Genetic factors associated with lactose malabsorption were studied in slc-Wistar rats. A decline in the maximum level of blood glucose attained in the lactose tolerance test (LTT) using 1g per kg body weight administered as 20% lactose solution appeared at 5 to 6 weeks of age. The rats were classified into three groups (L, M and H) according to the maximum level of blood glucose upon LTT at 11 weeks of age. Lactase activity and the degree of the decline in the maximum blood glucose level differed among these groups. The heritabilities of the maximum blood glucose level upon LTT and lactase activity were estimated to be 0.4-0.6 and 0.7-0.8, respectively. The foundation population used for the selection experiment was designated as generation 0, and consisted of 124 litters obtained from random mating of slc-Wistar rats. Populations L and H were selected for low and high lactose absorption, respectively based on the maximum blood glucose level upon LTT at 11 weeks of age and on the lactase activity of parents. Population H showed an increase in the maximum blood glucose level and lactase activity, while population L showed a decrease in comparison with the unselected population M. Clinical symptoms such as diarrhea and loose bowels were observed in population L during LTT performed with a lactose dose of more than 1.5 g/kg B.W. These results indicate that lactose intolerance has a high degree of heritability.

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Microfibrillated cellulose-pectin (MFC-P) was incorporated into the diet of rats as a dietary fiber (DF) source and its effects on growth, organs weights, fecal weight and gastrointestinal transit time were examined at three dietary levels (5%, 7.5% and 10%) in comparison with cellulose powder (CP) and cellulose powder+pectin (CP+P). The results were as follows ; 1) Food intake tended to increase as the DF level increased. No significant difference, however, was observed in body weight gain. 2) MFC-P tended to increase the length of the small intestine as its dietary level increased. 3) Fecal output was higher in the CP and MFC-P groups than in the CP+P group and was increased significantly as the DF level increased. Fecal water retention was significantly higher in the MFC-P group than in the CP and CP-FP groups. 4) Gastrointestinal transit time was shortened significantly in the MFC-P and CP-FP groups compared with that in the CP group, and this was more evident in the groups given higher DF levels.

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Three types of microfibrillated cellulose (MFC) -carbohydrate mixture (1: 1); MFC-lactulose (MFC-LL), MFC-oligofructose (MFC-FO) and MFC-polydextrose (MFC-PD), and three kinds of cellulose powder (CP) +carbohydrate mixture (1: 1); CP+LL, CP+FO and CP+PD, were fed to rats at the 10% level in diets for three weeks, and their effects on growth and gastrointestinal function in the rats were examined. The results were as follows; 1) Fecal output of the groups fed on MFC-carbohydrate diet was higher than that of the groups fed a CP+carbohydrate diet. 2) Gastrointestinal transit time was shortened in the groups fed on MFC-carbohydrate diet compared with that in the groups fed a CP+carbohydrate diet. 3) Apparent digestibility of dietary protein was significantly low in all the groups fed on MFC-carbohydrate diet. Digestibility of fat was decreased to a slight extent in the group fed on MFC-LL diet. 4) Higher apparent absorption of minerals (Ca, Fe, Zn and Cu) was observed in the groups fed a CP+carbohydrate diet than in the groups fed on MFC-carbohydrate diet, with the exception of Cu absorption in the group fed on MFC-FO diet.

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The intake regulation of the non-essential amino acids, glycine (Gly) and tyrosine (Tyr), in weanling rats was investigated using the self-selection feeding method, and the data obtained were compared with those previously reported for essential amino acids. When rats were offered in a choice paradigm of two diets containing various levels of Gly or Tyr alone, they preferred a diet with a higher content. However, the animals displayed aversion when diets containing 7% Gly, or not less than 3% Tyr were offered. The weight gains of all rats used for the Gly or Tyr selection experiment were not significantly different from each other and were the same as the maximum levels observed in a fixed feeding experiment. From these results it became clear that rats have an ability to select Gly and Tyr in their diet within a range that maintain their maximum growth, and that the maximum intake of these amino acids may be controlled by a mechanism which prevents amino acid toxicity due to excessive ingestion.

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The bioavailability for human intestinal bacteria of water-soluble dietary fiber preparations isolated from various cereals was examined. The effect of a hemicellulose preparation isolated from defatted rice bran (RBH) and high-methoxylated pectin (HMP) on fecal microflora and fermentation products in rats was also investigated. 1) Almost all the water-soluble dietary fiber preparations tested were rather resistant to bacterial degradation. RBH was simply degraded by Bifidobacterium compared with the other dietary fiber preparations. However, HMP was not degraded by the strains of intestinal bacteria used. 2) An increase in the fecal population of Bifidobacterium was shown in the dietary RBH group. The Bacteroidaceae population increased in the HMP group. The cecal pH value decreased in the dietary RBH and HMP groups, but was significantly lower in the former than in the latter. The addition of water-soluble dietary fiber to the diet resulted in an increase in the quantities of organic acids (mainly acetic acid) in the cecum and feces. These findings suggest that water-soluble dietary fiber, especially RBH, is effective for modifying colonic conditions.

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The preventive effects of catechins (catechin, epigallocatechin, epigallocatechin gallate and catechin mixture) on the thermal decomposition of tocopherol (Toc) in some edible oils were investigated. Samples of hardened rapeseed, olive, soybean and corn oil with or without catechins were each heatedin a Pyrex glass tube (2.7×20cm) at 180°C for 10 or 28 h using an oil bath. After heating of each oil, the residual Toc and oxidative stability were determined by HPLC and the oven test at 60°C, respectively. Catechins suppressed the thermal decomposition of Toc in each oil during heating. The order of suppression of the thermal decomposition of Toc in hardened rapeseed oil was as follows: catechin>epigallocatechin>epigallocatechin gallate>catechin mixture. Thermal decomposition of Toc in hardened rapeseed oil decreased with increasing concentration of catechin. Citric acid in combination with catechin had no synergistic effect on the thermal decomposition of Toc. Catechins improved the oxidative stability of each oil after heating. Upon comparison of catechin with gallic acid, the latter had a more pronounced preventive effect on the thermal decomposition of Toc and produced a higher oxidative stability of heated oils containing it. Decomposition of Toc in oil was apparently promoted by oxidized fatty acids from the heated oil.

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Commercial foods containing fat and oil in Japan were surveyed for oxidative deterioration. The samples used were twelve of each of seventeen kinds of foods including butter-roasted peanuts, potato chips, fried dough cakes (karintou), fried rice crackers (agesenbei), doughnuts, crackers, puddings, cocoa, bread, instant noodles, instant curry sauce, soybean paste (miso), mayonnaise, small boiled/dried sardines (niboshi), sausages, salami sausages and canned tuna. Two thirds of the selected seventeen foods showed peroxide values (POV) and acid values (AV) within the limits specified by the Food Hygiene Law (POV under 30.0meq/kg; AV under 3.0). However, only 33% of the butter-roasted peanut samples and 17% of the niboshi samples used in the present work satisfied the prescribed POV levels. The reason for such low percentages of butter-roasted peanuts and niboshi satisfying the prescribed POV level was considered to be lipid autoxidation as well as enzymatic oxidation during preduction or storage, giving rise to deterioration. Furthermore, the present POV data for seven kinds of foods including butter-roasted peanuts, potato chips, karintou, agesenbei, doughnuts, crackers and instant noodles were compared with those obtained in 1975. As a result, six of the above foods except for butter-roasted peanuts showed sufficiently lower levels of POV than those in 1975, although both sets of data were within the prescribed standard, thus confirming that these foods have been improved with regard to quality control. Therefore, it seems necessary that appropriate methods of oxidation prevention and preservation should be established for butter-roasted peanuts and niboshi.

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On the basis of the results of a dietary investigation carried out in the Kitakyushu district in 1985, the nickel content of food was measured for representative daily diets taken by 6 adult males and females over the course of 3 consecutive days. The food specimens were subjected to flameless atomic absorption analysis after wet-ashing with an H₂SO₄ and HNO₃ acid mixture and daily nickel intake was estimated from the analytical values. The nickel content of rice was 22±19 μg/100 g, showing differences among specimens. The nickel content was less than 10.0 μg/100 g for the majority of foods, but higher amounts were detected in soybean, miso, soy, rice, spinach and cabbage. As a whole, vegetable foods showed higher nickel contents than animal foods. Nickel intake per day per capita was 280±90 μg for males and 190±40 μg for females. Rice, vegetable food other than rice, and animal food accounted for about 30, 65 and 5% of the daily nickel intake, respectively.

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Knowledge of the elemental composition and content of plants is very important in considering the diet of humans. However, to our knowledge, there have been few studies concerning the trace elements found in plants. Therefore, we analyzed the principal elemental components in plants. In this study, we performed quantitative analysis of ten elements (Na, Mg, Cl, K, V, Mn, Fe, Zn, Rb, Se) in the flesh and rind of ten varieties of grapes using non-destructive thermal neutron activiation analysis and obtained the following results. 1) Of the ten elements, Se was not found in determinable amounts. The remaining nine elements were distributed widely over a range from 10^-2μg/g to 10⁴μg/g. 2) The distribution of elemental contents was in the order K>Mg>Cl>Na>Fe>Rb>Zn, Mn>V in both the flesh and rind. 3) Among the specimens, especially the flesh, there was extensive fluctuation in the coefficients of elemental contents. In rinds, there were large values for every essential element except Fe.

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The dietary fiber (DF) contents of 52 kinds of food were determined by the enzymatic-gravimetric method. In 12 cereal samples determined, the DF content of rice was quite low. DF contents of wheat soft flour, barley, buck-wheat straight flour, rye whole grain and oatmeal were higher than the respective reference values obtained by the NDF method. Similarly, the DF contents of 3 kinds of potatoes were higher in comparison with the respective values obtained by the NDF method. DF contents of 8 kinds of pulses lay within a range of 15 to 20%. In 15 kinds of vegetables determined, most of the DF contents of fresh samples ranged from 1 to 3%, except for edible burdock root showing 10.89%. Kanpyo and kiriboshi-daikon contained high amounts of DF (24.77% and 16.94%, respectively). DF contents of 8 kinds of fresh fungi ranged from 1 to 3%. These values were lower than the respective reference values obtained by the NDF method. Seaweeds were shown to be superior as DF sources.

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