The polyamines putrescine, spermidine and spermine are essential for cell renewal and, therefore, are needed to keep the body healthy. It was previously believed that polyamines are synthesized by every cell in the body when required. However, in the present paper evidence is provided to show that, as in the case of the essential amino acids, the diet can supply sufficient amounts of polyamines to support cell renewal and growth. Systematic analysis of different foods was carried out and from the data obtained, the average daily polyamine consumption of British adults was calculated to be in the range 350–500 μmol/person per d. The major sources of putrescine were fruit, cheese and non-green vegetables. All foods contributed similar amounts of spermidine to the diet, although levels were generally higher in green vegetables. Meat was the richest source of spermine. However, only a part of the polyamines supplied by the diet is available for use by the body. Based on experiments with rats it was established that polyamines were readily taken up from the gut lumen, probably by passive diffusion, and were partly metabolized during the process of absorption. More than 80% of the putrescine was converted to other polyamines and non-polyamine metabolites, mostly to amino acids. The enzyme responsible for controlling the bioavailability of putrescine was diamine oxidase (EC 1.4.3.6). For spermidine and spermine, however, about 70–80% of the intragastrically intubated dose remained in the original form. Considering the limitations on bioavailability (metabolism and conversion), the amounts of polyamines supplied by the average daily diet in Britain should satisfy metabolic requirements.

Although subjective appetite scores are widely used, studies on the reproducibility of this method are scarce. In the present study nine healthy, normal weight, young men recorded their subjective appetite sensations before and during 5 h after two different test meals A and B. The subjects tested each meal twice and in randomized order. Visual analogue scale (VAS) scores, 10 cm in length, were used to assess hunger, satiety, fullness, prospective food consumption and palatability of the meals. Plasma glucose and lactate concentrations were determined concomitantly. The repeatability was investigated for fasting values, Δ-mean 5 h and mean 5 h values, Δ-peak/nadir and peak/nadir values. Although the profiles of the postprandial responses were similar, the coefficients of repeatability (CR = 2SD) on the mean differences were large, ranging from 2·86 to 5.24 cm for fasting scores, 1·36 to 1·88 cm for mean scores, 2·98 to 5·42 cm for Δ-mean scores, and 3·16 to 6·44 cm for peak and Δ-peak scores. For palatability ratings the CK values varied more, ranging from 2·38 (taste) to 8·70 cm (aftertaste). Part of the difference in satiety ratings could be explained by the differences in palatability ratings. However, the low reproducibility may also be caused by a conditioned satiation or hunger due to the subjects' prior experience of the meals and therefore not just be a reflection of random noise. It is likely, however, that the variation in appetite ratings is due both to methodological day-to-day variation and to biological day-to-day variation in subjective appetite sensations.

The present paper is an aalysis of 138 5- or 7-d diet diaries collected from a free-living population of people aged 68–90 years in Norwich. Men had higher intakes than women of energy and most nutrients, but patterns of variation across the week were similar for both sexes. Intakes of meat, meat products, fish and vegetables varied across the week both in frequency and amount eaten, but the other main food groups showed no significant variation. Alcohol was taken more frequently at weekends but the amount did not vary significantly. Intakes of energy, protein and many micronutrients varied significantly with day of the week, with increased intake at weekends, especially of vegetable-derived micronutrients on Sundays, and generally decreased intake on Mondays and Fridays. Nutrient densities of carotene, retinol equivalents, folate, vitamin C, pantothenate and Zn Were all highest on Sundays, providing further evidence of variation of diet quality on different days of the week.

The effects of either low (25 μmol/min) or high (235 μmol/min) infusion of NH4Cl into the mesenteric vein for 5 d were determined on O2 consumption plus urea and amino acid transfers across the portal-drained viscera (PDV) and liver of young sheep. Kinetic transfers were followed by use of 15NH4Cl for 10 h on the fifth day with simultaneous infusion of [1-13C]lleucine to monitor amino acid oxidation. Neither PDV nor liver blood flow were affected by the additional NH3 loading, although at the higher rate there was a trend for increased liver O2 consumption. NH3-N extraction by the liver accounted for 64–70% of urea-N synthesis and at the lower infusion rate the additional N required could be more than accounted for by hepatic removal of free amino acids. At the higher rate of NH3 administration additional sources of N were apparently required to account fully for urea synthesis. Protein synthesis rates in the PDV and liver were unaffected by NH3 infusion but both whole-body (P < 0·05) and splanchnic tissue leucine oxidation were elevated at the higher rate of administration. Substantial synthesis of [15N]glutamine occurred across the liver, particularly with the greater NH3 supply, and enrichments exceeded considerably those of glutamate. The [15N]urea synthesized was predominantly as the single labelled, i.e. [14N15N], species. These various kinetic data are compatible with the action of ovine hepatic glutamate dehydrogenase (EC 1.4.1.2) in periportal hepatocytes in the direction favouring glutamate deamination. Glutamate synthesis and uptake is probably confined to the perivenous cells which do not synthesize urea. The implications of NH3 detoxification to the energy and N metabolism of the ruminant are discussed.

Two experiments were carried out to investigate the capacities of pigs for bulky feeds. In Expt 1 fifteen pigs were offered, from 12 to 25 kg live weight, ad lib. access to one of five feeds which were made by progressively diluting a high-quality feed with wheat bran. Intake initially increased, and then declined, as the proportion of wheat bran was increased. The pigs became better able to accommodate to the more bulky feeds over time. In Expt 2 thirty-six pigs, initially of 12 kg live weight, were used. The feeds were the same high-quality basal feed as in Expt 1 and three others made almost entirely of either wheat bran, dried grass or dried citrus pulp, respectively. The equal-parts mixtures of each of these three bulky feeds with the basal feed were also made to give three series of feeds each comprising the basal, the mixture and the bulky feed. The three feeds in each series were given ad lib. to twelve pigs in a design of two replicated Latin squares with three time-periods. Within each series, and across periods, the intakes of the feeds that were limiting intake were directly proportional to live weight and so a scaled intake, expressed as g/kg live weight per d, was calculated. Across the six limiting feeds, scaled intakes in the final 5 d of each period, when the pigs were in equilibrium with their feeds, were directly proportional to the reciprocal of the water-holding capacities (WHC) of the feeds, as measured by a centrifugation method. There were large effects of feed changes on intake, in the short term, with previous experience of a bulky feed leading to higher intakes of another bulky feed. The intake of the basal feed was not affected by the feed given previously. It was concluded that: (a) the time of adaptation to bulky feeds needs to be considered when attempting to measure, or predict, the rates of intake on different bulky feeds and, (b) the WHC of the feeds could be an appropriate measurement of‘bulk’responsible for limiting their intake, and could be used to predict the maximum feed intake capacity of pigs on different bulky feeds.

The objective of the present study was to evaluate effects of condensed tannins in faba beans (Vicia faba L.) on morphological and functional variables of the small-intestinal mucosa of piglets. In an experiment with young piglets (8–17 kg body weight), fed on either a control diet or a diet containing 200 g/kg of low- or high-tannin faba bean hulls (with < 0·10 and 3·3% catechin equivalents of condensed tannins respectively), morphological and functional characteristics of the jejunal mucosa were determined. Results of the study showed that the morphological variables of the mucosa of the three groups of piglets were similar. Also, no changes due to dietary tannins were observed in sucrase (EC 3.2.1.48)–isomaltase (EC 3.2.1.10) activity in homogenates of mucosa plus submucosa. However, aminopeptidase (EC 3.4.11.2) activity in these homogenates in the proximal part of the small intestine of the animals of the group fed on the high-tannin diet was significantly lower than that in the animals fed on the control diet or the diet with low-tannin hulls (P < 0·05).

The effect of long-term dietary protein excess and deficit on whole-body protein-N turnover (WBPNT) was examined in lambs nourished by intragastric infusions of nutrients. Ten sheep were given 500 mg N/kg metabolic weight (W0.75) per d from casein for 2 weeks and then either 50 (L), 500 (M) or 1500 (H) mg N/kgW0.75 per d for 6 weeks. Volatile fatty acids were infused at 500 kJ/kgW0.75 per d. Daily WBPNT was measured by continuous intravenous infusion of [l-13C]leucine 3 d before, and on days 2, 21 and 42 after the alteration in protein intake. Whole-body protein-N synthesis (WBPNS) was calculated as the difference between WBPNT and the protein-N losses as urinary NH3 and urea. Whole-body protein-N degradation (WBPNS) was then estimated from WBPNS minus protein gain determined from N balance. Fractional rates of WBPNS and WBPND were calculated against fleece-free body N content. WBPNS rates at the L, M and H intakes were respectively 35·1, 41·5 amd 6·37 g/d (P < 0.001) on average over the 6 weeks and WBPND rates were 39·5, 41·1 and 56·8 g/d (P < 0.001). The fractional rates of WBPNS were 5·01, 6·37 and 7·73% per d (P < 0.001) while those of WBPND were 5·64, 6·29 and 6·81% per d (P < 0.005) respectively. On days 2, 21 and 42, WBPNS rates at intake H were 54·0, 61·8 and 75·4 g/d (P = 0·03) respectively, and WBPND rates were 43·2, 56·4 and 70·9 g/d (P = 0.03); at intake L the amounts were 38·2, 34·2 and 32·8 g/d for WBPNS (P = 0.003) and for WBPND were 43·4, 38·0 and 36·9 g/d (P = 0·016) respectively. There were no significant (P > 0·05) differences in fractional rates of WBPNS and WBPND with time at either the L or H intake. We concluded that absolute protein turnover was affected both by dietary protein intake and by body condition while the fractional rate of turnover was predominantly influenced by intake.

The present study was undertaken to provide detailed information on the effect of dietary fibre (DF) level on body composition, visceral organ weight, nutrient digestibility and on energy and protein metabolism of rats housed in cold (16°), warm (24°) or hot (32°) thermal environments. High- or low-fibre diets (257 v. 56 g DF/kg dry matter (DM)) were studied in a 6-week balance experiment (initial body weight about 100 g). Heat production was measured using open-air circuit respiration chambers. Pea fibre and pectin were used to adjust the DF level in the high-fibre diet. The ranking order of daily gain of rats kept in different environments was: 24°>16°>32°, while the ranking order for carcass protein was: 16°>24°>32°. Rats on the high-DF diet had a lower daily gain than those on the low DF diet, and more protein in DM of empty body weight (EBW) and less fat. The relative weights (g/kg EBW) of liver, heart and kidney decreased when increasing the environmental temperature. The relative weight of the heart was highest in rats on the high DF level, while liver and kidney weights were unaffected by DF. Per kg EBW, the stomach, small intestine, caecum and colon and the length of colon were significantly greater in rats consuming the high-fibre diet compared with those on the low-fibre diet. Rats kept at low temperature had a significantly heavier gastrointestinal (GI) tract than those kept at the highest temperature. Digestibility of protein, DM and energy was lowest for rats fed on the high-fibre diet. Heat production (HP) of fed rats as well as fasting HP decreased significantly as environmental temperature increased. HP as a proportion of metabolizable energy (ME) was significantly lower for rats at 24° compared with the other environmental temperatures. The proportion of energy retained as protein was slightly higher in rats fed on the high-fibre than on the low-fibre diet. Based on the results of the present study the authors measured a net energy value of 5·4 kJ/g DF fermented; approximately 50% of the DF came from peas. Possible implications of the present findings are discussed.

The present experiment was carried out to study the endogenous losses of purine and pyrimidine derivatives from pregnant sows. Three pregnant and three non-pregnant Large White × Landrace sows were fed on a purine-free diet composed of starch, glucose, sucrose and vegetable oil, with casein as the protein source. The experiment began, for the six animals, after diagnosis of pregnancy and was divided into six 12 d periods. Urine was collected during the first 3 d of each experimental period by means of a urethral catheter for determination of allantoin, uric acid, xanthine, hypoxanthine and pseudouridine concentrations. In the absence of dietary nucleic acids (N A), allantoin and, as a consequence, excretion of total purine derivatives (PD) decreased significantly to a constant value (128·3 (se 7·07) μmol/kg metabolic live weight (W0·7) per d), an amount assumed to represent endogenous excretion. Excretion of uric acid (38·7 (SE 2·15) μmol/kg W0·75 per d), hypoxanthine (21·0 (SE 2·58) μmol/kg W0·75 per d) and xanthine (11·2 (SE 0·83) μmol/kg W0·75 per d) were not affected by the experimental treatment, although there was a significant decrease in hypoxanthine excretion in pregnant sows (from 25·5 to 5·2 μmol/kg W0·75 per d) compared with non-pregnant sows (from 26·7 to 44·8 μmol/kg W0·75 per d). Creatinine excretion was not affected by pregnancy and was used as an internal urinary marker. Purine excretion, either expressed as μmol/kg W0·75 per d or as the ratio PD:creatinine, was not affected by experimental treatment, although an apparent increase in pseudouridine excretion, a modified unsalvageable catabolite of RNA-pyrimidine, was found in late pregnancy (3·6 ν 52 mol/100 mol creatinine in on-pregnant sows compared with pregnant sows at 102 d collection).

Results from analysis of 24 h urine collections, verified for completeness with para-amino benzoic acid, and blood samples collected over 1 year were compared with 16 d weighed records of all food consumed collected over the year, and with results from 24 h recalls, food-frequency questionnaires and estimated food records in 160 women. Using the weighed records, individuals were sorted into quintiles of the distribution of the urine N excretion: dietary N intake ratio (UN:DN). UN exceeded DN in the top quintile of this ratio; mean ratio UN:DN = 1·13 Individuals in this top quintile were heavier, had significantly greater body mass indices, were reportedly more restrained eaters, had significantly lower energy intake:basal metabolic rate ratios (EI:BMR), and had correlated ratios of UN:DN and EI:BMR (r - 0·62). Those in the top quintile reported lower intakes of energy and energy-yielding nutrients, Ca, fats, cakes, breakfast cereals, milk and sugars than individuals in the other quintiles but not lower intakes of non-starch polysaccharides, vitamin C, vegetables, potatoes or meat. Correlations between dietary intake from weighed records and 24 h urine K were 0·74 and 0·82, and between dietary vitamin C and β-carotene and plasma vitamin C and β-carotene 0·86 and 0·48. Correlations between dietary N intake from weighed records and 24 h urine excretion were high (0·78–0·87). Those between N from estimated food records and urine N were r 0·60–0·70. Correlations between urine N and 24 h recalls and food-frequency questionnaires were in the order of 0·01 to 0·5. Despite problems of underreporting in overweight individuals in 20% of this sample, weighed records remained the most accurate method of dietary assessment, and only an estimated 7 d diary was able to approach this accuracy.

The ability of β-carotene to protect against oxidative stress in vitro was assessed. Primary cultures of chicken embryo fibroblasts (CEF) were oxidatively stressed by exposure to paraquat (PQ). Activities of the antioxidant enzymes superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6) and glutathione peroxidase (GSH-Px; EC 1.11.1.9) were measured as indices of oxidative stress. CEF incubated with 0·25 mM-PQ for 18 h exhibited increased SOD and CAT activities and decreased GSH-Px activity compared with the control (P < 0·001). Incorporation of added β-carotene (0·1 μM) into 0·25 mM-PQ-treated CEF returned SOD activity to that seen in non-PQ-treated cells. β-Carotene (0·1 μM) reduced the CAT activity from that seen in PQ-treated cells and returned the GSH-Px activity to its control value thus protecting the cells against PQ-induced oxidative stress. However, at higher concentrations of β-carotene (10 μM), SOD and CAT activities increased significantly (P < 0·001) relative to non-PQ-treated cells and GSH-Px activity decreased relative to its control value. Similar trends were observed when CEF grown in β-carotene-enricbed media (0·1–10μM) were oxidatively stressed by exposure to 0·25 mM-PQ for 18 h.β-Carotene: Chicken embryo fibroblasts: Oxidative stress Antioxidant enzymes

It is well established that marine n-3 fatty acids measured in erythrocyte phospholipids of non-pregnant subjects reflect the subjects intake of these fatty acids. In 135 pregnant women in the 30th week of gestation we compared intake of marine n-3 fatty acids and energy, estimated by a combined dietary self-administered questionnaire and interview, with fatty acids measured in erythrocyte phospholipids. Daily intake (g/d) and nutrient density of marine n-3 fatty acids (mg/MJ) correlated with the n-3 fatty acid: arachidonic acid ratio (FA-ratio) with correlation coefficients of 0·48 and 0·54 respectively. In a linear regression model with three frequency questions about marine sandwiches, marine cooked meals and fish oil as explanatory variables, and the FA-ratio as dependent variable, the multiple correlation coefficient was 0·46. Conclusions from the study were (1) levels of erythrocyte fatty acids in pregnant women may be employed as a qualitative method to rank subjects according to intake of marine n-3 fatty acids; (2) with respect to the power to explain FA-ratio variability, three simple marine food frequency questions were comparable with intake of marine n-3 fatty acids assessed by an elaborate semiquantitative dietary method involving an interview.

Novel methodology is described for the estimation of food intake in the particularly difficult circumstance where groups of people eat directly from a shared bowl of cooked food. Detailed observation and measurement of meal preparation is combined with food table values for composition to calculate the nutrient content of each meal. The distribution of food between individuals is estimated by a suitable algorithm. The ability of the algorithm to identify seasonal changes in energy intakes is demonstrated by comparison of the calculated energy intakes with values for the total energy expenditure of free-living adult male subjects, as measured by the stable isotope, doubly-labelled water technique. This comparison suggests that the energy intake calculated from detailed observation of two cooked meals per day is equivalent to approximately 80% of the total energy expenditure and, by inference, total dietary energy intake. The remaining energy intake may well be derived from uncooked ‘snack foods’, such as raw fruit and vegetables, or from cooked food obtained, by purchase or as a gift, away from the home. This is the first description of a successful method for the estimation of food intake when people eat directly from shared bowls of food.

The effect of a probiotic composed of Bacillus, Lactobacillus, Streptococcus, Saccharomyces and Candida species (each at 107–8 colony-forming units (cfu)/g rice bran), given at a level of 150 g/kg diet for 6 weeks, on lipid metabolism was examined in the faeces, serum and liver of male rats. Liver weight decreased 35% in the rats fed on a high-fat, high-cholesterol diet containing the probiotic. Total cholesterol concentration in the serum was significantly lower in the probiotic group than in the control group throughout the experimental period in rats fed on the high-fat, high-cholesterol diet, and HDL-cholesterol concentration was significantly higher (P < 0·05) in the probiotic group than in the control group which was fed for the 6 week experimental period on a basal diet. The serum VLDL + IDL + LDL cholesterol concentrations in the probiotic groups were reduced compared with those of the corresponding control groups. The probiotic groups fed on the high-fat, high-cholesterol diet and the basal diet had lower hepatic cholesterol concentrations than did the corresponding control groups (P < 0·05). Hydroxymethylglutaryl coenzyme A reductase (NADPH) (EC. 1.1.1.34) activity in the liver was lower in rats fed on the high-fat, high-cholesterol diet with the probiotic. The neutral and acidic steroid concentrations in faeces were higher in the probiotic group than in the control group fed on the high-fat, high-cholesterol diet. Escherichia coli decreased and Bifidobacterium and Eubacterium increased in the faecal microflora of rats fed on the dietary probiotic. Lactobacillus in the probiotic groups was higher than that in the control groups. The present study shows that the probiotic promotes Bifidobacterium and Eubacterium in the faecal microflora, and reduces cholesterol levels in the serum and liver of rats.

Four non-lactating, rumen-fistulated cows were fed ad lib. on two grass silages (first cut (FC) and second cut (SC)) harvested at different growth stages, resulting in different crude-protein (CP) and neutral-detergent-fibre (NDF) contents (FC, 152 g CP/kg, 515g NDF/kg and SC, 210 g CP/kg, 442 g NDF/kg). Voluntary intake and rumen contents, total as well as organic matter were higher for silage FC. Fractional passage rate from the rumen, calculated from the logarithmic decline in Cr-NDF rumen pool, was higher for silage FC (0·0395/h and 0·0446/h for silages SC and FC respectively). When fractional passage rates from the rumen were calculated by dividing the intake of indigestible organic matter by the mean rumen poo! of this fraction, the same differences between silages were found, although the actual levels were much lower (0·0258$sol;h and 0·0300/h for silages SC and FC respectively). The results from the present experiment suggest that disappearance rate from the rumen of particles with a size between 1·25 and 0·071 mm is the rate-limiting step in the control of rumen fill.

Adaptation of energy metabolism to undernutrition and to the duration of undernutrition was studied in adult, non-pregnant, non-lactating ewes at the whole-animal, portal-drained viscera, liver and hindquarters levels. Arterio-venous and indirect calorimetry techniques were used. Animals were successively fed at 1 times (3 weeks) and at 0.5 times (7 weeks) their metabolizable energy requirements for maintenance (MEm). Portal, hepatic and hindquarters blood flows in quietly standing ewes decreased by 22, 19 and 11% respectively within the first week of undernutrition and remained at that level thereafter. Standardizing hindquarters blood flow to that in a given posture (quietly standing) reduced blood flow by 9.8%. In the portal-drained viscera and liver, O2 extraction rates decreased, leading to 34 and 38% drops in O2 consumption with underfeeding respectively. In the hindquarters, O2 extraction rate increased, partly counterbalancing the drop in blood flow. Thus O2 consumption of hindquarters tended to decrease but the effect was not significant. All changes appeared to be completed from day 5 of underfeeding. Consequently, the portal-drained viscera, liver and carcass were responsible for 39, 32 and 5% respectively of the drop in whole-animal O2 consumption with underfeeding. At the end of the 0.5 X MEm period, in vivo metabolic rates averaged 1.65, 4.89 and 0.38 mmol O2 consumed/d per g fresh weight of adipose-tissue-free portal-drained viscera, liver and boneless hindquarters respectively. Undernutrition imposed a much greater nutritional challenge to splanchnic tissues than to hindquarters. The former reduced theirenergy expnditure whereas hindquarters metabolism adapted by counteracting the slight drop in nutrient supply.

The body weight and feed intake of rats fed on a Zn-deficient diet for 28 d were reduced compared with those of control rats. The feed intakes of the Zn-deficient and control groups during the period were 10·2 (SE 0·3) and 15·7 (SE 0·2) g/d respectively. Cyclic variations in feed intake and body-weight changes were found in analysis not only of all the data for five rats but also that in each individual rat. Cosinor analysis revealed that the cyclical period of both the feed intake and body-weight change in the Zn-deficient rats was 3·5 (SE 0·1) d. The mesor and amplitude value of the feed intake in the Zn-deficient rats was 10 1 (SE 0·4) g/d and 3·5 (SE 0·5) g/d respectively, and that of body-weight change was 1·4 (SE 0·1) g/d and 7·9 (SE 1·3) gObihiro d respectively. Among pyrimidine-catabolizing enzymes, dihydropyrimidinase (EC3.5.2.2) activity showed significantretardation in the Zn-deficient rat liver with decrease of the enzyme protein. The ratio of apo-form to holo-form dihydropyrimidinase in the liver was not affected by the Zn-deficient diet.

The effects of NH3 and amines on grass-silage intake, intake behaviour and rumen characteristics were studied in sheep. From a single sward, two direct-cut grass silages were prepared, either untreated (WAS) or with 4·51 formic acid/tonne (FAS). Four experimental diets: WAS, FAS, FAS with addition of 2·9 g NH3/kg DM (FAS + N) and FAS with 2·8 g amines/kg DM (FAS + A), were offered ad lib. once daily to four rumen-cannulated wethers in a 4 × 4 Latin square design. Daily DM intake (DMI) tended to be influenced by dietary treatment (P = 0·09). Compared with FAS, DMI was lower for WAS. Addition of NH3 did not alter DMI, whereas amine addition slightly lowered daily DMI. Reduced DMI resulted from lower intake rates during both the principal meal and the subsequent small meals. Lower initial intake rate during the principal meal suggested reduced palatability of WAS and FAS + A. Amines and NH3, however, did not influence chewing efficiency. No treatment effects were observed on total rumen pool size, DM and neutral-detergent fibre content. Furthermore, NH3, and amines did not alter rumen pH, NH3, and volatile fatty acid concentrations to the extent that they could act on chemostatic intake regulation. Amine addition, however, lowered osmolality of the rumen liquid. No treatment effects on rumen motility were observed. In conclusion, daily DMI was not reduced by the addition of NH3, suggesting that NH3per se is not the causal factor in the negative correlations between silage NH3 content and intake observed by other authors. Amines, however, tended to reduce DMI only by their effect at the oro-pharyngeal level of intake control.

Orlistat, a selective inhibitor of gastrointestinal lipases, was used to investigate triacylglycerol absorption. Using mice and a variety of emulsified dietary lipids we found that the absorption of radiolabelled tripalmitin (containing the fatty acid 16:0), but not of triolein (18: 1n−9) or tri-γ-linolenin (18:3n−6), was incomplete from meals rich in esterified palmitate. Further, the absorption of radiolabelled tri-γ-linolenin, from both saturated and unsaturated dietary triacylglycerols, was 1·3- to 2-fold more potently inhibited by orlistat than that of triolein and tripalmitin. These radiolabelled triacylglycerols, which have the same fatty acid in all three positions, may not always be accurate markers of the absorption of dietary triacylglycerols. Orlistat was more effective at inhibiting the absorption of radiolabelled triacylglycerols with which it was codissolved than those added separately, which indicates that equilibration between lipid phases in the stomach may not always be complete. The saturation of the dietary lipid had little or no effect on the potency of orlistat. Orlistat provides a novel approach for studying the role of triacylglycerol hydrolysis in the overall process of triacylglycerol absorption.

Energy expenditure, and therefore energy requirement, generally decreases with advancing age because of a decrease in basal metabolic rate (BMR) and physical activity. The aim of the present study was to measure total energy expenditure (EE) and activity level in a group of healthy elderly (sixteen men aged 71·3 (SD 4·9) years; ten women aged 67·6 (SD 4·1) years) and young adults (nineteen men aged 30·4 (SD 5·0) years; ten women aged 27·2 (SD 3·9) years) by using the doubly-labelled water method in combination with measurements of BMR. Age-related differences in body composition and their relationship to BMR and activity level were studied. EE was lower in elderly compared with young adults, partly due to a significantly lower BMR. The lower BMR was not fully explained by the lower fat-free mass (FFM) in the elderly. Energy expended (MJ/d) on activity was higher for the younger subjects although there was no significant difference in the physical activity index (PAI = EE/BMR) between the two age groups. The effect of physical activity level is twofold: first it has a positive effect on the BMR, and second it has a positive effect on the FFM. Both effects involve an increase in the total EE with an increased level of physical activity. At energy balance this will lead to increased energy and nutrient intake, making especially the elderly less vulnerable to inadequate energy and nutrient intake.