Zinc in selected hospital diets. Comparison of analysis vs. calculation

Sample hospital meals for breakfast and the noon and evening meals for regular, ovo-lacto-vegetarian, and renal diets were collected for seven consecutive days. The daily zinc content of each diet was determined, using atomic absorption spectrophotometric analysis and by calculation, using the USDA provisional tables on the zinc content of individual foods. The data indicated that the provisional tables provide a reasonable estimation of zinc content of regular or renal diets with errors approximately 10%. However, a 35% overestimation occurred for vegetarian diets. A major cause of error between assayed and calculated values was probably due to substituting items not included in the tables. The mean zinc content for the regular diet, as offered, was 97% of the adult recommended allowance for zinc, while the vegetarian diet provided 81% of the allowance. The average renal diet contained 49% of the allowance. Certain types of vegetarian and low-protein diets may be inadequate in total and/or available zinc. Also important in evaluating hospital diets for adequacy of zinc are the actual intake and the condition of the patient.