Zinc Absorption by Adults Is Similar from Intrinsically Labeled Zinc-Biofortified Rice and from Rice Fortified with Labeled Zinc Sulfate.

BACKGROUND: Biofortification of staple food crops is a promising strategy to combat zinc deficiency, and it is of particular interest for rice and crops that are not consumed as flours and therefore not suitable for postharvest fortification. Because zinc absorption is decreased by phytic acid (PA) and perhaps other dietary components, it is important to measure the absorption of zinc from a biofortified crop before determining its efficacy. OBJECTIVE: In this study, we compared the zinc absorption from zinc-biofortified rice (hydroponically enriched with (70)Zn) with that from a control rice of the same variety fortified with (70)ZnSO4 at point of use to reach the same total zinc content of 1.1 mg/meal. Both rice meals had a PA:Zn molar ratio of 12. METHODS: Fractional absorption of zinc (FAZ) was measured with the use of the double-isotope tracer ratio method in 16 apparently healthy adults [18-45 y old; BMI (in kg/m(2)) 19-25] who consumed 2 single meals at 4-wk intervals in random order in a crossover design. RESULTS: The FAZ from the biofortified rice (mean ± SD: 25.1 ± 8.7%) did not differ significantly from that of the point-of-use fortified rice (mean ± SD: 20.8 ± 7.1%) (P = 0.08). CONCLUSIONS: These results suggest that the native zinc accumulated in the biofortified rice was readily released from the rice matrix and that its absorption by adults was influenced by PA and other food components in a similar way to the inorganic zinc compound added to the rice at point of use. Moreover, rice biofortification is likely to be as good as postharvest zinc fortification as an intervention strategy to combat zinc deficiency. This trial was registered at clinicaltrials.gov as NCT01633450.

Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide.

The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with (67)Zn and (70)Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6-71.0) and was not different from that from zinc gluconate with 60.9% (50.6-71.7). Absorption from zinc oxide at 49.9% (40.9-57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627.

Influence of phytase, EDTA, and polyphenols on zinc absorption in adults from porridges fortified with zinc sulfate or zinc oxide.

Fortification of cereal staples with zinc is recommended to combat zinc deficiency. To optimize zinc absorption, strategies are needed to overcome the inhibitory effect of phytic acid (PA) and perhaps polyphenols. Five zinc absorption studies were conducted in young adults consuming maize or sorghum porridges fortified with 2 mg zinc as zinc sulfate (ZnSO4) or zinc oxide (ZnO) and containing combinations of PA or polyphenols as potential inhibitors and EDTA and phytase as potential enhancers. Fractional absorption of zinc (FAZ) was measured by using the double isotopic tracer ratio method. Adding phytase to the maize porridge immediately before consumption or using phytase for dephytinization during meal preparation both increased FAZ by >80% (both P < 0.001). Adding Na2EDTA at an EDTA:zinc molar ratio of 1:1 increased FAZ from maize porridge fortified with ZnSO4 by 30% (P = 0.01) but had no influence at higher EDTA ratios or on absorption from ZnO. FAZ was slightly higher from ZnSO4 than from ZnO (P = 0.02). Sorghum polyphenols had no effect on FAZ from dephytinized sorghum porridges but decreased FAZ by 20% from PA-rich sorghum porridges (P < 0.02). The combined inhibitory effect of polyphenols and PA was overcome by EDTA. In conclusion, ZnSO4 was better absorbed than ZnO, phytase used to degrade PA during digestion or during food preparation substantially increased zinc absorption from zinc-fortified cereals, EDTA at a 1:1 molar ratio modestly enhanced zinc absorption from ZnSO4-fortified cereals but not ZnO-fortified cereals, and sorghum polyphenols inhibited zinc absorption in the presence, but not absence, of PA. This trial was registered at clinicaltrials.gov as NCT01210794.

Observational Study of Lipid Profile and C-Reactive Protein after a Seven-Day Fast.

Fasting is becoming an increasingly popular practice. Nevertheless, its clinical benefits and possible inconveniences remain limitedly evaluated. We observed the effects of a seven-day fast conducted in a non-medical center located in the Swiss Alps. Clinical parameters were measured on the first and last day of fasting (D1 and D7), and two months later (D60). Among the 40 participants, blood analyses were done on 25 persons with an increased metabolic risk, with the primary goal of assessing the lasting effect on low-density lipoprotein (LDL) cholesterol. By comparing D60 with D1, high-density lipoprotein cholesterol (HDL) (+0.15 mmol/L) and insulin-like growth factor-1 (IGF-1) (+2.05 mmol/L) increased (both p < 0.009), all other blood parameters (LDL, glucose, total cholesterol, triglycerides, C-reactive protein (CRP)) did not change; weight (-0.97 kg) and hearth rate (-7.31 min-1) decreased (both p < 0.006). By comparing D7 with D1, total cholesterol (+0.44 mmol/L), triglycerides (+0.37 mmol/L) and CRP (+3.37 mg/L) increased (all p < 0.02). The lack of LDL variation at D60 may be due to the low metabolic risk level of the participants. The increase of total cholesterol, triglycerides and CRP at D7 warrants studies to understand whether such fluctuations represent a stress reaction to the fasting state, which may vary in different fasting types.