The Role of L-Glutamate as an Umami Substance for the Reduction of Salt Consumption: Lessons from Clinical Trials

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article addresses a specific and timely gap in nutritional science and public health related to strategies for salt reduction while maintaining palatability and compliance. The paper focuses on the challenge of sustaining reduced salt intake in diets, which is crucial for preventing non-communicable diseases like hypertension. Based on the article here are specific methodological improvements and further controls that the authors should consider:

1. Most trials referenced were short-term. Future studies should implement longitudinal designs to better assess the sustainability of reduced salt intake with glutamate over months.
2. Several studies focus on narrow participant groups. Future research should ensure greater demographic diversity in age, gender and health status.
3. Baseline dietary sodium intake was not always well-controlled or reported. A run-in period with standardized sodium intake across all participants would improve the internal validity of the findings.

Implementing these improvements and controls would enhance the study's rigor, validity, and policy implications.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study by Hideki Matsumoto et al. summarized recent advances in the study of the role of glutamate as umami substance for the reduction of salt consumption. The review is informative and interesting. I have the following questions and comments.

1, the resolution of figure 3 to figure 8 is very low. Please revise. All these figures need to be replaced.

2, for a review study, the authors must specify how the literature was searched, the keywords used for the collection of the studies. The reason why some studies were included and why others were excluded should also be discussed.

3, are there any side effects if we replace salt with glutamate in our daily diet? This must be discussed. 

4, some of the paragraphs in the manuscript is too long. The authors may consider divide them into different parts. For example, line 35 to 56, line 224 to 246. 

5, I suggest the authors to add a new table to summarize the most important findings in different human clinical trails. This would help the readers to understand the study more easily. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents an interesting narrative review devoted to the use of glutamate as an umami substance to reduce the sodium uptake. This question is actual and important. The review is generally well and competently written. The conclusions and practical prospects are scientifically sound.

Lines 5-8: Dear Authors, please write the names of the Department and Faculty starting words with capital letters, like in lines 9-10

Line 5: Start from the lower unit: first department, then faculty

Lines 39-41: If to be precise, is NaCl or Na+ involved in the processes listed?

Figure 1: Please correct “Hypermatremia” to “Hypernatremia”

Line 92: “the capacity of Glu”, I propose “the capacity of glutamate (Glu)”

Lines 107/108:” Created by the author“, there are multiple authors so it would be more appropriate to write “by the authors” or add initials after “the author”; the same refers to Figures 5 and 7

Lines 149/150:” Glu receptors in the oral cavity (taste bud) and the mucosa of the digestive tract”, I would suggest “Glu receptors in the oral cavity (in taste buds) and in the mucosa of the digestive tract”

Figure 4: “Five basic taste”, please correct to “Five basic tastes”

Line 209:” 5’-ribonucreotide”, which 5’-ribonucleotide?

Line 271: “CgA”, please explain the acronym on the first use

Abbreviations: Please write institution names: each word in a capital letter

Please format References according to the requirements of the journal

Comments on the Quality of English Language

All words in the names of the Department and Faculty (Affiliations) should start words with capital letters.The same referrs to the names of institutions (Abbreviations)

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors the revised the manuscript accordingly. It can be considered for publication.