Naturally occurring nitrate and nitrite in foods in relation to infant methaemoglobinaemia

The nitrate and nitrite content of vegetables and commercially prepared baby food has been reviewed in the light of literature reports of infant methaemoglobinaemia. Methaemoglobinaemia results from absorption of the nitrite ion formed by conversion of nitrate. Documented evidence indicates conversion prior to ingestion as the primary health hazard and European experience implicates only nitrate-rich unprocessed spinach. Unprocessed spinach should be stored for a minimum length of time under proper conditions, and home-prepared spinach should never be stored for subsequent feeding. No cases of toxicity resulting from nitrates in foods have been reported in North America, but in view of the apparent sensitivity of young infants, prudence would dictate that foods, such as spinach and beets, containing high levels of nitrate should not be introduced into the diet of children below 3 months of age. Selectivity should be used in the choice of foods given during infancy if signs of gastro-intestinal disorder become apparent. There is no evidence that the nitrate content of commercially prepared foods available on the Canadian market constitutes a hazard to human health.