Methemoglobinemia induced by vegetable intake in infants in northern Spain

Acquired methemoglobinemia (MHb) induced in infants by intake of vegetables is a condition uncommonly reported in the literature. The purpose of the present study was to study new vegetables involved and other epidemiological risk factors.

Seventy-eight cases of diet-induced MHb seen in Pamplona from 1987 to 2010 are reported. Infant characteristics were collected, and a case-control study was conducted using as controls 78 age- and sex-matched infants selected at the same geographic area. Bivariate logistic regression analyses were performed to detect factors involved in MHb occurrence. Nitrate levels were tested in natural vegetables used to prepare purées.

A clear relation was found between MHb and use of borage (Borago officinalis) (OR 5.2; 95% CI 1.1-24.6) and maybe chard (Beta vulgaris var cicla) (OR 2.0; 95% CI 0.4-8.7), time from preparation to use (OR 17.4, 95% CI 3.5-86.3 if the purée had been prepared 24-48 hours before and OR 24.9, 95% CI 3.3-187.6 if prepared >48 hours before), and breast-feeding (OR 10.4; 95% CI 1.9-57.2). Tests confirmed that vegetables with the highest nitrate levels were borage (n = 15), with mean nitrate levels of 3968 mg/kg, and chard (n = 17), with mean levels of 2811 mg/kg.

The main associated factors were shown to be time from purée preparation to use (>24 hours), use of certain vegetables (borage and chard), and breast-feeding. Nitrate levels in both vegetables implicated as etiological factors in acquired MHb are high.