Evaluation of randomized controlled trials of foods with functional claims request: The learning outcomes from studies in Japan

Research Quality of Clinical Trials Reported for Foods with Function Claims in Japan, 2023-2024: Evaluation Based on a Revised Tool to Assess Risk of Bias in Randomized Trials

BACKGROUND

The Foods with Function Claim was introduced in Japan in April 2015 to make more products available that are labeled with health functions. A product's functionality of function claims must be explained by the scientific evidence presented in clinical trials (CTs) or systematic reviews, but the quality of recent CTs is unclear. The purpose of this study was to evaluate the risk of bias (RoB) using "a revised tool to assess risk (RoB 2)" published in 2018 for notifications based on all recent CTs published on the Consumer Affairs Agency website.

METHODS

A total of 38 submitted papers based on CTs that were published on the Consumer Affairs Agency website during the period from 1 January 2023 to 30 June 2024 were eligible. The RoB 2 tool provides a framework for considering the risk of bias in the findings of any type of randomized trial. This tool with five domains was used to evaluate the quality of research methods.

RESULTS

Eligible CTs were assessed as "low risk" (11%, n = 4), "medium risk" (13%, n = 5), and "high risk" (76%, n = 29). A number of highly biased papers were published. Bias occurred in all five domains, especially "bias in selection of the reported result (Domain 5)", which was the most serious ("high risk"; 75%). For elements correlated with RoB, there was no significant difference (p = 0.785) in the RoB 2 score between for-profit and academic research in the author's affiliated organization. There was no significant difference (p = 0.498) in the RoB score between the published year categories of 2000-2019 and 2020-2024, and no significant difference (p = 0.643) in the RoB score between English and Japanese language publications.

CONCLUSION

Overall, the quality of the latest CTs submitted after 2023 was very low, occurring in all five domains, and was most serious for "bias in selection of the reported result (Domain 5)".

[Current Status and Issues on the Foods with Function Claims System in Japan: Evidence of Functionality of the Foods]

The purpose of this narrative review was to clarify the current status and issues of scientific evidence for functionality in the Foods with Function Claims system based on previous research. From the introduction of the system in April 2015 to January 1, 2023, there were 6606 notifications, of which 6297 (95.3) were systematic reviews (SRs) and 309 (4.7%) were clinical trials (CTs). SRs were identified the following problems: i) inadequate description based on the first version of PRISMA checklist, and ii) very low levels of quality assessment in the first version of AMSTAR checklist and AMSTAR 2. CT was reported to have the following problems: i) inconsistencies between the protocol and the content in the paper (non-compliance), ii) high risk of bias, and iii) not described based on the CONSORT 2010 checklist. Since SRs and randomized controlled trials (RCTs) often have low-quality notifications, it is necessary to correctly communicate this information to consumers in order to make appropriate purchasing decisions.

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

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.

Compliance of Clinical Trial Protocols for Foods with Function Claims (FFC) in Japan: Consistency between Clinical Trial Registrations and Published Reports

Background: A new type of foods with a health claims notification system, the Foods with Function Claims (FFC), was introduced in Japan in April 2015. This cross-sectional study sought to clarify compliance of clinical trial protocols reported as the scientific basis of efficacy in the FFC system. Methods: All articles based on clinical trials published on the Consumer Affairs Agency website from 1 July 2018 to 30 June 2021 were reviewed. Items assessed included first author characteristics (for-profit or academia), journal name, year published, journal impact factor in 2020, article language, name of clinical trial registration (CTR), and seven compliance items (Title: T, Participant: P, Intervention: I, Comparison: C, Outcome: O, Study design: S, and Institutional Review Board, IRB). Among studies that conducted CTR, consistency with these seven compliance items was evaluated. Results: Out of 136 studies that met all inclusion criteria, 103 (76%) performed CTR, and CTR was either not performed or not specified for 33 (24%). Compliance between the protocol and the text was high (≥96%) for items P and S, but considerably lower for items T, I, C, O, and IRB (52%, 15%, 13%, 69%, and 27%, respectively). Furthermore, 43% of protocols did not include functional ingredients or food names in items T or I. The total score was 3.7 ± 1.1 pts (out of 7). Conclusions: Some CTs had no protocol registration, and even registered protocols were suboptimal in transparency. In addition to selective reporting, a new problem identified was that the content of the intervention (test food) was intentionally concealed.

Functional Foods: Product Development, Technological Trends, Efficacy Testing, and Safety

Functional foods is a very popular term in the social and scientific media; consequently, food producers have invested resources in the development of processed foods that may provide added functional benefits to consumers' well-being. Because of intrinsic regulation and end-of-use purposes in different countries, worldwide meanings and definitions of this term are still unclear. Hence, here we standardize this definition and propose a guideline to attest that some ingredients or foods truly deserve this special designation. Furthermore, focus is directed at the most recent studies and practical guidelines that can be used to develop and test the efficacy of potentially functional foods and ingredients. The most widespread functional ingredients, such as polyunsaturated fatty acids (PUFAs), probiotics/prebiotics/synbiotics, and antioxidants, and their technological means of delivery in food products are described. The review discusses the steps that food companies should take to ensure that their developed food product is truly functional.

Establishing What Constitutes a Healthy Human Gut Microbiome: State of the Science, Regulatory Considerations, and Future Directions

On December 17, 2018, the North American branch of the International Life Sciences Institute (ILSI North America) convened a workshop "Can We Begin to Define a Healthy Gut Microbiome Through Quantifiable Characteristics?" with >40 invited academic, government, and industry experts in Washington, DC. The workshop objectives were to 1) develop a collective expert assessment of the state of the evidence on the human gut microbiome and associated human health benefits, 2) see if there was sufficient evidence to establish measurable gut microbiome characteristics that could serve as indicators of "health," 3) identify short- and long-term research needs to fully characterize healthy gut microbiome-host relationships, and 4) publish the findings. Conclusions were as follows: 1) mechanistic links of specific changes in gut microbiome structure with function or markers of human health are not yet established; 2) it is not established if dysbiosis is a cause, consequence, or both of changes in human gut epithelial function and disease; 3) microbiome communities are highly individualized, show a high degree of interindividual variation to perturbation, and tend to be stable over years; 4) the complexity of microbiome-host interactions requires a comprehensive, multidisciplinary research agenda to elucidate relationships between gut microbiome and host health; 5) biomarkers and/or surrogate indicators of host function and pathogenic processes based on the microbiome need to be determined and validated, along with normal ranges, using approaches similar to those used to establish biomarkers and/or surrogate indicators based on host metabolic phenotypes; 6) future studies measuring responses to an exposure or intervention need to combine validated microbiome-related biomarkers and/or surrogate indicators with multiomics characterization of the microbiome; and 7) because static genetic sampling misses important short- and long-term microbiome-related dynamic changes to host health, future studies must be powered to account for inter- and intraindividual variation and should use repeated measures within individuals.

Quality of Systematic Reviews of the Foods with Function Claims in Japan: Comparative Before- and After-Evaluation of Verification Reports by the Consumer Affairs Agency

Background: In Japan, a new type of foods with health claims, called Foods with Function Claims (FFC), was introduced in April 2015 in order to make more products available that are clearly labeled with certain health functions. Regarding substantiating product effectiveness, scientific evidence for the proposed function claims must be explained by systematic reviews (SRs), but the quality of SRs was not clear. The objectives of this review were to assess the quality of SRs based on the FFC registered on the Consumer Affairs Agency (CAA) website in Japan, and to determine whether the CAA’s verification report in 2016 was associated with improvement in the quality of SRs. Methods: We evaluated the reporting quality of each SR by the AMSTAR checklist on methodological quality. We searched the database from 1 April to 31 October 2015 as the before-SR and from 1 July 2017 to 31 January 2018 as the after-SR. Results: Among the 104 SRs reviewed, 96 final products were included: 51 (53.1%) were supplements, 42 (43.8%) were processed foods without supplements, and 3 (3.1%) were fresh foods. Of the 104 SRs, 92 (88.5%) were qualitative reviews (i.e., without meta-analysis) and 12 (11.5%) performed a meta-analysis. The average quality score of before-SRs and after-SRs was 6.2 ± 1.8 and 5.0 ± 1.9, respectively, a statistically significant decrease (p < 0.001). Conclusion: Overall, the methodology and reporting quality of after-SRs based on the FFC were poorer than those of before-SRs. In particular, there were very poor descriptions and/or implementations of study selection and data extraction, search strategy, evaluation methods for risk of bias, assessment of publication bias, and formulating conclusions based on methodological rigor and scientific quality of the included studies.