According to law, everything we eat and drink is classified as either food or medicine. Health foods (also called dietrary supplements or functional foods) are classified as food. For many years the government has strongly regulated health foods as fake medicine. However, advertising of health foods that falsely claim medical effects has not decrease and a large number of people continue buying health foods, believing in their medical effects. In this special edition, safety and functions of health foods are discussed by six authors helping to provide an understanding of dietary supplements and how we can wisely use them.

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From the viewpoint of the Consumer Affairs Agency (CAA), we introduce the systems of foods with health claims in Japan. In particular, the CAA focuses on foods with function claims versus foods for specified health uses. Here we review the CAA system, explaining the functional claims system and what consumers need to consider when ingesting foods with health claims.

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Today, various“so-called health foods⁠” are available in the market or through the internet in Japan and consumers must personally decide whether to eat “health foods⁠” in contrast to prescribed medicines. However, scientific information about food safety or quality necessary for this consumer choice is not fully provided.
The Food Safety Committee Japan (FSCJ) has summarized reports and published 19 recommendations for ⁠“so-called health foods,” thus providing scientific information for consumers so that food safety can be ensured as much as possible.

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Along with an increase in self-care and self-medication practices, the use of health foods as primary and secondary methods of disease prevention has increased. Consumers are aware only of the health benefits of dietary ingredients in health foods; however, the potential risks associated with ingredients in these products are mostly unknown. In fact, adverse events associated with the use of health foods have been reported. So, information based on scientific evidence should be provided to consumers. To address this issue, National Institute of Health and Nutrition constructed an online database, ⁠“Health Foods Network (HFNet)⁠” in 2004 that compiles reports on the safety and effectiveness of health foods and their ingredients. This database serves to disseminate information based on scientific research not only in Japan but also all over the world. In addition, HFNet provides information about safety alerts related to health foods. This information serves as a helpful source to avoid adverse events resulting from the use of illegal products. We also provide research about the prevalence of health food use and incidence of adverse events related to health food use. These results indicate inappropriate usage of health foods among consumers and suggest the necessity to deliver the right information to the right people. We hope HFNet will be helpful for health-care professionals and consumers to develop an environment in which health foods are properly used by consumers.

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National Consumer Affairs Center of Japan has reported increasing numbers of injury complaints from health foods via PIO-NET (Practical Living Information Online Network System) after introduction of “Foods with Function Claims” in 2015. However, administrative actions have not always resulted from these complaints because it is very difficult to establish causal association between consuming a health food and a symptom experienced by the patient. Some health foods look like drugs, but the system to ensure consumer safety is quite different. For example, health foods containing Pueraria candollei var. mirifica has continued to be sold after many complaints by consumers and warnings by Ministry of Health, Labour and Welfare. In the case of drugs, the company would halt sales quickly if required by the authority. In contrast, health foods providers expect consumers to manage safety by themselves. Therefore, consumers need to know exactly how safe health foods are. In fact, health foods are in highest risk category among foods even though many consumers do not realize that. The gap between perceived risk and real risk represents challenges and difficulties in food safety management. Risk communication is the key as is always the case with food safety, but especially for the safety of health foods.

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There are various issues in the health foods industry in Japan. First is strengthening safety measures to prevent health damage derived from intake of health foods. In particular, novel ingredients and materials need to be assessed carefully for their safety. Second is the need for appropriate efforts under the Foods with Health Claims system. In some cases, ⁠“a systematic literature review to assess function claim⁠”, a key of the system, fails to be properly performed and this may lead to serious problems. Labelling with willful misuse under the system of Foods with Nutrient Function Claims is also occasionally found. It will be difficult to maintain the reliability of the food protection systems unless these problems are promptly resolved. Third is the issue of relevance with labelling and advertising of health foods. Wordings that conflict with relevant laws such as the Unjustifiable Premiums and Misleading Presentations Act and the Pharmaceutical and Medical Device Act have been found. In recent years, there has been a surge in consumer troubles associated with ⁠“periodical purchase⁠” versus simply purchased as a “trial⁠”. Therefore, the business ethics and compliance consciousness of distributors has been a recent topic for discussion. In addition, the reorganization of scattered industry associations associated with the health foods industry of Japan is an important subject for discussion.

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Experimental results indicate that the magnitude of the pharmacological actions of health foods is small. Therefore, it is hard to think that health foods may play an important role in maintaining and improving the health of people. In contrast, many people realize the effects of health foods and continue to use them. This discrepancy may be due to the fact that some health foods have not only pharmacological effects but also placebo effects. If so, health foods with a placebo effect are considered to be highly valuable. In order to utilize the placebo effect, it is important to disseminate the correct knowledge of the placebo effect. By making full use of the placebo effect, health foods may help to maintain and promote human health.

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Staphylococcal enterotoxin A (SEA) is a toxic protein and is the most common cause of staphylococcal food poisoning. In our previous studies, we identified some polyphenols that inhibited SEA toxin activities. In the present study, we investigated the interaction between four catechins (EC, ECG, EGC and EGCG) and SEA and the inhibitory effects of catechins on SEA activity. The interactions of catechins with SEA toxin active sites were analyzed using 4 different synthetic peptides and rabbit antibodies to their corresponding peptides (A-2, A-3, A-6 and A-10). As a result, EGCG inhibited the binding affinity of the all anti-peptides. When we examined whether EGCG inhibits cell proliferation and interferon-γ (IFN-γ) production induced by SEA in mouse spleen cells, we found that EGCG strongly inactivated cell proliferation and IFN-γ production induced by SEA. We examined changes in binding affinity of EGCG under digestive tract conditions by treatment under acidic or alkaline pH (pH2.4-8.0) with or without protein (bovine serum albumin). Results showed EGCG maintained binding affinity to SEA. We further investigated the binding of catechins to SEA using surface plasmon resonance (Biacore), isothermal titration calorimetry and protein-ligand docking. According to thermodynamic parameters, a negative ΔG indicated that the interaction between EGCG and SEA was spontaneous, and the electrostatic force accompanied by hydrophobic binding forces may play a major role in the binding. Data from Western blot analysis and docking simulation suggest that the hydroxyl group at position 3 of the galloyl group in the catechin structure was responsible for binding affinity with the Y91 of the A-6 region in SEA active sites. Our results provide further understanding of the binding interactions between catechins and SEA, and the inhibition of toxin activities by catechins.

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Chili peppers (Capsicum spp.) originated in the Bolivia- Peru region of South America and were introduced to Europe, Africa and Asia after Columbus discovered the Americas. Chili pepper was introduced to Japan during the Azuchi Momoyama period, was accepted in the early Edo period (around A.D. 1600), and various varieties have since been cultivated and used. In present Japan, local traditional varieties of chili peppers are distributed from Hokkaido in the north to Okinawa in the south, where they are grown and eaten. Among them, Nagano Prefecture has a wide diversity of local traditional varieties, where varieties from lower pungency to higher pungency are cultivated and used. Capsaicin, a pungent component of chili pepper, is synthesized by a biosynthetic pathway consisting of two parts, a phenylpropanoid pathway and a branched fatty acid pathway. Non pungent chili pepper varieties such as sweet peppers, paprika and ‘Murasaki,’ which is one of the local traditional variety in Nara, are functionally deficient in pun1, the last gene of the pathway. The other local traditional variety in Nara called ⁠“Himo⁠” also has no pungency, however it has a functional Pun1 gene and a functionally deficient pamt gene. Recently, chili pepper breeding has been conducted using the results of research on genetic aspects of capsaicin synthesis.

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Nara Prefecture in Japan, which is a large-scale production area of persimmon (kaki), started a new business using leaves instead of fruits. About 20% of the persimmon farms will be abandoned for cultivation, and companies will start developing and selling processed leaf products focusing on persimmon leaf production that can reduce costs. Persimmon leaves contain more than 20 times as much vitamin C as lemon and are rich in polyphenols. Originally, persimmon leaf was used as a raw material for healthy tea and as a strongly preserving packaging material for sushi (kakinoha-sushi, traditional food in NARA). It is said that persimmon leaves have antioxidative action, antiseptic action, bactericidal action and deodorizing action as well as lowering blood sugar level, decomposing chlorine components and being nonallergenic.
By making products that can be delicious when consumed and expanding the possibilities for use of raw materials, we aim to maintain and continue persimmon farming, stop the abolition of persimmon farming, and inform our customers about the wonders of the food of Nara.

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