Dietary zinc intake of a group of long-stay mentally handicapped women - Some bioavailability considerations

Dietary factors affecting zinc bioavailability were evaluated according to their relative distribution in the individual daily meals making up the bas ic diet of 17 institutionalized, mentally handicapped adult women. Mean int ake values of zinc, phytate, nonstarch polysaccharides (NSP), calcium, prot ein, and energy were calculated from a dietary survey of 7 consecutive days , which also served to obtain values for the two zinc bioavailability predi ctor formulas, phytate/Zn millimolar ratio and [Ca][phytate]/[Zn][energy] r atio. Mean daily zinc intake was 8.5 +/- 1.8 mg, with noon and evening meal s accounting for the highest contribution to this value (45% and 35%, respe ctively), whereas breakfast meals' contribution was 16%. The mean protein i ntake was 55 +/- 13 g, with noon and evening meals being the major contribu tors to total daily intake (42% and 38%, respectively). Breakfast meals acc ounted for 77% of daily phytate intake, giving a respective phytate/Zn mill imolar 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 w ere 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, whi le suggesting that zinc bioavailability is unlikely to be adversely affecte d, indicated that dietary fiber intake levels are probably inadequate, part icularly in view of the nonambulant condition and low physical activity pre valent in such individuals, who may, as a consequence, be susceptible to he alth disorders associated with impaired bowel function and constipation.