Consumption of a Single Dose of Prebiotic Galacto-Oligosaccharides Does Not Enhance Iron Absorption from Micronutrient Powders in Kenyan Infants: A Stable Iron Isotope Study.

BACKGROUND: Long-term feeding of prebiotic galacto-oligosaccharides (GOS) increases iron absorption in African infants, but the underlying mechanism and how long GOS need to be fed to infants to achieve an increase in absorption is uncertain. OBJECTIVES: In Kenyan infants, we tested whether the addition of GOS to a single test meal would affect iron absorption from a micronutrient powder (MNP) containing ferrous sulfate (FeSO4) and another MNP containing ferrous fumarate (FeFum) and sodium iron ethylenediaminetetraacetate (NaFeEDTA). METHODS: In a randomized-entry, prospective crossover study, iron deficient (87%) and anemic (70%) Kenyan infants (n  = 23; mean ± SD age, 9.9 ± 2.1 months) consumed 4 stable iron isotope-labeled maize porridge meals fortified with MNPs containing 5 mg iron as FeFum + NaFeEDTA, or FeSO4, either without or with 7.5 g GOS. The primary outcome, fractional iron absorption (FIA), was assessed by erythrocyte incorporation of isotopic labels. Data were analyzed using a 2-way repeated-measures ANOVA. RESULTS: There was no significant interaction between GOS and the iron compounds on FIA, and the addition of GOS did not have a significant effect on FIA. There was a statistically significant difference in FIA between the meals fortified with FeSO4 and with FeFum + NaFeEDTA (P  < 0.001).Given with GOS, FIA from FeSO4 was 40% higher than from FeFum + NaFeEDTA (P  < 0.001); given without GOS, it was 51% higher (P  < 0.01). CONCLUSIONS: The addition of GOS to a single iron-fortified maize porridge test meal in Kenyan infants did not significantly increase iron absorption, suggesting long-term feeding of GOS may be needed to enhance iron absorption at this age. This study was registered at clinicaltrials.gov as NCT02666417.

Iron Absorption is Greater from Apo-Lactoferrin and is Similar Between Holo-Lactoferrin and Ferrous Sulfate: Stable Iron Isotope Studies in Kenyan Infants.

BACKGROUND: Whether lactoferrin (Lf) binds iron to facilitate its absorption or to sequester iron from potential enteropathogens remains uncertain. Bovine Lf is added to many infant formulas, but previous studies in infants reported that Lf had no effect on or inhibited iron absorption. The effects of the apo (iron-free) or the holo (iron-loaded) forms of Lf on iron absorption are unclear. OBJECTIVES: Our objective was to compare iron absorption from a maize-based porridge containing: 1) labeled ferrous sulfate (FeSO4) alone; 2) labeled FeSO4 given with bovine apo-Lf; and 3) intrinsically labeled bovine holo-Lf. METHODS: In a crossover study, we measured iron absorption in Kenyan infants (n = 25; mean ± SD age 4.2 ± 0.9 months; mean ± SD hemoglobin 109 ± 11 g/L) from maize-based test meals containing: 1) 1.5 mg of iron as 54Fe-labeled FeSO4; 2) 1.42 mg of iron as 58Fe-labeled FeSO4, given with 1.41 g apo-Lf (containing 0.08 mg iron); and 3) 1.41 g holo-Lf carrying 1.5 mg iron as 57Fe. The iron saturation levels of apo- and holo-Lf were 0.56% and 47.26%, respectively primary outcome was fractional iron absorption (FIA), assessed by erythrocyte incorporation of isotopic labels. RESULTS: The FIA from the meal containing apo-Lf + FeSO4 (geometric mean, 9.8%; -SD and +SD, 5.4% and 17.5%) was higher than from the meals containing FeSO4 (geometric mean, 6.3%; -SD and +SD, 3.2% and 12.6%; P = 0.002) or holo-Lf (geometric mean, 5.0%; -SD and +SD, 2.8% and 8.9%; P <0.0001). There was no significant difference in FIA when comparing the meals containing holo-Lf versus FeSO4 alone (P = 0.24). CONCLUSIONS: The amount of iron absorbed from holo-Lf was comparable to that of FeSO4, and the addition of apo-Lf to a test meal containing FeSO4 significantly increased (+56%) iron absorption. These findings suggest that Lf facilitates iron absorption in young infants. Because Lf binds iron with high affinity, it could be a safe way to provide iron to infants in low-income countries, where iron fortificants can adversely affect the gut microbiome and cause diarrhea. This study was registered at clinicaltrials.gov as NCT03617575.

Prebiotics increase iron absorption and reduce the adverse effects of iron on the gut microbiome and inflammation: a randomized controlled trial using iron stable isotopes in Kenyan infants.

BACKGROUND: Iron fortificants tend to be poorly absorbed and may adversely affect the gut, especially in African children. OBJECTIVE: We assessed the effects of prebiotic galacto-oligosaccharides/fructo-oligosaccharides (GOS/FOS) on iron absorption and gut health when added to iron-fortified infant cereal. METHODS: We randomly assigned Kenyan infants (n = 191) to receive daily for 3 wk a cereal containing iron and 7.5 g GOS/FOS (7.5 g+iron group), 3 g (3-g+iron group) GOS/FOS, or no prebiotics (iron group). A subset of infants in the 2 prebiotic+iron groups (n = 66) consumed 4 stable iron isotope-labeled test meals without and with prebiotics, both before and after the intervention. Primary outcome was fractional iron absorption (FIA) from the cereal with or without prebiotics regardless of dose, before and after 3 wk of consumption. Secondary outcomes included fecal gut microbiota, iron and inflammation status, and effects of prebiotic dose. RESULTS: Median (25th-75th percentiles) FIAs from meals before intervention were as follows: 16.3% (8.0%-27.6%) without prebiotics compared with 20.5% (10.4%-33.4%) with prebiotics (Cohen d = 0.53; P < 0.001). FIA from the meal consumed without prebiotics after intervention was 22.9% (8.5%-32.4%), 41% higher than from the meal without prebiotics before intervention (Cohen d = 0.36; P = 0.002). FIA from the meal consumed with prebiotics after intervention was 26.0% (12.2%-36.1%), 60% higher than from the meal without prebiotics before intervention (Cohen d = 0.45; P = 0.007). After 3 wk, compared with the iron group, the following results were observed: 1) Lactobacillus sp. abundances were higher in both prebiotic+iron groups (P < 0.05); 2) Enterobacteriaceae sp. abundances (P = 0.022) and the sum of pathogens (P < 0.001) were lower in the 7.5-g+iron group; 3) the abundance of bacterial toxin-encoding genes was lower in the 3-g+iron group (false discovery rate < 0.05); 4) fecal pH (P < 0.001) and calprotectin (P = 0.033) were lower in the 7.5-g+iron group. CONCLUSIONS: Adding prebiotics to iron-fortified infant cereal increases iron absorption and reduces the adverse effects of iron on the gut microbiome and inflammation in Kenyan infants. This trial was registered at clinicaltrials.gov as NCT03894358.

Gut microbiome function and composition in infants from rural Kenya and association with human milk oligosaccharides.

The gut microbiota evolves rapidly after birth, responding dynamically to environmental factors and playing a key role in short- and long-term health. Lifestyle and rurality have been shown to contribute to differences in the gut microbiome, including Bifidobacterium levels, between infants. We studied the composition, function and variability of the gut microbiomes of 6- to 11-month-old Kenyan infants (n = 105). Shotgun metagenomics showed Bifidobacterium longum to be the dominant species. A pangenomic analysis of B. longum in gut metagenomes revealed a high prevalence of B. longum subsp. infantis (B. infantis) in Kenyan infants (80%), and possible co-existence of this subspecies with B. longum subsp. longum. Stratification of the gut microbiome into community (GMC) types revealed differences in composition and functional features. GMC types with a higher prevalence of B. infantis and abundance of B. breve also had a lower pH and a lower abundance of genes encoding pathogenic features. An analysis of human milk oligosaccharides (HMOs) classified the human milk (HM) samples into four groups defined on the basis of secretor and Lewis polymorphisms revealed a higher prevalence of HM group III (Se+, Le-) (22%) than in most previously studied populations, with an enrichment in 2'-fucosyllactose. Our results show that the gut microbiome of partially breastfed Kenyan infants over the age of six months is enriched in bacteria from the Bifidobacterium community, including B. infantis, and that the high prevalence of a specific HM group may indicate a specific HMO-gut microbiome association. This study sheds light on gut microbiome variation in an understudied population with limited exposure to modern microbiome-altering factors.

Examining Associations of HIV and Iron Status with Nutritional and Inflammatory Status, Anemia, and Dietary Intake in South African Schoolchildren.

The etiology of multifactorial morbidities such as undernutrition and anemia in children living with the human immunodeficiency virus (HIV) (HIV+) on antiretroviral therapy (ART) is poorly understood. Our objective was to examine associations of HIV and iron status with nutritional and inflammatory status, anemia, and dietary intake in school-aged South African children. Using a two-way factorial case-control design, we compared four groups of 8 to 13-year-old South African schoolchildren: (1) HIV+ and low iron stores (inflammation-unadjusted serum ferritin ≤ 40 µg/L), n = 43; (2) HIV+ and iron sufficient non-anemic (inflammation-unadjusted serum ferritin > 40 µg/L, hemoglobin ≥ 115 g/L), n = 41; (3) children without HIV (HIV-ve) and low iron stores, n = 45; and (4) HIV-ve and iron sufficient non-anemic, n = 45. We assessed height, weight, plasma ferritin (PF), soluble transferrin receptor (sTfR), plasma retinol-binding protein, plasma zinc, C-reactive protein (CRP), α-1-acid glycoprotein (AGP), hemoglobin, mean corpuscular volume, and selected nutrient intakes. Both HIV and low iron stores were associated with lower height-for-age Z-scores (HAZ, p < 0.001 and p = 0.02, respectively), while both HIV and sufficient iron stores were associated with significantly higher CRP and AGP concentrations. HIV+ children with low iron stores had significantly lower HAZ, significantly higher sTfR concentrations, and significantly higher prevalence of subclinical inflammation (CRP 0.05 to 4.99 mg/L) (54%) than both HIV-ve groups. HIV was associated with 2.5-fold higher odds of iron deficient erythropoiesis (sTfR > 8.3 mg/L) (95% CI: 1.03-5.8, p = 0.04), 2.7-fold higher odds of subclinical inflammation (95% CI: 1.4-5.3, p = 0.004), and 12-fold higher odds of macrocytosis (95% CI: 6-27, p < 0.001). Compared to HIV-ve counterparts, HIV+ children reported significantly lower daily intake of animal protein, muscle protein, heme iron, calcium, riboflavin, and vitamin B12, and significantly higher proportions of HIV+ children did not meet vitamin A and fiber requirements. Compared to iron sufficient non-anemic counterparts, children with low iron stores reported significantly higher daily intake of plant protein, lower daily intake of vitamin A, and lower proportions of inadequate fiber intake. Along with best treatment practices for HIV, optimizing dietary intake in HIV+ children could improve nutritional status and anemia in this vulnerable population. This study was registered at clinicaltrials.gov as NCT03572010.

The effect of iron dosing schedules on plasma hepcidin and iron absorption in Kenyan infants.

BACKGROUND: In adults, oral iron doses increase plasma hepcidin (PHep) for 24 h, but not for 48 h, and there is a circadian increase in PHep over the day. Because high PHep decreases fractional iron absorption (FIA), alternate day iron dosing in the morning may be preferable to consecutive day dosing. Whether these effects occur in infants is uncertain. OBJECTIVE: Using stable iron isotopes in Kenyan infants, we compared FIA from morning and afternoon doses and from consecutive, alternate (every second day) and every third day iron doses. METHODS: In prospective studies, we measured and compared FIA and the PHep response from 1) meals fortified with a 12-mg iron micronutrient powder given in the morning or afternoon (n = 22); 2) the same given on consecutive or alternate days (n = 21); and 3) a 12-mg iron supplement given on alternate days or every third day (n = 24). RESULTS: In total, 65.7% of infants were anemic. In study 1, PHep did not differ between morning and afternoon (P = 0.072), and geometric mean FIA[-SD, +SD](%) did not differ between the morning and afternoon doses [15.9 (8.9, 28.6) and 16.1 (8.7, 29.8), P = 0.877]. In study 2, PHep was increased 24 h after oral iron (P = 0.014), and mean FIA [±SD](%) from the baseline dose [23.3 (10.9)] was greater than that from the consecutive day dose (at 24 h) [20.1 (10.4); P = 0.042] but did not differ from the alternate day dose (at 48 h) [20.9 (13.4); P = 0.145]. In study 3, PHep was not increased 48 and 72 h after oral iron (P = 0.384), and the geometric mean FIA[-SD, +SD](%) from doses given at baseline, alternate days, and every third day did not differ [12.7 (7.3, 21.9), 13.8 (7.8, 24.2), and 14.8 (8.8, 24.8), respectively; P = 0.080]. CONCLUSIONS: In Kenyan infants given 12 mg oral iron, morning and afternoon doses are comparably absorbed, dosing on consecutive days increases PHep and modestly decreases iron absorption compared with alternate day dosing, and dosing on alternate days or every third day does not increase PHep or decrease absorption. This trial was registered at clinicaltrials.gov as NCT02989311 and NCT03617575.