Data published the American Journal of Clinical Nutrition indicated that formulating GOS/FOS into the iron-fortified infant cereal also reduced the adverse effects of iron on the gut microbiome and inflammation in the infants.
“To our knowledge, this study demonstrated for the first time that not only a single dose of prebiotics but also previous conditioning of the infant gut with prebiotics facilitates increased iron absorption,” wrote scientists from ETH Zurich, Danone Nutricia Research, Jomo Kenyatta University of Agriculture and Technology, Biopolis S.L.-ADM., Msambweni County Referral Hospital and the University of Oxford.
“This effect may be important in that it suggests that overall dietary iron absorption in infancy might be increased by provision of prebiotics. In addition, we confirm earlier findings describing prebiotic mitigation of adverse iron effects from MNPs on the African infant gut and extend these findings to iron-fortified infant cereals, which are provided to many infants worldwide.”
Prebiotics and mineral absorption
The ability of prebiotics, particular inulin, FOS and GOS, to improve absorption of minerals such as calcium and magnesium has been reported many times over the past 20 years. The mechanism of action is reportedly linked to the selective fermentation of the prebiotics to produce short chain fatty acids (SCFAs), which in turn reduce the pH and facilitate mineral absorption.
Scientists from Shenzhen University reported that GOS and FOS could boost iron absorption in lab animals, which they claimed was the first report of such benefits (Molecular Nutrition & Food Research, 2022).
The new study is reportedly the first to show similar benefits in infants.
According to the World Health Organization (WHO), about 30% of the world’s population may have low red blood cell numbers due to insufficient iron. In the U.S., almost 10% of toddlers have inadequate bodily stores of iron. A 2021 study from scientists at Columbia University suggests that we may be underestimating the prevalence of iron deficiency.
Study details
For the new study, 191 Kenyan infants were recruited and randomly assigned to consume an iron-fortified infant cereal formulated with 7.5 g of GOS/FOS, 3 g of GOS/FOS or no prebiotics. The GOS to FOS ratio was 9:1, and the intervention lasted three weeks.
Results showed that the fractional iron absorption (FIA) in the prebiotic groups was 26%, 60% higher than from consuming a non-prebiotic cereal meal before the intervention.
The research team also reported that the prebiotic groups displayed significantly higher abundances of Lactobacillus sp., compared to the control group. Additionally, abundances of undesirable Enterobacteriaceae sp. and other pathogens were significantly lower in the high-dose prebiotic group.
Significantly lower fecal pH was also reported for the 7.5 g prebiotic group.
Commenting on the potential mechanism(s) of action, the researchers stated: “First, prebiotics might increase short-chain fatty acid and lactic acid production by gut commensal bacteria, thereby decreasing distal gut luminal pH and increasing iron dissolution and absorption, although colonic iron absorption in humans is believed to be minimal.
“Second, animal studies have shown that prebiotics can stimulate proliferation of enterocytes creating a greater surface for iron absorption and/or increase gene expression of enterocyte proteins involved in iron absorption.
“Third, in this study, Lactobacillus sp. abundance increased significantly in both prebiotic groups compared with that in the iron group, and in mice, microbiota metabolites, particularly from Lactobacillus species, may modulate iron absorption.
“Finally, prebiotics may facilitate iron absorption by reduction of gut and/or systemic inflammation and may increase Hb [hemoglobin] concentration.”
The researchers concluded: “Iron strategies should provide the lowest effective iron dose that minimizes adverse effects on the infant gut, and iron absorption be maximized.”
Source: The American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.ajcnut.2023.11.018
“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”
Authors: N. Mikulic et al.