Although theoretically all glycoprotein sugars can be derived from glucose, it may be hypothesized that specific dietary sugars could be preferential substrates for glycoprotein synthesis. To test this hypothesis, groups of rats received either continuously (continuous-labelling experiment) or for a single nutritional period (pulse-labelling experiment) a 13C-rich diet containing either maize starch or artificially labelled [13C]glucose. Some groups of rats were also provided during a single nutritional period with low amounts (20–200 mg/animal) of low-13C dietary sugars (mannose, galactose, fucose or fructose). If specific dietary sugars were preferentially incorporated into glycoproteins instead nf glucose-derived labelled sugars, a decrease would be expected in the intestinal or serum glycoprotein-sugar 13C enrichment monitored by gas chromatography-isotope-ratio mass spectrometry (GC-IRMS). Contrary to this hypothesis the results showed no significant decrease with any of the specific dietary sugars. Furthermore, with dietary low-13C mannose or galactose, a significant increase in 13C enrichment of glycoprotein-sugars was observed compared with some other nutritional groups. Moreover, in the pulse-labelling experiment, dietary mannose and galactose induced similar patterns of 13C enrichment in intestinal and serum glycoprotein-sugars. Therefore, although specific dietary sugars do not appear to be preferential substrates for glycosylation under conditions and doses relevant to current concepts of nutrition, regulatory roles of some specific dietary sugars in relation to glycoprotein-sugar metabolism might be hypothesized. These findings could lead to similar studies using stable-isotope methodology in man which could have practical consequences, especially in parenteral nutrition where glucose is the only sugar provided to the metabolism.

Leucocytes from subjects from 0 to 80 years old were separated into mononuclear and granulocyte fractions and the retinoids and retinoid-binding fractions were examined. Both leucocyte ractions were found to contain retinol, retinoic acid and an additional retinoid; retinoic acid Comprised 40% of retinoids in some samples. The protein fractions containing retinoids included a 200 k Da protein and several 14–18 k Da proteins. Plasma concentrations of retinol changed little with increasing age. In contrast, leucocyte concentrations of retinoids and retinoid-binding proteins increased quadratically with age. However, in granulocytes from young children retinoids were almost undetectable.

The primary aim of the present study was to expand the glycaemic index (GI) database by determining the GI and insulin index values of thirty-nine foods containing sugars in healthy adults. The second aim was to examine the hypothesis that glycaemic and insulin responses to foods which contain added sugar(s) are higher than responses to foods containing naturally-occurring sugars. Eight healthy subjects drawn from a pool of eighteen consumed 50 g carbohydrate portions (except 25 g carbohydrate portions for fruits) of the test foods. The GI and insulin index were determined according to standardized methodology and expressed on a scale on which glucose = 100. The median GI and insulin index values of all foods tested were 56 (range 14 to 80) and 56 (range 24 to 124) respectively. The median GI of the foods containing added sugars was similar to that of foods containing naturally-occurring sugars (58 v. 53 respectively, P = 0·08). Likewise, the median insulin index of the foods containing added sugars was not significantly different from that of foods containing naturally-occurring sugars (61 v. 56 respectively, P = 0·16). There was no evidence of‘rebound hypoglycaemia’or excessive insulin secretion relative to the glucose response. We conclude that most foods containing sugars do not have a high GI. In addition, there is often no difference in responses between foods containing added sugars and those containing naturally-occurring sugars.

Experimental sepsis in rats induces a restriction in spontaneous food intake and a drop in liver glutathione, cytochrome P-450 (P-450) and aminopyrine demethylase (AD) activity. The present study was designed to assess the effects of antibiotics alone or when combined with food deprivation on these variables. Eighty-nine male Sprague-Dawley rats were assigned to six groups: control (C), acute infection (experimental pyelonephritis, I), acute infection with antibiotics and food given ad lib. (IA), control with antibiotics (CA), acute infection with antibiotics pair-fed to I (IAR), and sham-operated pair-fed to I (SR). Liver glutathione, P-450 and AD activities were reduced by 45·2, 79·8 and 41·2% respectively in group I. Glutathione and AD significantly increased only in those infected rats given antibiotics and allowed free access to food. P-450 did not normalize within the study period in infected rats receiving antibiotics and food repletion. The risk of drug hepatotoxicity in acute septic states is therefore closely related to the nutritional status. From this point of view, nutritional support is almost as important as treatment of infection.

Three castrated male Holstein cattle (423 (SD 19) kg live weight) fitted with elevated carotid artery, portal, and mesenteric venous catheters, and abomasal and ileal cannulas were used to study small-intestinal starch digestion. The cattle were infused abomasally with water (275 ml/h), glucose (66 g/h), maize dextrin (66 g/h) or maize starch (66 g/h) in an incomplete Latin square design, with eight infusion periods. Infusion with carbohydrate resulted in higher arterial glucose concentrations and greater net portal glucose flux than when cattle were infused with water. Arterial glucose concentration and net portal glucose flux were highest when glucose was infused. In the small intestine, 85% of abomasally infused glucose, 78% of infused dextrin, and 66% of infused starch disappeared. Of the carbohydrate that disappeared in the small intestine, that which could be accounted for as net portal glucose flux was 73% for glucose, 60% for dextrin, and 57% for starch. Ileal digesta contained unpolymerized glucose, and short-chain soluble α-glucoside. Of the infused dextrin flowing past the ileum (14 g/h), 0·3 g/h was glucose, 6·2 g/h was soluble α-glucoside, and 7·5 g/h was insoluble α-glucoside. Of the infused starch flowing at the ileum (22·2 g/h), 0-9 g/h was glucose, 5·3 g/h was soluble α-glucoside, and 15·9 g/h was insoluble α-glucoside. The average chain lengths of the soluble α-glucosides in ileal digesta were 2·07 and 2·36 for dextrin and starch infusions respectively, indicating mostly di- and to a lesser extent trisaccharides. We conclude that (1) when 66 g raw starch is presented to the small intestine per h, about half of the intestinal disappearance appears as glucose in the portal vasculature, and (2) α-1,4 glucosidase (EC 3.2.1.20) activity at the brush border is the rate-limiting step to small-intestinal starch digestion in cattle.

The effects of oat saponins (a mixture of avenacosides A and B) on plasma and liver lipids in gerbils (Meriones unguiculatus) and rats were investigated. Cholesterol-containing diets high in total and saturated fat and with different avenacoside contents (zero (ethanol-extracted oats), normal (oats) and twice normal (ethanol-extracted oats plus added avenacosides)) were used. Compared with a cellulose control group the oat diets in both species gave a significantly higher cholesterol content in the HDL fraction and a significantly lower liver cholesterol content. No significant differences in total plasma cholesterol, HDL-cholesterol and plasma triacylglycerols were found, however, between the groups fed on oats with different avenacoside content. The liver weight, total liver cholesterol and free liver cholesterol were also similar, whereas the liver lipid content was significantly lower in rats given the highest amount of avenacosides compared with zero or normal amounts. The tendency was the same in gerbils. Thus, the oat saponins had only minor effects on lipid metabolism in gerbils and rats.

Male Wistar rats were meal-fed on diets containing various amounts of resistant starch in the form of raw starch (either amylomaize starch, potato starch or modified high-amylose starch) or retrograded starch (prepared from each of the starches) for 6 weeks. Two diets containing normal maize starch were fed as diets poor in resistant starch. Energy absorption (energy consumption minus faecal energy loss), growth, weight of the epididymal fat pads, serum total cholesterol and triacylglycerol concentrations and a number of intestinal and faecal variables were determined. The resistant starches affected all the variables determined except the serum total cholesterol concentration. Relationships were found between energy absorption and both growth and the weight of the fat pads, and between the weight of the fat pads and both the serum triacylglycerol concentration and the serum total cholesterol concentration. No clear differences between the effects of ihe two types of resistant starch (raw starch ν. retrograded starch) were found except that raw potato starch hardly stimulated H2 excretion and led to lower amounts of propionic and butyric acids in the caecal contents than the other starches. The results suggest that dietary resistant starch reduces energy absorption leading to less abdominal depot fat and lower serum triacylglycerol concentrations.

The present study was designed to investigate teh relationship between smoking and antioxidant nutriennt intake and status. Smoker (n44) and non-smoker (n 44) male students attending Dhake University, aged between 22 and 28 years and living in a University Hall of Residence, were selected for the present study. Mean age, body weigh, BMI and blood pressure were similer for both the smokers and non-smokers. Mean energy, protein and fat intakes were similar for both groups. Smokers had lower intakes of dietary viamin C, carotenes and Zn but only the difference in Zn intake was statistically significant. There was no significant difference between smokers and non-smokers for either serum vitamin A (retinol) or vitamin E (α-tocopherol) level. The plasma vitamin C level of smokers was significantly lower than that of non-smokers (P = 0·004). Smokers had significantly lower serum Cu (P = 0·04) and higher seum Zn levels (P = 0·003). Further, a significant dose-response relationship between and vitamin C status was observed. Linear-regression analysis showed a significantly positive correlation between dietary intake and plasma vitamin C values in non-smokers (r 0·50; P = 0·0005). On the country, no such association was observed in smokers. These findings suggest that smoking may cause an imbalance in antioxidant nutrient intake and status.

Department of Occupational and Environmental Medicine, University of Lund, Lund, Sweden In Sweden fish is considered to be an important source of dietary Se. Therefore Se status was assessed in forty-one middle-aged men with widely varying fish consumption. Glutathione peroxidase (EC 1·11·1·9) and selenoprotein P in plasma were measured by radioimmunoassay. Plasma Se among the men increased slightly with increasing consumption of fish, but no such increases in the concentrations of glutathione peroxidase and selenoprotein P in plasma were observed. Moreover, no correlation was found between plasma Se and glutathione peroxidase or selenoprotein P. Instead, glutathione peroxidase was significantly correlated with selenoprotein P (r 0·73, P <0·001), indicating that both glutathione peroxidase and selenoprotein P were functional indicators of Se status in this group. The proportion of plasma Se located in glutathione peroxidase decreased with increasing plasma Se. The results suggest that the Se consumed from fish had no apparent effect on the amount of Se incorporated into the functional selenoproteins of plasma. It is concluded that in some cases selenoproteins may be better biological markers of Se status than the total concentration of Se.

Various tannin-complexing agentsw have been used to study the potential adverse effects of tannis on rumen metabolism. Using a method based on turbidity formation, the binding of various tannin-complexing agents (polyvinyl polypyrrolidone (PVPP), polyethylene glycol (PEG) of molecular weights 2000 to 35000, and polyvinyl pyrrolidone (PVP) of molecular weight 10000, 40000 and 360000) to tannins (tannic acid, purified tannins from quebracho (Aspidosperma quebracho) and leaves of trees and shrubs (Acioa barteri, Dichostachys cinerea, Guiera senegalensis, Piliostigma reticulatum)) was investigated at different pH values. The binding of all the tannins with PVPP was highest at pH 3–4 and lowest at pH 7. For all the pH range (3–7) studied, the binding of PEG was higher than that of PVP. For all the tannins except tannic acid, the binding to PVP was the same from pH 4·7 to 7. Similar results were observed for the PEG of molecular weight 6000 or higher for all the tannins except quebracho tannins for which the binding increased as the pH increased from 3 to 7. The binding with PEG 2000 decreased to a greater extent as the pH reached near neutral and for PEG 4000 this decrease was slightly lower. Addition of these tannin-complexing agents to the in vitro gas system resulted in higher gas production from tannin-rich feeds (increase varied from 0 to 135%). The PEG were the most effective followed by PVP and PVPP. The PEG 35000 was least effective. The efficiency of other PEG was similar. The PEG 6000 was preferred to PEG 2000 or 4000 as its binding to tannins was higher at near neutral pH values. The gas production increased with an increase in the amount of PEG 6000 up to 0·6 g/40 ml rumen-fluid-containing medium containing 0·5 g tannin-rich feed, beyond which no increase was observed. The percentage increase in gas value at 24 h fermentation correlated significantly with tannin values, the highest correlation (r 0·95) being with protein precipitation capacity of tannins. The increase in gas production was associated with higher production of short-chain fatty acids with little change in their molar proportions, suggesting an increase in organic matter digestibility by inclusion of the PEG in tannin-rich feeds. However, apparent and true digestibilities were lower on addition of the PEG, due to the presence of PEG-tannin complexes in the residues. The use of this bioassay (percentage increase in gas production in the presence of PEG 6000) along with other tannin assays would provide a better insight into the nutritional significance of tannins.

The exact mechanisms by which non-starch polysaccharides increase stool output are unknown. In the present study the hypothesis that the site of fermentation and short-chain fatty acid (SCFA) accumulation is related to the action of non-starch polysaccharides (NSP) on stool output was tested. The basal diet (45 g NSP/kg) of forty-three male Wistar rats was supplemented with 50 g/kg of either guar, karaya, tragacanth, gellan, xanthan or ispaghula for 28 d. A further twenty-three rats were maintained on the basal diet for the same time period. Faeces were then collected over 2 d and caecal contents obtained post-mortem. Caecal and faecal wet and dry weights and SCFA were measured. Each supplement had a different effect on the caecal and faecal contents but they appeared to fall into three groups when compared with the basal diet. In group 1, guar gum affected only caecal SCFA. It had no effect on stool output or faecal SCFA. In group 2, karaya increased caecal SCFA and tragacanth, karaya and xanthan increased faecal SCFA and faecal water. In group 3, ispaghula and gellan had no consistent effect on caecal or faecal SCFA concentrations but increased Total faecal SCFA output and increased faecal wet and dry weight. Although the knowledge that SCFA are rapidly absorbed in the large intestine has led us to believe that they play no role in determining faecal output, these results suggest that in some cases where NSP are slowly fermented, and increase faecal SCFA, the role of the SCFA may need to be reassessed.

The digestion of freeze-dried green banana flour in the upper gut was studied by an intubation technique in six healthy subjects over a 14 h period. Of α-glucans ingested, 83.7 % reached the terminal ileum but were almost totally fermented in the colon. Structural study of the resistant fraction showed that a small part of the α-glucans which escaped digestion in the small intestine was composed of oligosaccharides from starch hydrolysis, whereas the rest was insoluble starch in granule form with physical characteristics similar to those of raw banana starch. Passage through the small intestine altered granule structure by increasing susceptibility to further α-amylase hydrolysis. Compared with resistant starch values in vivo, those obtained with the in vitro methods tested were inadequate to estimate the whole fraction of starch reaching the terminal ileum.

Urinary Mg is suggested to be an effective inhibitor of the formation and growth of calcium oxalate stones. In order to examine the influence of variations in dietary Mg on urinary Mg excretion, ten healthy male subjects were kept on two different standard diets for 5 d each. In the course of the test period, 24 h urine samples were collected. Diets 1 and 2 were calculated according to the dietary recommendations of the German Society of Nutrition (Deutsche Gesellschaft für Ernährung, 1986). Diet 1 was established as a model of a balanced mixed diet, whereas diet 2 represented an ovo-lacto-vegetarian meal plan. Diets 1 and 2 were isoenergetic with equal amounts of the main nutrients, estimated from food tables, and a constant fluid intake. In contrast to the content of Mg (336 mg) and dietary fibre (28 g) of diet 1, diet 2 was rich in Mg (553 mg) and dietary fibre (52 g). On the ingestion of diet 1, renal Mg excretion was 5·09 (SEM 0·35) mmol on the control day and increased slightly but not significantly to 5·40 (SEM 0·52) mmol on the corresponding day on diet 2. Urinary Mg excretion as a percentage of estimated dietary intake was about double on the balanced mixed diet (37%) than on the Mg-rich vegetarian diet (24%). As both diets contained equal amounts of most nutrients, these results indicate a lower excretion rate of Mg from the vegetarian diet than from the mixed diet. This would appear to be primarily due to the higher Mg and fibre contents and to the lower Mg utilization, that are important factors in decreasing Mg absorption and consequently urinary excretion rate.

Activities of twelve hydrolytic enzymes in the digestive tract of young rabbits before weaning (4 weeks old) and adult rabbits (3 months old) were measured. The principal digestive enzymes in both groups of rabbits appeared to be amylase (EC 3.2.1.1), maltase (EC 3.2.1.20), pectinase (EC 3.2.1.15) and proteinases. The stomach of young rabbits contained most of the lipolytic activity and 45.7 % of the total proteolytic activity of the digestive tract. The highest specific activities (per g digesta) of amylase, maltase and proteinase in young rabbits were found in the small intestine. Total activities (per segment) of amylase and maltase in the small intestine and the caecum were similar. Activities of cellulase (EC 3.2.1.4), inulinase (EC 3.2.1.7) and β-glucosidase (EC 3.2.1.21) were low and activity of pectinase was fairly high in all segments of the digestive tract. The highest activity of urease (EC 3.5.1.5) was found in the caecum. Enzymic profiles of the colonic chymus resembled those of the caecum. Total hydrolytic activity was lower in the colon than in the caecum. Specific activities of amylase and invertase (EC 3.2.1.26) were lower and those of inulinase and lactase (EC 3.2.1.23) higher in 4-week-old rabbits than in 3-month-old rabbits. Gastric proteinase represented almost half of the total proteolytic activity of the digestive tract, whereas lipolytic activity of gastric contents was not found in measurable quantities in adult rabbits. The caecal contents of adult rabbits contained most of the total activity of lipase (EC 3.1.1.3), cellulase, xylanase (EC 3.2.1.32), pectinase, lactase, invertase, β-glucosidase and urease present in the digestive tract. The presence of microbial enzymes (pectinase, cellulase, xylanase, inulinase and urease) in non-fermentative segments of the digestive tract reflects the reingestion of caecal contents during coprophagy.

The effect of changes in dietary Na+ intake on plasma aldosterone levels and electrogenic amiloride-sensitive Na+ transport (Iamil) was studied in the rat distal colon. Five groups of rats were fed on diets containing different amounts of Na+. Estimated Na+ intake ranged from about 400–80000 ?equiv Na+ /kg body weight (BW) per d. Both variables investigated, Iamil and plasma aldosterone, depended non-linearly on Na+ intake. Reduction of the daily Na+ intake increased plasma aldosterone levels and if these levels reached the value 200 pg/ml or more then Iamil was induced. The corresponding Na+ intake was 1300 ?equiv Na+/kg BW per d. Iamil was not observed at lower aldosterone levels and higher Na+ intakes. Aldosterone infusion for 7 d produced similar changes in Iamil compared with dietary Na+-depleted animals and made the estimation of maximum transport capacity of Iamil possible. We conclude that Iamil operates only if Na+ intake decreases below minimal Na+ requirement in growing rats and that the maximum transport capacity of this pathway is reached only after very severe Na+ deprivation.

In chicks, immature pullets and laying hens, the inhibition of gastric acid secretion by omeprazole, an H+,K+-transporting ATPase (EC 3.6.1.36) inhibitor, greatly increased proventricular and gizzard pH values. Consequently, gizzard soluble Ca concentration deceased and the insoluble Ca fraction increased. Inhibition of acid secretion increased duodenal pH values in immature pullets and laying hens but not in chicks. Duodenal soluble and ionic Ca concentrations were lowered by gastric acid inhibition in chicks and to a larger extent in immature pullets and laying hens. The use of Ca of coarse particle size increased the gizzard insoluble Ca fraction in chicks and pullets. However, it did not influence its soluble Ca fraction in chicks but tended to reinforce the negative effect of omeprazole on soluble Ca in the gizzard and duodenum of chicks and laying hens. Coarse particles of Ca led to an increase in gizzard and duodenal soluble Ca at the end of eggshell calcification in laying hens. An enhancement in the level of Ca in the diet from 10 to 36 g/kg increased gizzard soluble Ca and duodenal soluble and ionic Ca concentrations in immature and adult hens. Intestinal Ca retention and bone mineralization was unaffected by gastric acid inhibition in chicks but were largely diminished by the use of coarse particles of Ca. Gastric acid inhibition was associated in laying hens with decreased Ca retention to a small extent and with reduced eggshell quality. These observations confirm that gastric acid secretion is of importance for CaCO, solubilization but question its role as a prerequisite for intestinal Ca retention in chicks and even in hens fed on a high Ca diet.

The effects of the trace lipids (Ll and L2) extracted from two kinds of whey-mineral complex on bone metabolism were studied in young ovariectomized (OW) rats. The concentrations of oestradiol in the L1 and L2 oils were 305 and 1313 pg/ml respectively, wbile the concentrations of progesterone were 34.3 and 36.9 ng/ml respectively. Trace amounts of lα, 25dibydroxycbolecalciferol (lα29(0H)2D) were detected: 56 pg/ml in the L1 oil and 132 pg/ml in the L2 oil. The OVX rats were orally given 0.4 ml each test oil twice weekly. Other animals were given with only a vehicle (control) or an oil mixture with similar levels of oestradiol and progesterone to those in L2 oil (PE oil) for comparison. The Ca absorption rate, bone density of the humerus and femoral Ca content in the rats given L2 were significantly higher than those in the control rats (P < 0.05). Serum calcitonin and lα,25-(OH)2D from rats given L2 were both sigdicantly higher than those from the control rats, while serum progesterone in the L2 group was slightly lower. It is suggested that the bone metabolism of rats given L2 reflected the compound effect of 1,2yOH), D and oestradiol in the L2 oil. In contrast, the relatively low level of these hormones might have been associated with the mediacre bone cbarocteriStcs of the L1 group. It is suggested from these results that the trace level of hormones could be one of the reasons why wbey-mineral complex showed good Ca availability.

Female Wistar rats were weaned onto a diet deficient in riboflavin and compared with weight-matched and ad lib.-fed controls. The effects of riboflavin deficiency on villus morphometry and enterocyte number on the villi in the upper small intestine were studied. Riboflavin depletion was associated with increased villus length and a proportional increase in the number of cell positions along the villi. The total DNA, RNA and protein contents in the intestinal mucosa were not significantly different between any of the groups. Villus hypertrophy in the absence of increased cell number in the small intestine suggests that villus number may be reduced in riboflavin deficiency. Riboflavin deficiency did not influence the number of mucus-producing goblet cells or the amount of mucosal glycoprotein in the small intestine. Impaired production of mucus appeared not to be involved in the structural and functional changes seen in riboflavin deficiency.