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 6,606 notifications, of which 6,297 (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 RCTs often have low-quality notifications, it is necessary to correctly communicate this information to consumers in order to make appropriate purchasing decisions.

Recently, a novel quantitative method using relative molar sensitivity (RMS) was applied to quantify the ingredients of drugs and foods. An important development in this regard can be observed in the Japanese Pharmacopoeia (JP) 18, where the quantification of perillaldehyde, an unstable compound, in crude drug “Perilla Herb”, was revised to incorporate the RMS method.

In this study, the primary objective was to improve the tester safety and reduce the amount of reagents used in the JP test. To achieve this, the quantification of three toxic Aconitum monoester alkaloids (AMAs) was explored using the RMS method, employing a single reference compound for all three targets. These AMAs, namely benzoylmesaconine hydrochloride, benzoylhypaconine hydrochloride, and 14-anisoylaconine hydrochloride, which are the quantitative compounds of Kampo extracts containing Aconite Root (AR), were quantified using the reference compound benzoic acid (BA). Reliable RMS values were obtained using both ¹H-quantitative NMR and HPLC/UV. Using the RMS of three AMAs relative to the BA, the AMA content (%) in commercial AMAs quantitative reagents were determined without analytical standards. Moreover, the quantitative values of AMAs using the RMS method and the calibration curve method using the three analytical standards were similar. Additionally, similar values were achieved for the three AMAs in the Kampo extracts containing AR using the RMS and the modified JP18 calibration curve methods. These results suggest that the RMS method is suitable for quantitative assays of the Kampo extracts containing AR and can serve as an alternative to the current method specified in the JP18.