A cross-sectional study of 132 adults attending an HIV clinic in Cape Town, South Africa, was conducted to determine predictors of low plasma vitamin A and Zn levels. No patients were on antiretroviral therapy. The possible confounding effect of the acute-phase response was controlled by including C-reactive protein levels in multivariate analysis and by excluding active opportunistic infections. Retinol levels were low (<1·05 μmol/l) in 39 % of patients with early disease (WHO clinical stages I and II) compared with 48 and 79 % of patients with WHO stage III and IV respectively (P<0·01). Plasma Zn levels were low (<10·7 μmol/l) in 20 % of patients with early disease v. 36 and 45 % with stage III and IV disease respectively (P<0·05). C-reactive protein levels were normal in 63 % of subjects. Weak, positive associations were found between CD4+ lymphocyte count and plasma levels of retinol (r 0·27; 95 % CI 0·1, 0·43) and Zn (r 0·31; 95 % CI 0·25, 0·46). Multivariate analysis showed the following independent predictors of low retinol levels: WHO stage IV (odds ratio 3·4; 95 % CI 2·1, 5·7) and body weight (odds ratio per 5 kg decrease 1·15; 95 % CI, 1·08, 1·25), while only body weight was significantly associated with low Zn levels (OR per 5 kg decrease 1·19; 95 % CI 1·09, 1·30). CD4+ lymphocyte count <200/μl was not significantly associated with either low retinol or Zn levels. In resource-poor settings, simple clinical features (advanced disease and/or weight loss) are associated with lowered blood concentrations of vitamin A and/or Zn. The clinical significance of low plasma retinol and/or Zn levels is unclear and more research is required to establish the role of multiple micronutrient intervention strategies in HIV disease.

Elucidating the role of carbohydrate quality in human nutrition requires a greater understanding of how the physico-chemical characteristics of foods relate to their physiological properties. It was hypothesised that rapidly available glucose (RAG) and slowly available glucose (SAG), in vitro measures describing the rate of glucose release from foods, are the main determinants of glycaemic index (GI) and insulinaemic index (II) for cereal products. Twenty-three products (five breakfast cereals, six bakery products and crackers, and twelve biscuits) had their GI and II values determined, and were characterised by their fat, protein, starch and sugar contents, with the carbohydrate fraction further divided into total fructose, RAG, SAG and resistant starch. Relationships between these characteristics and GI and II values were investigated by regression analysis. The cereal products had a range of GI (28–93) and II (61–115) values, which were positively correlated (r2 0·22, P<0·001). The biscuit group, which had the highest SAG content (8·6 (sd 3·7) g per portion) due to the presence of ungelatinised starch, was found to have the lowest GI value (51 (sd 14)). There was no significant association between GI and either starch or sugar, while RAG was positively (r2 0·54, P<0·001) and SAG was negatively (r2 0·63, P<0·001) correlated with GI. Fat was correlated with GI (r2 0·52, P<0·001), and combined SAG and fat accounted for 73·1 % of the variance in GI, with SAG as the dominant variable. RAG and protein together contributed equally in accounting for 45·0 % of the variance in II. In conclusion, the GI and II values of the cereal products investigated can be explained by the RAG and SAG contents. A high SAG content identifies low-GI foods that are rich in slowly released carbohydrates for which health benefits have been proposed.

There has been much recent interest in the cardiovascular benefits of dietary isoflavones. The aim of the present in vitro studies was to investigate potential anti-thrombogenic and anti-atherogenic effects of the isoflavones genistein and daidzein in platelets, macrophages and endothelial cells. Pre-treatment with either isoflavone inhibited collagen-induced platelet aggregation in a dose-dependent manner. In a macrophage cell line (RAW 264·7) activated with interferon γ plus lipopolysaccharide, both isoflavones were found to inhibit NO production and tumour necrosis factor α (TNF-α) secretion dose-dependently, but they did not affect mRNA levels for inducible nitric oxide synthase and cyclo-oxygenase-2. Both isoflavones also dose-dependently decreased monocyte chemoattractant protein-1 secretion induced by TNF-α in human umbilical vein endothelial cells. Compared with daidzein, genistein exerted greater inhibitory effects for all parameters studied. The present data contributes to our knowledge on the molecular mechanisms by which isoflavones may protect against coronary artery disease. Further studies are required to determine whether the effects of isoflavones observed in the current in vitro studies are relevant to the aetiology of coronary artery disease in vivo.

The growth rate of the young pig is generally much less than its potential and may be constrained by endocrine status as well as nutrient intake. The aim of the present study was to determine whether porcine (p) somatotropin (ST) treatment of the sucking pig could alter subsequent body composition. Twelve mixed-parity cross-bred sows with an average litter size of ten piglets were used to nurse pigs for the present study. On day 1 of lactation, the median two male pigs (by weight) from each litter were randomly allocated to one of two doses of pST (0 or 1 mg/kg per d) until weaning on day 21. Pigs were weaned and offered feed ad libitum until slaughter at 134 d of age. Body composition was measured using dual-energy X-ray absorptiometry (DXA) at 21, 49, 77, 105 and 133 d of age. There was no significant difference in growth rates between day 1 and 21 of lactation in pigs injected with either saline (9 g/l NaCl/l) or pST (258 v. 246 g/d for control and pST-treated pigs respectively, P=0·61), and as a consequence there was no significant difference in liveweight at weaning (7·13 v. 6·84 kg, P=0·59). However, fat mass at weaning tended to be decreased (1·18 v. 0·96 kg, P=0·064), while the % fat in the body at weaning was significantly (16·7 v. 13·9 %, P=0·008) decreased by exogenous pST treatment. In the immediate post-weaning period there was a reduction in lean tissue deposition (347 v. 300 g/d, P=0·021) but no effect on fat deposition (35 v. 33 g/d, P=0·72). Over the entire weaning-to-slaughter period, pST treatment of neonatal pigs decreased the rate of fat deposition (130 v. 112 g/d, P=0·033), but had no effect on lean tissue deposition (550 v. 538 g/d, P=0·49). Therefore, treatment of nursing pigs with high doses of pST for a short period before weaning may provide a means of reducing the fat content of pork and pork products.

Low n-3 polyunsaturated fatty acid (PUFA) status may be associated with neuro-degenerative disorders, in particular Alzheimer's disease, which has been associated with poor dietary fish or n-3 PUFA intake, and low docosahexaenoic acid (DHA) status. The present case–control study used an established biomarker of n-3 PUFA intake (serum cholesteryl ester-fatty acid composition) to determine n-3 PUFA status in patients with Alzheimer's disease, who were free-living in the community. All cases fulfilled the National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer's Disease and Related Disorders Association criteria for Alzheimer's disease. Detailed neuropsychological testing and neuroimaging established the diagnosis in all cases. The subjects (119 females and twenty-nine males) aged 76·5 (SD 6·6) YEARS HAD A CLINICAL DEMENTIA RATING (CDR) OF 1 (sd 0·62) and a mini mental state examination (MMSE) score of 19·5 (sd 4·8). The control subjects (thirty-six females and nine males) aged 70 (sd 6·0) years were not cognitively impaired (defined as MMSE score <24): they had a mean MMSE score of 28·9 (sd 1·1). Serum cholesteryl ester-eicosapentaenoic acid and DHA levels were significantly lower (P<0·05 and P<0·001 respectively) in all MMSE score quartiles of patients with Alzheimer's disease compared with control values. Serum cholesteryl ester-DHA levels were progressively reduced with severity of clinical dementia. DHA levels did not differ in patients with Alzheimer's disease across age quartiles: all were consistently lower than in control subjects. Step-wise multiple regression analysis showed that cholesteryl ester-DHA and total saturated fatty acid levels were the important determinants of MMSE score and CDR. It remains to be determined whether low DHA status in Alzheimer's disease is a casual factor in the pathogenesis and progression of Alzheimer's disease.

Thirty female Large White × Landrace pigs (average weight 57·2 (SD 1·9) kg) were allocated to one of six dietary treatments containing 0, 1·25, 2·5, 5·0, 7·5 or 10·0 g 55 % conjugated linoleic acids (CLA) isomers (CLA-55)/kg diet and fed for 8 weeks. Each pig was scanned at 0, 28 and 56 d and again at post slaughter using dual-energy X-ray absorptiometry (DXA) to determine the temporal pattern of body composition responses. Values determined by DXA were adjusted using regression equations generated from validation experiments between chemically and DXA-predicted values. Overall, there was a significant linear reduction in fat content with the increasing levels of CLA in the diet (P=0·007, P=0·011, P=0·008 at week 4, week 8 and for the carcass, respectively). The greatest improvement was recorded at the early stages of CLA supplementation and for the highest dose of CLA (week 4, −19·2 % compared with week 8, −13·7 %). In the first 4 weeks of feeding CLA, pigs receiving 10 g CLA-55/kg diet deposited 93 g less fat/d than pigs fed basal diets (P=0·002) compared with only 6 g less fat than control animals in the final 4 weeks. Lean content and lean deposition rate were maximised at 5 and 2·5 g CLA-55/kg diet for the first 4 weeks (P=0·016) and the final 4 weeks of treatment (P=0·17), respectively. DXA estimates of bone mineral content and bone mineral density were not affected by CLA supplementation throughout the experiment. These data demonstrate that dietary CLA decreases body fat in a dose-dependent manner and that the response is greatest over the initial 4 weeks of treatment.

Three series of experiments were conducted with fast-growing chickens in order: to evaluate the effects of dietary Ca and P on cholecalciferol metabolism and expression; to determine dietary Ca requirements; to determine dietary P requirements. The results of the first series confirmed previous results on the effects of dietary Ca and P on some variables of vitamin D metabolism and expression, Ca homeostasis and P metabolism in the young chicken (1- to 21-d-old), and extended them to older birds (22- to 43-d-old). The bone formation rate and the duodenal calbindin content were maintained at high levels until the age of 43 d. Dietary Ca or P restriction increased duodenal calbindin and decreased bone ash in both 22- and 43-d-old chickens, but the effect on bone ash was less pronounced in the 43-d-old birds than in the younger ones. These results suggest that: (a) the capabilities for adaptation to dietary Ca and P restriction remain high during the whole growing period; (b) the growing broilers express a high adaptive capability even when the diet contains the recommended Ca and P contents. The results of the second and third series of experiments suggest that: (c) unlike the Ca requirements of the 1- to 22-d-old chick, P requirements for growth and bone ash are similar, and are as high in the older chicks as in the younger ones (7·4–8·3 g P/kg or 4·8–5·7 g non-phytate P/kg diet); (d) although growth and bone ash in the 29- to 43-d-old chickens appear to be less sensitive to dietary Ca content, within a range close to the calculated P requirement, 10 g Ca/kg diet appears to be required for best tibia mineralization, and to a lesser extent for better growth at this age.

We have compared lipoprotein metabolism in, and susceptibility to atherosclerosis of, two strains of male Golden Syrian hamster, the Bio F1B hybrid and the dominant spot normal inbred (DSNI) strain. When fed a normal low-fat diet containing approximately 40 g fat and 0·3 g cholestero/g, triacylglycerol-rich lipoprotein (chylomicron+VLDL) and HDL-cholesterol were significantly higher (P<0·001) in Bio F1B hamsters than DSNI hamsters. When this diet was supplemented with 150 g coconut oil and either 0·5 or 5·0 g cholestero/g, significant differences were seen in response. In particular, the high-cholesterol diet produced significantly greater increases in plasma cholesterol and triacylglycerol in the Bio F1B compared with the DSNI animals (P=0·002 and P<0·001 for cholesterol and triacylglycerol, respectively). This was particularly dramatic in non-fasting animals, suggesting an accumulation of chylomicrons. In a second experiment, animals were fed 150 g coconut oi/g and 5·0 g cholestero/g for 6 and 12 months. Again, the Bio F1B animals showed dramatic increases in plasma cholesterol and triacylglycerol, and this was confirmed as primarily due to a rise in chylomicron concentration. Post-heparin lipoprotein lipase activity was significantly reduced (P<0·001) in the Bio F1B compared with the DSNI animals at 6 months, and virtually absent at 12 months. Bio F1B animals were also shown to develop significantly more (P<0·001) atherosclerosis. These results indicate that, in the Bio F1B hybrid hamster, cholesterol feeding reduces lipoprotein lipase activity, thereby causing the accumulation of chylomicrons that may be associated with their increased susceptibility to atherosclerosis.

Phyto-oestrogens are dietary components found in some plants, which act in vivo like weak oestrogens. They may reduce the risk of some degenerative diseases moderated by oestrogen, including breast cancer and osteoporosis. The most widely studied are the isoflavones genistein and daidzein from soyabeans, but lignans may be more prevalent in the European diet. Soya foods have traditionally been consumed in the Orient for millennia, and are now widely available to European consumers. Levels of isoflavone in soyabeans from published literature vary between 560 and 3810 mg/kg, depending on variety and growing conditions. Soya protein concentrates and isolates derived from soyabeans contain 466–615 mg isoflavones/kg. Traditional soya milk, bean curds, bean sprouts, etc. contain 13 to 2030 mg isoflavone/kg, depending on the starting raw material and final water content. Fermented foods have a different isoflavone conjugate profile, which may be important in absorption and metabolism. Soya analogues of European foods include dairy and meat products, which contain 38 to 3000 mg total isoflavones/kg, depending the source of soya and dilution with other ingredients. A wide range of foods contain low levels of soya-derived isoflavones, but such foods do not make a significant contribution to mean intakes in Europe. Flaxseed is by far the richest source of lignan precursors. However, foods such as cereal brans, legumes and some vegetables are a more important source in the diets of Europeans because they are more widely consumed. For similar reasons, compared with soya isoflavones, lignans may be a more important source of phyto-oestrogens in the diets of Europeans.

Caseinophosphopeptides (CPP) were detected for the first time in ileostomy fluid, collected at 2 h intervals for 10 h post milk and CPP ingestion, from human volunteers with an ileostomy. The level of CPP present in ileostomy fluid obtained from milk-fed volunteers was markedly higher than that from volunteers fed with selected CPP preparations. The findings are based on HPLC analysis in combination with peptide-bound P determination, thin-layer electrophoresis and amino acid analysis, together with ELISA studies using polyclonal antibodies raised against a set of CPP to detect immunoreactive CPP in ileostomy fluid. These procedures allowed the detection of nm concentrations of CPP. CPP, which can be released during intestinal digestion, may function as bioactive constituents and carriers for different minerals, especially Ca, and may be used as ingredients in functional foods or pharmaceutical preparations.

Dietary vitamin A as retinyl ester is hydrolysed and re-esterified with long-chain fatty acids in the small intestine. The esterified vitamin A is subsequently stored in the liver, where it is hydrolysed to free retinol to be transported by carrier proteins to the target tissue. A decreased availability of retinol carrier proteins has been suggested to be responsible for affecting metabolic availability of vitamin A in type 1 diabetes. Using BB Wistar rats, the present study was undertaken to examine whether the presence of a hyperglycaemic state modifies retinyl ester hydrolase (REH) activity in the intestine and the liver. At the onset of diabetes, hepatic REH enzymatic activity was significantly (P<0·05) decreased. However, REH activity remained unaffected in the small intestine, including both ileum and jejunum. Diabetes also resulted in decreased plasma and liver concentrations of retinol. An in vitro study was conducted to examine the effect of diabetes on the intestinal uptake of retinyl palmitate. Jejunum and ileum from diabetic and non-diabetic BB rats were incubated with labelled retinyl palmitate at different concentrations ranging from 32 to 256 nmol/l. The uptake of retinyl palmitate was increased in both diabetic and non-diabetic rats together with the increase of substrate concentration. However, no significant difference was observed in the uptake of retinyl palmitate between diabetic and non-diabetic rats. These present results suggest that the depressed hepatic REH activities may contribute to the diabetes-associated metabolic derangement of vitamin A.

It is not known if the ruminant animal gastrointestinal tract (GIT) can oxidise essential amino acids (AA) other than leucine. Therefore, the oxidation of four essential AA (leucine, lysine, methionine and phenylalanine), supplied systemically as labelled 1-13C forms, was monitored across the mesenteric-drained viscera (MDV; small intestine) and portal-drained viscera (PDV; total GIT), as part of a 4×4 Latin square design, in four wether sheep (35–45 kg) fed at 1·4 × maintenance. Oxidation was assessed primarily by appearance of 13CO2, corrected for sequestration of [13C]bicarbonate. The GIT contributed 25 % (P<0·001) and 10 % (P<0·05) towards whole-body AA oxidation for leucine and methionine respectively. This reduced net appearance across the PDV by 23 and 11 % respectively. The contribution of MDV metabolism to total PDV oxidation was 40 % for leucine and 60 % for methionine. There was no catabolism of systemic lysine or phenylalanine across the GIT. Production and exchange of secondary metabolites (e.g. 4-methyl-2-oxo-pentanoate, homocysteine, 2-aminoadipate) across the GIT was also limited. Less AA appeared across the PDV than MDV (P<0·001), indicative of use by tissues such as the forestomach, large intestine, spleen and pancreas. The PDV: MDV net appearance ratios varied (P<0·001) between AA, e.g. phenylalanine (0·81), lysine (0·71), methionine (0·67), leucine (0·56), histidine (0·71), threonine (0·63) and tryptophan (0·48). These differences probably reflect incomplete re-absorption of endogenous secretions and, together with the varied oxidative losses measured, will alter the pattern of AA net supply to the rest of the animal.

The objective of the present experiment was to examine the effect of substituting different quantities of soyabean protein for casein on renal function and lipid metabolism in rats with chronic renal failure induced by a five-sixths nephrectomy. Experimental animals were subjected to a nephrectomy and fed either casein or soyabean protein (200 or 100 g/kg diet). The diets were isoenergetic with identical fat, Na, K and P contents. Rats ingesting 200 g casein/kg diet showed a significantly (P<0·05) accelerated course of chronic renal failure, while the soyabean-protein groups showed retarded progression of the experimentally induced renal disease and hypercholesterolaemic effects. Rats in the low-soyabean-protein diet (100 g/kg) also demonstrated increased serum albumin and decreased serum triacylglycerol, total cholesterol concentrations and blood urea-N; however, the low-casein diet significantly (P<0·05) increased serum triacylglycerol. Results of the present study show that the replacement of casein by soyabean protein was related to the rate of progression of renal failure and improvement in lipid profiles in serum of five-sixths nephrectomized rats.

Acetyl-CoA carboxylase (ACoAC) catalyses the carboxylation of acetyl-CoA into malonyl-CoA. This product plays a pivotal role in the regulation of energy metabolism since it is both a substrate for fatty acid synthesis and an inhibitor of the oxidative pathway. The present study was initiated to analyse the modulation of ACoAC activity in liver and selected extrahepatic tissues of rainbow trout (Oncorhynchus mykiss) by dietary changes as a contribution to the understanding of the nutritional control of lipid metabolism in fish. Short-term effects of food intake were studied by measuring ACoAC activity in the liver and dorsal white muscle at different time intervals after a meal. Only slight variations were observed in the muscle during the period 2–72 h after the meal. The long-term effects of an increase in dietary lipids or carbohydrates levels were examined by measuring ACoAC activity in the liver, adipose tissue, intestine, kidney, red muscle, dorsal and ventral white muscles of trout after 3 months of feeding with different diets. ACoAC activity is stimulated by a high-digestible starch diet in the abdominal adipose tissue and the white muscle. A high-lipid diet decreases ACoAC activity in the liver and the intestine, but not in other tissues. Contrary to mammals, a rapid adaptation of ACoAC activity to food supply is not effective in rainbow trout. However, a long-term nutritional control of ACoAC activity does occur in this species, but the target tissue differs with the predominant non-protein energy sources in the diet. The present results suggest the potential existence of two ACoAC isoforms with different tissue distribution as has been observed in mammals and birds.

Using reverse-phase HPLC after pyridylamination, we quantified the concentrations of major neutral oligosaccharides in the milk of sixteen Japanese women collected at 4, 10, 30 and 100 d postpartum. In colostrum and mature milk (30 d lactation), lacto-N-fucopentaose (LNFP) I was the most abundant oligosaccharide, followed by 2′-fucosyllactose (2′-FL) + lacto-N-difucotetraose (LNDFT), LNFP II + lacto-N-difucohexaose II (LNDFH II), and 3-fucosyllactose (3-FL). Together these accounted for 73 % of the total weight of neutral oligosaccharides in colostrum and mature milk. Changes in concentration occurred during the course of lactation. LNFP I and 2′-FL + LNDFT increased from 4 to 10 d postpartum, and then declined by 100 d. LNFP II + LNDFH II steadily increased during the first 30 d and then declined. In contrast, 3-FL increased steadily throughout the entire 100 d of study. Large differences were observed between our data and previously published data in Italian women, in terms of both the concentration and temporal changes of each oligosaccharide. These differences may be caused by different assay methodology, although racial differences cannot be ruled out.

The term phyto-oestrogen encompasses isoflavone compounds, such as genistein and daidzein, found predominantly in soya products and the lignans, such as matairesinol and secoisolariciresinol, found in many fruits, cereals and in flaxseed. There is evidence that they have potential health benefits in man particularly against hormone-dependent diseases such as breast and prostate cancers and osteoporosis. This has led to intense interest in their absorption and biotransformation in man. The metabolism of isoflavones and lignans in animals and man is complex and involves both mammalian and gut microbial processes. Isoflavones are present predominantly as glucosides in most commercially available soya products; there is evidence that they are not absorbed in this form and that their bioavailability requires initial hydrolysis of the sugar moiety by intestinal β-glucosidases. After absorption, phyto-oestrogens are reconjugated predominantly to glucuronic acid and to a lesser degree to sulphuric acid. Only a small portion of the free aglycone has been detected in blood, demonstrating that the rate of conjugation is high. There is extensive further metabolism of isoflavones (to equol and O-desmethylangolensin) and lignans (to enterodiol and enterolactone) by gut bacteria. In human subjects, even those on controlled diets, there is large interindividual variation in the metabolism of isoflavones and lignans, particularly in the production of the gut bacterial metabolite equol (from daidzein). Factors influencing absorption and metabolism of phyto-oestrogens include diet and gut microflora.

A whole-body radioassay procedure was used to assess the retention and apparent absorption by rats of Cd in kernels of durum wheat (Triticum turgidum L. var. durum) harvested from plants grown hydroponically in 109Cd-labelled nutrient solution. Wholegrain wheat, containing 5 μmol Cd (570 μg)/kg dry weight labelled intrinsically with 109Cd, was incorporated into test meals fed to rats that had been maintained on diets containing marginally adequate, adequate or surplus levels of Zn (0·12 mmol (8 mg), 0·43 mmol (28 mg) or 1·55 mmol (101 mg) Zn/kg respectively), and either 0 or 50 g durum wheat/kg. Regardless of diet, all rats consumed about 99 % of the test meal offered. In rats fed diets without wheat, initial Cd absorption averaged 7·7, 4·6 and 2·4 % of the dose when the diet contained 0·12 mmol (8 mg), 0·43 mmol (28 mg) or 1·55 mmol (101 mg) Zn/kg diet respectively. In rats fed wheat-containing diets, initial Cd absorption averaged 3·8 and 2·6 % of the dose when dietary Zn concentration was 0·12 mmol (8 mg) and 0·43 mmol (28 mg)/kg diet respectively. The amount of Cd retained in the body at 15 d postprandial was <2 % of the dose in all rats, and decreased as Zn in the diet increased. Even at 15 d postprandial, 32 to 44 % of the Cd retained in the body was still in the gastrointestinal tract. The results show that: (1) the bioavailability to rats of Cd in wholegrain durum wheat was depressed when wholegrain wheat was part of the regular diet; (2) increased intake of dietary Zn lowered Cd absorption and retention; (3) retention of Cd in the body at 15 d postprandial from diets containing adequate Zn was <1·3 %.

Protein, generally agreed to be the most satiating macronutrient, may differ in its effects on appetite depending on the protein source and variation in digestion and absorption. We investigated the effects of two milk protein types, casein and whey, on food intake and subjective ratings of hunger and fullness, and on postprandial metabolite and gastrointestinal hormone responses. Two studies were undertaken. The first study showed that energy intake from a buffet meal ad libitum was significantly less 90 min after a 1700 kJ liquid preload containing 48 g whey, compared with an equivalent casein preload (P<0·05). In the second study, the same whey preload led to a 28 % increase in postprandial plasma amino acid concentrations over 3 h compared with casein (incremental area under the curve (iAUC), P<0·05). Plasma cholecystokinin (CCK) was increased by 60 % (iAUC, P<0·005), glucagon-like peptide (GLP)-1 by 65 % (iAUC, P<0·05) and glucose-dependent insulinotropic polypeptide by 36 % (iAUC, P<0·01) following the whey preload compared with the casein. Gastric emptying was influenced by protein type as evidenced by differing plasma paracetamol profiles with the two preloads. Greater subjective satiety followed the whey test meal (P<0·05). These results implicate post-absorptive increases in plasma amino acids together with both CCK and GLP-1 as potential mediators of the increased satiety response to whey and emphasise the importance of considering the impact of protein type on the appetite response to a mixed meal.

The decline of Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska appears to have been associated with a switch of diet from one dominated by fatty forage fishes (such as herring; Clupea pallasi) to one dominated by low-fat fish (such as pollock; Theragra chalcogramma). Observations made during the decline include reduced body size of sea lions, low pregnancy rates, and high mortality. We used the general mammalian model, the laboratory rat (Rattus norvegicus), to test whether changing the quality of prey consumed could cause changes in size and reproductive performance. Five groups of twelve female, weanling rats were fed diets composed of herring (H), pollock (P), pollock supplemented with herring oil (PH), pollock supplemented with pollock oil (PP), or a semi-purified diet (ICN). Mean body weights were greatest for H, followed by PH, P, PP and finally ICN, although ICN was the only group significantly different from the others (P<0·05). Food intakes before mating were 10 % higher for groups on the lower-fat diets (P and ICN), resulting in similar energy intakes in all groups. The protein efficiency ratio was highest for the H diet, slightly lower for all pollock diets, and significantly lower for ICN (P<0·05). The fetal weights for mothers fed P were significantly reduced (P<0·05). The present study shows that the energy content was a major limiting factor in the nutritional quality of pollock. When food intake was adjusted to meet energetic requirements, there were no detrimental consequences from eating pollock. However, supplementation of pollock meal with additional pollock oil may reduce growth and reproductive performance, although the reasons for this were not apparent.

The aim of the present study was to investigate the potential nutritional and metabolic impact of trans (t) fatty acids (FA) on an appropriate experimental dietary model. Since previously reported experimental designs have been matter of concern, we developed a dietary model to compare the effect of t isomers and/or the saturation of FA independently of other variables. Wistar rats were fed diets containing identical amounts of nutrients and high levels of dietary fats (200 g/kg) for 30 d. Dietary fat rich in t-FA was compared with fat rich in saturated (s) FA or rich in cis (c) FA, maintaining the same length of C chain of the FA. The fats were obtained through isomerization or hydrogenation of the c-FA present in the control fat. Apparent fat absorption, energy efficiency and triacylglycerol levels in serum and liver were different in rats fed t-FA or s-FA than c-FA. The apparent fat absorption was (%): s-FA 85·7 (SD 3·4)<T-FA 93·1 (sd 0·4)<c-FA 96·7 (sd 1·1) (P<0·05). The efficiency of energy utilization was lower in t-FA (11·7 %) and s-FA (18·5 %) diets, reaching statistical significance only between s-FA and c-FA. A striking finding was the change in the lipid profile in serum and liver. Serum and hepatic triacylglycerol levels were greater for t-FA and s-FA diets than in c-FA; however, the increases on serum triacylglycerol concentrations were greater with the s-FA diet and the increases on hepatic triacylglycerol content were greater with t-FA. Knowledge of the t-FA effects on this kind of experimental dietary model could contribute to determine the potential risk of t-FA intake for man.