Are changes in food consumption patterns associated with lower biochemical zinc status among women from Dunedin, New Zealand?

Abstract

Reductions in red meat and increases in cereals in the diet may compromise the intake and bioavailability of Zn. In this cross-sectional study of 330 premenopausal New Zealand women aged 18–40 years, we have assessed the inter-relationships among dietary intakes (via computer-administered food-frequency questionnaire), biochemical Zn status, and anthropometric indices, and compared our results with earlier data. Fasting serum (12·00 (SD 1·36) ΜMOL/L) AND HAIR ZN (2·71 (sd 0·36) μmol/g) were lower than those for young Dunedin, New Zealand, women in 1973 (non-fasting serum Zn 18·6 (sd 4·6) μmol/l, hair Zn 2·99 (sd 0·35) μmol/g). Further, our mean serum Zn was at the 25th percentile of the US National Health and Nutrition Examination Survey (NHANES) (1976–1980) reference sample for women aged 20–44 years. Meat–poultry–fish contributed only 28 % total Zn in the present study, a level comparable with that from cereals–nuts–legumes (27 %), compared to about 40 % in 1989. Significant negative correlations existed between serum Zn and dietary [phytate]:[Zn] molar ratios ( r -0·163, P<0·01); 35 % had diets with [phytate]:[Zn] >15, a level said to compromise Zn status. Mean serum Zn of a subgroup of non-oral contraceptive users free of infection was higher in the red-meat eaters ( n 149) compared with non-red-meat eaters ( n 48) (12·2 v. 11·8 μmol/g, P<0·05). In contrast, serum Zn was lower in those with dietary [phytate]:[Zn] ratios >15 v. <15 (i.e. 11·9 v. 12·3 μmol/l, P=0·04). We postulate that the lower biochemical Zn status of these New Zealand women may be associated in part with changes in food selection patterns, which have led to a reduction in the bioavailability of dietary Zn.