Fig. 4: Relative faecal microbiota distribution changes after dietary intervention (n = 43) at the phylum level.

a Relative abundances (%) of Bacteroidota (b), Firmicutes (c) and Actinobacteriota (d) according to dietary iron (Ferric citrate vs. Haemoglobin) and calcium (Control vs. Mineral vs. Dairy) contents are detailed. Individual values within box and whisker are represented with “+” as means. For statistical analysis, two-way ANOVA, followed by Holm-Šídák’s multiple comparisons tests were performed. *padj < 0.05, **padj < 0.01, ***padj < 0.001 according to dietary iron form. Detailed F-statistic and p values are provided as Supporting Information Table S1.