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. 2026 Sep 24;13:1923649. doi: 10.3389/fnut.2026.1923649

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Copyright © 2026 Zheng, Yan, Fan, Zhai, Jiang, Xu and Tian.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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PRISMA 2020 flow diagram for updated systematic reviews presents the process of identification, screening, and inclusion of studies. It shows two pathways: previous studies with 13 observational and 3 RCTs, and new studies identified from nine databases totaling 4,265 records. After removing 1,106 duplicates, 3,159 records are screened; 3,135 are excluded. Twenty-four reports assessed lead to inclusion of 4 new observational studies and 6 new RCTs. In total, 17 observational studies and 9 RCTs are included in the review, with 8 of each entering meta-analysis. The diagram highlights records and reports excluded at each step with reasons. — Flow diagram of the literature search process.