Background When neonates and infants are not breastfed or require supplemental feedings, American Academy of Paediatrics recommends iron-supplemented formula. Cow’s milk-based formula can be allergenic; however, this allergic response may be secondary to formula components as opposed to milk. The allergen may be inscrutable leading to false assumptions. In this case, an unusual religious clue solved such mystery.

Method Case analysis

Results An orthodox Jewish infant initially breastfed was transitioned to formula. Enfamil 4ounces q4hours caused upper respiratory mucus build-up directly post ‘bottle-time’; formula was changed to ProSobee (soy-based) with resolution of ‘formula intolerance.’ At 12 months, cow’s milk was initiated without allergic response. At 15 months, when diet included solid foods, she developed a peri-oral rash temporally associated with meals in her parents’ home and following a meal in another family’s home. Initial assessment revealed no new foods during these meals; however, this new allergy occurred during Passover, with strict dietary laws, suggesting a common new food. Ashkenazi Passover dietary laws preclude kitniyot (legumes, derivatives and associated crops including corn/soybeans/corn oil/soybean oil). Common Passover cooking oils include safflower oil. As both families were Ashkenazi Jews, the apparent common new food was safflower oil used in both homes. Safflower oil is an Enfamil ingredient. The presumptive allergen common to formula and Passover meals was safflower oil.

Conclusions Allergen determination may be secondary to fortuitous double exposure. Complete clinical histories need to allow for possible double exposure with willingness to consider cultural, religious, dietary law, and holiday dietary law factors.