dl, 95% CI 16.2-29.3; p<0.001). Zinc deficiency was present in 86.7% of cases (33.3% severe, 53.3% mild) versus 26.7% of controls (p<0.001). Each 1 µg/dl decrease in serum zinc was associated with 1.15-fold greater odds of pneumonia (OR 1.15, 95% CI 1.07-1.24; p<0.001). No significant associations were found with anthropometric indices, disease severity, or length of hospital stay.

Conclusions Low serum zinc was strongly associated with childhood pneumonia, even among children with normal growth parameters, consistent with the ‘hidden hunger’ phenomenon. Prospective multi-centre studies are needed to confirm these findings.