Zinc Absorption from Fortified Milk Powder in Adolescent Girls

Abstract

Zinc (Zn) is essential for development, growth, and reproduction. The Mexican government subsidizes micronutrient-fortified milk for risk groups, with positive effect on the targeted groups' plasma Zn level, inferring a good absorption is achieved although it has not being measured. The aim of this study was to determine the impact of micronutrient-fortified milk intake during 27 days on Zn absorption in adolescent girls from northwest Mexico. Therefore, Zn absorption was evaluated in 14 healthy adolescent girls (14.1 years old) with adequate plasma Zn levels, before and after 27 days of fortified Zn milk intake. Fractional Zn absorption (FZA) was calculated from urinary ratios of stable isotopic Zn tracers administered orally and intravenously on days 0 and 27, and total absorbed Zn (TZA) was calculated. At the beginning, Zn intake was 6.8 ± 0.85 mg/d (mean ± SE), and 50 % of the adolescent girls did not achieve their requirement (7.3 mg/d). Additionally, FZA was negatively correlated with Zn intake (r =-0.61, p = 0.02), while TZA (1.06 mg/d) was insufficient to cover the physiologic requirements of adolescent girls (3.02 mg/d). At the end of the intervention, all the girls reached the Zn intake recommendation and TZA, 3.09 mg/d, which was enough to meet the physiological requirement for 57 % of the adolescent girls. Therefore, the low Zn intake and the Zn status of adolescent girls were positively impacted by Zn-fortified milk intake and its good absorption rate.

Zinc Fortification: Current Trends and Strategies

“…For example, the DITR method was recently used to compare the absorption of different zinc salts used in post-harvest fortification [ 20 , 21 ], for determining the interaction with other mineral fortificants such as iron [ 20 ], and for comparing different fortification modes, such as biofortification versus post-harvest [ 22 , 23 ], or fortified maize versus fortified water [ 24 ]. When the studies are done in local settings where fortification will be implemented, the DITR results can be used to evaluate the potential impact of fortification strategies towards meeting a population’s zinc physiological requirements [ 21 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

“…Zinc stable isotope methods may readily be applied to test zinc fortified foods in the context of meals containing local, commonly consumed foods or feeding an overall dietary pattern typical of that consumed locally. Recent examples of this approach have been published [ 25 , 26 , 27 , 28 ].…”

“…Recently, there has also been a trend to fortify milk and milk products with zinc for populations other than infants, i.e., toddlers [ 92 ], pre-school [ 93 ] and school-age children [ 28 , 94 , 95 ], non-pregnant [ 96 ] and pregnant women [ 97 ], and the elderly [ 62 ]. These studies included the fortification of milk or milk-based beverages [ 28 , 62 , 92 , 93 , 94 ], and yogurt [ 95 , 98 ].…”

“…In adolescents, zinc fortified milk providing 6 mg zinc per day increased zinc absorption from 1.1 mg per day to 3.1 mg per day [ 28 ]. The researchers used stable isotopic tracers to measure the zinc absorption from the milk and from the rest of the diet at the same time.…”