The present study was designed to determine the quantitative effects of starchy meals containing guar gum on rates of net apparent glucose absorption and net apparent insulin and gastric inhibitory polypeptide (GIP) production in growing pigs. The effects of these meals on the viscosity of jejunal digesta were also examined and correlated to changes in glucose absorption. Four growing pigs were each given either a low-fat semi-purified diet (control) or the same diet supplemented with a high-molecularweight par gum at concentrations in the diet of 20 or 40g/kg. Blood samples were removed simultaneously via indwelling catheters from the mesenteric artery and the hepatic portal vein. Samples of jejunal digesta were removed via a T-piece cannula and used immediately for viscosity measurements at 39'. The 'zero-shear' viscosity of each sample was then calculated. Blood-flow measurements were made using an ultrasonic flow probe fitted to the hepatic portal vein. All measurements were made at intervals of 10 or 30 min during a 4 h postprandial period. Meals containing guar gum significantly increased (P < 0.05) the viscosity of jejunal digesta, an effect that was strongly dependent on the concentration of guar gum in the original diet. No significant differences in blood-flow rates were found between the control and guar-containing diets. Both concentrations of guar gum significantly reduced (P < 0.05) glucose absorption and insulin and GIP secretion rates over the 4 h postprandial period. An inverse relationship between the rate of glucose absorption and the 'zero-shear' viscosity of jejunal digesta was found. This study also provides direct evidence for the important role played by the enteroinsular axis in modifying the glycaemic response to a meal containing guar gum.

I . Four pigs initially of 30 kg live weight were surgically prepared with two re-entrant cannulas in the jejunum 1.0 m apart which allowed an isolated loop to be formed through which solutions were perfused. Wr-EDTA was used as a marker for measuring net secretion or absorption.2. A new Ringer solution was made, the ionic content of which resembled more closely that found in the jejunum of pigs given similar diets, than Krebs-Ringer solution.3. The absorption of glucose and water from Krebs-Ringer and new Ringer solutions was compared. 4.The effect of guar gum on the absorption of glucose and water from solutions of glucose and maltose was studied.5. There was a trend (not significant) for greater absorption of glucose and water from the new Ringer solution than from the Krebs-Ringer solution.6. Guar gum significantly reduced the net absorption of glucose from glucose or maltose solutions from 74.2 to 41.4% (P i 0401) and 71.1 to 35.0% (P < 0.001) respectively. 7.Guar gum significantly reduced the net absorption of water from the glucose solution from 42.7 to 8.3% (P < 0.01) and from the maltose solution from 49.2 to 5.1% (P < 0@01).8. The lack of differences between the absorption of glucose from solutions of glucose or maltose suggested that maltase (EC 3.2.1.20) activity was not inhibited to the extent that this limited the rate of glucose absorption.The beneficial effects of guar gum on glucose tolerance in normal (Jenkins et al. 1977) and diabetic (Jenkins et al. 1976) man are well established. The principal effect of adding guar gum to the diet is a decrease in postprandial hyperglycaemia. However, its mode of action remains unclear. Several hypotheses have been proposed to explain its action within the gut. These include a reduced rate of emptying of the stomach, altered motility in the stomach and small intestine, poorer mixing of digesta and enzymes in the gut lumen, slower hydrolysis of dietary components by brush-border enzymes in the small intestine and a reduction in the rate of absorption across the epithelial cell membrane (Low et al.

1. We have investigated the relations between changes in plasma insulin and 3,5,3'-triiodothyronine (T,), and muscle growth and protein turnover in the rat in response to diets of varying protein concentrations.2. Young rats were fed ad lib. on a control (180 g casein/kg) diet or low-protein diets containing 80, 45 and 0 g casein/kg in four separate experiments. Measurements were made of food intakes, muscle and body-weight growth rates, muscle protein turnover in vivo, plasma insulin, and plasma free and total T,.3. The food intakes of the 80 and 45 g casein/kg diet groups were variable, with the 80 g casein/kg diet group consuming either the same or more than the controls, and the 45 g casein/kg diet group consuming less or more than the controls. Body-weight and skeletal-muscle growth rates varied with the protein but not energy intakes, which in turn reflected both dietary composition and the food intake, with the hyperphagic 80 g casein/kg diet group of rats growing almost normally and the 0 g caseinlkg diet group losing body-weight and muscle mass. 4. Changes in rates of muscle growth were accompanied by parallel changes in rates of protein synthesis and degradation, as well as parallel changes in concentrations of plasma insulin and free T,, to the extent that all these variables were highly correlated with each other.5. Partial correlation analysis was used to separate interactions between variables. This indicated that dietary energy had no identifiable influence on muscle growth. In contrast dietary protein appeared to stimulate muscle growth directly by increasing muscle RNA content and inhibiting proteolysis, as well as increasing insulin and free T, levels. Insulin and free T, stimulated each other as well as muscle protein turnover; insulin stimulating the RNA activity particularly at low insulin levels, free T, stimulating the RNA content and both hormones stimulating proteolysis.6 . These apparent relations are shown to be consistent in the main part with previous studies of the mechanism of action of insulin and T,, but the possibility cannot be discounted that other anabolic hormones not measured in these studies are involved, particularly in the apparent direct influence of dietary protein on muscle.

There is strong evidence that the intake of EPA and DHA reduces the risk of adverse cardiac events. Fish and fish oil capsules are not necessarily an ideal source of EPA and DHA for every individual. The aim of the present study was to evaluate the effect of a convenience drink enriched with 500 mg EPA and DHA on then-3 index, a biomarker of EPA and DHA status in an individual. Of the 190 subjects with atherosclerotic disease screened between February and June 2009, 50 were recruited based on ann-3 index < 5 %. Participants were randomly assigned to receive a convenience drink supplemented either withn-3 fatty acids (n40, 200 mg EPA and 300 mg DHA) or placebo (n10, 1·1 g linoleic acid, C18 : 2n-6, from maize oil) daily for 8 weeks. The primary end point was a change in then-3 index. Intention-to-treat analysis was done. After 8 weeks of daily intake of 200 mg EPA+300 mg DHA, the meann-3 index increased from 4·37 (sd0·51) to 6·80 (sd1·45) % (P < 0·001). Interindividual variability in response was high (CV of the Δ,cv = 0·21). The control group showed no change in then-3 index. The results showed that daily intake of a convenience drink supplemented withn-3 fatty acids leads to a significant increase of then-3 index with high interindividual variability in response. Dose and preparation used were safe, well tolerated and highly palatable.

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