Efficacy of highly bioavailable zinc from fortified water: a randomized controlled trial in rural Beninese children12

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ABSTRACT

Background: Zinc deficiency and contaminated water are major contributors to diarrhea in developing countries. Food fortification with zinc has not shown clear benefits, possibly because of low zinc absorption from inhibitory food matrices. We used a novel point-of-use water ultrafiltration device configured with glass zinc plates to produce zinc-fortified, potable water.

Objective: The objective was to determine zinc bioavailability from filtered water and the efficacy of zinc-fortified water in improving zinc status.

Design: In a crossover balanced study, we measured fractional zinc absorption (FAZ) from the zinc-fortified water in 18 healthy Swiss adults using zinc stable isotopes and compared it with zinc-fortified maize porridge. We conducted a 20-wk double-blind randomized controlled trial (RCT) in 277 Beninese school children from rural settings who were randomly assigned to receive a daily portion of zinc-fortified filtered water delivering 2.8 mg Zn (Zn+filter), nonfortified filtered water (Filter), or nonfortified nonfiltered water (Pump) from the local improved supply, acting as the control group. The main outcome was plasma zinc concentration (PZn), and the 3 groups were compared by using mixed-effects models. Secondary outcomes were prevalence of zinc deficiency, diarrhea prevalence, and growth.

Results: Geometric mean (−SD, +SD) FAZ was 7-fold higher from fortified water (65.9%; 42.2, 102.4) than from fortified maize (9.1%; 6.0, 13.7; P < 0.001). In the RCT, a significant time-by-treatment effect on PZn (P = 0.026) and on zinc deficiency (P = 0.032) was found; PZn in the Zn+filter group was significantly higher than in the Filter (P = 0.006) and Pump (P = 0.025) groups. We detected no effect on diarrhea or growth, but our study did not have the duration and power to detect such effects.

Conclusions: Consumption of filtered water fortified with a low dose of highly bioavailable zinc is an effective intervention in children from rural African settings. Large community-based trials are needed to assess the effectiveness of zinc-fortified filtered water on diarrhea and growth. These trials were registered at clinicaltrials.gov as NCT01636583 and NCT01790321.

Keywords:

Benin
school-age children
water fortification
zinc absorption
zinc fortification

ABBREVIATIONS

AGP
α1-acid glycoprotein
CRP
C-reactive protein
ETH
Swiss Federal Institute of Technology
FAZ
fractional zinc absorption
FM+W
zinc-fortified maize porridge consumed with ultrapure water
FW
zinc-fortified water alone
LSF
LifeStrawFamily
M+FW
arm with unfortified maize porridge but with zinc-fortified water
MEM
mixed-effects models
PZn
plasma zinc concentration
RCT
randomized controlled trial
SRSS
sparse random serial sampling

Cited by (0)

1

Supported by Vestergaard, Lausanne, Switzerland.

2

Supplemental Table 1 and Supplemental Figures 1 and 2 are available from the “Online Supporting Material” link in the online posting of the article and from the same link in the online table of contents at http://ajcn.nutrition.org.

8

These are joint first authors.

9

These authors contributed equally to the article.