The Role of Polyunsaturated Fatty Acids (PUFAs) in the Primary Prevention of Allergic Diseases in Children: A Position Paper of the SIAIP Primary and Secondary Prevention of Allergic Diseases and Nutraceuticals Committees

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overall evaluation: This article is a position paper of the Special Committee of the Italian Society of Pediatric Allergy and Immunology (SIAIP), systematically reviewing the role of polyunsaturated fatty acids, especially Omega-3 long-chain fatty acids (EPA, DHA), in the primary prevention of allergic diseases in children. The article summarizes the current status of allergic diseases, the classification and food sources of PUFA, and the molecular mechanisms of immune regulation. It systematically evaluates the clinical evidence of maternal supplementation during pregnancy and lactation and Omega-3 exposure in infancy, compares the fatty acid and pollutant differences between wild and farmed salmon, summarizes the recommended doses from EFSA and SIAIP, and provides a comprehensive prevention strategy. Main contributions: It clearly identifies that the 1000-day period before birth is a critical window for Omega-3 intervention; it confirms that adequate EPA/DHA supplementation during pregnancy and lactation can reduce the respiratory allergic risks such as wheezing and asthma in offspring; it clarifies that Omega-3 acts through multiple pathways such as lipid mediators, Th1/Th2 balance, gut microbiota, and ferroptosis-immune-metabolic axis; it provides standardized supplementation doses, ingredient selection, formulation screening, and integrated prevention strategies, providing authoritative evidence-based guidance for clinical pediatric, obstetric nutrition, and allergy prevention. Main reviewers' comments are as follows:
1. The studies included RCTs, observational studies, and Meta-analyses, but the methodological quality of the included literature was not evaluated. The quality of the literature was not assessed using JBI, AMSTAR, or Cochrane bias risk tools. The results of low-quality studies were analyzed together with high-quality studies. It is recommended to score the quality of each type of study, conduct stratified analysis of the conclusions of high-quality literature, eliminate studies with high bias risk, and enhance the argumentation of evidence level classification.
2. The clinical evidence of Omega-3 supplementation in infancy is highly heterogeneous, but the source of heterogeneity was not analyzed, and the reasons for the differences in results were not analyzed from dimensions such as intervention timing, formula type, and baseline family history of allergies. It is recommended to conduct a source analysis of heterogeneity, stratify by supplementation before 6 months / after 6 months, and by ordinary formula / fortified formula, and clarify the differences in allergic prevention effects under different intervention conditions.
3. The conclusion section is too general, and the applicable population for primary prevention, the optimal intervention window period, and the preferred supplementation method (dietary / formulation) are not distinguished. It does not form a direct implementation clinical pathway. It is recommended to reconstruct the conclusion, categorize it into ordinary children, children with high-risk allergies, and pregnant and lactating women, and clearly define the intervention timing, dosage, ingredient selection, and standardized follow-up management path.
4. In Section 2.1 of the article, lines 79-125, there is no concise structural diagram for the classification of Omega-3 and Omega-6, and the description is cumbersome. It is recommended to supplement a classification structure diagram of PUFA families to visually display the derivative relationships of ALA, EPA, DHA, LA, and AA.
5. In lines 176-195 of Table 2, the unit annotations for the EPA+DHA content of fish from different cooking methods are not uniform. Some are g/100g, some are mg g⁻¹, and the use of mixed units can cause readers' confusion. It is recommended to uniformly use g/100g throughout the text and correct the unit annotation explanations in the table notes.
6. In the comparison of wild and farmed salmon in Table 3 on page 196, the unit layout of pollutant indicators is misaligned, and the TEQ and µg/100g annotation formats are not standardized. It is recommended to uniformly arrange the physical and chemical indicators layout, align the values with the units, and standardize the abbreviation explanations of toxicological terms.
7. In lines 300-303 of Figure 1, the mechanism schematic diagram has no Chinese explanations and abbreviations are not immediately marked under the figure. Only an abbreviation table is provided at the end, making reading inconvenient. It is recommended to supplement all English abbreviations with concise explanations in the figure below, matching the four major functional pathways of the figure. 8 Table 6, lines 461-483, the research information in the table is incomplete. The dosage and follow-up duration are not fully marked, and the table entries are incomplete. It is recommended to supplement the missing intervention dosage, follow-up years, and sample size data, and improve the completeness of the table.
9 References starting from page 626, some journal names in the references are not standardized, page numbers are missing, and the DOI format is incorrect. The Chinese and English reference formats are not unified. It is recommended to uniformly adopt the reference format of the "Nutrients" journal, and complete the missing page numbers and standardize the DOI.

Author Response

Comments to the Author

Comment 1. The studies included RCTs, observational studies, and Meta-analyses, but the methodological quality of the included literature was not evaluated. The quality of the literature was not assessed using JBI, AMSTAR, or Cochrane bias risk tools. The results of low-quality studies were analyzed together with high-quality studies. It is recommended to score the quality of each type of study, conduct stratified analysis of the conclusions of high-quality literature, eliminate studies with high bias risk, and enhance the argumentation of evidence level classification.

Response: We thank the Reviewer for this crucial methodological remark. We fully agree that distinguishing the quality of the included evidence is essential to strengthen the authoritative value of a Scientific Society Position Paper. Regarding the suggestion to use AMSTAR, Cochrane, and JBI, we would like to clarify that these tools address different study designs. AMSTAR-2 is specifically designed to evaluate systematic reviews, while Cochrane RoB 2 is strictly for RCTs. Since this SIAIP Position Paper covers a broad clinical and biological landscape, integrating both randomized trials and observational/epidemiological data, we have adopted the Joanna Briggs Institute (JBI) Critical Appraisal Tools, which offer specific and distinct checklists for different study designs. To address the concern regarding the joint analysis of low- and high-quality studies, we have performed the following updates to the manuscript: we have revised the Methods section, specifying the adoption of the JBI framework for evidence appraisal. We also have updated Tables 6 to explicitly show the methodological quality and risk of bias for each major clinical study cited. Moreover, we have stratified our document in the discussion, clearly highlighting where recommendations are supported by robust, high-quality RCTs versus where they rely on observational data with higher risk of bias. Consequently, the tone of our consensus statements has been adjusted to reflect the strength of the underlying evidence.

Comment 2. The clinical evidence of Omega-3 supplementation in infancy is highly heterogeneous, but the source of heterogeneity was not analyzed, and the reasons for the differences in results were not analyzed from dimensions such as intervention timing, formula type, and baseline family history of allergies. It is recommended to conduct a source analysis of heterogeneity, stratify by supplementation before 6 months / after 6 months, and by ordinary formula / fortified formula, and clarify the differences in allergic prevention effects under different intervention conditions.

Response. We agree. Given the high heterogeneity and limited robustness of the postnatal evidence, we decided not to retain a separate postnatal supplementation recommendation. The revised manuscript now acknowledges the limitations of the postnatal evidence and focuses the SIAIP Position Statement on maternal omega-3 intake during pregnancy and lactation, where the evidence base is comparatively stronger.

Comment 3. The conclusion section is too general, and the applicable population for primary prevention, the optimal intervention window period, and the preferred supplementation method (dietary / formulation) are not distinguished. It does not form a direct implementation clinical pathway. It is recommended to reconstruct the conclusion, categorize it into ordinary children, children with high-risk allergies, and pregnant and lactating women, and clearly define the intervention timing, dosage, ingredient selection, and standardized follow-up management path.

Response. We agree with the Reviewer. In the revised manuscript, we have substantially refined the conclusions and recommendations to better define the applicable population, the intervention window, and the preferred supplementation approach. Consistent with the overall revision of the Position Statement, we have removed the section addressing postnatal infant supplementation, as the available evidence was judged to be weak, heterogeneous, and insufficient to support a specific recommendation. The revised text now focuses on maternal omega-3 intake during pregnancy and lactation, for which the evidence is comparatively more robust, particularly from higher-quality prenatal randomized controlled trials and evidence syntheses evaluating wheeze/asthma-related outcomes in selected populations. We have therefore clarified that the most relevant intervention window is the prenatal period, with possible continuation during lactation, especially in women with low omega-3 intake/status or increased familial risk of allergic disease. We also revised the conclusions to distinguish dietary intake from targeted supplementation, emphasizing that dietary optimization should remain the first-line approach, while purified, quality-controlled omega-3 preparations may be considered when dietary intake is insufficient. Dose considerations, product-quality criteria, and the need for individualized clinical assessment have also been clarified in the revised Position Statement and Discussion.

Comment 4. In Section 2.1 of the article, lines 79-125, there is no concise structural diagram for the classification of Omega-3 and Omega-6, and the description is cumbersome. It is recommended to supplement a classification structure diagram of PUFA families to visually display the derivative relationships of ALA, EPA, DHA, LA, and AA.

Response. We added a new structural classification table of the PUFA families. This now visually summarizes the omega-3 pathway, ALA -> EPA -> DPA -> DHA, and the omega-6 pathway, LA -> GLA -> DGLA -> AA. 

Comment 5.  In lines 176-195 of Table 2, the unit annotations for the EPA+DHA content of fish from different cooking methods are not uniform. Some are g/100g, some are mg g⁻¹, and the use of mixed units can cause readers' confusion. It is recommended to uniformly use g/100g throughout the text and correct the unit annotation explanations in the table notes.

Response. We corrected Table 2, now Table 3, and its legend so that EPA + DHA content is expressed uniformly as g/100 g of edible product. We also clarified that the daily portion was calculated based on the amount required to provide 1 g/day of EPA + DHA.

Comment 6.  In the comparison of wild and farmed salmon in Table 3 on page 196, the unit layout of pollutant indicators is misaligned, and the TEQ and µg/100g annotation formats are not standardized. It is recommended to uniformly arrange the physical and chemical indicators layout, align the values with the units, and standardize the abbreviation explanations of toxicological terms.

Response. We revised Table 3, now Table 4 and its caption. The unit “µg/100 gr” was corrected to “µg/100 g”, and the table legend now clarifies that values are expressed per 100 g of edible product unless otherwise specified. We also standardized the definitions of TEQ and DL-PCBs.

Comment 7. In lines 300-303 of Figure 1, the mechanism schematic diagram has no Chinese explanations and abbreviations are not immediately marked under the figure. Only an abbreviation table is provided at the end, making reading inconvenient. It is recommended to supplement all English abbreviations with concise explanations in the figure below, matching the four major functional pathways of the figure. 8 Table 6, lines 461-483, the research information in the table is incomplete. The dosage and follow-up duration are not fully marked, and the table entries are incomplete. It is recommended to supplement the missing intervention dosage, follow-up years, and sample size data, and improve the completeness of the table.

Response. We expanded the figure legend. The caption now defines EPA, DHA, SPMs, Th1/Th2, HMOs, NF-kB, and PPAR directly below the figure and links them to the main functional pathways represented.

Comment 8. Table 6, lines 461-483, the research information in the table is incomplete. The dosage and follow-up duration are not fully marked, and the table entries are incomplete. It is recommended to supplement the missing intervention dosage, follow-up years, and sample size data, and improve the completeness of the table.

Response. We thank the Reviewer for this comment. Following the overall revision of the manuscript, we have decided to remove the table addressing postnatal supplementation, as the available postnatal evidence was considered substantially weaker, more heterogeneous, and insufficiently robust to support specific recommendations. This decision is consistent with the revised scope of the Position Statement, which now focuses on maternal omega-3 intake during pregnancy and lactation, where the evidence base is comparatively stronger.

Comment 9. References starting from page 626, some journal names in the references are not standardized, page numbers are missing, and the DOI format is incorrect. The Chinese and English reference formats are not unified. It is recommended to uniformly adopt the reference format of the "Nutrients" journal, and complete the missing page numbers and standardize the DOI.

Response. We revised the reference list to improve consistency with Nutrients style, including journal abbreviations, volume and page or article numbers, and standardized DOI formatting

Reviewer 2 Report

Comments and Suggestions for Authors

Klain et al. review the role of omega‑3 long‑chain polyunsaturated fatty acids in preventing allergic diseases during early life, emphasizing maternal intake during pregnancy and lactation. This is an important and timely topic. The manuscript is generally well‑written and contains useful sections, including the mechanistic overview and the detailed tables on dietary sources. However, there are some deficiencies that should be corrected before the manuscript can be considered for publication, as outlined below.

1) It is stated that a narrative review was conducted, but the description of the search strategy needs to be improved. Aspects to consider include a clearer inclusion/exclusion criteria, a description of study selection, and some indication of how evidence quality was assessed.

2) The manuscript contains excessive redundancy. Many concepts are repeated multiple times throughout the manuscript and, in general, they are seldom treated with the necessary depth. These repetitions disrupt the flow and should be removed to improve clarity. More importantly, a substantial portion of Section 3, Mechanism of Immunomodulation, is duplicated. Specifically, the text spanning lines 231–259 is repeated in lines 263–291. This appears to be an unintended copy‑paste error.

3) Related with the point above, the specialized pro‑resolving mediators (SPMs), referred to multiple times throughout the manuscript, are presented as fully established, despite this remaining a highly debated area. There is strong controversy regarding SPM detection, quantification, and physiological relevance in humans. Absence of any mention, even minimal, of this debate gives the impression of a consensus which does not really exist.

4) The manuscript tends to emphasize positive findings, while giving less attention to neutral or negative ones; the narrative consistently favors omega-3 benefits even when the evidence is weak or inconsistent. For example, the conclusion that maternal omega‑3 intake may reduce wheeze or asthma risk is reasonable, but some sections imply stronger causality than the evidence supports. A more balanced treatment of inconsistent results would help strengthen the manuscript.

5) Also related to the previous point, the manuscript repeatedly implies causality where evidence is simply emerging. For example, the possible involvement of omega-3 fatty acids in ferroptosis is mentioned multiple times throughout the manuscript. This is an interesting issue and adds novelty to the manuscript; however, the way it is worded tends to present the ferroptosis/immune/metabolic axis as an established mechanism in allergic disease prevention rather than a still largely exploratory area of research.

6) The manuscript indicates that DHA is released by cytosolic phospholipase A₂. This phospholipase is well known to preferentially hydrolyze arachidonate-containing phospholipids, but evidence for efficient DHA release is limited and context dependent. This statement should either be supported with appropriate citations or revised to reflect the uncertainty.

7) The manuscript focuses extensively on EPA and DHA, which is understandable given the current literature. However, docosapentaenoic acid (DPA, 20:5n-3) is absent. This omission is notable because DPA is relatively abundant in several innate immune cell populations and may contribute independently to inflammatory regulation and resolution pathways. Including at least a brief discussion of DPA biology, its relationship to EPA and DHA metabolism, and its potential relevance in allergic disease and immune development would strengthen the manuscript and help distinguish it from many existing reviews that focus almost exclusively on EPA and DHA.

8) Throughout most of the manuscript, the authors use the omega nomenclature, which is the usual in nutrition literature. However, in Section 8 the manuscript switches briefly to the n minus x notation (n‑3), which is the IUPAC‑recommended form. The sudden shift may confuse readers. For the sake of clarity and stylistic coherence, please apply the terminology consistently throughout the manuscript. Although deprecated by IUPAC, maintaining the omega notation would likely be the most accessible choice, given the journal’s audience.

Author Response

Comment 1. It is stated that a narrative review was conducted, but the description of the search strategy needs to be improved. Aspects to consider include a clearer inclusion/exclusion criteria, a description of study selection, and some indication of how evidence quality was assessed.

Response: We agree. The manuscript has been reframed throughout as a SIAIP Position Paper based on a scoping literature review and consensus process rather than as a narrative review. The Abstract and Methods have been revised to remove the previous wording and to describe the literature search, eligibility criteria, databases searched (PubMed/MEDLINE, Scopus, and Embase), and qualitative JBI-based evidence appraisal. This change aligns the methodology with the broad mapping purpose and consensus nature of the manuscript.

Comment 2. The manuscript contains excessive redundancy. Many concepts are repeated multiple times throughout the manuscript and, in general, they are seldom treated with the necessary depth. These repetitions disrupt the flow and should be removed to improve clarity. More importantly, a substantial portion of Section 3, Mechanism of Immunomodulation, is duplicated. Specifically, the text spanning lines 231–259 is repeated in lines 263–291. This appears to be an unintended copy‑paste error.

Response. We agree. We removed the duplicated text in Section 3 and revised the mechanisms section to improve clarity, flow, and readability.

Comment 3. Related with the point above, the specialized pro‑resolving mediators (SPMs), referred to multiple times throughout the manuscript, are presented as fully established, despite this remaining a highly debated area. There is strong controversy regarding SPM detection, quantification, and physiological relevance in humans. Absence of any mention, even minimal, of this debate gives the impression of a consensus which does not really exist.

Response. We revised this section to provide a more cautious and balanced interpretation. The manuscript now acknowledges that SPM detection, quantification, and physiological relevance in humans remain technically debated. SPM-related mechanisms are now presented as biologically plausible contributors rather than definitive proof of clinical efficacy.

Comment 4. The manuscript tends to emphasize positive findings, while giving less attention to neutral or negative ones; the narrative consistently favors omega-3 benefits even when the evidence is weak or inconsistent. For example, the conclusion that maternal omega‑3 intake may reduce wheeze or asthma risk is reasonable, but some sections imply stronger causality than the evidence supports. A more balanced treatment of inconsistent results would help strengthen the manuscript.

Response: We thank the Reviewer for this important point. We have revised the manuscript to use a more cautious and evidence-weighted tone. The Limitations section now acknowledges the absence of a de novo systematic review or meta-analysis, the qualitative nature of evidence grading, heterogeneity in study design and exposure timing, limited power for allergy endpoints in several RCTs, and residual confounding in observational studies. In line with these methodological considerations, we have removed the sections addressing postnatal infant supplementation, as the available evidence was considered substantially weaker, more heterogeneous, and insufficiently robust to support specific recommendations. The revised SIAIP Position Statement and Conclusions now focus on maternal EPA/DHA exposure during pregnancy and lactation, for which the clinical signal is comparatively stronger. Recommendations are now individualized according to dietary intake, baseline omega-3 status, hereditary risk, product quality, safety, and clinical counselling. We believe that these revisions address the methodological concerns and improve the transparency, balance, and practical clinical value of the Position Paper.

Comment 5. Also related to the previous point, the manuscript repeatedly implies causality where evidence is simply emerging. For example, the possible involvement of omega-3 fatty acids in ferroptosis is mentioned multiple times throughout the manuscript. This is an interesting issue and adds novelty to the manuscript; however, the way it is worded tends to present the ferroptosis/immune/metabolic axis as an established mechanism in allergic disease prevention rather than a still largely exploratory area of research.

Response. We revised the ferroptosis paragraph to avoid overstating causality. The ferroptosis-immune-metabolic axis is now described as exploratory and hypothesis-generating, rather than as an established mechanism of allergy prevention.

Comment 6. The manuscript indicates that DHA is released by cytosolic phospholipase A₂. This phospholipase is well known to preferentially hydrolyze arachidonate-containing phospholipids, but evidence for efficient DHA release is limited and context dependent. This statement should either be supported with appropriate citations or revised to reflect the uncertainty

Response. We corrected this statement. The revised text now specifies that cytosolic phospholipase A2 alpha preferentially hydrolyses arachidonate-containing phospholipids and that EPA/DHA release is cell- and context-dependent.

Comment 7. The manuscript focuses extensively on EPA and DHA, which is understandable given the current literature. However, docosapentaenoic acid (DPA, 20:5n-3) is absent. This omission is notable because DPA is relatively abundant in several innate immune cell populations and may contribute independently to inflammatory regulation and resolution pathways. Including at least a brief discussion of DPA biology, its relationship to EPA and DHA metabolism, and its potential relevance in allergic disease and immune development would strengthen the manuscript and help distinguish it from many existing reviews that focus almost exclusively on EPA and DHA.

Response. We added a paragraph on docosapentaenoic acid (DPA), including its metabolic relationship with EPA and DHA, its presence in immune-cell phospholipids, its possible role in lipid mediator biology, and the current lack of sufficient evidence to support DPA-specific recommendations in pediatric allergy prevention.

Comment 8. Throughout most of the manuscript, the authors use the omega nomenclature, which is the usual in nutrition literature. However, in Section 8 the manuscript switches briefly to the n minus x notation (n‑3), which is the IUPAC‑recommended form. The sudden shift may confuse readers. For the sake of clarity and stylistic coherence, please apply the terminology consistently throughout the manuscript. Although deprecated by IUPAC, maintaining the omega notation would likely be the most accessible choice, given the journal’s audience.

Response. We standardized the terminology throughout the main text by using omega-3 and omega-6 consistently, in order to improve clarity and maintain stylistic coherence for the target readership.

 

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

None.