The effect of the nature and form of supply of dietary lipids on larval development was investigated in European sea bass larvae, by considering the expression of several genes involved in morphogenesis. Fish were fed from 7 to 37 d post-hatch with five isoproteic and isolipidic compound diets incorporating different levels of EPA and DHA provided by phospholipid or neutral lipid. Phospholipid fraction containing 1·1 % (PL1 diet) to 2·3 % (PL3 diet) of EPA and DHA sustained good larval growth and survival, with low vertebral and cephalic deformities. Similar levels of EPA and DHA provided by the neutral lipid fraction were teratogenic and lethal. Nevertheless, dietary phospholipids containing high levels of DHA and EPA (PL5 diet) induced cephalic (8·5 %) and vertebral column deformities (35·3 %) adversely affecting fish growth and survival; moreover, a down-regulation of retinoid X receptor α (RXRα), retinoic acid receptor α, retinoic acid receptor γ and bone morphogenetic protein-4 genes was also noted in PL5 dietary group at day 16. High levels of dietary PUFA in neutral lipid (NL3 diet) first up-regulated the expression of RXRα at day 16 and then down-regulated most of the studied genes at day 23, leading to skeletal abnormalities and death of the larvae. A moderate level of PUFA in neutral lipids up-regulated genes only at day 16, inducing a lesser negative effect on growth, survival and malformation rate than the NL3 group. These results showed that retinoid pathways can be influenced by dietary lipids leading to skeletal malformation during sea bass larvae development.

It has previously been demonstrated that soya protein, which contains isoflavones and low methionine–glycine and lysine–arginine ratios, has a hypocholesterolaemic effect. In the present study, the hypocholesterolaemic effects of an isoflavone-enriched casein diet (HDI) and a single-cell protein-based diet (SCP) devoid of isoflavones but with low methionine–glycine and lysine–arginine ratios were investigated in obese Zucker rats after 6 weeks of feeding. The control diet contained casein, which has high ratios of methionine–glycine and lysine–arginine. HDI and SCP feeding reduced the concentrations of total cholesterol and cholesteryl esters in plasma and liver, and changed the fatty acid composition of the hepatic cholesteryl esters. Faecal cholesterol and bile acid levels were markedly higher in SCP-fed rats than in controls, whereas HDI feeding had only minor effects. However, both HDI and SCP feeding increased the hepatic gene expression of cholesterol 7α hydroxylase. In contrast, the hepatic acyl-CoA synthetase and acyl-CoA:cholesterol acyltransferase activities and the gene expression of the LDL receptor were increased by HDI, but not by SCP feeding. The present results suggested that the cholesterol-lowering effect of SCP was related to the enterohepatic circulation, whereas HDI seemed to lower the plasma cholesterol via the circulation. Plasma homocysteine level was reduced in rats fed HDI and SCP compared to rats fed casein. In summary, diets enriched in isoflavones or containing proteins with low methionine–glycine and lysine–arginine ratios lowered the plasma cholesterol and homocysteine levels, changing the plasma profile from atherogenic to cardioprotective.

Fifteen potential precursors of propionate were tested for their ability to decrease CH4 production by ruminal fluid in vitro. Sodium acrylate and sodium fumarate produced the most consistent effects in batch cultures, with 50 % of the added precursors being fermented to propionate and CH4 production decreasing by between 8 and 17 %, respectively. Additives were more effective when added as free acids, but this also decreased the pH and may have inhibited fibre digestion. Changing the dietary substrate from predominantly grass hay to predominantly concentrate had no influence on the effectiveness of acrylate and fumarate. In an in vitro fermentor (the rumen simulating technique, Rusitec) with a grass hay—concentrate (50:50, w/w) diet as substrate, both compounds were again fermented to propionate (33 and 44 % conversion to propionate, respectively). However, fumarate appeared more effective as a H2 sink compound. It was calculated to capture 44 % of the H2 previously used for CH4 formation compared with a 22 % capture of H2 with acrylate. Fumarate also caused a stimulation in fibre digestion. Thus, sodium fumarate was the preferred propionate precursor for use as a feed ingredient to decrease CH4 emissions from ruminants.

Previous studies indicate that regular consumption of a diet rich in fruits and vegetables is associated with a lower risk for age-related diseases. The aim of the present study was to evaluate whether the often-reported age-related decrease of plasma antioxidants in man depends on differences in dietary intake or on other age- and gender-related factors. In this observational case-control study, thirty-nine community-dwelling healthy subjects aged 65 years and older consuming high intakes of fruits and vegetables daily (HI) and forty-eight healthy subjects aged 65 and older consuming low intakes of fruit and vegetables daily (LI) were enrolled. Plasma levels of retinol, tocopherols, carotenoids and malondialdehyde (MDA) as well as content of protein carbonyls in Ig G were measured. Plasma levels of retinol, tocopherols and carotenoids were significantly higher in group HI than in group LI subjects independent of age and gender. MDA levels were inversely correlated with vitamin A and α-carotene. Protein carbonyls were inversely correlated with γ-tocopherol. In the elderly, a higher daily intake of fruits and vegetables is associated with an improved antioxidant status in comparison to subjects consuming diets poor in fruits and vegetables. Modification of nutritional habits among other lifestyle changes should be encouraged to lower prevalence of disease risk factors in later life.

Flaxseed is a dietary source of possible chemopreventive compounds such as lignans and α-linolenic acid (ALA). To study the effects of a flaxseed mixture on adenoma formation in multiple intestinal neoplasia mice, the mice were fed a diet containing 2·7 % flaxseed, 4·5 % fibre and 3·7 % ALA. To elucidate the effect of oils of the mixture we also composed a diet without flaxseed but with the same oil composition. The median number of adenomas in the small intestine was fifty-four for the control group, and thirty-seven (P=0·023) and forty-two (P=0·095) for flaxseed and oil groups, respectively. Compared with controls (1·2 mm), the adenoma size was smaller in the flaxseed (0·9 mm; P=0·002) and oil (1·0 mm; P=0·012) groups. Both diets changed the proportions of n-3 and n-6 fatty acids in the colonic mucosa. Membrane β-catenin and protein kinase C (PKC)-ζ levels were reduced in the adenoma v. mucosa (P<0·05), and an inverse association was found between the membrane PKC-ζ in the mucosa and the adenoma number (r −0·460, P=0·008, n 32). Only the flaxseed diet increased lignan levels in the caecum (P=0·002) and in plasma (P=0·002) but they were not associated with tumour formation. The results suggest that the preventive effect of flaxseed on colon carcinogenesis may be due to the oil part of flaxseed, and the loss of β-catenin and PKC-ζ from the membranes of the mucosal tissue may play a permissive role in intestinal tumour development.

We have evaluated the changes in arterial blood pressure caused in spontaneously hypertensive rats (SHR) by long-term intake of an Enterococcus faecalis CECT 5728-fermented milk with significant angiotensin-converting enzyme (ACE)-inhibitory activity. After being weaned, male 3-week-old SHR were randomized into five groups. Until the 20th week of life, rats in each group were given one of the following drinking fluids: tap water (negative control 1), a fermented milk without ACE-inhibitory activity (negative control 2), captopril (100 mg/kg) (positive control), the E. faecalis CECT 5728-fermented milk that had significant ACE-inhibitory activity, or Ca-enriched E. faecalis CECT 5728-fermented milk. Animals in the different groups were then given tap water as drinking fluid from the 20th to 25th week of life. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured weekly in the rats, from the 6th to 25th week of life, by the tail-cuff method. A definite decrease in SBP and DBP could be observed in the rats treated with captopril and also in the rats that received the E. faecalis CECT 5728-fermented milks. The greatest antihypertensive effect was observed when the pharmacological treatment was administered. The effect of the Ca-enriched fermented milk was slightly more accentuated and more constant than the effect of the E. faecalis CECT 5728-fermented milk that had not been enriched in Ca. SBP and DBP increased in the treated SHR when the corresponding antihypertensive treatment was removed. Fermentation of milk with E. faecalis CECT 5728 may therefore be a successful strategy to produce a functional food with antihypertensive activity.

Erythritol, a naturally occurring polyol, is gaining attention as a bulk sweetener for human nutrition. Industrially, it is produced from glucose by fermentation. From various studies it is known to be non-cariogenic. Moreover, it is rapidly absorbed in the small intestine and quantitatively excreted in the urine. Only about 10 % enters the colon. Earlier in vitro experiments showed that erythritol remained unfermented for a fermentation period of 12 h. In order to investigate whether fresh human intestinal microbiota is able to adapt its enzyme activities to erythritol, a 24 h lasting fermentation was carried out under well-standardised in vitro conditions. For comparison maltitol, lactulose and blank (faecal inoculum only) were incubated as well. Fermentation patterns were established by following total gas production, hydrogen accumulation, changes in pH value, SCFA production and substrate degradation. Taking all fermentation parameters into account, erythritol turned out to be completely resistant to bacterial attack within 24 h, thus excluding an adaptation within that period. Since under in vivo conditions more easily fermentable substrates enter the colon continuously, it seems very unlikely that erythritol will be fermented in vivo.

Fibres with a range of abilities to perturb cholesterol homeostasis were used to investigate how the serum cholesterol-lowering effects of insoluble dietary fibres are related to parameters of intestinal cholesterol absorption and hepatic cholesterol homeostasis in mice. Cholestyramine, chitosan and cellulose were used as examples of fibres with high, intermediate and low bile acid-binding capacities, respectively. The serum cholesterol levels in a control group of mice fed a high fat/high cholesterol (HFHC) diet for 3 weeks increased about 2-fold to 4·3 mm and inclusion of any of these fibres at 7·5 % of the diet prevented this increase from occurring. In addition, the amount of cholesterol accumulated in hepatic stores due to the HFHC diet was reduced by treatment with these fibres. The three kinds of fibres showed similar hypocholesterolaemic activity; however, cholesterol depletion of liver tissue was greatest with cholestyramine. The mechanisms underlying the cholesterol-lowering effect of cholestyramine were (1) decreased cholesterol (food) intake, (2) decreased cholesterol absorption efficiency, and (3) increased faecal bile acid and cholesterol excretion. The latter effects can be attributed to the high bile acid-binding capacity of cholestyramine. In contrast, incorporation of chitosan or cellulose in the diet reduced cholesterol (food) intake, but did not affect either intestinal cholesterol absorption or faecal sterol output. The present study provides strong evidence that above all satiation and satiety effects underlie the cholesterol-lowering properties of insoluble dietary fibres with moderate or low bile acid-binding capabilities.

Rats were fed a grape seed extract (GSE) containing (+)-catechin, (−)-epicatechin and dimers, trimers, tetramers and polymeric procyanidins. Liver, kidney, brain and gastrointestinal (GI) tract together with plasma, urine and faeces were collected over a 24 h period and their flavan-3-ol content was analysed by HPLC with tandem mass spectrometry and diode array detection. Small amounts of the GSE flavan-3-ols moved out of the stomach and into the duodenum/jejunum, and to a greater extent the ileum 1 h after ingestion, and into the caecum after 2 h with relatively small amounts being detected in the colon after 3 h. The GI tract contained the parent GSE flavan-3-ols and procyanidins with only trace amounts of metabolites and there were no indications that proanthocyanidins were depolymerised in the GI tract releasing monomeric flavan-3-ols. Plasma contained exclusively catechin glucuronides and methylated glucuronide metabolites which were also detected in the liver and kidneys. These metabolites were also present in urine together with sulphated metabolites and low amounts of the procyanidin dimers B1, B2, B3 and B4 as well as the trimer C2 and an unknown GSE trimer. The amounts of (+)-catechin and (−)-epicatechin metabolites excreted in urine relative to the quantity of the monomers ingested were 27 and 36 %, respectively, after 24 h. This is similar to the levels of urinary excretion reported to occur by other investigators after feeding (−)-epicatechin to rats and provides further, albeit indirect, evidence that the procyanidin oligomers in the GSE were not depolymerised to monomers to any extent after ingestion. No convincing analytical data were obtained for the presence of flavan-3-ol metabolites in the brain.

Lactation alters maternal metabolism and increases food intake in rats to support milk production. Pancreatic lipase (PL) is primarily responsible for fat digestion in adults and is regulated by dietary fat. The present research determined the regulation of PL by lactation and dietary fat. In Expt 1, eighteen Sprague–Dawley dams and twelve age-matched virgins (controls) were fed a low-fat diet (LF; 11 % energy as safflower oil) for 7–63 d. At postpartum (day 0), peak lactation (day 15) and post-lactation (day 56) and after 7 d in virgins, the pancreas was removed for mRNA and enzyme analyses. In Expt 2, thirty-six Sprague–Dawley dams were fed LF until day 9 postpartum when dams were divided into three groups of twelve; one continued to be fed LF, one was fed a moderate-fat diet (MF; 40 % energy as safflower oil); and one was fed a high-fat diet (HF; 67 % energy as safflower oil) diet. At peak lactation (day 15) and post-lactation (day 56), the pancreas was removed for mRNA and enzyme analyses. Expt 1 revealed that lactation and post-lactation significantly (P<0·001) decreased PL mRNA (67 % and 76 %, respectively), but only post-lactation decreased PL activity. Increased dietary fat in Expt 2 significantly increased PL mRNA (LF<MF<HF, P<0·001) and PL activity (LF<MF=HF, P<0·02) in both lactation and post-lactation. In summary, lactation and post-lactation decreased PL mRNA significantly even though dietary fat still regulated PL activity and mRNA in lactation and post-lactation.

Processing of maize grain is known to modulate the site of starch digestion, thus the nature and amount of nutrients delivered for absorption. We assessed the effect of site of starch digestion on nutrient net fluxes across portal-drained viscera (PDV). Three steers, fitted with permanent digestive cannulas and blood catheters, successively received two diets containing 35 % starch as dent maize grain. Diets differed according to maize presentation: dry and cracked (by-pass, BP) v. wet and ground (control, C). Ruminal physicochemical parameters were not significantly affected. Between C and BP, the decrease in ruminal starch digestion was compensated by an increase in starch digestion in the small intestine. The amount of glucose and soluble α-glucoside reaching the ileum was not affected. The amount of glucose disappearing in the small intestine increased from 238 to 531 g/d between C and BP, but portal net flux of glucose remained unchanged (−97 g/d). The portal O2 consumption and net energy release were not significantly affected, averaging 16 % and 57 % of metabolizable energy intake, respectively. The whole-body glucose appearance rate, measured by jugular infusion of [6, 6-2H2]glucose, averaged 916 g/d. The present study shows that the increase in the amount of glucose disappearing in the small intestine of conventionally fed cattle at a moderate intake level induces no change in portal net flux of glucose, reflecting an increase in glucose utilization by PDV. That could contribute to the low response of whole-body glucose appearance rate observed at this moderate level of intestinal glucose supply.

The sympathetic nervous system is involved in the control of energy metabolism and expenditure. Diet-induced thermogenesis is mediated partly by the ß-adrenergic component of this system. The aim of the present study was to investigate the role of genetic variation in the ß2-adrenoceptor in diet-induced thermogenesis. Data from twenty-four subjects (fourteen men and ten women; BMI 26·7(sem 0·8) kg/m2; age 45·2(sem1·4) years) with different polymorphisms of the ß2-adrenoceptor at codon 16 (Gly16Gly, Gly16Arg or Arg16Arg) were recruited for this study. Subjects were given a high-carbohydrate liquid meal, and the energy expenditure, respiratory exchange ratio, and plasma concentrations of NEFA, glycerol, glucose, insulin and catecholamines were measured before and over 4 h after the meal. The AUC of energy expenditure (diet-induced thermogenesis) was not significantly different between polymorphism groups, nor was the response of any of the other measured variables to the meal. In a multiple regression model, the only variable that explained a significant proportion (32 %) of the variation in diet-induced thermogenesis was the increase in plasma adrenaline in response to the meal (P<0·05). The ß2-adrenoceptor codon16 polymorphisms did not contribute significantly. In conclusion, an independent contribution of the codon 16 polymorphism of the ß2-adrenoceptor gene to the variation in thermogenic response to a high-carbohydrate meal could not be demonstrated. The interindividual variation in thermogenic response to the meal was correlated with variations in the plasma adrenaline response to the meal.

Oxysterols are oxygenated derivatives of cholesterol that may be formed endogenously or absorbed from the diet. Significant amounts of oxysterols have frequently been identified in foods of animal origin, in particular highly processed foods. To date, oxysterols have been shown to possess diverse biological activities; however, recent attention has focused on their potential role in the development of atherosclerosis. Oxysterols have been reported to induce apoptosis in cells of the arterial wall, a primary process in the development of atheroma. The aim of the present study was to identify the role of the mitochondria in the apoptotic pathways induced by the oxysterols 7β-hydroxycholesterol (7β-OH) and cholesterol-5β,6β-epoxide (β-epoxide) in U937 cells. To this end, we investigated the effects of these oxysterols on mitochondrial membrane potential, caspase-8 activity, the mitochondrial permeability transition pore and cytochrome c release. 7β-OH-induced apoptosis was associated with a loss in mitochondrial membrane potential after 2 h, accompanied by cytochrome c release from the mitochondria into the cytosol after 16 h. Pre-treatment with a range of inhibitors of the mitochondrial permeability transition pore protected against 7β-OH-induced cell death. In contrast, β-epoxide induced a slight increase in caspase-8 activity but had no effect on mitochondrial membrane potential or cytochrome c release. The present results confirm that 7β-OH-induced apoptosis occurs via the mitochondrial pathway and highlights differences in the apoptotic pathways induced by 7β-OH and β-epoxide in U937 cells.

Cellular retinol-binding protein type II (CRBPII) is involved in the transport of vitamin A and its metabolism in the small intestine. In the present study, we demonstrated diet-related variations in CRBPII expression in rat jejunum. The CRBPII protein and mRNA levels increased in parallel after the start of feeding period regardless of whether the feeding period was restricted to the hours of darkness or of light. In addition, this variation was observed in the rats fed high-fat diet or low-fat diets, but not in those fed a fat-free diet or in fasted rats. A similar diet-induced variation was seen in the mRNA of liver-type fatty acid-binding protein in rat jejunum. In the transient transfection experiment, unsaturated fatty acid increased rat CRBPII gene promoter activity via the PPARα/retinoid X receptor-α heterodimer. Taken together, these results suggest that the diet-related variation in CRBPII expression in rat jejunum may be brought about by the transcriptional induction of CRBPII gene expression mainly triggered by dietary fatty acids.

The plasma membrane oxidoreductase (PMOR) activity, which mainly utilises ascorbate as intracellular electron donor, represents a major mechanism for cell-dependent reduction of extracellular oxidants and might be an important process used by the erythrocytes to keep a reduced plasma environment. We previously reported that in human erythrocytes, myricetin and quercetin act as intracellular substrates of a PMOR showing a novel mechanism whereby these flavonoids could exert beneficial effects under oxidative stress conditions. Here, we evaluated the ability of different flavonoids (quercetin, myricetin, morin, kaempferol, fisetin, catechin, luteolin, apigenin, acacetin, rutin, taxifolin, naringenin, genistein) and of two in vivoO-methylated metabolites of quercetin (isorhamnetin and tamarixetin) to be substrates of PMOR, by comparing their antioxidant capacity (i.e. direct interaction with the oxidant ferricyanide or with the free radical 1,1-diphenyl-2-picryl-hydrazil) with their ability to penetrate the erythrocytes and donate electrons to the PMOR. The results obtained indicate that, although most of the flavonoids display significant antioxidant activities, only those (quercetin, myricetin, fisetin) that combine the cathecol structure of the B ring (responsible for the reducing activity) with the 2,3 double bond and 4-oxo function of the C ring (responsible for the uptake by erythrocytes) can act as intracellular substrates for PMOR. It is of note that the metabolites of quercetin enter erythrocytes and donate electrons to the PMOR as the parent compound. The present data show a relationship between the flavonoid structures and their ability to provide electrons to the PMOR, suggesting an additional mechanism whereby dietary flavonoids may exert beneficial effects in man.

Since in vitro and animal studies suggest that the combination of starch with sucrose may be more cariogenic than sucrose alone, the study assessed in situ the effects of this association applied in vitro on the acidogenicity, biochemical and microbiological composition of dental biofilm, as well as on enamel demineralization. During two phases of 14 d each, fifteen volunteers wore palatal appliances containing blocks of human deciduous enamel, which were extra-orally submitted to four groups of treatments: water (negative control, T1); 2 % starch (T2); 10 % sucrose (T3); and 2 % starch+10 % sucrose (T4). The solutions were dripped onto the blocks eight times per day. The biofilm formed on the blocks was analysed with regard to amylase activity, acidogenicity, and biochemical and microbiological composition. Demineralization was determined on enamel by cross-sectional microhardness. The greatest mineral loss was observed for the association starch+sucrose (P<0·05). Also, this association resulted in the highest lactobacillus count in the biofilm formed (P<0·05). In conclusion, the findings suggest that a small amount of added starch increases the cariogenic potential of sucrose.

The aim of the study was to investigate the effects of a chicken-meat extract known as Essence of Chicken (EOC) on immune function in a normal and scalded animal model. In this experimental study, 120 rats were randomly allocated into three groups: a SHAM group (inflicted with a sham wound), a BURN group (inflicted with a full-thickness scald wound covering 30 % of total body surface area) and a CONTROL group. Rats in the SHAM and BURN groups were further divided into normal saline (NS)-fed and EOC-fed groups. They were fed by force-feeding with a feeding needle and blood samples were taken from each group on days 1, 8, 15 and 22 postburn. Serum IgG, IgA and IgM concentrations were determined by ELISA and the results of the EOC-fed and NS-fed cohorts of both the SHAM and BURN groups were compared. The level of significance was set at P<0·05. Serum IgG level of both SHAM-EOC and BURN-EOC cohorts showed significant elevation on day 8. IgA exhibited a significant increase in the SHAM-EOC group on day 15 and in the BURN-EOC group on day 22. A significant increase of IgM level was found on days 1 and 22 for the SHAM-EOC group and on day 15 for the BURN-EOC group. Conclusively, EOC was shown to have an enhancing effect on serum Ig levels for both normal and tissue-stressed rats. It is suggested that EOC may help improve immune function when the immune system is at normal status or when it faces a challenge.

The relative benefit of replacing saturated fatty acid with linoleic acids is still being debated because a linoleic acid-enriched diet increases oxidative and inflammatory stresses, although it is associated with a reduction in serum cholesterol levels. The present study was conducted to evaluate the effect of dietary supplementation of linoleic acid-rich (HL) fat, compared with a saturated fatty acid-rich (SF) fat on atherosclerotic lesion areas, serum and liver cholesterol levels, oxidative stress (urinary isoprostanes and serum malondialdehayde) and inflammatory stress (expression of aortic monocyte chemoattractant protein-1; MCP-1) in apo E-deficient mice. Male and female apo E-deficient mice (8 weeks old; seven to eight per group) were fed an AIN-76-based diet containing SF fat (50 g palm oil and 50 g lard/kg) or HL fat (100 g high-linoleic safflower-seed oil/kg) for 9 weeks. Compared with the SF diet, the HL diet lowered atherosclerosis (P<0·05). It reduced serum total cholesterol levels (P<0·05), increased HDL-cholesterol levels (P<0·05) and lowered liver esterified cholesterol levels (P<0·01). The HL diet-fed mice showed increased expression of MCP-1 mRNA (P<0·05), serum levels of malondialdehayde (P<0·05) and urinary excretion of 2,3-dinor-5,6-dihydro-8-iso-prostaglandin F2α; P<0·05). These results suggest that having biomarkers in vivo for oxidative stress and inflammatory status of endothelial cells does not necessarily indicate predisposition to an increased lesion area in the aortic root in apo E-deficient mice fed an HL or SF diet.

Studying the secondary structure of proteins leads to an understanding of the components that make up a whole protein, and such an understanding of the structure of the whole protein is often vital to understanding its digestive behaviour and nutritive value in animals. The main protein secondary structures are the α-helix and β-sheet. The percentage of these two structures in protein secondary structures influences protein nutritive value, quality and digestive behaviour. A high percentage of β-sheet structure may partly cause a low access to gastrointestinal digestive enzymes, which results in a low protein value. The objectives of the present study were to use advanced synchrotron-based Fourier transform IR (S-FTIR) microspectroscopy as a new approach to reveal the molecular chemistry of the protein secondary structures of feed tissues affected by heat-processing within intact tissue at a cellular level, and to quantify protein secondary structures using multicomponent peak modelling Gaussian and Lorentzian methods, in relation to protein digestive behaviours and nutritive value in the rumen, which was determined using the Cornell Net Carbohydrate Protein System. The synchrotron-based molecular chemistry research experiment was performed at the National Synchrotron Light Source at Brookhaven National Laboratory, US Department of Energy. The results showed that, with S-FTIR microspectroscopy, the molecular chemistry, ultrastructural chemical make-up and nutritive characteristics could be revealed at a high ultraspatial resolution (∼10 μm). S-FTIR microspectroscopy revealed that the secondary structure of protein differed between raw and roasted golden flaxseeds in terms of the percentages and ratio of α-helixes and β-sheets in the mid-IR range at the cellular level. By using multicomponent peak modelling, the results show that the roasting reduced (P<0·05) the percentage of α-helixes (from 47·1 % to 36·1 %: S-FTIR absorption intensity), increased the percentage of β-sheets (from 37·2 % to 49·8 %: S-FTIR absorption intensity) and reduced the α-helix to β-sheet ratio (from 0·3 to 0·7) in the golden flaxseeds, which indicated a negative effect of the roasting on protein values, utilisation and bioavailability. These results were proved by the Cornell Net Carbohydrate Protein System in situ animal trial, which also revealed that roasting increased the amount of protein bound to lignin, and well as of the Maillard reaction protein (both of which are poorly used by ruminants), and increased the level of indigestible and undegradable protein in ruminants. The present results demonstrate the potential of highly spatially resolved synchrotron-based infrared microspectroscopy to locate ‘pure’ protein in feed tissues, and reveal protein secondary structures and digestive behaviour, making a significant step forward in and an important contribution to protein nutritional research. Further study is needed to determine the sensitivities of protein secondary structures to various heat-processing conditions, and to quantify the relationship between protein secondary structures and the nutrient availability and digestive behaviour of various protein sources. Information from the present study arising from the synchrotron-based IR probing of the protein secondary structures of protein sources at the cellular level will be valuable as a guide to maintaining protein quality and predicting digestive behaviours.

Raising the dietary PUFA:saturated fatty acids (SFA) ratio has been recommended for the prevention of CVD. However, a high PUFA:SFA (P:S) ratio diet enhances oxidative stress because PUFA are highly susceptible to lipid peroxidation. Thus, we focused on the role of the dietary P:S ratio and peroxidisability index (PI) value on serum and liver tissue and investigated the effects of dietary P:S ratios (0·4, 1·0, and 4·8) with a fixed PI value (81) on serum lipid parameters and hepatic enzyme activities (experiment 1). To elucidate whether those phenomena were unique to the P:S ratio, we examined the effects of dietary PI values (36, 81, 126, and 217) with a constant P:S ratio (1·0) (experiment 2). Female Sprague–Dawley rats weighing 240–280 g were fed experimental diets for 4 weeks. When dietary PI value was maintained at 81, serum HDL-cholesterol (HDL-C) increased with increasing dietary P:S ratio. When the P:S ratio was fixed at 1·0, HDL-C was the lowest with mid–low PI (MLPI) (PI value of 81). In both experiments, serum LDL-cholesterol:HDL-C ratio kept in the range of 0–2. The hepatic superoxide dismutase, catalase, and glutathione peroxidase (GSH-Px) activities and thiobarbituric acid reactive substance (TBARS) concentrations were the highest in the lowest dietary P:S ratio group (experiment 1). GSH-Px, glutathione-S-transferase, and TBARS were the lowest in rats fed the MLPI diet (experiment 2). In conclusion, these results indicate that a P:S ratio of 1·0–1·5 and a PI value of 80–90 in the diet are within a favourable range to reduce the risk of CVD.