Zinc Absorption From Fortified Water

• Fractional absorption (FA) of oral zinc isotope [ Time Frame: At baseline (day 1) and day 5. ] [ Designated as safety issue: No ]
  A spot urine sample will be collected at baseline (day 1) and 96+/-3 hours (at day 5) after test meal administration and will be used to quantify zinc FA from the test meal. The FA from the zinc enriched LSF water consumed with and without food will be compared with the FA from the zinc fortified cereal.
  
  

• Plasma zinc (PZn) [ Time Frame: day 1 ] [ Designated as safety issue: No ]
  Plasma zinc (PZn)concentration in blood samples will be analysed. PZn will be used to indicate if a participant is zinc deficient and therefore its absorption value from the test meals have to be treated with caution. PZn values will be compared to the corresponding cut-off values.
  
  
• C-reactive protein (CRP) [ Time Frame: day 1 ] [ Designated as safety issue: No ]
  C-reactive protein (CRP) concentration in blood samples will be analysed. CRP will indicate the inflammation/infection status of the subject at time of screening. Inflammation/infection is a confounder of zinc deficiency.
  
  

Zinc bioavailability from a food or diet depends on the content of zinc and the presence of inhibitors of zinc absorption, e.g. inositol phosphate, also known as phytic acid (PA), and it is typically estimated with the phytate to zinc molar ratio (Phy:Zn). A zinc absorption of 10-15% is estimated from diets containing mainly unrefined cereal grains or legumes with negligible amounts of animal proteins, which are dominant in developing countries (characterised by a Phy:Zn > 15). For comparison, a mixed animal and plant product diet (Phy:Zn ranging 5-15) is estimated to have an average zinc bioavailability of 20-30% whereas a diet with ample refined cereals and rich in animal foods (Phy:Zn < 5) would have average zinc bioavailability of 30-50% (12, 19). Fractional absorption from aqueous zinc sulphate or zinc chloride solutions taken in a fasting state has been shown to range 56-74% for doses of 0.5-10 mg zinc (20-24) and decreasing to 37-62% for doses of 13-30.1 mg zinc (22, 24). Zinc from drinking water consumed away from meals appears to be substantially better absorbed than that from composite foods. Alternative strategies, designed for providing zinc through the water supply, could prove useful in the global effort to control zinc deficiency.

To investigate whether zinc eluted from Lifestraw Family® (LSF) device via its specific zinc delivery system is more bioavailable than zinc from fortified cereals as zinc sulphate, we will perform a human absorption study based on the double isotopic tracer ratio technique. The fractional absorption of zinc (FAZ) from LSF-fortified water consumed with or without food will be compared to the FAZ from a fortified cereal. This will allow quantifying zinc bioavailability from the LSF eluted zinc 1) when LSF-water is consumed in fasting state 2) when LSF-water is consumed together with other foods 3) to compare the latter two with zinc absorption from a zinc fortified cereal.

The results of this study will provide information on the potential advantages of LSF fortification over zinc food fortification, which is currently the recommended delivery vehicle for zinc in country fortification programs (25, 26). Furthermore, comparing zinc bioavailability from LSF-water consumed alone or in combination with food will instruct about the optimal way to consume it. This information can be used to optimally design the delivery strategy in the planned efficacy trials. In the future, this information could also be integrated in the information recommendations for use for prospective end-consumers.