Effects of Fermented Onion on Gut Health in Dextran Sodium Sulfate (DSS)-Induced Inflammatory Bowel Disease (IBD) Rats

Round 1

Reviewer 1 Report

In this manuscript, Neeracha et al studies the effect of fermented onion on the gut histopathology, inflammation and oxidative stress in DSS-induced IBD rats. It sounds a meaningful investigation. However, the data cannot meet the study aim or support the conclusion. Authors should carefully consider the following problems.

# As authors described, high content FODMAPs foods can exert adverse effect on IBD, therefore onion fermentation becomes a necessary process. However, authors did not examine the fructan content of fermented onion or other chemicals, which should explain the beneficial mechanism of fermented onion.

# 2.1 Materials and chemicals, authors should detail the commercial probiotics, i.e. names, taxonomy and background. Most of all, why did authors select it as a positive control? Does it have a beneficial effect on IBD?

# 2.2 Preparation of fermented onion, onion was fermented by the starter culture Lactobacillus casei, how did authors select this strain? In my opinion, it’s better to choose the same strain as both starter culture and positive control, which can reveal the functional factors in fermented onion, chemical components or bacteria after the comparison of positive control and fermented onion.

# For DSS-induced colitis model, authors should firstly examine whether treatment with fermented onion can decrease lethality or attenuate the clinical signs.

# SCFA data alone cannot make sense, authors should also pay attention to the changes of gut microbial composition which are associated with the administration of fermented onion.

#supplementary materials, as the Figure S1 showed, the weight of HO group was the lowest, and all groups reduced the food and water intake. Please explain it in the manuscript.

Other remarks:

# Abstract, the sentence “Rats were divided into 6 groups and treated orally with saline, probiotics, low and high-dose fermented onion, or fresh onion extract for 3 weeks” refers to six rat groups, but only five was listed, which makes readers confusing, change it.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

This is a very interesting manuscript dealing with the current topic of intestinal disorders and the importance of diet in relation to this aspect. The topic addressed in the manuscript is original and interesting for the scientific community, and the techniques used in the work are novel.

The introduction covers adequately the topic of the paper and the reason for the research performed is clearly justified.

The paper develops the subject logically. The methodology is clearly presented, and the data discussed support the conclusions offered by the paper. The conclusions are focused on the hypothesis of the study.

Finally, the subject of the study is of considerable interest and deserves a more in-depth dissertation.

However, some minor aspects are recommended to be analyzed and please assess the opportunity to be taken into consideration:

-The description of the sample preparation in the paragraph 2.2. Preparation of fermented onion could be more concrete or detailed. In addition, the source or a minimal description of the strain of Lactobacillus casei used for the experiments would be useful.

-line 409-410 – “Butyrate was significantly decreased in DSS-induced groups while increased in both LO and HO groups” – please assess the opportunity to slightly rephrase the sentence in order to understand that the LO and HO groups are exceptions among the DSS-induced groups.

-lines 350 + 409 - figure 7 (in text) should be renamed as figure 6.

-lines 439-443 – the last paragraph includes relevant assumptions of several compounds that are not mentioned in the manuscript. It is recommended to make a better connection with the aspects discussed or to formulate it in a clear and logical manner.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

No more comments.