[A Study on the Scientific Reliability of Notification Data in the Foods with Function Claims].

We conducted a comprehensive survey of Foods with Function Claims (FFC) submitted from April to August 2022 to examine the scientific reliability of the systematic review (SR), which is the basis for functional claims. The results of the review of 611 functional claims for 398 products showed that there were 121 functionally active substances and 87 health claims (Hc) that were labeled, with some functionally active substances having multiple functions. SRs, meta-analyses, and clinical studies were submitted as the basis of functionality for 87%, 10%, and 3% of the reports, respectively. Of these SRs, 39% of the SRs included a single paper. In 67% of the SRs with a single paper included, some of the authors of the included paper and the person who conducted the SR had the same affiliation, which raises concerns about conflicts of interest. The median of clinical trial participants in papers included for SR was relatively small, 38, and the smallest total number of SRs was 6. Thus, it was shown that there are many SRs for FFC that are based on only a single paper or a small-scale clinical trial and that lack reliability as scientific evidence.

Relationship between body adiposity parameters and insulin resistance: a preliminary study of surrogate markers in Japan.

PURPOSE: According to the Japan National Health and Nutrition Survey 2019, the proportion of people with prediabetes is estimated to be 27.3%. Western-style dietary habits can lead to obesity and a functional abnormality of the adipose tissue, which can cause insulin resistance and predispose one to diabetes. We examined the relationship between insulin resistance using body adiposity parameters as surrogate markers. METHODS: This study enrolled 248 healthy participants to determine the association of six body adiposity parameters, namely, body mass index (BMI), waist circumference (WC), visceral adiposity index (VAI), lipid accumulation product index (LAP), waist circumference-triglyceride index (WTI), and triglyceride (TG)/high-density lipoprotein (HDL) ratio with insulin resistance. Receiver operating characteristics curve analyses were performed to assess the accuracy of these parameters in identifying insulin resistance. RESULTS: The data of the 248 participants (women 79 and men 169) were examined in this study. WC showed the highest accuracy in the obese women group (cut-off value: 89.8 with sensitivity: 0.900 and specificity: 0.522, AUC: 0.680) and men group (cut-off value: 90.0 with sensitivity: 0.862 and specificity: 0.508, AUC: 0.701). The TG/HDL ratio showed the highest accuracy in men with non-obesity (cut-off value: 0.8 with sensitivity: 0.857 and specificity: 0.649, AUC: 0.780). CONCLUSION: Application of this finding should be useful in the early screening of obesity in men with non-obesity, such as during regular health check-up with the TG/HDL ratio in addition to the usually used WC, to assess insulin resistance and prevent lifestyle-related diseases that can lead to cardiovascular events.

Web-Based Content on Diet and Nutrition Written in Japanese: Infodemiology Study Based on Google Trends and Google Search.

BACKGROUND: The increased availability of content of uncertain integrity obtained through the internet is a major concern. To date, however, there has been no comprehensive scrutiny of the fitness-for-purpose of web-based content on diet and nutrition. OBJECTIVE: This cross-sectional study aims to describe diet- and nutrition-related web-based content written in Japanese, identified via a systematic extraction strategy using Google Trends and Google Search. METHODS: We first identified keywords relevant for extracting web-based content (eg, blogs) on diet and nutrition written in Japanese using Google Trends. This process included identification of 638 seed terms, identification of approximately 1500 pairs of related queries (top) and search terms, the top 10% of which were extracted to identify 160 relevant pairs of related queries (top) and search terms, and identification of 107 keywords for search. We then extracted relevant web-based content using Google Search. RESULTS: The content (N=1703) examined here was extracted following a search based on 107 keywords. The most common themes included food and beverages (390/1703, 22.9%), weight management (366/1703, 21.49%), health benefits (261/1703, 15.33%), and healthy eating (235/1703, 13.8%). The main disseminators were information technology companies and mass media (474/1703, 27.83%), food manufacturers (246/1703, 14.45%), other (236/1703, 13.86%), and medical institutions (214/1703, 12.57%). Less than half of the content (790/1703, 46.39%) clearly indicated the involvement of editors or writers. More than half of the content (983/1703, 57.72%) was accompanied by one or more types of advertisement. The proportion of content with any type of citation reference was 40.05% (682/1703). The themes and disseminators of content were significantly associated with the involvement of editors or writers, accompaniment with advertisement, and citation of reference. In particular, content focusing on weight management was more likely to clearly indicate the involvement of editors or writers (212/366, 57.9%) and to be accompanied by advertisement (273/366, 74.6%), but less likely to have references cited (128/366, 35%). Content from medical institutions was less likely to have citation references (62/214, 29%). CONCLUSIONS: This study highlights concerns regarding the authorship, conflicts of interest (advertising), and the scientific credibility of web-based diet- and nutrition-related information written in Japanese. Nutrition professionals and experts should take these findings seriously because exposure to nutritional information that lacks context or seems contradictory can lead to confusion and backlash among consumers. However, more research is needed to draw firm conclusions about the accuracy and quality of web-based diet- and nutrition-related content and whether similar results can be obtained in other major mass media or social media outlets and even other languages.

Patients Are Using Dietary Supplement for the Treatment of Their Diseases without Consultation with Their Physicians and Pharmacists.

Inappropriate use of dietary supplements by patients might exacerbate their diseases. The aim of this study was to clarify the situation of dietary supplement use for disease treatment among patients. A cross-sectional online questionnaire survey was conducted between 18 and 30 November 2022. A preliminary survey revealed that the proportion of patients who used dietary supplements to treat their disease ranged from 7.7% (cancer) to 28.2% (menopausal disorder). In the actual survey, across all diseases, patients who used dietary supplements for treatment purposes were satisfied with their therapeutic effects. Information obtained via the internet was the most common reason given for starting to use supplements. The proportions of patients who used supplements concurrently with medicine ranged from 25.4% (liver disease) to 72.2% (mental disorder). Most users of supplements did not consult with their physicians or pharmacists about them. However, patients preferred face-to-face consultation with a physician or pharmacist when discussing the concomitant use of medicines. In conclusion, the role of pharmacists is important for the appropriate use of dietary supplements among patients, especially concomitant use with medicines. More awareness about dietary supplements is needed for healthcare professionals to consult with their patients.

[Perception of Public Health Nurses on Health Foods and Utilization of Health Food Informationduring Specific Health Guidance].

This study aimed to investigate the awareness of public health nurses (PHNs) regarding health foods and the actual utilization of health food-related information in specific health guidance. A questionnaire survey among PHNs working in municipalities in Kagoshima Prefecture (n=170, response rate; 41.5%) was conducted in September 2022. As a result, 39.4% of the PHNs had experience using health foods, and 43.5% consulted about health food from local residents. Major topics of consultation included effectiveness (78.4%) and drug interactions (35.1%). Approximately 10.2% of the PHNs always confirm the use of health food during specific health guidance, while 41.6% did not ever check. Additionally, 36.3% of the PHN were aware of the obligation to report adverse events caused by health foods to the prefectural governments and Ministry of Health, Labor, and Welfare. The present study showed that recognition and intelligibility on health foods varied among PHNs. Therefore, knowledge acquisition on safety and efficacy is needed for proper use of health foods.

Extracting the latent needs of dementia patients and caregivers from transcribed interviews in japanese: an initial assessment of the availability of morpheme selection as input data with Z-scores in machine learning.

BACKGROUND: Given the increasing number of dementia patients worldwide, a new method was developed for machine learning models to identify the 'latent needs' of patients and caregivers to facilitate patient/public involvement in societal decision making. METHODS: Japanese transcribed interviews with 53 dementia patients and caregivers were used. A new morpheme selection method using Z-scores was developed to identify trends in describing the latent needs. F-measures with and without the new method were compared using three machine learning models. RESULTS: The F-measures with the new method were higher for the support vector machine (SVM) (F-measure of 0.81 with the new method and F-measure of 0.79 without the new method for patients) and Naive Bayes (F-measure of 0.69 with the new method and F-measure of 0.67 without the new method for caregivers and F-measure of 0.75 with the new method and F-measure of 0.73 without the new method for patients). CONCLUSION: A new scheme based on Z-score adaptation for machine learning models was developed to predict the latent needs of dementia patients and their caregivers by extracting data from interviews in Japanese. However, this study alone cannot be used to assign significance to the adaptation of the new method because of no enough size of sample dataset. Such pre-selection with Z-score adaptation from text data in machine learning models should be considered with more modified suitable methods in the near future.

Nutrient Intake from Voluntary Fortified Foods and Dietary Supplements in Japanese Consumers: A Cross-Sectional Online Survey.

Consuming voluntary fortified foods (vFFs) and dietary supplements (DSs) is one method for addressing micronutrient inadequacy, but their efficacy is unclear. This study explored the use of vFFs and DSs, and the role of package labels. We conducted a nationwide online survey of 4933 Japanese adults in 2020. The use of vFFs and DSs was 23.3%. The reported vFFs were cereal products (n = 370), milk products/milk substitutes (n = 229), and one-shot drinks (n = 144). Vitamins, calcium, and iron were the main micronutrients added to the vFFs. Most users consumed vitamins C and B from vFFs and/or DSs, and females also consumed iron. The median intake of vitamins B6 and C, selenium, and zinc (plus vitamin B2 and copper in females) exceeded 50% of the respective estimated average requirement values. Approximately 60-70% of the users referred to nutrition labels. However, only a small percent of the respondents clearly understood the nutrient content. To address insufficient nutrient intake, the use of vFFs and DSs may be a good alternative; however, consumer education on the use of vFFs/DSs and package labels needs to be implemented before encouraging their use.

Safety assessment of herbal supplement components targeting hepatotoxicity and CYP3A4 induction in cell-based assay using HepG2 cells.

Herbal supplements can cause hepatotoxicity and drug interactions via hepatic cytochrome P-450 (CYP) in some cases. However, there is no simple and stable cell-based assay to conduct a screening for hepatotoxicity and CYP induction. In the present study, we selected 14 components of the herbal supplement based on our previous reports and investigated the safety of the herbal supplement components focusing on toxicity and CYP3A4 induction in a cell-based assay using HepG2. The toxicity of the components was examined by lactate dehydrogenase (LDH) and cell proliferation assays. Then, the CYP3A4 induction of the components were examined by a reporter assay using reporter vectors of CYP3A4. The vector includes the CYP3A4 proximal promoter (CYP3A4PP) and the xenobiotic-responsive enhancer module (XREM) regions. Luteolin (LU) significantly increased LDH activity and decreased cell proliferation activity that suggests LU may cause toxicity in HepG2 cells. Quercetin (QU) increased the transcriptional activity of CYP3A4 (1.5-fold of control) in the reporter assay. However, the induction of QU was slightly in comparison to the validation of the transcriptional activity of CYP3A4 treated with CYP3A4 inducers. The CYP3A4 induction of QU may not involve CYP3A4PP but involves the XREM response. Throughout our results, the method in the present study may be useful for a safety assessment of herbal supplements, primarily focusing on hepatotoxicity and CYP3A4 induction. PRACTICAL APPLICATION: Even though there are problems with herbal supplements, studies related to toxicity are not actively carried out. The present methods may apply to the safety assessment for herbal supplements and be useful for the prevention and verification of health hazards caused by herbal supplements (the summary is shown in Figure S2).

The Prevalence of Dietary Supplements That Claim Estrogen-like Effects in Japanese Women.

Recently, adverse events, such as irregular vaginal bleeding and menstrual disorders, associated with the use of dietary supplements containing Pueraria mirifica, have been reported in Japan. P. mirifica contains phytoestrogens, such as deoxymiroestrol and miroestrol. Therefore, we investigated the use of supplements that claim to have estrogen-like effects (i.e., estrogen-like supplements) in Japanese women aged from 15 to 69 years old in an online survey. The prevalence of estrogen-like supplement use was 5%, accounting for approximately 15% of the sample, including ex-users. The majority of the users were in their 40s and 50s, mainly using these supplements for the treatment of menopausal symptoms. In contrast, the younger generation mainly used them for beauty purposes, such as weight loss, mastogenic effects, and skin care. Many of them visited a clinic or took medicines for menstrual-related troubles. In all age groups, soybeans/isoflavones were the most commonly used, followed by equol and placenta. Participants in their teens and 20s also used P. mirifica. Among them, 16.2% had experienced adverse events, including irregular vaginal bleeding, breast swelling and pain, and heavy menstruation. In conclusion, estrogen-like supplement use is associated with adverse events; thus, it is necessary to pay attention to the use of these supplement. Furthermore, because the purpose of use differs depending on generation, caution according to each generation is necessary.

Food Labeling Systems in Japan: Nutrition and Health Claims.

Japan is one of the countries with the highest life expectancy in the world, and maintaining good health is the key component to extend healthy life expectancy. According to World Health Organization, self-care is the ability to promote health, prevent disease, and maintain health. Food labels play an important role in healthy dietary habits for self-care. Food labels comprise nutrition claims and health claims. In Japan, the nutrition component exhibits the contents of energy, protein, fat, carbohydrates, and salt equivalent, which are mandatory, and saturated fat and dietary fiber, which are recommended. On the other hand, the health portion exhibits health maintenance and health promotion by nutrients/ingredients in foods. Under the Food Labeling Act, foods allowed to display health claims, are specified as "Foods with Health Claims" in Japan. The Consumer Affairs Agency reported that most consumers could not utilize food labels, even though the nutrition label serves as a parameter for a healthier food choice. In this regard, front-of-pack labels (FOPLs), are a beneficial tool which encourages people to choose healthier foods, and conduct self-care. However, FOPLs is still unfamiliar in Japan, so we have to investigate which nutrients and which type of FOPLs are the best for Japanese people. In addition to FOPL promotion, education is important to get consumers using food labels for extending their healthy life expectancy.

[Frequency of Worsening Clinical Test Values Related to Supplement Use: Estimation by Using Nationwide Online Survey].

This study examined the frequency of worsening clinical test values related to supplement use using a nationwide online survey, with a focus on liver function markers, and clarified the differences between outcome indices of diarrhea or skin manifestations. A nationwide online survey was conducted with 73,010 supplement users from the previous year. Of these, 221 individuals with worsening clinical test values responded to the full-scale survey. To compare surveys with different outcome indices, we used previously reported data from similar surveys.Only 0.5% of individuals who self-reported worsening of clinical test values caused by supplement use recognized an almost certain causal relationship. Among the test items, blood lipids were the most frequently reported. The frequency of worsening liver function markers was 0.2% in supplement users. Among those who experienced worsening clinical test values, 56.1% received no treatment and 82.4% did not report the incidence of worsening clinical test values anywhere. The ingredient-based classification of products revealed more "Peptides or animal by-products" and "Combination products/not classifiable products" than those associated with other categories. Compared to the results of the survey about the experience of diarrhea or skin manifestations, those who experienced worsening clinical test values were predominantly men, frequent and long-term users, and individuals whose products could not be identified.Few supplement users experience worsening of liver function markers, which does not seem serious. However, it is difficult for supplement users to recognize abnormal changes by themselves. Thus, it is important to record product information, usage, and changes in physical condition.

Differences in the Perception of Dietary Supplements between Dietary Supplement/Medicine Users and Non-Users.

Some patients use dietary supplements and medicines concomitantly, with an inappropriate perception of their safety and efficacy. To clarify the perception between dietary supplement and medicine users and non-users, we conducted an internet survey. In this survey, 38.9% of participants used dietary supplements, 32.6% used prescription medicines, and 14.7% used dietary supplements and prescription medicines concomitantly. Then, we conducted a further survey on four groups, dietary supplement and prescription medicine users, dietary supplement only users, prescription medicine only users, and non-users (500 each). Dietary supplement users had favorable outcomes in terms of both the safety and efficacy of dietary supplements compared to dietary supplement non-users. This perception of dietary supplements was independent from medicine use. The awareness of the Health Food Network consumer navigation site, which provides information about dietary supplements for consumers, was the highest among dietary supplement and prescription medicine users, but it was still low (2.2%). In conclusion, consumers who use dietary supplement and prescription medicine concomitantly have favorable outcomes for their safety and efficacy and a low awareness of their interaction. There is a need to provide information, especially regarding the risk of interaction, that takes into account the consumer's situation.

The Prevalence of Dietary Supplement Use for the Purpose of COVID-19 Prevention in Japan.

COVID-19 is still the biggest issue worldwide. Many dietary supplements on the market claim to have anti-COVID-19 effects without scientific evidence. To elucidate the prevalence of dietary supplement usage for the prevention of COVID-19, we conducted an online cross-sectional questionnaire survey among Japanese adults in January 2022. The prevalence of dietary supplement use for the prevention of COVID-19 was 8.3%, and there was no gender difference. We also conducted additional research on these dietary supplement users (1000 males and 1000 females). The most popular ingredient used was vitamin C (61.0%), with vitamin D (34.9%) and probiotics (33.4%) following. Half of these participants reported using supplements for more than one year. The information sources that reportedly led them to start using dietary supplements for the prevention of COVID-19 were the Internet (44.0%), television and radio (29.9%), and family or friends (26.0%), and these information sources differed among generations. In conclusion, some of the population used vitamin/mineral supplements for the prevention of COVID-19 that might be beneficial for their health, but some used ingredients with no scientifically proven effects against the virus at this time. Therefore, information-based scientific evidence is important to prevent the inappropriate use of dietary supplements by consumers.

The usefulness of a checklist approach-based confirmation scheme in identifying unreliable COVID-19-related health information: a case study in Japan.

Consumers are increasingly able to easily access health information online about food products. However, consumers have difficulty identifying reliable health information from diverse sources along with information about the coronavirus disease (COVID-19) pandemic because the inundation of information (both true and false) overwhelm consumers. We investigated the usefulness of a checklist confirmation scheme for identifying unreliable COVID-19-related health information. Data were collected from June 30-July 1, 2021. First, we measured 700 participants' baseline health literacy levels by having them read unreliable health information about the efficacy of green tea intake in preventing COVID-19 based on the results of animal experimentation. Second, participants read an explanation with a five-step flowchart of how to identify reliable health information. Thereafter, we remeasured participants' health literacy levels. To identify the factors hindering the effect of the confirmation scheme, a logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Overall, 77.9% (293/376) of those with low health literacy levels at baseline still had low literacy after the intervention. The factor that hindered the confirmation scheme's usefulness was benefit perceptions of food ingredients (OR: 0.493; 95% CI: 0.252-0.966). Consumers with higher benefit perceptions of a target product faced more difficulties using the confirmation scheme effectively. Therefore, the most effective strategies involve filtering information at the organizational level rather than the individual level, which should help consumers correctly identify misinformation concerning food and health and promote accurate decision-making.

The Perception of Minerals and Their Prevalence in Fortified Foods and Supplements in Japan.

People's intake of some minerals does not meet the nutrient reference values even in high-income countries. Recently, the deficiency of zinc and/or selenium has been considered to cause greater risk of COVID-19 infection and severity. To investigate consumer awareness, we conducted a cross-sectional questionnaire online survey among Japanese people (7500 males and 7500 females) concerning their perceptions of each mineral and the prevalence of mineral-fortified foods and/or mineral supplements. People's perception of each mineral varied: the highest was for calcium (91.8%) and the lowest was for selenium (44.7%). In addition, only a portion of participants believed that they consumed a sufficient amount of each mineral; the highest was sodium (23.7%), and the lowest was manganese (5.2%). In addition, 18.2% of them felt that they could not consume enough sodium, even though most of the Japanese's intake is excessive. Among mineral-fortified-food and/or mineral-supplement users, the purposes for these products were to maintain health (80.6%), supplement nutrients (48.0%), and prevent infectious diseases (23.2%). Only 18.4% of participants knew what amount they took. In conclusion, education is needed to prevent not only the insufficiency/deficiency of each mineral but also an excess intake of sodium.

Short-chain fatty acids, acetate and propionate, directly upregulate osteoblastic differentiation.

Short-chain fatty acids, including acetate, propionate, and butyrate are metabolites of dietary fibre produced by microbiota in the large intestine, have been proposed to contribute to effects on bone homeostasis. However, it is unclear whether they are used in osteoblasts and directly affect bone formation. We investigated whether short-chain fatty acids are absorbed in osteoblast cells and influence early osteoblastic differentiation using MC3T3-E1 cells. Acetate and propionate upregulated alkaline phosphatase activity, which is an osteoblast differentiation marker, and acetate upregulated alkaline phosphatase mRNA expression after treatment for 9 days, whereas butyrate did not in MC3T3-E1 cells. Butyrate was absorbed more rapidly and to a greater extent than acetate and propionate. These results indicate that short-chain fatty acids were used in osteoblastic cells, and particularly acetate and propionate directly upregulated differentiation in primary osteoblasts. Therefore, acetate and propionate might be useful for maintaining a positive balance of bone turnover.

[Recognition and Prevalence of "Designated Ingredient, etc." in Health Foods].

From 2012 to 2017, many adverse events, such as irregular vaginal bleeding and menstrual disorders, associated with the use of health foods containing Pueraria mirifica were reported in PIO-NET. Health foods containing P. mirifica claim mastogenic or body shaping effects, and it is for this reason that many women use these products. As a result, the Japanese government investigated and assessed the possibility of the occurrence of adverse effects associated with the use of other ingredients in health foods and labelled P. mirifica, Coleus forskohlii, black cohosh, and greater celandine as "designated ingredient, etc."The present study showed that recognition of "designated ingredient, etc." was 45.9% and that there was a difference between consumers and healthcare professionals. The prevalence of food containing P. mirifica use was 1.2%. Almost half of users experienced adverse events, such as irregular vaginal bleeding and menstrual disorder. Some subjects had a good perception towards "designated ingredient, etc.," such as "It seems effective"(32.7%) and "It seems good for health"(18.9%). After reading the descriptive text, their positive perceptions decreased.In conclusion, the recognition of "designated ingredient, etc." is insufficient. To avoid adverse events associated with "food containing designated ingredient, etc.," detailed information should be provided.

[Consultation and Information Source of Interaction between Drugs and Health Foods among Pharmacists and Dietitians].

The prevalence of health food use is increasing not only among healthy individuals but also among patients. Many patients consume drugs and health foods concomitantly, and most of them use more than one drug and one health food. In this regard, the interactions between drugs and health foods should be addressed. However, it is not clear where healthcare professionals can get sufficient information about the interactions between drugs and health foods. To address this issue, we conducted an online questionnaire about the consultation and attitude concerning and information source of interactions between drugs and health foods among pharmacists and dietitians. Only 29.7% of pharmacists and 14.0% of dietitians always confirmed the use of health foods among their patients, even though they work at pharmacies or hospitals. Regarding concomitant use, 79.2% of pharmacists and 60.2% of dietitians allowed their patients to continue concomitant use, and less than 20% of them advised their patients to avoid concomitant use. Most of them checked the manufacturer's website and could not obtain sufficient information about the interactions between drugs and health foods. However, they utilized the "Information system on safety and effectiveness for health foods (HFNet)," which is the website of the National Institutes of Biomedical Innovation, Health and Nutrition, to obtain information, if they were aware of this. In conclusion, pharmacists and dietitians need more information about the interactions between drugs and health foods, and HFNet may play an important role as information source.

Reliability in viscosity measurement of thickening agents for dysphagia management: Are results obtained by cone-and-plate rheometers reproducible between laboratories?

Viscosity measurement using a cone-and-plate rheometer is considered to provide an objective and reliable evaluation of thickening agents for dysphagia management. Here, we showed its measurement uncertainty in the context of an inter-laboratory study. Eight test samples (i.e., four viscosity standard liquids, one xanthan gum reagent powder, and three commercial thickening agent powders) were distributed to 10 laboratories in a blinded manner. According to the same standard operating procedure, each laboratory dissolved the xanthan gum or thickening agents at four concentrations (0.5-4.0 g/100 g) and then measured their viscosity (35-803 mPa∙s). As for the viscosity of the standard liquids, the grand means were 98-100% of the certified values, and the relative standard deviations for repeatability (RSDr ) and reproducibility (RSDR ) were ca. 1% and ca. 5%, respectively, suggesting good accuracy in the measurement process. On the other hand, as for the viscosity of the thickening agents, RSDr and RSDR were ca. 2-6% and ca. 5-8%, respectively; however, heterogeneity in the preparation process comprising a manual dissolving step may increase these to near 60%. Furthermore, RSDr and RSDR of estimated additive concentrations to achieve targeted viscosities (50-500 mPa∙s) based on concentration-viscosity curves were ca. 1-3% and ca. 3-5%, respectively, with a few exceptions. These findings suggest that a strictly standardized procedure provides reliable data on the viscosity measurements for thickening agents.

Japanese newspaper advertisements for dietary supplements before and after COVID-19: a content analysis.

OBJECTIVES: Public health institutions have alerted consumers about advertising for dietary supplements with false claims of preventing or treating COVID-19. We quantitatively and qualitatively examined newspaper advertisements for dietary supplements before and after the COVID-19 spread. DESIGN: Content analysis. PARTICIPANTS: We analysed advertisements for dietary supplements in two major Japanese newspapers in February-July 2019 and February-July 2020. Our analysis covered 2167 advertisements. RESULTS: The number of advertisements for dietary supplements that claimed to be effective in infection prevention (p=0.009) and improving joint (p=0.002) and digestive functions (p=0.002) significantly increased after the spread of COVID-19 compared with before. Dietary supplements that claimed to be effective in preventing infection were advertised in combination with recommendations for gargling and handwashing. Such terms as 'defence' and 'prevent' were used to promote the preventive effect. CONCLUSIONS: False and misleading claims in advertising for dietary supplements may result in consumer harm, such as overdosing and failure to take preventive behaviour. While the pandemic continues, there will be an increasing need for disseminating accessible information about the appropriate use of dietary supplements, consumer education and warnings to manufacturers.