A Foodborne Outbreak Traced to Niacin Overenrichment

In September 1983, the Vermont Department of Health identified seven employees who developed facial and skin flushing and erythema within minutes of eating lunch in a hospital cafeteria. None had vomiting or diarrhea. Because of the unusual nature of the symptoms, a case-control study was undertaken. All symptomatic individuals were interviewed regarding symptoms and food consumption. A case was defined as anyone who experienced visible erythema after lunch at the hospital on September 16. For each case, two friends who had eaten lunch in the cafeteria on the same day were selected as controls. All ill persons had consumed beef-rice soup, which was significantly associated with illness (P<0.001). The median time from consumption of soup to onset of symptoms was 10 min. The nature of symptoms and the brief incubation period suggested a toxic reaction to niacin. The niacin content per serving of soup consumed was determined to be 162 mg (12 times the total daily recommended amount of 13 mg). The niacin content of the enriched rice used to make the soup was 2,636 mg per pound (160 times the amount declared by the manufacturer). The excess niacin was traced to inadequate mixing of rice with enrichment powder at the processing plant. The investigation underscores the potential for toxic effects from foods which are improperly enriched.