Recent Progress of Functional Food Research in Japan

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1 Chapter 1 Recent Progress of Functional Food Research in Japan Downloaded via on November 6, 2018 at 18:50:49 (UTC). See for options on how to legitimately share published articles. Toshihiko Osawa Department of Applied Biological Sciences, Nagoya University, Chikusa, Nagoya , Japan "Functional Foods" research project started first in 1984, under the sponsorship of the Japanese Ministry of Education, Science and Culture, and the concept for "tertiary function" has been proposed first. This paper mainly focused on foods with "tertiary function" which are expected to contribute to disease prevention by modulating modulation of physiological systems such as immune, endocrne, nervous, circulatory and digestive systems. Following the activation and development of systematic and large -scale"functional Foods Research" sponsored by the Ministry of Education, Science andculture, a national policy has approved "Functional Foods" in terms of FOSHU (Foods for Specified Health Uses) by Minstry of Welfare. Until now, more than 100 food items have been approved and introduced to market as FOSHU according to new legislation by minstry of Welfare. In this paper, I explain the reason why "Functional Foods"started in Japan, and I also discuss the background and recent progress of Functional Food Research in Japan. In this paper, we also review the recent progress of research on functions of dietary antioxidants as one example for "Functional Foods" American Chemical Society

2 3 Definition of Functional Foods Recently, many research have been carried out on food components which have "tertiary" function. The primary or nutritional function is the fundamental and basic function and much public interest has been focused on "primary function" when the most Japanese suffered extreme food shortage. During the improvement in life-style in the 1960's, Japanese graduary put more focus on sensory satisfaction along with the rapid development of industry. By the 1980's, much attention has been focused on the foods having "tertiary" functional activity. With the definition of functional activity, "primary" function means the role of standard nutrient components, and "secondary" function has been difinited as "sensory" functions related with flavour, taste, color and texture etc. By the 1980's many Japanese Scientists began to recognize the importance of the concept of prevention of age-related and gerriatric disease through daily dietary habits. As shown in Table I, recent research had shown that a variety of food components could be expected to disease prevention by modulating physiological systems such as immune, endocrne, nervous and circulatory and digestive systems. In 1984, Japanese Ministry of Education, Science and Culture funded basic scientific research at Universities to design and create the physiologically functional foods (simply, functional foods) on the basis of substances which have tertiary functions. Table I. Functions of Food Primary function Secondary function Tertiary function nutrition sensory satisfaction modulation of physiological systems (immune, endocrne, nervous, circulatory and digestive) Recent Development of Functional Foods Research In 1992, a new academic research project (Grant-in Aid for Scientific Research on Priority Area No.320) has been created under the sponsorship by the Japanese Ministry of Education, Science and Culture. This third 3-year project entitled "Analysis and Molecular Design of Functional Foods" has been chaired by Prof. S.Arai (1). Total of 59 research teams from 23 Universities joined together and details of the research program are shown in Table II.

4 Table II. Three Year "Grant-in-Aid" Research Program for "Functional Foods" Headed bydr. S. Arai I. Analysis and Design of Body-regurating Factors of Foods a. Factors of the active form 1.

3 4 Table II. Three Year "Grant-in-Aid" Research Program for "Functional Foods" Headed bydr. S. Arai I. Analysis and Design of Body-regurating Factors of Foods a. Factors of the active form 1. To fanction by inducing endogenous substances 2. To function as if they were endogenous substances b. Factors in the precursor form (Protein-derived peptides) 1. To function at the preabsorptive stage. 2. To function at the postabortive stage. II. Analysis and Design of Body-defending factors of Foods a. Factors involved in the immunological Mechanism 1. Immunostimulants 2. Immunosuppressants b. Factors involved in the immunological mechanism 1. Anti-infection factors 2. Anti-tumor factors m. Development of a Technological Basis for the Design of Functional Foods a. Design of microscopic structures 1. Molecular breeding 2. Molecular tailoring b. Design of Macroscopic Structures 1. Development of new methods for the structure conversion 2. Development of new methods for structural analysis The design and construction of functional foods would be positioned to use for targeting to enrich the concentration of the quantities of functional food components, or to remove some unfavorable toxic components. In 1990, "Designer Food " project started in U.S.A., and new concept "Food Phytochemicals for Cancer Prevention" has been created (2). In 1995, International Conference entitled "Food Factors for Cancer Prevention" has been organized in Hamamatsu in December 1995, and more than 1000 participants attended this Conference. The conference brought together leading researcher from all over ther world to present the most up-to-date findings on the role of diets in cancer prevention. The proceedings of this Conference has been published in 1997, and contain more than 100 papers (3), and new concept "Food Factors"is now acceptable not only in Japan but also U.S.A. and Europe. Next International Conference for food factors is scheduled in Kyoto in December 1999.

5 Definition of Food for Specific Health Use (FOSHU) In the late 1980's the Japanese Ministry of Health and Welfare has started to make an investigation to establish a category of foods which have

4 5 Definition of Food for Specific Health Use (FOSHU) In the late 1980's the Japanese Ministry of Health and Welfare has started to make an investigation to establish a category of foods which have health promoting effects to reduce the escalating cost of health care in Japan, because of the decreased consumption of fruits and vegetables by the emerging Western trends in Japanese diets. From these backgrounds, the Japanese Ministry of health and Welfere decided to introduce new concept "Food for Specific Health Use" (FOSHU). The Japanese Ministry of Health and Welfare defined FOSHU as "processed foods containing ingredients that aid specific bodily functions in addition of nutritions" which: O to which some ingredients to help get into shape are added; O from which allergens are removed; O the result of such addition/removal is scientifically evaluated;and to which the ministry of Health and Welfare has given permission to indicate the nature of effectiveness to the health. In order to get an approval for FOSHU, each food product should be judged based on the comprehensive examination and permission/approval will be issued by MHW only to those food products that have cleared the examination of product-specific documents submitted by the applicants. Such conprehensive examination is conducted by the experienced specialists in a broad research area.. Until now, more than 100 food items have been approved and introduced to market as FOSHU according to new legislation by the Minstry of Health and Welfare (MHW). In order to get permission/approval, the applicants are required to use an ingredient that is approved, then they must ask MHW for the examination of the FOSHU product that they have developed using that ingredient (4). Now, there are 11 categories of the ingredients for FOSHU products: l)dietary fiber 2)01igosaccharides 3)Sugar alcohols 4)Polyunsaturated fatty acids 5)Peptides and proteins 6)Glycosides, isoprenoids and vitamins 7)Alcohols and phenols 8)Cholines 9)Lactic acid bacteria 10 )Minerals 1 l)others. After 10 years of development of FOSHU products, we are greatly disappointed and have to clarify the distinction between "Functional Foods" and FOSHU, because MHW decided not to use the term "Functional Foods" for the legislation. Many researchers in academic mainly put the focus on prevention of life-style related diseases including cancer, heart diseases and cerebravascular diseases etc by food components which have tertiary functions including new physiological activities. Now, the term "Functional Foods" became much popular and evaluated as the best term compared with "Designer Foods" and "Nutraceuticals". Our research group has been involved in development of novel type of dietary antioxidants for protection in oxidative stress. In this paper, we also review the recent progress of research on functions of dietary antioxidants as one example for "Functional Foods".

6 Case of Functional Foods for Prevention of Oxidative Stress Although "tertiary function" means many different type of biological activities, much attention has been focused on prevention of

5 6 Case of Functional Foods for Prevention of Oxidative Stress Although "tertiary function" means many different type of biological activities, much attention has been focused on prevention of life-style related diseases, in particular prevention of diseases induced by oxidative stress (5). Our research group has been involved in isolation and identification of dietary antioxidants for a long time, and now developing novel and convenient evaluation systems by application of immunochemical methods for prevention of life-style related diseases such as atherosclerosis, diabetes and cancer etc. Oxidative Stress and Diseases. Recently, much attention has been focused on oxidative damages caused by degradation products or free radicals formed during lipid peroxidation of the cell membranes, although the active species were not identified. Excess production of oxygen radical species such as hydroxy radicals can easily initiate the lipid peroxidation in the cell membranes to form the lipid peroxides. Lipid peroxidation is known to be a free radical chain reaction which takes place in in vivo and in vitro and forms lipid hydroperoxides and secondary products such as MDA and 4-hydroxynonenal (HNE). These lipid peroxides are highly reactive and have been shown to interact with many biological components such as proteins, amino acids, amines, and DNA. Until now, many different type of detection and quantification methods of lipid peroxides have been developed by an instrumental analyses including application of HPLC. Recently we have been involved in developing novel type of evaluation systems for oxidative stress using immunochemical methods by application of polyclonal antibodies which are specific to 13-hydroperoxy linoleic acid (13- HPODE) (6), malondialdehyde (MDA) and 4-hydeoxynonenal (HNE) (7), because immunochemical methods are specific, simple and convenient. We have also succeeded in developing a novel monoclonal antibody which are specific to HNEmodified BSA (8). There are many indications that lipid peroxidation may play an important role in many age-related diseases including carcinogenesis, and there is speculation that oxidative damage can occur in DNA during the peroxidative breakdown of the membrane polyunsaturated fatty acids, in particular, oxidation of 2'- deoxyguanosine to 8-hydroxydeoxy-guanosine (8-OH-dG) by hydroxy radical. Although development of many sensitive methods for the detection of 8-OH-dG, in particular, ECD (Electrochemical Detector) equipped HPLC techniqui became the most popular method, despite the cost of the apparatus and requirement of many steps for sample preparation (9). In order to develop a more sensitive and convenient method, we decided to make an evaluation for the protective role of dietary antioxidants against to oxidative damages by monitoring the amount of 8-OH-dG in biological samples using the monoclonal antibody method (10). After obtaining specific monoclonal antibody to 8-OH-dG, we have been we develope a new ELISA (enzyme-linked immunosorbent assay) method in quantitating 8-OH-dG by competitive inhibition (11). These immunochemical methods for detection of lipid peroxidation products and oxidatively damaged DNA are very specific and useful technique to investigate the lipid peroxidation mechanism from the viewpoint of molecular level. By application of the immunochemical technique to the antioxidative assay systems, we can make the reliable, simple and convenient evaluation methods of antioxidative substances.

6 7 Dietary Antioxidants as Functional Foods. From our hypothesis that endogenous antioxidants in plants must play an important role for antioxidative defense systems from oxidative stress, an intensive search for novel type of natural antioxidants has been carried out from numerous plant materials, including those used as foods, and we have isolated and identified a number of lipid-soluble and water-soluble dietary antioxidants from crop seeds, sesame seeds and some spices. Rice (Oryza sativa Linn.) is the principle cereal food in Asia and the staple food nearly half of the world's population. Recently, the authors succeeded in isolating and identifying an antioxidative component present in rice hull as isovitexin, a C- glycosyl flavonoid. The authors have also been involved in isolation and identification of antioxidative pigments from black rices, because black rice seeds have an ability to maintain the viability even after the long-term storage, although the white rice seeds lost viability on shorter storage. By the large scale purification and isolation of the antioxidative pigments, cyanidine-3-o-p-d-glucoside (C3G) was isolated and identified, which was found to exhibit the strong antioxidative activity in the acidic regions. C3G was also isolated and identified as the antioxidative pigments in the black and red beans, and relationship between the variety and contents of these antioxidative pigments and also antioxidative mechanism of C3G have been examined (12). By our detailed examination on antioxidative mechanism of C3G, C3G was found to have the strong antioxidative activity and be converted to protocatechuic acid which also posess the antioxidative activity when scavenging free radicals (13). Sesame seeds and sesame oils have been used traditionally in Japan, China, Korea, and also in other eastern countries. As the lipid soluble antioxidant, sesaminol, has been found to be produced in the sesame salad oil (unroasted sesame oil) during the refining process. We have also made a large scale investigation on water-soluble antioxidants, sesaminolglucosides and found four different type of pinoresinol glucosides. Although these lignan glucosides are unique in sesame seeds, we focused mainly sesaminol glucosides, which we found in sesame seeds in a large quantity (14). Sesaminol triglucoside, main water-soluble antioxidant present in sesame seeds together with mono and diglucosides (about 1% concentration). By feeding these lignan glucosides to rats, P-glucosidase of intestinal bacteria was found to be able to hydralize enzymatically sesaminol glucosides to sesaminol and glucose. Therefore, sesaminol can be available from two sources; one route is an intermolecular transformation from sesamolin during the refining process of sesame oil, and other route is an enzymatical hydrolysis by P-glucosidase of intestinal bacteria. Sesaminol is an unique antioxidant because it has a superior heat stability, and also is able to effectively increase the availability of tocopherols in biological systems. Recently, the protective role of sesaminol against oxidative damage of low density lipoprotein has also been examined, and this data showed that the presence of sesaminol effectively reduced oxidative modificatrion of apo protein by caused by lipid peroxidation products in the presence of a peroxidation initiator. The authors found that sesaminol inhibited the oxidative modification of DNA by monitoring the excretion of 8-OH-dG using ELISA by application of monoclonal antibody in urine of

7 8 rats after feeding carbontetrachloride (CC1 4) as the in vivo sytem (5). By this experiment, we observed a marked increase of lipid peroxidation in blood plasma induced by CC1 4 administration, and we found that sesaminol inhibited effectively the formation of TBARS, and was effective in reducing the excretion of 8-OH-dG. These data indicated the potentiality of sesaminol for inhibition of the oxidative damages in DNA caused in vivo system, and long term feeding experiments of sesaminol and sesaminol glucoside are now undergoing. CONCLUSION The term of "Functional Foods" and its concept are now internationally accepted. It seems that such an international interest in "Functional Foods" reflects the current research activities in Japan, however, MHW decided not to use the term "Functional Foods" and adopted the term FOSHU instead. Looking back on the FOSHU systems over five years after introduction to Japanese Food Industries, many companies have a frustration because of the limitation of health claim and labelling. However, research scientists in both academics and industries in many countries including Japan are now ready to develop a new age "Functional Foods" which are evaluated by clinical testing and approved to make a health labelling for prevention of life-style related diseases including atherosclerosis, diabetes and cancer etc. There are many indications that lipid peroxidation plays an important role in carcinogenesis, although there is no definite evidence. Modification of immune systems are also very important approach to prevent diseases, however, I mainly focused on prevention of oxidative stress by dietary antioxidative components as one of the examples for "Functional Foods" in this paper. Our group started novel approach to develop evaluation and detection methods of lipid peroxidation products by application of monoclonal and polyclonal antibodies. We have also started our new project to investigate a novel biomarker of oxidative DNA damage other than 8- OH-dG. Of course, research efforts on metabolic pathways of dietary antioxidants in the digestive tracts are also required. Although these approach started just recently, they help us to understand the relationship between antioxidative activity and cancer prevention. REFERENCES 1. Arai, S. (1996) Studies on Functional Foods in Japan-State of the Art, Biosci. Biotech. Biochem., 60, Huang, M-T., Ho, C-T., Osawa, T. and Rosen, R.T. (1994) Food Phytochemicals for CancerPrevention I and II, ACS, Washington. 3. Ohigashi, H., Osawa, T., Terao, J., Watanabe, S. and Yoshikawa, T. eds. (1997) Food Factors for Cancer Prevention, Springer, Tokyo. 4. The Japan Health Food and Nutrition Food Association (1995) A Quick Guide to: Food for Specified Health Use.

9 5. Osawa,T.,Yoshida,A., Kawakishi,S., K. Yamashita,K. and Ochi,H. (1995) Protective Role of Dietary Antioxidants in Oxidative Stree, Oxydative Stress and Aging, R.G. Cutler, J. Bertman, L.

8 9 5. Osawa,T.,Yoshida,A., Kawakishi,S., K. Yamashita,K. and Ochi,H. (1995) Protective Role of Dietary Antioxidants in Oxidative Stree, Oxydative Stress and Aging, R.G. Cutler, J. Bertman, L. Packer and A. Mori, eds.,p , Birkhauser Verlag Basel/Switzerland. 6. Kato,Y.,Makino, Y. and Osawa,T. (1997) Characterization of a Specific Polyclonal Antibody against 13-Hydroperoxyoctadecadienoic acid -modified Protein, J. Lipid Res., 38, Uchida, K., Toyokuni, S., Nishikawa, K., Kawakishi, S., Oda, H., Hiai, H. and Stadtman, E.R. (1994) Michael Addition Type 4-Hydroxy-2-nonenal Adducts in Modified Low Density Lipoproteins: Markers for Atherosclerosis, Biochemistry 33, Toyokuni, S., Miyake, N., Hiai, H.,Hagiwara, M., Kawakishi, S., Osawa, T. and Uchida, K. (1995) The Monoclonal Antibody Specific for the 4-Hydroxy-2- nonenal Histidine Adduct, FEBS Lett. 359, Toyokuni,S.,Tanaka,T., Hattori,Y., Nishiyama,Y. Yoshida,A., Uchida,K., Ochi, H. and Osawa,T.(1996) Quantitative Immuno-histochemical Determination of 8-hydroxy-2'-Deoxyguanosine by a Monoclonal Antibody N45.1: Its Application to Ferric Nitrilotriacetate-induced Renal Carcinogenesis Model, Laboratory Invest., 76(3), Hattori,Y.,Nishigari,C.,Tanaka,T.,Uchida,K.,Nikaido,O.,Osawa,T.,Hiai,H., Imamura,S.and Toyokuni,S.(1996) Formation of 8-Hydroxy-2'-deoxyguanosine in Epidermal Cells of Hairless Mice after Chronic UVB Exposure, J. Invest. Dermat., 107(5), Erhola,M.,Toyokuni,S.,Okada,K.,Tanaka,T.,Hiai,H.,Ochi,H.,Uchida,K.,Osawa, T.,Nieminen, M.M.,Alho,H. and K-Lehtinen, P. (1997) Biomarker Evidence of DNA Oxidation in Lung Cancer Patients: Association of Urinary 8- Hydroxy-2'-deoxyguanosine Excrerin with Radiotherapy, Chemotherapy, and Response to Treatment, FEBS Letters, 409, Tsuda, T., Shiga, K., Ohshima, K. and Osawa T.(1996) Inhibition of Lipid Peroxidation and Active Oxygen Radical Scavenging Effect of Anthocyanin Pigments Isolated from Phaselous vulgaris L., Biochem. Pharmacol., 52, Tsuda,T.,Oshima,K.,Kawakishi,S., and Osawa, T.(1997) Oxidation Products of Cyanidin 3-O-β-D-glucoside with Free Radical Initiator, Lipids, 31, Katsuzaki, H., Kawakishi, S. and Osawa, T. (1994) Sesaminol Glucosides in Sesame Seeds, Phytochem., 35,

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