Interactions of Astaxanthin and Omega-3 Fat in Health and Disease

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is an interesting article about astaxanthin and omega-3 fats and their impact on oxidative stress, inflammation, health, and disease. The article is well organized and complex topics are explained in a way that most readers can understand. I have a few suggestions for improvement below:

For the keywords, I recommend adding “antioxidant” and “astaxanthin”.

Introduction

Please provide citations for lines 23 through 27.

Methods

I recommend adding a methods section to describe your search terms, databases used, timeframe for articles, and inclusion/exclusion criteria for articles used. It should also be noted what type of review this is – narrative, scoping, systematic, etc. It appears to be narrative.

 

Section 2 - Food sources of Ast and omega-3 PUFAs

In lines 41-45 where you describe the chemical structure of Ast, it would help to have a figure showing the structures of the various isomers. I see the structure of one form in figure 3, but having another figure focused on the various isoform structures that you describe would be helpful to the reader.

In line 60 you mentioned that Ast is on the FDA GRAS list. Does this refer only to the free form, or are the esterified forms also on the GRAS list?

In line 87, you may want to consider removing the website link and just providing a citation with the web link in the reference section. You could also consider using a web archiving service to preserve the information in the link in case the website page changes in the future. This is just a suggestion.

In lines 88 through 95 it would be worth mentioning that another food source for algae is seaweed, especially since seaweed is becoming more common as a food item. Krill can also be purchased as a food item and not just an oil or supplement. Although seaweed and krill may not be popular food items, it is still worth mentioning to encourage people to consume omega 3s through food when possible rather than supplements.

 

Section 3 - Digestion, absorption, and transport of Ast and omega-3 PUFAs

In the first sentence of the Figure 1 legend, I suggest writing out the full name of astaxanthin followed by the abbreviation.

 

Second section 3 (should be section 4?)- Mechanisms involved in the beneficial actions of Ast and omega-3 PUFAs

This section should be marked as the next section since you already have a section 3 on digestion, etc.

This is a just small detail, but in line 175 it is more common to say “reactive oxygen and nitrogen species” rather than “reactive oxygen-nitrogen species” since ROS and RNS are usually separate species.

In figure 2, the large green arrow in the bottom left corner is the only confusing part of this figure. I think it means that there is reduced oxidative stress and inflammation based on the increased production of endogenous antioxidants. However, it may be better to use the inhibition arrow and point it towards the Oxidative Stress and Inflammation term.

In line 281, just a small typo for the word “reducing”. Everything else that follows looks good.

 

Section 4 (should be section 5?) - Mechanisms involved in the beneficial actions of Ast and omega-3 PUFAs

This section is very informative. There is mainly information about the action of Ast and w-3 PUFAs separately, and less about their interactions, but it is still valuable information and shows that we still have more to learn.

Author Response

Thank you for thorough reading of the review and providing constructive critiques. 

1. added antioxidant into the keywords.
2. citations for the introduction section: relevant literature is cited. 
3. chemical structure of Ast isoforms are added to the figure 3.
4. FDA GRAS list is updated - thank you for your feedback.
5. The website link is removed.
6. Other food sources including seaweed and krill are added.
7. Figure 1 legend - spelled out the full name of astaxanthin. 
8. Section numbering has been updated.
9. changed reactive oxygen-nitrogen species into reactive oxygen and nitrogen species. 
10. Figure 2 has been modified based on the reviewer's suggestion.
11. fixed the typo for the word “reducing”.

Thank you!

 

Reviewer 2 Report

Comments and Suggestions for Authors

I congratulate the Author for the work

The paper is readible and fluent. 

The number of sections is correct, and topics are covered in depth. Your conclusions are in line with the literature presented.

I have some suggestions to improve the paper.

 

line 47 please rephrase "They contain mostly as Ast-esters and the common FAs are myristic acid ..." I think can sound better "They contain mostly as Ast-esters, while the more common FAs are myristic acid... " (if I understood correctly the meaning)

line 75 please add a reference to genetic differences in elongases and desaturases that influence functionality and PUFA metabolism. These differences can be regional, too, thus oriental people can have less requirement of LC-PUFA, for example.

 

line 84 please specify that atlantic/farm raised salmon contains an excess of omega 6, too

 

Line 162 Is there a contribution by DNL (conversion of CHO in FA) in a typical Western diet? I think you can improve this paragraph with a more recent reference in the light of newer discoveries about the topic.

 

figure 2: please change the font to make more readable this nice image 

Line 219-220 Which is the reference for this statement?

Author Response

The author appreciate the reviewer's careful reading of the manuscript and constructive feedback.

1. The sentence, "they contain mostly as Ast-esters......" has been rephrased. 
2. "Genetic differences in elongases and desaturases...." - has been added with references. 
3. The fact that Farmed salmon contains more omega-6 fatty acids has been added. 
4. Regarding DNL - while we agree with the point raised by the reviewer, more description of this topic is beyond the scope of the paragraph describing digestion, absorption and transport of omega-3 fatty acids.  
5. Font style has been modified to make the figure more readable. 
6. Line 219-220: the sentence has been removed as it is redundant with the prior sentence.

Thank you again.