Zinc Nutritional Status in Korean Adults from Rural, Urban and Metropolitan Areas

Abstract

The zinc intake and status of South Koreans from rural, urban and metropolitan areas were compared to evaluate the zinc nutritional status in different regional areas in South Korea. The dietary habits of 721 healthy adult subjects (271 from rural, 240 from urban, 210 from metropolitan city) with an age range 30～64 (mean age 54±18) were assessed using a food frequency questionnaire. Mean daily Zn intake for rural, urban, and metropolitan areas was 6.5 mg, 7.3 mg, and 11.4 mg (p＜0.05), respectively, which was 54%, 61% and 95% of the Korean RDA for man (12 mg/d). Mean phytate : zinc molar ratios for rural, urban, and metropolitan city were 41, 34, and 30, respectively (p＜0.05), which were higher than the cutoff level of 20 for poor zinc status. The zinc intake and phytate : Zn molar ratio in the rural area were 0.5 and 1.3-fold compared to those of the metropolitan city, which can cause poor zinc nutriture in the rural area. Most of the zinc biomarkers were lower in the rural area than in the metropolitan city (p＜0.05) (mean rural and metropolitan values for plasma Zn: 80.8 μg/dL and 119.8 μg/dL, respectively; RBC Zn: 7.8 μg/dL and 8.8 μg/dL, respectively; plasma alkaline phosphatase (ALP) activity: 87 mU/mL and 100.4 mU/mL, respectively). It seems that a lower zinc intake in the rural area decreased zinc biomarker levels, such as plasma and RBC zinc, and plasma alkaline phosphatase activity, and caused the poor zinc nutritional status in this area. Most of the zinc biomarkers, such as RBC zinc and urinary and plasma zinc levels, in the subjects from the three localities, were within the normal range even when zinc intake of rural and urban subjects was low. The exception was plasma ALP activity in the rural area, which was lower than the reference level. Thus, marked zinc deficiency in these subjects were not observed, however, the potential for marginal zinc deficiency should be considered, especially for the rural area, because of the low zinc intake and the biomarker levels for marginal zinc deficiency.