Page 64 - Read Online

Page 8 of 18 Chen et al. Microbiome Res Rep 2025;4:8 https://dx.doi.org/10.20517/mrr.2024.44

Table 3 provides an overview of all fecal microbiota outcomes. Three out of four studies reported findings
on alpha diversity from the second day of life to the sixth week of life [31-33] . Arboleya et al. reported a higher
Shannon index from day 10 onwards, with the Chao1 index only higher at day 10 in the DHM group
[31]
compared to MOM (all P-values < 0.05) . In addition, they reported a decreasing alpha diversity over time
in the MOM group, but the decrease was less pronounced in the DHM group. It is important to note that in
the study by Arboleya et al., these diversity measures are specific to Bifidobacterium bacteria only, rather
than overall diversity . The remaining two studies showed no difference in alpha diversity indices, but
[31]
Ford et al. observed lower operational taxonomic unit (OTU) richness in the DHM group across all time
points (P = 0.013) .
[33]

Subgroup B
Three out of four studies reported findings on alpha diversity from birth to day 60 of life [19,36,37] . In all three
studies, alpha diversity measures were found to be lower in the DHM group compared to the MOM group.
week of life, whereas the DHM-fed infants did not .
Cong et al. observed that the Gini-Simpson index increased over time in both groups, but was continuously
lower in the DHM group from birth to the 30th day of life, with feeding type explaining this difference (P <
0.01) . Gregory et al. showed a lower Shannon diversity index overall, although it increased more rapidly
[36]
over time compared to the MOM group . Morais et al. showed a lower Chao1 index on the 26th day of life,
[19]
[37]
but no differences in the Shannon index .
Overall
Most studies reporting on different alpha diversity measures found either no difference or significantly
lower alpha diversity in the DHM groups compared to those infants receiving predominantly MOM [19,33,36,37] .
In contrast to the other studies, Arboleya et al. focused specifically on Bifidobacterium diversity solely,
showing a higher Shannon diversity index in the DHM group at all time points starting from the tenth day
of life, rather than reporting on overall microbial diversity .
[31]
Beta diversity
Subgroup A
All four studies reported beta diversity differences based on feeding type. Three studies demonstrated
distinct clustering based on feeding type [31,32,34] . Arboleya et al. showed distinct separation from the tenth day
[31]
of life onwards (P < 0.05) . Kumbhare et al. showed that MOM intake explained 22% and 18% of the Bray-
Curtis dissimilarity (P < 0.01) at PMA of 33 and 35 weeks, respectively . Piñeiro-Ramos et al. showed a
[34]
different microbial composition on the 10th and the 30th day of life (P = 0.04) . Ford et al. observed
[32]
different microbiome successions per week of life, with MOM-fed infants showing apparent clustering per
[33]

Subgroup B
All four studies reported findings on beta diversity. Three out of four studies showed distinct clustering
based on feeding type [19,35,36] . Cong et al. and Gregory et al. showed feeding type explained the greatest
variance in Bray-Curtis dissimilarity (11%, P < 0.01 and 21%, P < 0.001, respectively) [19,36] . Parra-Llorca et al.
observed differences in microbial composition through multivariate redundant discriminate analysis .
[35]
Morais et al. assessed beta diversity only at postnatal day 26 (PMA around 34 weeks) but found no
differences between feeding groups .
[37]

Overall
All but one study reported findings on beta diversity between the DHM and MOM groups. Six of them
showed distinct microbial clustering between DHM and MOM groups, starting from the 10th day of
life [19,31,32,34-36] until PMA 36 weeks. Morais et al. was the exception, reporting no differences .
[37]