There is a need for studies on colonic fermentation in order to learn more abouthealth and diseases of the colon. The aim of the present study was to evaluate the fate of twodifferent doses of fructo-oligosaccharides (5 and 15 g/d) v. glucose in the intestine of healthy men. Twenty-four volunteers participated in a 5-weekstudy. The study was a completely balanced multiple crossover trial using an orthogonal Latin-square design for three periods, with supplement periods of 7 d and two 7 d wash-out periods. Breath samples and faecal samples were collected. There was a clear gaseous response to the consumption of fructo-oligosaccharides. The highest dose significantly increased 24 h integratedexcretion of breath H2 (P < 0·05). Breath H2 excretion after ingestion of 5 g fructo-oligosaccharides was higher than control, but did not reach significance. No effects on the total concentration of short-chain fatty acids in faeces were observed, no modification of the molar proportions of the various short-chain fatty acids was observed. The faecal pH did not change. No changes in faecal weight were observed. No fructo-oligosaccharides were recovered in faeces. We conclude that fructo-oligosaccharides added to the diet of young Western subjects are fully metabolized in the large intestine. The level of fermentation seems to be dose-dependent.

The effect of a mixture of organisms (a probiotic mixture) comprising Bacillus, Lactobacillus, Streptococcus, Clostridium, Saccharomyces and Candida(107–8 colony-forming units/g rice bran of each component) on lipid metabolism was compared with that of L. acidophilus and that of S. faecalis. There were four treatment groups: rice bran (control), the mixture of organisms, L. acihphifus or S. faecds (30g/kg) were given to rats in a fat- and cholesterol-enriched diet for 4 weeks. The serum total cholesterol concentration of the group fed on the mixture of organisms was reduced by 15–33% compared with the other groups at the end of the 4week feeding period (P < 0·05). This group also had a lower hepatic cholesterol concentration (36–44%) than the two single-bacteria groups (P < 0·05). 3-Hydmxy-3-methylglutaryl-Co A reductase (NADPH; EC 1.1.1.34) activities of the mixed-organism and L. acidophifus groups were significantly lower (61–63%) than those of the other groups (P < 0·05); the activity of the S. faecalis group was also signikantly lower (42%) than that of the control group (P < 0·05). The faecal cholesterol and bile acid concentrations of the mixed-organism group increased compared with those of the L. acidophilus and S. faecalis groups (P < 0·05). The capacity of the mixed- organism cells to bind bile salt in vitro was significantly higher (approximately 50%) than that of the singlebacteria cells (P < 0·05). On the other hand, cholesterol micelle formation for the mixed-organism cells was significantly (approximately 9%) lower than that of the singlebacteria cells (P < 0·05). These results indicate that the mixture of organisms decreased the synthesis of cholesterol in the liver and increased the loss of steroids from the intestine, in rats. Thus, the mixture of organisms had a hypocholeaterolaemic role

Ninety-six crossbred young pigs (body weight 7.8 kg) were used in a 5-week trial to determine the effectiveness of microbial phytase (EC 3.1.3.26) in improving the bioavailabilities of P and other nutrients in maize–soyabean-meal diets and, thus, replacing inorganic P with phytase. A 2 x 5 factorial arrangement of treatments was employed with two available P (aP) levels (0.7 and 1.6 g/kg) and five phytase levels (0, 350, 700, 1050, 1400 U (the quantity of enzyme that liberates 1µmol inorganic phosphate/min from 5.1 mm-sodium phytate at pH 5.5 and 37°)/kg diet). In addition, two extra diets were formulated to supply the National Research Council (1988) recommended level of aP (3.2 g/kg) with 0 or 1400 U phytase. The addition of graded levels of phytase resulted in linear increases in average daily weight gain, average daily feed intake and weight gain:feed intake for pigs fed on diets containing 0.7 or 1.6 g aP/kg (P < 0.04). Also, the addition of phytase linearly increased apparent digestibilities of P and Ca (P < 0.01), whereas faecal P excretion was linearly decreased (P < 0.01). Linear increases in shear force, shear energy and ash content of both the metacarpal and tenth rib, and shear stress of the metacarpal were found to respond to added phytase (P < 0.01). These improvements in performance, apparent P absorption and bone measurements by phytase were also observed by increasing dietary aP levels for most measurements. Adding 1400 U phytase to the 3.2 g aP/kg diet further increased average daily weight gain, average daily feed intake, apparent absorption of P, Ca and N and metatarsal shear force and ash content (P < 0.01 to 0.05). Generally, maximum responses occurred at a phytase level of 1050 U/kg diet for the 0.7 g aP/kg diets and 700 U for the 1.6 g aP/kg diets. Based on non-linear and linear response equations generated for the phytase and aP levels, the average function of the equivalency of P (Y, g/kg) v. microbial phytase (X, U/kg) was developed across aP levels of 0.7 and 1.6 g/kg for average daily weight gain and apparent digestibility of P: Y = 2.622–2.559e-0.00185x. The replacement of 1 g inorganic P as defluorinated phosphate would require about 246 U microbial phytase. This represents 41% of released P from phytate.

The aims of the present study were (a) to maintain the structure and function of the small intestine of the piglet after weaning, and (b) to compare the capacity in vivo of sucking and weaned piglets to digest oral boluses of lactose and sucrose and absorb their monosaccharide products. Piglets were fed on cows' whole milk ad libitum every 2 h for 5 d after weaning. Physiological doses of lactose plus fructose (treatment LAC + FRU) and sucrose plus galactose (treatment SUC + GAL) were administered on day 27 of lactation and on the fifth day after weaning, after which time piglets were killed. Villus height and crypt depth were maintained (P > 0·05) by feeding cows' milk after weaning. The areas under the curves (AUC) for galactose and glucose, adjusted for live weight and plasma volume, increased (P < 0·05) after weaning. Despite the enhancement of gut function after weaning, the galactose index (Gall: AUC for galactose ingested as lactose divided by the AUC for the same dose of galactose ingested as the monosaccharide) and fructose index (FruI: AUC for fructose ingested as sucrose divide by the AUC for the same dose of fructose ingested as the monosaccharide), which are indices of digestive and absorptive efficiency, both decreased after weaning. This apparent anomaly may be reconciled by increased growth, and hence surface area, of the small intestine between weaning and slaughter such that ‘total’ digestion and absorption most probably increased despite apparent decreases in GalI and FrnI. Positive correlations (P < 0.05) between villus height and Gall are consistent with the maximum activity of lactase occurring more apically along the villus. Significant linear relationships (P < 0·05) were recorded between villus height at the proximal jejunum and adjusted AUC for galactose and glucose following treatment LAC + FRU, and between villus height at the proximal jejunum and adjusted glucose AUC following treatment SUC + GAL. These relationships suggest that maximum digestion and absorption occurs at increasing distances along the crypt:villus axis in the weaned pig.

A new guar-containing wheatflake product was developed to assess its effect on carbohydrate tolerance in normal-weight, healthy subjects. The extruded wheatflake breakfast cereals containing 0 (control) or approximately 90 g guar gum/kg DM were fed to ten fasting, normal-weight, healthy subjects using a repeated measures design. The meals were similar in energy (approximately 1·8 MJ), available carbohydrate (78 g), protein (15 g) and fat (5·4 g) content. The guar gum content of the test meals was 6·3 g. Venous blood samples were taken fasting and at 15, 30, 45,60, 90, 120, 150 and 240 min after commencing each breakfast and analysed for plasma glucose, insulin and C-peptide. The guar wheafflake meal produced a significant main effect for glucose and insulin at 0-60 min and 0-240 min time intervals respectively, but not for the C-peptide levels compared with the control meal. Significant reductions in postprandial glucose and insulin responses were seen following the guar wheatflake meal compared with the control meal at 15 and 60 min (glucose) and 15, 60, 90 and 120 min (insulin). The 60 and 120 min areas under the curve for glucose and insulin were significantly reduced by the guar gum meal, as was the 240 min area under the curve for insulin. Thus, it can be concluded that the use of a severe method of heat extrusion to produce guar wheatflakes does not diminish the physiological activity of the guar gum.

The effects of olive oil and rapeseed oil, two different high-o1eic-acid oils, on plasma LDL and hepatic cholesterol metabolism were compared in guinea-pigs. Animals were fed on semipurified diet containing 150 g fat/kg as either olive oil (OL), rapeseed oil plus 100 g palm oil/kg (C-P) or olive oil plus 350 g safflowerseed oil/kg (OL-S). Olive oil was enriched with safllowerseed oil (OL-S diet) to increase linoleic acid and to decrease palmitic acid concentrations, in order to evaluate whether differences in plasma LDL concentrations were due to intrinsic effects of the specific oil (rapeseed or olive oil) or to differences in the content of specific fatty acids. No differences due to dietary fat source were found in plasma total and HDL-cholesterol levels or in LDL composition. Plasma LDL-cholesterol levels were lower on the C-P diet than the OL diet (P < 0·05) while plasma LDL-cholesterol levels in animals fed on the OL-S diet were not significantly different from either dietary group (P > 0·05). The number of hepatic apo B/E (LDL) receptors was on average 25% higher in animals fed on the C-P diet compared with those fed on diets containing olive oil. Likewise, cardiac muscle lipoprotein lipase (EC 3.1.1.34) activity was significantly higher in the C-P group than in the OL and OL-S dietary groups. Dietary fat source had no effect on hepatic cholesterol levels or 3-hydroxy-3-methylglutaryl (HMG) CoA reductase (EC 1.1.1.34) activity. The results indicate that olive oil and rapeseed oil, both rich sources of monoumaturated fatty acids, differ in their effect on LDL metabolism in the guinea-pig.

An in vitro dialysis method was employed to determine the effect on the Fe and Zn absorption of the type (beef, pork and soyabean) and the amount (10 and 30 g/kg) of protein present. In addition, the effects of low- and high-molecular-weight (LMW and HMW respectively) digestion products were investigated. After in vitro digestion and dialysis a lower percentage of N, Fe and Zn was found in the LMW fractions from beef, pork and soyabean proteins when the protein level was increased from 10 to 30 g/kg; the higher level of protein being associated with a lower percentage of hydrolysed protein. The highest percentage levels of intrinsic Fe were always found in the HMW fractions, independent of the type and the level of proteins studied, while in the case of Zn, both HMW and LMW fractions gave similar values. An interaction was found between inorganic Zn and non-haem-Fe. The addition of inorganic Zn (10 μg/ml) caused a significant decrease in the in vitro availability of Fe from soyabean protein, while it did not affect the dialysability of intrinsic Fe from beef and pork proteins. Our results showed that the type and the level of the protein had a positive effect on the dialysability of extrinsic Fe. We postulate that the effect of a protein on the absorption of extrinsic Fe could be accounted for by free amino acids and/or small peptides released during the digestion process and also by the undigested or partially-digested HMW fractions of hydrolysed proteins which could play a fundamental role in the availability of this essential element.

The human vitamin K requirement is not known precisely, but the minimal requirement is often assumed to be between 0·5 and 1 x 10−6g/kg body weight. In the present study we addressed the question to what extent circulating vitamin K concentrations are influenced by the form in which the vitamer is consumed. The experimental group consisted of five healthy volunteers who received phylloquinone after an overnight fast. On the first day of three successive weeks the participants consumed 1 mg (2·2 µmol) phylloquinone, either in the form of a pharmaceutical preparation (Konakion®), or in the form of spinach + butter, or as spinach without added fat. Circulating phylloquinone levels after spinach with and without butter were substantially lower (7·5- and 24·3-fold respectively) than those after taking the pharmaceutical concentrate. Moreover, the absorption of phylloquinone from the vegetables was 1·5 times slower than from Konakion. In a second experiment in the same five volunteers it was shown that relatively high amounts of menaquinone-4 enter the circulation after the consumption of butter enriched with this vitamer. It is concluded that the bioavailability of membrane-bound phylloquinone is extremely poor and may depend on other food components, notably fat. The bioavailability of dietary vitamin K (phylloquinone+menaquinones) is lower than generally assumed, and depends on the form in which the vitamin is ingested. These new insights may lead to a revision of the recommended daily intake for vitamin K.

The aim of the present study was to determine the gastro-ileal behaviour of pea protein in humans. For this purpose, twelve healthy volunteers were intubated with an intestinal tube located either in the jejunum (n 5) or in the ileum (n 7). After fasting overnight, they ingested 195 mmol N of [15N]pea. Intestinal samples were collected for 6 h in the jejunum and for 8 h in the ileum. Before meal ingestion the basal liquid flow rate (ml/min) was 2·01 (SD 0·31) in the jejunum and 2·02 (SD 0·33) in the ileum. After meal ingestion the liquid phase of the meal peaked in the 40–60 min period in the jejunum and in the 150–180 min period in the ileum. The jejmo-ileal transit time of the liquid phase of the meal was 102 min. The basal flow rate of endogenous N (mmol N/min) was 0·22 (SD 0·15) in the jejunum and 016 (SD 0·10) in the ileum. The endogenous N flow rate peaked significantly ( P < 0·05) in the jejunum in the 40–60 min period whereas no stimulation of endogenous N could be detected in the ileum after meal ingestion. A significantly increased (P < 0·05) concentration of exogenous N was detected in the jejunum during the 20–3u)lnin period and during the 9–480 min period in the iteum. The overall true gastro-ileal absorption of pea N was 894 (SD 1·1)% with 69 (SD 14)% absorbed between the stomach and the proximal jejunum and 20·4% between the proximal jejunum and the terminal ileum. The percentage of ethanol-insoluble fraction (PN) in the exogenous N at the terminal ileum increased significantly ( P < 0·05) to 75% after 360 min. These results suggest that heat-treated pea protein has a digestibility close to that of animal protein

Two experiments were conducted to investigate whether the utilization of lysine in growing pigs is affected by the level of excess protein in the diet. Nine lysine-deficient diets containing 100,200 or 300g crude protein/kg and between 1·2 and 6·8 g ileal digestible lysine/kg were prepared. In the first experiment the apparent ileal digestibility of lysine in three of the nine diets was determined using pigs with simple T-cannulasand Cr2O3, as an indigestible marker. Ileal digestibility of lysine in the other diets was calculated by interpolation. In the second experiment N retention, as a measure of lysine utilization, was determined in all nine diets using growing pigs over the weight range 30–50 kg. The effect of excess protein on lysine utilization was assessed by comparing the regression of N retention v. lysine (ileal digestible) intake at the three levels of protein. Increasing ileal digestible lysine in the diets resulted in a linear increase in N retention with all three protein levels and there was no significant difference amongst the three regressions, indicating that lysine utilization was not affected by the level of protein.Therefore, all data were pooled together to calculate a single regression for all treatments.An increase of 1·0 g ileal digestible lysine led to an increase of 1·43 g N or 8·96 g protein (N x 6·25) retained. Assuming a lysine concentration in the retained body protein of 65–72 mg/g, lysine was utilized with an efficiency of 0·58–0·65

Dietary supplementation with oligofructose (OFS; 100 g/kg), a non-digestibleoligomer of β-D-fructose, decreases serum triacylglycerols in serum and VLDL of rats. In order to investigate the role of hepatic metabolism in the hypolipidaemic effect of OFS, male Wistar rats were fed on a standard diet with or without 1OOg Raftilose® P95/kg as OFS source for 30 d. OFS feeding (1) significantly decreased triacylglycerol and phospholipid concentrations in both blood and liver, (2) increased the glycerol-3-phosphate liver content but decreased the hepatic activity of glycerol-3-phosphate acyltransferase (EC 2.3.1.15), suggesting a decrease in acylglycerol synthesis, (3) did not affect the blood non-caterified fatty acid concentrations, but (4) reduced by 54% the capacity of isolated hepatocytesto synthesize and secrete triacylglycerols from labelled acetate; the activity of fatty acid synthase, a key lipogenic enzyme was also significantly decreased. These findings suggest that OFS decreases serum triacylglycerols by reducing de nova fatty acid synthesis in the liver; the lower insulin level in the serum of OFS-fed rats could explain, at least partly, the metabolic effect induced by such nondigestible carbohydrates.

Changes in splanchnic energy and N metabolism were studied in sheep, prepared with vascular catheters across the portal-drained viscera (PDV) and the Liver, and maintained on supramaintenance intakes of either grass or grass + barley pellets. The animals were challenged, on both diets, with 4 d intra- mesenteric vein infusions of NH4CI (25 µmol/min) plus NH4HCO3 (at either 0 or 125 µmol/min). On the final day of each treatment the natural abundance NH4Cl was replaced with 15NH4Cl over a 10 h infusion while over the same period [l-13C]leucine was infused via a jugular vein. Measurements were made of blood flow plus mass transfers of NH3, urea, free amino acids and O2, across the PDV and liver. Enrichments of [14N15N]urea and [15N15N]urea plus [15N]glutamine, aspartate and glutamate were also monitored. Whole-body urea flux was determined by infusion of [14C]urea. At the end of the study the animals were infused for 3 h with 15NH4CI, killed and liver samples assayed for intracellular free amino acid enrichments and concentrations. Blood flows across the splanchnic region were unaffected by either diet or level of ammonium salt infusion. At the lower ammonium salt infusion there was a trend for greater absorption of NH3 across the PDV (P<0·10) with grass + barley than with the grass diet, while removal of urea was unaltered. At the higher ammonium salt infusions there was a significantly greater appearance of NH, across the PDV and this exceeded the extra infused. Urea-N removal, however, was also elevated and by more than that required to account for the additional NH3. The PDV contributed 19–28% to whole-body O2 consumption and the liver 23–32%. Hepatic extraction of absorbed NH3 was complete on all treatments and systemic pH remained constant. The fractions of urea-N apparently derived from NH3, were similar on the grass (0·59–0·64) and grass + barley (0·64–0·67) diets. Hepatic production of urea agreed well with urea flux measurements. Between the two levels of ammonium salt infusion and within diets the additional NH3 removed across the PDV was accounted for by the increased urea-N production. The [14N15N]: [15N15N] ratio of the urea produced was 97:3, while the enrichment of hepatic intracellular free aspartate was lower than that of [14N15N]urea. Glutamine enrichments were 0·23–0·37 those of [14N15N]urea, indicating a minor role for those hepatocytes (probably perivenous) which contain glutamine synthetase (EC 6.3.1.2). Leucine kinetics, either for the whole body or splanchnic tissues, were not different between diets or level of ammonium salt infusion, except for oxidation which was less on the grassfbarley ration. Amino acid concentrations were lower on the grass + barley diet but net PDV absorptions were similar. The pattern of essential amino acids absorbed into the PDV showed good agreement with the published composition of mixed rumen microbial protein. Fractional disappearances of absorbed free essential amino acids across the liver varied from 0·4 (branched chains) to near unity (histidine, phenylalanine)

The present study tested the influence of protein undernutrition and re-alimentation on mammary gland size and secretory cell activity in lactating rats. During gestation, female Sprague-Dawley rats were offered a high-protein diet (215 g crude protein (N x 625; CP)/kg DM; H); litters were standardized to twelve pups at parturition. During lactation, two diets were offered ad libitum, diet H and a low- protein diet (90 g CP/kg DM; L). Lactational dietary treatments were the supply ad libitum of either diet H (HHH) or diet L (LLL) for the first 12 d of lactation, or diet L transferring to diet H on either day 6 (LHH) or 9 (LLH) of lactation. On days 1, 6, 9 and 12 of lactation, rats from each group (n > 6) were used to estimate mammary dry mass, fat, protein, DNA and RNA; the activities of lactose synthetase (EC 2.4.1.22) enzyme and Na+, K+-ATPase (EC 3.6.1.37) were also measured. Rats offered a diet considered protein sufficient (H) from day 1 of lactation showed a decrease in mammary dry mass and fat but an increase in DNA, RNA and protein on day 6, after which there was no further change, except for mammary protein which continued to increase. However, rats offered diet L showed a steady loss in mammary mass and fat throughout the 12 d lactation period and no change in mammary DNA, RNA or protein. Rats previously protein restricted for either the first 6 or 9 d of lactation had their mammary dry mass and mammary fat loss halted and showed a rapid increase in mammary DNA, RNA and protein on re-alimentation. Lactose production in group HHH, as measured by lactose synthetase activity, was similar on days 1 and 6 of lactation, after which a significant increase was seen. Protein- restricted rats showed no change in lactose synthetase activity during the 12 d experimental period. Changing from diet L to diet H led to a significant increase in lactose synthetase activity to levels comparable with those offered diet H from day 1. These results show that rats offered a protein-restricted diet during lactation suffer mammary underdevelopment, but this may be rapidly reversed by re-alimentation with a high-protein diet

The aim of the present study was to investigate the influence of dietary nucleotides on liver morphology. Adult rats were fed for 21 d on a nucleotide-containing diet or the same diet free of nucleotides. Liver sections were examined by light and transmission electron microscopy, as well as for nucleic acid and protein contents. Morphometric analysis was performed for different variables. Deprivation of dietary nucleotides resulted in a reduction in hepatocyte nuclear and nucleolar areas as well as in nuclear chromatin condensation. In addition, the rough endoplasmic reticulum was reduced, as were ribosome association and abundance, whereas fat accumulated. These findings portray dietary nucleotides as required nutrients for the liver under normal physiological conditions and suggest that an inadequate supply of nucleotides for a certain period of time has transient negative effects on liver ultrastructure and function.

Recent epidemiological studies in people whose birth weights were recorded many years ago suggest links between impaired growth during early life and the development of diseases, including diabetes, much later in life. The long-term effects of retarded early growth are proposed to result from malnutrition at critical periods of fetal or infant development leading to reduction in the growth of organs and permanent changes in their metabolism or structure, or both. In order to investigate this, a rat model was established which involved feeding either a diet containing 200 g protein/kg or an isoenergetic diet containing 80 g protein/kg to pregnant and lactating rats. In addition, cross-fostering techniques were employed which allowed a separate evaluation of the prenatal or the postnatal periods. The offspring were studied at 21 d of age or were weaned onto a normal laboratory chow and studied at 11 months of age. The 80g protein/kg diet during pregnancy did not affect the overall reproductive performance although more subtle differences were evident. Permanent growth retardation was evident in offspring subjected to maternal protein restriction during the postnatal period. At 21 d of age the offspring of protein-restricted mothers exhibited selective changes in organ growth: compared with the body weight, the lung and brain experienced a smaller decrease in weight; the heart, kidney and thymus decreased proportionately; whereas, the pancreas, spleen, muscle and liver showed a greater reduction in weight. In older animals the muscle weight was lower in the male rats and the relative weight ofpancreas was increased in the female rats.

Indian River male broiler chickens growing from 7 to 28 d of age were fed on diets containing 120,210 and 300 g crude protein/kg diet and 0, 1–67 or 16·7 g added tryptophan (TRP)/kg diet. The hypothesis tested was that crude protein levels and TRP would affect both growth and neurotransmitter metabolism. Heart, brain and pancreatic neurotransmitter (noradrenaline (NA), dopamine(DA), serotonin (5-HT) and 5-hydroxy-indole-3-acetic acid (5-HIAA) concentrations were determined by HPLC separation and electrochemical detection. Malate dehydrogenase (2-oxoglntarate decarboxylating) (NADP+) (MDH(NADP+); EC 1.1.1.40), isocitrate dehydrogenase (NADP+) (ICD(NADP+); EC 1.1.1.42) and aspartate aminotransferase (AAT; EC 2.6.1.1) activities were also measured. Supplemental TRP decreased growth and feed intake. Increasing dietary crude protein decreased MDH(NADP+), but increased (ICD(NADP+) and AAT activities. Additional dietary TRP decreased MDH(NADP+) activity, but had no effect on other enzyme activities. Cardiac NA concentrations were directly related to dietary crude protein levels while pancreatic levels were inversely related. An increase in dietary crude protein decreased both brain NA and DA. Supplemental dietary TRP increased both 5- HIAA and 5-HT. Changes in feed intake caused by different levels of botb dietary crude protein and TRP are accompanied by altered levels of neurotransmitters. The present study indicates that much arger amounts of TRP are required to make simultaneous changes in feed intake and neurotransmitters.

Possible changes in the fatty acid composition of dietary fats and oils which might occur during digestion, absorption and formation of chylomicrons and chylomicron remnants were investigated. Chylomicrons were collected from the thoracic duct of rats tube-fed with olive, maize, palm or fish oil or butter fat, and their fatty acid composition was determined and compared with that of their parent lipids. In turn, these lipoproteins were converted to chylomicron remnants infunctionally hepatectomized rats and their composition re-determined. The predominant fatty acids in each of the oils and fats also predominated in their respective chylomicrons, but their proportions were reduced during the processes leading to their formation. Endogenous contributions of linoleic, eicosapentaenoic, and docosahexaenoic acids were particularly noted when these fatty acids were not well-represented in the original oils and fats, suggesting that they may be obligatory constituents in the formation of chylomicrons. The conversion of chylomicrons to remnants further attenuated the extremes in fatty acid composition of the dietary oils and fats. These results indicate that following an acute intake of oil or fat, the resulting chylomicrons and chylomicron remnants presented to the tissues contain a more balanced distribution of saturated, mono-and polyunsaturated fatty acids than the oils and fats from which they were derived.

Retinol-binding protein (RBP) and transthyretin (TTR) in the plasma, liver and kidney, retinol in plasma, and total vitamin A in the liver were measured in rats 6 weeks after diabetes mellitus had been induced by streptozotocin (STZ). The diabetic rats gained 83% less weight despite consuming 45% more feed than the non-diabetic controls. Plasma and kidney concentrations of RBP and TTR were significantly lower in diabetic than in the non-diabetic control rats. Unlike the retinol carrier proteins, plasma albumin concentrations remained unaffected. Plasma concentrations of retino1 were decreased while its hepatic levels increased in the diabeticanimals. The depressed circulatory levels of retinol may reflect an altered metabolism of its transport proteins

Two suggested modes of action of yeast in stimulating rumen fermentation were investigated. The first, that yeast respiratory activity protects anaerobic rumen bacteria from damage by O2, was tested using different strains of yeast that had previously been shown to have differing abilities to increase the viable count of rumen bacteria. Saccharomyces cerevisiae NCYC 240, NCYC 1026, and the commercial product Yea-Sacc®, added to rumen fluid in vitro at 1·3 mg/ml, increased the rate of O2 disappearance by between 46 and 89%. The same three preparations also stimulated bacterial numbers in an in vitro fermenter (Rusitec).S. cerevisiae NCYC 694 and NCYC 1088, which had no influence on the viable count in Rusitec, also had no effect on O2 uptake. Respiration-deficient (RD) mutants of S. cerevisiae NCYC 240 and NCYC 1026 were enriched by repeated culturing in the presence of ethidium bromide. S. cerevisiae NCYC 240 and NCYC 1026 stimulated the total and cellulolytic bacterial populations in Rusitec, while the corresponding RD mutants did not. Rigorous precautions to exclude air from Rusitec resulted i“n S. cevevisiae NCYC 240 no longer stimulating total bacterial numbers, although it still increased numbers of cellulolytic bacteria. The second hypothesis, that yeast provides malic and other dicarboxylic acids which stimulate the growth of some rumen bacteria, was examined by comparing the effects of yeast and malic acid on rumen fermentation in sheep. Three mature sheep were given 0·85 kg barley/d plus 0·55 kg chopped ryegrass hay/d either unsupplemented, or supplemented with 4 g S. cerevisiae NCYC 240/d or 100 mg l-malic acid/d either mixed with the diet or in aqueous solution infused continuously into the rumen. Yeast increased the total viable count of bacteria (P < 0·05)whereas malic acid did not, and no other effect of the treatments reached statistical significance. It was concluded, therefore, that the stimulation of rumen bacteria by S.cerevisiae is at least partly dependent on its respiratory activity, and is not mediated by malic acid.

Boiled coffee contains the lipid compounds cafestol and kahweol, which raise cholesterol strongly in man. These lipids are retained by paper filters. In a search for an animal model for the effect of coffee lipids on serum cholesterol concentrations, we fed hamsters (Mesocvicetus aurutus) and rats on mash diets consisting of a purified base diet and either boiled water, unfiltered boiled coffee or filtered boiled coffee. After a feeding period of 8 weeks there was no statistically significant effect of unfiltered boiled coffee on serum total cholesterol and triacylglycerol concentrations in either the hamsters or the rats. The level of serum cholesterol did respond predictably to the addition of cholesterol and/or saturated fatty acids to the diet. The lack of effect of unfiltered boiled coffee in the hamsters and the rats, when compared with the previously reported activity in humans, could not be explained by dosage, duration of treatment, mode of administration or by insufficient statistical power. It is concluded that hamsters and rats are insensitive to unfiltered boiled coffee and thus are unsuitable models for investigating its hyper- cholesterolaemic effect.