SEARCHCROSS-SECTIONALnutrition, public_health

cross-sectional·nutrition, public_health, epidemiology, health_policy·PMC10180741

A Cross-Sectional Study Based on Forty Systematic Reviews of Foods with Function Claims (FFC) in Japan: Quality Assessment Using AMSTAR 2

Nutrients · 8 authors, 8 centres

AI SUMMARY

FIDELITY 100%

POPULATIONSystematic reviews submitted as notifications for Foods with Function Claims (FFC) in Japan (FY2022, H series)

INTERVENTIONAssessment using AMSTAR 2 tool

COMPARISONNot applicable (cross-sectional quality assessment, no comparison group)

This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.

AGENT 01 · STRUCTURED SUMMARY

TRACE TO SOURCE

“

TL;DR

This cross-sectional study assessed the methodological quality of 40 systematic reviews (SRs) used as the scientific basis for Foods with Function Claims (FFC) in Japan using the AMSTAR 2 tool. The results showed that 95% of the reviewed SRs were rated as "critically low" quality, with a mean AMSTAR 2 percentage score of only 51.1%. The findings indicate that despite eight years since the FFC system's introduction, the quality of SRs remains very poor, highlighting an urgent need for mandatory protocol pre-registration, comprehensive literature searches, and better methodological training.

Full summary

3,256 CHARS

**Background:** Japan introduced Foods with Function Claims (FFC) in April 2015, allowing manufacturers to notify the Consumer Affairs Agency (CAA) about health functions of food products without pre-market evaluation. Companies can substantiate claims using either clinical trials (RCTs) or systematic reviews (SRs). By January 2023, 94.5% of 6,247 notifications used SRs. Previous studies using the original AMSTAR tool in 2017 and 2019 found poor SR quality, but no improvement trend was observed. This study aimed to assess SR quality using the updated AMSTAR 2 tool.

**Methods:** From 519 SRs (H1-H535) published on the CAA website between April 1, 2022 and October 31, 2022, 40 SRs were randomly selected. Exclusion criteria included clinical/observational studies and duplicate SRs for the same functional ingredient. Four reviewers independently assessed quality using AMSTAR 2 (16 items, 7 critical domains). Inter-rater reliability showed substantial agreement (91.9%, k=0.849). Items were scored as yes (1), partial yes (0.5), or no (0), with percentage scores categorized as good (80-100%), poor (50-79%), or very poor (0-49%). Overall confidence was rated as high, moderate, low, or critically low.

**Key Results:** Of the 40 SRs, 25 (62.5%) were supplements, 14 (35.0%) processed foods, and 1 (2.5%) fresh food. 36 (90%) were qualitative reviews without meta-analysis, and 4 (10%) included meta-analysis. The mean AMSTAR 2 percentage score was 51.1% (SD 12.1%, range 19-73%). Overall confidence ratings were: high 0 (0%), moderate 0 (0%), low 2 (5%), and critically low 38 (95%). Among critical domains, items with good descriptions included: #11 (appropriate meta-analysis methods, 100%), #15 (publication bias investigation, 100%), #7 (list of excluded studies, 92.5%), and #9 (satisfactory RoB assessment, 80%). Critical domains with very poor descriptions were: #2 (review protocol, 5%), #4 (comprehensive literature search, 0%), and #13 (accounting for RoB in interpretation, 47.5%). Non-critical domains with very poor descriptions included: #5 (study selection in duplicate, 17.5%), #8 (adequate description of included studies, 10%), #10 (reporting funding sources, 2.5%), #14 (explanation of heterogeneity, 15%), and #16 (reporting conflicts of interest, 17.5%). The number of critical domain deficiencies per SR was: 4 deficiencies in 7.5%, 3 in 52.5%, 2 in 35%, and 1 in 5%.

**Clinical Implications:** The overwhelming majority (95%) of SRs in the FFC system are of critically low quality, meaning they should not be relied upon to provide accurate summaries of available evidence. This poses risks to consumer protection and informed decision-making. Key deficiencies—lack of protocol registration, inadequate literature searches, and insufficient RoB consideration—are correctable through mandatory pre-registration, requiring publication in peer-reviewed journals, and providing methodological guidance based on AMSTAR 2, PRISMA 2020, and GRADE frameworks. The study's limitations include potential publication bias from random sampling, lack of author clarification for unclear items, no assessment of primary study quality or functional mechanisms, and inability to link results to specific companies due to legal concerns.

PICO

PPOPULATION

Systematic reviews submitted as notifications for Foods with Function Claims (FFC) in Japan (FY2022, H series)

IINTERVENTION

Assessment using AMSTAR 2 tool

OOUTCOME

Methodological quality ratings (high, moderate, low, critically low) and percentage scores on AMSTAR 2 items

STUDY TYPE

cross-sectional

SPECIALTY

nutrition

SUMMARISED BY

AI pipeline

FIDELITY CHECK

100% · A

ORIGINAL PAPER

PMC10180741

A Cross-Sectional Study Based on Forty Systematic Reviews of Foods with Function Claims (FFC) in Japan: Quality Assessment Using AMSTAR 2

Nutrients

READ THE FULL PAPER

JUMP TO SECTION

ABSTRACT

Abstract Background: The Foods with Function Claims (FFC) was introduced in Japan in April 2015 to make more products available that are labeled with health functions. The products’ functionality of function claims must be explained by scientific evidence presented in systematic reviews (SRs), but the quality of recent SRs is unclear. This study assessed the quality of SRs in the FFC registered on the Consumer Affairs Agency (CAA) website in Japan. Methods: We searched the database from 1 April to 31 October 2022. Confidence in the methodological quality of each SR was evaluated by the AMSTAR 2 checklist. Results: Forty SRs were randomly extracted on the basis of the eligibility criteria and recruitment procedures. Overall confidence was rated as “high” ( N = 0, 0%), “moderate” ( N = 0, 0%), “low” ( N = 2, 5%), or “critically low” ( N = 38, 95%). The mean AMSTAR 2 score was 51.1% (SD 12.1%; range 19–73%). Among the 40 SRs, the number of critical domain deficiencies was 4 in 7.5% of SRs, 3 in 52.5% of SRs, 2 in 35% of SRs, and 1 in 5% of SRs. Registering the review’s protocol and comprehensive search strategies were particularly common deficiencies. Additionally, the risk of bias (RoB) was insufficiently considered. Conclusion: Overall, the methodological quality of the SRs based on the FFC, introduced eight years earlier, was very poor. This was especially true in the interpretation and discussion of critical domains, which had many deficiencies in terms of protocol registration, a comprehensive literature search strategy, and accounting for the RoB. Keywords: food, supplement, randomized controlled trial, risk of bias, systematic review

CITATION EXPORT

Hiroharu Kamioka, Hideki Origasa, Kiichiro Tsutani et al.. A Cross-Sectional Study Based on Forty Systematic Reviews of Foods with Function Claims (FFC) in Japan: Quality Assessment Using AMSTAR 2. Nutrients. (2023). https://doi.org/10.3390/nu15092047

AUTHORS

8 · 8 CENTRES

Hiroharu Kamioka, Hideki Origasa, Kiichiro Tsutani, Jun Kitayuguchi, Takahiro Yoshizaki, Mikiko Shimada, Yasuyo Wada, Hiromi Takano-Ohmuro

1Faculty of Regional Environment Science, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
2The Institute of Statistical Mathematics, 10-3 Midori-cho, Tachikawa, Tokyo 190-8562, Japan
3The Institute of Seizon and Life Sciences, 4-5-1 Ginza, Chuo-ku, Tokyo 104-0061, Japan
4Physical Education and Medicine Research Center Unnan, 328 Uji, Unnan City 699-1105, Japan
5Faculty of Food and Nutritional Sciences, Toyo University, 1-1-1 Izumino, Itakura Town 374-0193, Japan
6Department of Nutrition, Faculty of Health Care, Kiryu University, 606-7 Asami, Midori City 379-2329, Japan
7Department of Health Promotion, National Institute of Public Health, 2-3-6 Minami, Wako City 351-0197, Japan
8Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Aramachi, Nishitokyo, Tokyo 202-8585, Japan