After the Second World War, following the economical growth, the living standard had been rapidly elevated in Japan, and the dietary life had also been changed greatly. These changes, together with the improvements in the social hygienic conditions and also these of the medical and pharmacological sciences, have brought about the elongation of life span to Japanese, so they can now enjoy their longevity. But, contrary to these good results, there are some problems due to the over intake of nutrients. In 1985, the Ministry of Health and Welfare issued the Dietary Guidelines for Japanese to keep the ideal dietary life and to maintain the health. In Japan, the results of the National Nutrition Survey were chronologically accumulated from 1946, and it became clear from these results, that the lipid energy ratio of 1988 broke through 25%, and this value is about three times high compared with this of 1950. Then, as to the lipids in meals, this Dietary Guidelines recommend to consider not only the quantity but also the quality of lipids in meals. In this article, dietary guidelines of several developed countries were compared and the ideal lipids level in meals was searched.
Dietary fat and oil has very important role in human nutrition. Linoleic, linolenic and arachidonic acids exert as the essential fatty acid which are sources of icosanoids. High energy density are useful for the decrease of diet induced thermogenesis. Also, lipids compose cell membrane and adipose tissue as the important constituents. However, recent National Nutrition Survey in Japan indicated the over intake of fat as 25% of energy which associated with coronary heart diseases, colon cancer and cholesterol gallstone. Intake balance of polyunsaturated fatty acid (P) and saturated fatty acid (S) is important as well as the balance of n-6 and n-3 fatty acids. P/S ratio is 1.1, and (n-6) / (n-3) ratio is 3.6 in Japan. It seemes that appropriate balanced intake of fat and oil is maintained in Japanese.
The production of oilseeds, and oils and fats in the world has gradually been increasing. Average capita supply of oils and fats in the advanced countries, such as U.S.A. and EEC, is about 10 times as large as a few developing countries. The greater part of oilseeds, and oils and fats in Japan is imported from foreign countries. Japanese average capita intake of total oils and fats in foods exceeds 25% of the total energy. Recently the yearly amount of quantities per household of edible oil is on a slight decrease.
“Functional Foods” are defined as a group of foods that are produced to draw out the satisfactory functions useful for human health. Each constituent of so-called “Functional Foods” is considered to take a role in maintenance of well-balanced physiological condition including the regulation of self-defence mechanisms, biological rythm in human life and prevention or recovery of various diseases. Standardization of “Functional Foods” aroused the public interest and various opinions were expressed by correlated people. A committee for the examination of “Functional Foods”, consisted by 22 expert members, fully discussed these opinions from all viewpoints including international movements. The final report by the committee was submitted to the Ministry of Health and Welfare in 1990. In this report, “Foods for Specified Health Use” is newly used instead of “Functional Foods”. This term is defined as the foods that are expected to have some good effects on the preservation of health from the consideration of the relationship between human health and foods or food constituents. “Foods for Specified Health Use” is permitted to be expressed on the foods for special people who take these foods for some limitted purpose related to the preservation of health. This manuscript will represent the process of the change of the terminology for this group of foods and an outline of the new institution for “Foods for Specified Health Use” will be shown.
“Guidelines for Safety Assessment of Food and Food Additives Produced by rDNA Method” has recently been reported by the Ministry of Health and Welfare. Since the guidelines are very useful for the evaluation of oil, fat and oil food produced by biotechnology, key parts of the guidelines are outlined. The guidelines consist of three parts, basic policy for the guideline, guideline for manufacturing processes and guideline for products. The guidelines are applicable only to those food and food additives produced by rDNA method which are identical to or similar to natural ones and recombinants are not to be eaten.
The role of dietary fats is discussed in the focus of the prevention of cardiovascular disease. The cut off points of plasma lipids have been recently established based on the incidence of ischaemic heart disease and stroke. In order to maintain the plasma lipids within the desirable range, several factors on the dietary fats should be considered such as total fat consumption and fatty acid compositions. Increased intake of polyunsaturated fats (n-6) accelerates removal of low density lipoprotein (LDL) through up-requlated LDL receptor and also stimulates the uptake of high density lipoprotein (HDL) by the liver. Increased intake of polyunsaturated fats (n-3) inhibits the production of triacylglycerol (triglyceride) and consequently reduces plasminogen activator inhibitor.
A relationship between income and quality of food in human life was introduced to discuss oil and fat consumption. Population explosion and food crisis were also touched upon. Oil and fat consumption in Japan and their consuming trend were followed where the increase of oil and fat consumption was found to be about 1.3% annually. Palm oil from Malaysia plays a major role to determine the prices of oil and fat, while soybean meal from China determines the meal prices in Japan, where the meal import from China depresses the crushing volume of soybean in Japan. Japanese crushing capacity and its actual processed volume were also discussed. Finally, some interesting topics among the Government, Universities and Industries were explored as follows : 1. Saturation of oil and fat intake in Japan. 2. Controversial arguments on the nutritional evaluation of vegetable oils. 3. Environmental polution by the fried and exhausted oil. 4. Safety of imported oil and fat for human life. 5. Reasonability and acceptability of setting a special date for delivery after production.
Essential fatty acids (EFAs) are linoleic acid (18 : 2 n-6) and α -linolenic (18 : 3 n-3) acid, and a series of polyunsaturated fatty acids (PUFAs) derived from them. The desaturationelongation products appear to have more potent functions than the parent molecules. Since minimum requirement of EFAs is 11.2% of energy intake as linoleic acid and 0.4% as α-linolenic acid, the EFA deficiency rarely happens insofar as we eat regular meals. The main functions of EFAs include structural constituents of the membranes, precursors of icosanoids and a barrier of skin permeability. When considering the physiological effects, intake of EFAs should be far more than the minimum requirement. EFAs appreciably relate to the development of various degenerative diseases such as atherosclerosis, immune disfunction and carcinogenesis. The amount and the balance of dietary n-6 and n-3 PUFAs are indeed important to prevent and improve these diseases. Desaturation of linoleic and α-linolenic acids are regulated ingeniously and influenced by a number of factors. In addition, there is a strong interference in the metabolism between n-6 and n-3 PUFAs. Although enormous efforts have been paid to acknowledge the optimum balance and composition of dietary n-6 and n-3 PUFAs, many questions still remain to be solved.
Phospholipid is an essential constituent of biological membranes in all the organisms and is biosynthesized from nutrients ingested as food. Recently, various roles of phospholipid in the expression of cell functions have been rapidly revealed as follows : phospholipid regulates the functions of cell membrane proteins, and is a source of various mediators including polyunsaturated fatty acids as precursors of icosanoids. PAF (platelet-activating factor) involved in allergic disorder and inflammation is also one kind of phosholipids. Lecithin, a well-known phospholipid which is commonly found in food, was commercialized as healthful food, and has been used as a medicine for chronic hepatic diseases since the 1960's. The authors, recently, found out icosapentaenoic acid (EPA) -producing bacteria and revealed that the bacterial EPA is bound to the β-position of the phospholipid molecule by an ester bond. Then the oral administration of the EPA-phospholipid to the SHR-SP rats showed a specific physiological activity, that is, the weight reduction of the adipose tissue in addition to the physiological activities of EPA previously described. Thus the research for physiological activity of phospholipid will be greatly progressing.
Non polar, water-insoluble lipids, such as cholesterylesters and triglycerides, are transported in body fluids by plasma lipoproteins, which consist of a core of these hydrophobic lipids surrounded by phospholipids and free cholesterol and then by specific proteins (apoproteins).Plasma lipoproteins are classified into four large groups according to the size, density and composition of apoproteins. After their synthesis and secretion by the liver and intestine, lipoproteins are metabolized in circulation and taken up by the particular tissues, and the process is regulated by the apoproteins, related enzymes, and specific receptors for lipoproteins. These factors are very important to control the transport and metabolism of cholesterol and other lipids. In this review, the structure, function and metabolism of each of four types of lipoproteins are described. The factors that control the metabolism of lipoproteins are also discussed on a molecular basis.
Although serum cholesterol level is closely related to atherosclerotic disease, cholesterol and its derivatives are important components of cell membranes, steroid hormones, bile acids and vitamin D. It remains unsolved why mammals developmentally selected cholesterol, but not other sterols as a regulatory component of biomembranes. This article describes the importance of cholesterol in mammalian cells from the biochemical as well as physicochemical aspects. The effects of oxidized cholesterol on metabolic functions are also briefly discussed.
The latest findings on polyunsaturated oil ingestion and phospholipid hydroperoxidation in biomembranes will be reviewed in this article from a view angle of membrane structures. Phospholipids, especially of aminolipids like phosphatidylethanolamine and phosphatidylserine, show potent antioxidant effects synergetically with endogenous tocopherols on autoxidation of dietary polyunsaturated oils, among which oxidation of perilla oil rich in α-linolenate is prevented by the presence of trace amount of aminolipids. This finding may also imply the importance of constituent phospholipids as antioxidant molecules with α-tocopherol in biomembranes. Among the physical conformations of phospholipid bilayers, hexagonal II phase is more susceptible to autoxidation than lamellar bilayer structures, thus suggesting that the hydroperoxidation proceeds rather on more dynamic non-bilayer phase transitions. For clinical interests, we could observe an abnormal accumulation of phospholipid hydroperoxides in red blood cell membranes of human senile dementia, in which phospholipid molecules containing icosapentaenoate and docosahexanoate are presumed to be the most peroxidizable membrane lipids in the dementia erythrocytes. With due regarding to those findings as cited here, the dietary treatment of polyunsaturated oils such as fish oil ingestion would need more careful consideration based on further studies from a viewpoint of membrane lipid hydroperoxidation and human health.
The antioxidative activities of vitamin E analogues were believed to be weak in foods systems to prevent oxidative deterioration or autoxidation of oils and fats. But, recent results have shown that α-tocopherol is consumed very rapidly during autoxidation of lipids or oils and fats, because it has high reactivity with oxygen radicals comparing with any other natural and synthetic antioxidants. So, α-tocopherol is present in biomembranes and organisms as the predominant antioxidant. Among vitamin E analogues α-tocopherol has the highest biological activity due to its excellent antioxidative activity. Also, vitamin E has good reactivity to quench singlet oxygen. Recently, biopotencies of stereo-isomers of natural α-tocopherol are discussed among researchers. RRR-α-tocopherol is believed to have the highest activity than other isomers of α-tocopherol.α-Tocopherol is transported with lipoproteins in blood such as LDL-and HDL-lipoproteins. A possible incorporation route into cells from blood is binding with LDL-receptors. In almost tissues and organs of RRR-α-tocopherol overdosed rats except liver upper concentrations of α-tocopherol are present, although upper limit values are depending on tissues properties. So, the low risk of hyper-vitamin E-dosis is due to such as low incorporation capacity of all of organs and tissues. But, since in liver the concentration of α-tocopherol increased with logarithmic relation with dose level and has no upper limit of α-tocopherol concentration, this phenomenon might cause a risk of extremely high intake of vitamin E in human such as daily intake over 10 gramms order.
Carotenoids are red and yellow pigments widely distributed in nature and were discoverd as long ago as 19th century. By the nutrition survey, those who ate vegetables and fruits rich in carotenoids, especially β-carotene had a much lower death rate due to lung cancer than who were not eating such foods. The ability of carotenoids to quench active oxygen species and protect cells and molecules in the body may be important role. The proposal that carotenoids may be effective substance in the prevention of human cancer has focussed. Some evidence for the proposal on the above were reviewed and also, metabolism of carotenoids in the plant and animal including human beings are shown.
In this paper, the recent trends of margarines are reviewed in point of nutrition as follows : (1) Trends of margarines for household use. (2) Trends of bakery margarines. (3) Trends of margarines in Europe. (4) New kinds of products, such as unhydrogenated fish oil spread. The production of margarines is remaining at almost the same level, but low calorie fat spread, which contains higher amount of water, is increasing both in Japan and in Europe from official statistics. The important things to consider in the production of low calorie fat spread are, to make stable water in oil (W/O) emulsion, to eliminate the spoilage caused by microorganisms, and to achieve good taste. In addition, many kinds of technics and new types of manufacturing machines are being developed.
The product amount of fat spread defined in Japanese Agricultural Standard has exceeded traditional margarine in 1990. Non-oil dressing is a new corner in these few years. On the other side, milk cream, soft bread, steamed cheese bread and freshly tasty chocolate are marked in recent food market concerning this title. Japanese consumers are choosing lower calorie, softer and freshly tasty foods recently. We can see many fatty products for mass production of these foods, but important products as follows are picked up and described related to edible fats and oils. These are creams including non dairy cream, whipping emulsified products, fluid type products, low calorie products and hard butters for chocolate industry.
In today's Japan, there are approximately 200 thousand patients with post-apoplexy were treated under the tubal alimentation. However there are few suitable tubal alimentation which could be rectify to prevent the recurrence of stroke by decreasing several risk factors. Form these points, major controllable risk factors (lipoprotein metabolism, fatty acid contents and platelet aggregation activity) of several tubal alimentations were thoroughtly discussed.
Favorable characteristics and confronting problems in developing the modern application of fish oil are reviewed. In order to expand the utilization of fish oil, daily and highly consumed linoleic acid and saturated fatty acids must be replaced in part by icosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrated fish oil, keeping the total lipid consumption at the level of modern Japan. For this purpose, technology in modifying lipids including enzymatic synthesis of EPA and DHA rich simple lipids as well as phospholipids is considered to be impelled.
Perilla and flaxseed oils (n-3 family) have many beneficial effects as compared to common n-6 family oils. Based on the results of animal test, physiological functions of these oils are reviewed. While these oils suppressed the development of cancer, thrombosis and allergic reaction, they enhanced the activity of brain and nerve systems. In the long-term feeding test of animals, perilla oil diet gave less hydroperoxide concentration of plasma and liver phospholipid than that in the fish oil diet
Market size of lecithin in the world and in Japan was roughly stated and main uses were introduced according to the classification of commercial products by PC content. Exchanging of salt type and the stability were stated relating to the processing technology for modifying the properties. Besides, practical functionalities for dietary use were reviewed with references.
New method was developed for separation and purification of polyunsaturated fatty acid ethyl esters using a silver ion-exchanged spherical clay mineral [SC (Ag)]. The SC (Ag) was prepared by ion-exchanging silver ion into synthetic hectorite that had been spray-dried to form a spherical shape. Ethyl icosapentaenoate and ethyl docosahexaenoate were separated and purified from the mixture of fatty acid ethyl esters originated from several natural lipids, using SC (Ag) preparative columns under the step gradient condition of organic solvent.
Recent advances in reactions which are useful in lipids industry and which are catalyzed by lipid-related enzymes such as lipases and phospholipases are reviewed. In the area of lipase-catalyzed reactions, types of reactions are first classified. As applications of lipase-catalyzed hydrolysis reactions, β-blocker synthesis, flavor formation and production of fatty acids are described. Various possible choices are presented for each industrial production of monoglyceride, cocoa-butter substitute and fish-oil enriched in polyunsaturated-fatty-acids. In the area of phospholipases-catalyzed reactions, process evaluation of lysolecithin production from soylecithin by phospholipase A2 and conversions of polar groups of phospholipids by transphosphatidylic action of phospholipase D are mostly reviewed.
Docosahexaenoic Acid (DHA) has important physiological activities, such as reduction of the plasma cholesterol and triglyceride, lowering effect of systolic blood pressure, anti-inflamatory and anti-tumor activities, etc. Recent studies also strongly suggest that DHA plays a key role in the brain and retina. DHA commonly exists in fish oil obtained from sardines, mackerels, menhadens, etc. Usually, however, it contains DHA at a relatively low level (5-10%) and many other polyunsaturated fatty acids, and thus isolation of pure DHA from fish oil is quite difficult. Recently, we found that (1) orbital fat of a bonito (Katsuwonus) and a tuna (Thunnus) fish was an excellent source of DHA, (2) DHA content in the total fatty acids of the orbital fat isolated from a bonito and a tuna fish was 42% and 30%, respectively, and (3) DHA existed as triglyceride in both cases. Purification of DHA was examined after ethanolysis of orbital fat oil obtained from a tuna fish, and resulted in 95%-99% purity of DHA-ethyl ester by a new method using Ag ion. Thus, finding of the excellent source and the purification procedure will greatly accelerate the research on DHA.