Dietary factors affecting zinc bioavailability were evaluated according to their relative distribution in the individual daily meals making up the basic diet of 17 institutionalized, mentally handicapped adult women. Mean intake values of zinc, phytate, nonstarch polysaccharides (NSP), calcium, protein, and energy were calculated from a dietary survey of 7 consecutive days, which also served to obtain values for the two zinc bioavailability predictor formulas, phytate/Zn millimolar ratio and [Ca][phytate]/[Zn][energy] ratio. Mean daily zinc intake was 8.5 +/- 1.8 mg, with noon and evening meals accounting for the highest contribution to this value (45% and 35%, respectively), whereas breakfast meals' contribution was 16%. The mean protein intake was 55 +/- 13 g, with noon and evening meals being the major contributors to total daily intake (42% and 38%, respectively). Breakfast meals accounted for 77% of daily phytate intake, giving a respective phytate/Zn millimolar ratio of 20.4 +/- 7.6 and a [Ca][phytate]/[Zn][energy] ratio of 336 +/- 127 mmol/Mcal. Values for both ratios based on noon and evening meals were negligible in comparison. The mean daily NSP intake was 9.8 +/- 4.2 g, with 53% of total daily intake supplied from breakfast meals, whereas noon and evening meals accounted for 30% and 14%, respectively. The results, while suggesting that zinc bioavailability is unlikely to be adversely affected, indicated that dietary fiber intake levels are probably inadequate, particularly in view of the nonambulant condition and low physical activity prevalent in such individuals, who may, as a consequence, be susceptible to health disorders associated with impaired bowel function and constipation.
