Review for 10.1186/s12876-025-04140-2 (2025)

Title: Impact of Microplastics on the Human Gut Microbiome: A Systematic Review of
Microbial Composition, Diversity, and Metabolic Disruptions
Version: 2 Date: 17 May 2025
Reviewer's report:
The manuscript entitled “Microplastics and Impacts on Human Gut Microbiome: A Systematic
Review on Microbiota Composition, Diversity, and Metabolic Disruptions” is a systematic
review summarizing the effects of MPs on the human gut microbiome, which focuses on the
microbial diversity, function, and metabolic pathways. The subject chosen for the review is
critical for understanding the impacts of microplastics (MPs) on human health. The study has
been systematically designed. and the methodology is reproducible. This draft is informative and
will be of interest to the readers of this journal. The tables are well-designed and informative.
The topic discussed is important and apt for the journal. I have a few suggestions that I believe
can help improve the quality of the manuscript.
Specific comments:
1. The authors may improve the keywords to aid better identification by readers.
2. The authors may include a list of abbreviations (maybe in a table before the introduction)
used in the text to enable better understanding.
3. The authors may include a graphical abstract that summarizes the manuscript effectively.
4. Line 24: Microplastics (MPs): Use the full form in the text once before abbreviations.
5. Line 55: Please remove “of”.
6. Line 87: Please include a few lines on the knowledge gaps in the available studies before
stating the aim of this review.
7. Line 101: The authors may use the abbreviations (MPs and NPs or MNPs) as the full form
has been mentioned already in the text.
8. I think Table 1 is unnecessary; the authors may integrate it into the text like an equation (with
arrows), maybe.
9. Line 171: Why or how could MPs reduce Bacteroidetes? Any assumptions or possible theories
or mechanisms?
10. Line 171: How does reduced SCFA production (by Bacteroidetes) lead to IBD? Also, in line
224, a study has found that PA MPs increased the abundance of Bacteroidetes. It’s an interesting
observation. The authors may discuss a line or 2 explaining the possible reasons.
11. Lines 225-229 are very alarming and interesting. Moreover, studies on meconium samples
are significant in understanding teratogenic effects. Were the concentrations mentioned in the
table the tested/spiked doses or actual MPs detected from meconium? Though out of the scope,
the authors may include just a line highlighting the risk of a potential MP/NP (or associated
pathogens) inhalation by fetuses and newborns due to meconium aspiration syndrome.
12. Table 6 is highly informative. But I don’t think it has been discussed sufficiently in the
text. Please discuss at this table. Especially, upregulation of certain pathways and decreased bile
production; This may enhance the impact of this review.
13. Conclusion can be separated into 2 sections – conclusion and way forward/recommendations
(from line 365).
14. The authors may consider adding a figure or a visual representation of the impacts, especially
on the metabolic pathways.
15. Please go through the manuscript for typos and proofread the draft once again.