The nutritional acid load hypothesis of osteoporosis is reviewed from its historical origin to most recent studies with particular attention to the essential but overlooked role of the kidney in acid–base homeostasis. This hypothesis posits that foods associated with an increased urinary acid excretion are deleterious for the skeleton, leading to osteoporosis and enhanced fragility fracture risk. Conversely, foods generating neutral or alkaline urine would favour bone growth and Ca balance, prevent bone loss and reduce osteoporotic fracture risk. This theory currently influences nutrition research, dietary recommendations and the marketing of alkaline salt products or medications meant to optimise bone health and prevent osteoporosis. It stemmed from classic investigations in patients suffering from chronic kidney diseases (CKD) conducted in the 1960s. Accordingly, in CKD, bone mineral mobilisation would serve as a buffer system to acid accumulation. This interpretation was later questioned on both theoretical and experimental grounds. Notwithstanding this questionable role of bone mineral in systemic acid–base equilibrium, not only in CKD but even more in the absence of renal impairment, it is postulated that, in healthy individuals, foods, particularly those containing animal protein, would induce ‘latent’ acidosis and result, in the long run, in osteoporosis. Thus, a questionable interpretation of data from patients with CKD and the subsequent extrapolation to healthy subjects converted a hypothesis into nutritional recommendations for the prevention of osteoporosis. In a historical perspective, the present review dissects out speculation from experimental facts and emphasises the essential role of the renal tubule in systemic acid–base and Ca homeostasis.

SCFA are important end products formed during colonic fermentation of dietary fibre (DF). It has been suggested that propionic and butyric acids affect metabolic parameters, low-grade systemic inflammation, insulin resistance and obesity. The aim of the present study was to investigate whether the various SCFA profiles observed after fermentation in the caecum of rats fed pectin, guar gum and fructo-oligosaccharides (FOS) were also represented in hepatic portal and aortic serum. The SCFA in serum were extracted using hollow fibre-supported liquid membrane extraction before GLC analysis. The concentrations of acetic, propionic and butyric acids in caecal content correlated well with those in portal serum (P< 0·001) for all the three diets. A weaker correlation was found for propionic and butyric acids between the caecal content and aortic serum (P< 0·05). Butyric acid concentration in caecal content was also reflected in the aortic serum (P= 0·019) of rats fed FOS. FOS gave rather low amounts of the SCFA, especially butyric acid, but caecal tissue weight was higher with FOS than with the other two diets. This may be explained by rapid fermentation and quick utilisation/absorption of the SCFA. The present study also showed that propionic acid was metabolised/utilised to a higher extent than butyric acid by colonocytes before reaching the liver. We conclude that the formation of propionic and butyric acids in the caecum is reflected by increased concentrations in the aortic blood. This approach may therefore simplify the evaluation and study of SCFA from DF in human subjects.

Acid–base disturbances caused by environmental factors and physiological events including feeding have been well documented in several fish species, but little is known about the impact of dietary electrolyte balance (dEB). In the present study, we investigated the effect of feeding diets differing in dEB ( − 100, 200, 500 or 800 mEq/kg diet) on the growth, nutrient digestibility and energy balance of Nile tilapia. After 5 weeks on the test diet, the growth of the fish was linearly affected by the dEB levels (P< 0·001), with the lowest growth being observed in the fish fed the 800 dEB diet. The apparent digestibility coefficient (ADC) of fat was unaffected by dEB, whereas the ADC of DM and protein were curvilinearly related to the dEB levels, being lowest and highest in the 200 and 800 dEB diets, respectively. Stomach chyme pH at 3 h after feeding was linearly related to the dEB levels (P< 0·05). At the same time, blood pH of the heart (P< 0·05) and caudal vein (P< 0·01) was curvilinearly related to the dEB levels, suggesting the influence of dEB on postprandial metabolic alkalosis. Consequently, maintenance energy expenditure (MEm) was curvilinearly related to the dEB levels (P< 0·001), being 54 % higher in the 800 dEB group (88 kJ/kg0·8 per d) than in the 200 dEB group (57 kJ/kg0·8 per d). These results suggest that varying dEB levels in a diet have both positive and negative effects on fish. On the one hand, they improve nutrient digestibility; on the other hand, they challenge the acid–base homeostasis (pH) of fish, causing an increase in MEm, and thereby reduce the energy required for growth.

To evaluate the action mode of Berberis vulgaris root extract in the alleviation of oxidative stress, female Japanese quails (n 180, aged 5 weeks) were reared, either at 22°C for 24 h/d (thermoneutral, TN) or 34°C for 8 h/d (heat stress, HS), and fed one of three diets: diets containing 0, 100 or 200 mg of B. vulgaris root extract per kg for 12 weeks. Exposure to HS depressed feed intake by 8·5 % and egg production by 12·1 %, increased hepatic malondialdehyde (MDA) level by 98·0 % and decreased hepatic superoxide dismutase, catalase and glutathione peroxidase activities by 23·5, 35·4 and 55·7 %, respectively (P< 0·001 for all). There were also aggravations in expressions of hepatic NF-κB and heat-shock protein 70 (HSP70) by 42 and 43 %, respectively and suppressions in expressions of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and haeme-oxygenase 1 (HO-1) by 57 and 61 %, respectively, in heat-stressed quails (P< 0·001 for all). As supplemental B. vulgaris extract increased, there were linear increases in performance parameters, activities of antioxidant enzymes and hepatic Nrf2 and HO-1 expressions (P< 0·001 for all) and linear decreases in hepatic MDA level and NF-κB and HSP70 expressions at a greater extent in quails reared under TN condition and those reared under HS condition. In conclusion, dietary supplementation of B. vulgaris root extract to quails reduces the detrimental effects of oxidative stress and lipid peroxidation resulting from HS via activating the host defence system at the cellular level.

One of the many functions of taurine is to protect cells against oxidation, by protecting mitochondrial integrity and respiration. Taurine metabolism has attracted much attention in fish nutrition due to the fact that as plant ingredients replace fishmeal, dietary taurine has declined. As the endogenous synthesis of taurine might be too low to protect cells against oxidative stress and apoptosis, the present study aimed to test whether taurine may protect liver cells from apoptosis. Liver cells isolated from Atlantic salmon (Salmo salar) were grown in media supplemented with a physiological concentration of taurine (25 (se 0·5) mm) or without any taurine supplementation (14 (se 3) μm) for 3 d. To increase oxidation in the mitochondria and maximise any cellular response of taurine supplementation, 100 μm-CdCl2 was added or not added to the cells at day 3. At day 4, cells were harvested and assessed for viability. As expected, the addition of CdCl2 decreased cell viability without showing any interaction with taurine supplementation. Cells grown in the taurine-supplemented media had lower protein abundance of active caspase-3. In addition, the protein abundance of phosphorylated mitogen-activating phosphokinase (P-p63, P-p42/44 and P-p38) as well as cytochrome P450 were reduced when taurine was added to the media. Cells grown without taurine supplementation had a more condensed chromatin and more smeared DNA, also pointing to a higher apoptosis in these cells. In conclusion, taurine attenuated apoptosis in primary liver cells isolated from Atlantic salmon, and as such, taurine may be conditionally indispensable in Atlantic salmon.

7-Ketocholesterol (7-KC)-induced apoptosis of macrophages is considered a key event in the development of human atheromas. In the present study, the effect of indicaxanthin (Ind), a bioactive pigment from cactus pear fruit, on 7-KC-induced apoptosis of human monocyte/macrophage THP-1 cells was investigated. A pathophysiological condition was simulated by using amounts of 7-KC that can be reached in human atheromatous plaque. Ind was assayed within a micromolar concentration range, consistent with its plasma level after dietary supplementation with cactus pear fruit. Pro-apoptotic effects of 7-KC were assessed by cell cycle arrest, exposure of phosphatidylserine at the plasma membrane, variation of nuclear morphology, decrease of mitochondrial trans-membrane potential, activation of Bcl-2 antagonist of cell death and poly(ADP-ribose) polymerase-1 cleavage. Kinetic measurements within 24 h showed early formation of intracellular reactive oxygen species over basal levels, preceding NADPH oxidase-4 (NOX-4) over-expression and elevation of cytosolic Ca2+, with progressive depletion of total thiols. 7-KC-dependent activation of the redox-sensitive NF-κB was observed. Co-incubation of 2·5 μm of Ind completely prevented 7-KC-induced pro-apoptotic events. The effects of Ind may be ascribed to inhibition of NOX-4 basal activity and over-expression, inhibition of NF-κB activation, maintaining cell redox balance and Ca homeostasis, with prevention of mitochondrial damage and consequently apoptosis. The findings suggest that Ind, a highly bioavailable dietary phytochemical, may exert protective effects against atherogenetic toxicity of 7-KC at a concentration of nutritional interest.

A 9-week feeding trial was conducted to evaluate the effects of dietary cholesterol supplementation at different levels (0, 0·3, 0·6, 0·9, 1·2 and 1·5 %) on growth and cholesterol metabolism of rainbow trout (Oncorhynchus mykiss) fed soyabean meal (SBM)-based diets. Daily growth coefficient (DGC) steadily increased when the supplemental cholesterol was increased by up to 1·2 %, but declined upon further addition. The total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) levels in plasma generally increased when the supplemental cholesterol was increased by up to 1·2 %. Thereafter, the TC level reached a plateau, the LDL-C level showed a marked decline, whereas the HDL-C level continued to increase. Dietary cholesterol supplementation generally increased the total lipid and cholesterol levels in liver; the total lipid and TAG levels in muscle; the TC, free cholesterol, cholesteryl ester and total bile acid levels in intestinal contents; and the triiodothyronine and Ca levels in plasma. However, significant differences were mainly observed with high levels of supplemental cholesterol (0·9–1·5 %). Low levels of supplemental cholesterol (0·3–0·9 %) decreased hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase and cholesterol 7α-hydroxylase activities, but high levels of supplemental cholesterol (1·5 %) increased hepatic acyl-CoA:cholesterol acyl transferase and cholesterol 7α-hydroxylase activities. These results suggest that rainbow trout fed SBM-based diets have a certain ‘cholesterol-buffering capacity’, which in turn suggests the possibility of the inhibition of exogenous cholesterol absorption and/or inadequate endogenous production of cholesterol in trout fed SBM-based diets. DGC increased steadily with increasing supplemental cholesterol level up to 1·2 %, and the growth-promoting effects might be related to the alleviation of the negative effects caused by a soyabean diet and/or make up for the deficiency of endogenous cholesterol in rainbow trout.

The role of very-low-carbohydrate ketogenic diets (VLCKD) in the long-term management of obesity is not well established. The present meta-analysis aimed to investigate whether individuals assigned to a VLCKD (i.e. a diet with no more than 50 g carbohydrates/d) achieve better long-term body weight and cardiovascular risk factor management when compared with individuals assigned to a conventional low-fat diet (LFD; i.e. a restricted-energy diet with less than 30 % of energy from fat). Through August 2012, MEDLINE, CENTRAL, ScienceDirect, Scopus, LILACS, SciELO, ClinicalTrials.gov and grey literature databases were searched, using no date or language restrictions, for randomised controlled trials that assigned adults to a VLCKD or a LFD, with 12 months or more of follow-up. The primary outcome was body weight. The secondary outcomes were TAG, HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), systolic and diastolic blood pressure, glucose, insulin, HbA1c and C-reactive protein levels. A total of thirteen studies met the inclusion/exclusion criteria. In the overall analysis, five outcomes revealed significant results. Individuals assigned to a VLCKD showed decreased body weight (weighted mean difference − 0·91 (95 % CI − 1·65, − 0·17) kg, 1415 patients), TAG (weighted mean difference − 0·18 (95 % CI − 0·27, − 0·08) mmol/l, 1258 patients) and diastolic blood pressure (weighted mean difference − 1·43 (95 % CI − 2·49, − 0·37) mmHg, 1298 patients) while increased HDL-C (weighted mean difference 0·09 (95 % CI 0·06, 0·12) mmol/l, 1257 patients) and LDL-C (weighted mean difference 0·12 (95 % CI 0·04, 0·2) mmol/l, 1255 patients). Individuals assigned to a VLCKD achieve a greater weight loss than those assigned to a LFD in the long term; hence, a VLCKD may be an alternative tool against obesity.

In vitro experiments have shown that isolated human gut bacteria are able to metabolise PUFA into conjugated PUFA like conjugated linoleic acids (CLA). The hypothesis of the present paper was that high-fat (HF) diet feeding and supplementation with fermentable carbohydrates that have prebiotic properties modulate the in vivo production of CLA by the mouse gut microbiota. Mice were treated for 4 weeks as follows: control (CT) groups were fed a standard diet; HF groups were fed a HF diet rich in linoleic acid (18 : 2n-6); the third groups were fed with the HF diet supplemented with either inulin-type fructans (HF-ITF) or arabinoxylans (HF-Ax). HF diet feeding increased rumenic acid (cis-9, trans-11-18 : 2 CLA) content both in the caecal and liver tissues compared with the CT groups. ITF supplementation had no major effect compared with the HF diet whereas Ax supplementation increased further rumenic acid (cis-9, trans-11-18 : 2 CLA) in the caecal tissue. These differences between both prebiotics may be linked to the high fat-binding capacity of Ax that provides more substrates for bacterial metabolism and to differential modulation of the gut microbiota (specific increase in Roseburia spp. in HF-Ax v. HF). In conclusion, these experiments supply the proof of concept that the mouse gut microbiota produces CLA in vivo, with consequences on the level of CLA in the caecal and liver tissues. We postulate that the CLA-producing bacteria could be a mediator to consider in the metabolic effects of both HF diet feeding and prebiotic supplementation.

Two experiments were conducted on broiler chickens to compare the effect of a new organic Se source, 2-hydroxy-4-methylselenobutanoic acid (HMSeBA; SO), with two practical Se additives, sodium selenite (SS) and Se yeast (SY). The relative bioavailability of the different Se sources was compared on muscle (pectoralis major) total Se, selenomethionine (SeMet) and selenocysteine (SeCys) concentrations and apparent digestibility of total Se (ADSe). In the first experiment, from day (d) 0 to d21, Se sources were tested at different supplied levels and compared with an unsupplemented diet (NC). No significant effects were observed on growth performance during the experimental period. However, the different Se sources and levels improved muscle Se concentration compared with the NC, with a significant source effect in the following order: SS < SY < SO (P< 0·05). Seleno-amino acids speciation results for NC, SY and SO at 0·3 mg Se/kg feed indicated that muscle Se was only present as SeMet or SeCys, showing a full conversion of Se by the bird. The second experiment (d0–d24) compared SS, SY or SO at 0·3 mg Se/kg feed. The ADSe measurements carried out between d20 and d23 were 24, 46 and 49 % for SS, SY and SO, respectively, with significant differences between the organic and mineral Se sources (P< 0·05). These results confirmed the higher bioavailability of organic Se sources compared with the mineral source and demonstrated a significantly better efficiency of HMSeBA compared with SY for muscle Se enrichment.

Ecological evidence suggests that niacin (nicotinamide and nicotinic acid) fortification may be involved in the increased prevalence of obesity and type 2 diabetes, both of which are associated with insulin resistance and epigenetic changes. The purpose of the present study was to investigate nicotinamide-induced metabolic changes and their relationship with possible epigenetic changes. Male rats (5 weeks old) were fed with a basal diet (control group) or diets supplemented with 1 or 4 g/kg of nicotinamide for 8 weeks. Low-dose nicotinamide exposure increased weight gain, but high-dose one did not. The nicotinamide-treated rats had higher hepatic and renal levels of 8-hydroxy-2′-deoxyguanosine, a marker of DNA damage, and impaired glucose tolerance and insulin sensitivity when compared with the control rats. Nicotinamide supplementation increased the plasma levels of nicotinamide, N1-methylnicotinamide and choline and decreased the levels of betaine, which is associated with a decrease in global hepatic DNA methylation and uracil content in DNA. Nicotinamide had gene-specific effects on the methylation of CpG sites within the promoters and the expression of hepatic genes tested that are responsible for methyl transfer reactions (nicotinamide N-methyltransferase and DNA methyltransferase 1), for homocysteine metabolism (betaine–homocysteine S-methyltransferase, methionine synthase and cystathionine β-synthase) and for oxidative defence (catalase and tumour protein p53). It is concluded that nicotinamide-induced oxidative tissue injury, insulin resistance and disturbed methyl metabolism can lead to epigenetic changes. The present study suggests that long-term high nicotinamide intake (e.g. induced by niacin fortification) may be a risk factor for methylation- and insulin resistance-related metabolic abnormalities.

The dual burden of malnutrition reportedly coexists in Malaysia; however, existing data are scarce and do not adequately represent the nutritional status of Malaysian children. The Nutrition Survey of Malaysian Children was carried out with the aim of assessing the nutritional status in a sample of nationally representative population of children aged 6 months to 12 years. A total of 3542 children were recruited using a stratified random sampling method. Anthropometric measurements included weight, height, mid-upper arm circumference, and waist and hip circumferences. Blood biochemical assessment involved analyses of Hb, serum ferritin, and vitamins A and D. Dietary intake was assessed using semi-quantitative FFQ, and nutrient intakes were compared with the Malaysian Recommended Nutrient Intakes (RNI). The prevalence of overweight (9·8 %) and obesity (11·8 %) was higher than that of thinness (5·4 %) and stunting (8·4 %). Only a small proportion of children had low levels of Hb (6·6 %), serum ferritin (4·4 %) and vitamin A (4·4 %), but almost half the children (47·5 %) had vitamin D insufficiency. Dietary intake of the children was not compatible with the recommendations, where more than one-third did not achieve the Malaysian RNI for energy, Ca and vitamin D. The present study revealed that overnutrition was more prevalent than undernutrition. The presence of high prevalence of vitamin D insufficiency and the inadequate intake of Ca and vitamin D are of concern. Hence, strategies for improving the nutritional status of Malaysian children need to consider both sides of malnutrition and also put emphasis on approaches for the prevention of overweight and obesity as well as vitamin D insufficiency.

The present single-dose study was performed to assess the effect of whole coffee fruit concentrate powder (WCFC), green coffee caffeine powder (N677), grape seed extract powder (N31) and green coffee bean extract powder (N625) on blood levels of brain-derived neurotrophic factor (BDNF). Randomly assorted groups of fasted subjects consumed a single, 100 mg dose of each material. Plasma samples were collected at time zero (T0) and at 30 min intervals afterwards, up to 120 min. A total of two control groups were included: subjects treated with silica dioxide (as placebo) or with no treatment. The collected data revealed that treatments with N31 and N677 increased levels of plasma BDNF by about 31 % under these experimental conditions, whereas treatment with WCFC increased it by 143 % (n 10), compared with baseline. These results indicate that WCFC could be used for modulation of BDNF-dependent health conditions. However, larger clinical studies are needed to support this possibility.

Replacing dietary fishmeal (FM) and fish oil (FO) with plant ingredients in Atlantic salmon (Salmo salar L.) diets decreases dietary cholesterol and introduces phytosterols. The aim of the present study was to assess the effect of dietary sterol composition on cholesterol metabolism in Atlantic salmon. For this purpose, two dietary trials were performed, in which Atlantic salmon were fed either 100 % FM and FO (FM-FO) diet or one of the three diets with either high (80 %) or medium (40 %) plant protein (PP) and a high (70 %) or medium (35 %) vegetable oil (VO) blend (trial 1); or 70 % PP with either 100 % FO or 80 % of the FO replaced with olive, rapeseed or soyabean oil (trial 2). Replacing ≥ 70 % of FM with PP and ≥ 70 % of FO with either a VO blend or rapeseed oil increased plasma and liver TAG concentrations. These diets contained high levels of phytosterols and low levels of cholesterol. Fish fed low-cholesterol diets, but with less phytosterols, exhibited an increased expression of genes encoding proteins involved in cholesterol uptake and synthesis. The expression of these genes was, however, partially inhibited in rapeseed oil-fed fish possibly due to the high dietary and tissue phytosterol:cholesterol ratio. Atlantic salmon tissue and plasma cholesterol concentrations were maintained stable independent of the dietary sterol content.

The effects of varying dietary digestible protein (DP) and digestible energy (DE) content on performance, nutrient retention efficiency and the de novo lipogenesis of DP origin were examined in triplicate groups of gilthead sea bream (Sparus aurata), fed nine extruded experimental diets. In order to trace the metabolic fate of dietary protein, 1·8 % fishmeal was replaced with isotope-labelled whole protein (>98 % 13C). The experiment was divided into a growth period lasting 89 d, growing fish from approximately 140 to 350 g, followed by a 3 d period feeding isotope-enriched diets. Isotope ratio MS was applied to quantify the 13C enrichment of whole-body lipid from dietary DP. Between 18·6 and 22·4 % of the carbon derived from protein was recovered in the lipid fraction of the fish, and between 21·6 and 30·3 % of the total lipid deposited could be attributed to dietary protein. DP retention was significantly improved by reductions in dietary DP:DE ratio, while the opposite was true for apparent digestible lipid retention. Both overall DE retention and whole-body proximate composition of whole fish were largely unaffected by dietary treatments, while feed conversion ratios were significantly improved with increasing dietary energy density. The present study suggests that gilthead sea bream efficiently utilises dietary nutrients over a wide range of DP:DE ratios and energy densities. In addition, they appear to endeavour a certain body energy status rather than maximising growth, which in the present trial was apparent from inherently high de novo lipogenesis originating from DP.

Human and guinea pig fetuses are completely dependent on an adequate maternal vitamin C (vitC) intake. Shortage of micronutrients can have negative implications for fetal health and pregnancy outcome; however, knowledge of maternal vitC deficiency's impact on fetal development is sparse and reports of pregnancy outcome have been divergent. The present study investigated whether maternal vitC deficiency affects pregnancy outcome and plasma vitC distribution between the mother and the offspring in a guinea pig model. A total of eighty pregnant Dunkin Hartley guinea pigs were randomised into two weight-stratified groups receiving either a deficient (100 mg/kg DEF) or a control (923 mg/kg CTRL) diet. VitC levels were measured in plasma during pregnancy and postpartum, and in the plasma and brain of newborns. Pregnancy outcome was recorded with respect to birth weight and perinatal survival and were similar between groups. Plasma vitC in dams declined throughout gestation in both groups (P< 0·01). Compared with maternal plasma vitC, plasma vitC of newborn pups was found to be significantly lower in the DEF group (P< 0·001) and higher in the CTRL group (P< 0·001), respectively. Brain vitC levels were significantly reduced in DEF newborn pups (P< 0·001). The present results indicate that preferential transport of vitC from the mother to the fetus is overridden during sustained maternal vitC deficiency, maintaining maternal vitC concentration at the expense of the offspring. This contradicts the notion that a fetus is protected from vitC deficiency by the placental Na-dependent vitC co-transporter, SVCT2, thus fetal development may be susceptible to the negative effects of maternal vitC deficiency.

Many functional foods and dietary supplements have been reported to be beneficial for the management of dyslipidaemia, one of the major risk factors for CVD. Soluble fibres and legume proteins are known to be a safe and practical approach for cholesterol reduction. The present study aimed at investigating the hypocholesterolaemic effect of the combinations of these bioactive vegetable ingredients and their possible effects on the expression of genes regulating cholesterol homeostasis. A total of six groups of twelve rats each were fed, for 28 d, Nath's hypercholesterolaemic diets, differing in protein and fibre sources, being, respectively, casein and cellulose (control), pea proteins and cellulose (pea), casein and oat fibres (oat), casein and apple pectin (pectin), pea proteins and oat fibres (pea+oat) and pea proteins and apple pectin (pea+pectin). Administration of each vegetable-containing diet was associated with lower total cholesterol concentrations compared with the control. The combinations (pea+oat and pea+pectin) were more efficacious than fibres alone in modulating cholesterolaemia ( − 53 and − 54 %, respectively, at 28 d; P< 0·005). In rats fed the diets containing oat fibres or apple pectin, alone or in combination with pea proteins, a lower hepatic cholesterol content (P< 0·005) and higher hepatic mRNA concentrations of CYP7A1 and NTCP were found when compared with the control rats (P< 0·05). In summary, the dietary combinations of pea proteins and oat fibres or apple pectin are extremely effective in lowering plasma cholesterol concentrations in rats and affect cellular cholesterol homeostasis by up-regulating genes involved in hepatic cholesterol turnover.

In the present controlled, randomised, multiple cross-over dietary intervention study, we aimed to identify potential biomarkers for dietary protein from dairy products, meat and grain, which could be useful to estimate intake of these protein types in epidemiological studies. After 9 d run-in, thirty men and seventeen women (22 (sd 4) years) received three high-protein diets (aimed at approximately 18 % of energy (en%)) in random order for 1 week each, with approximately 14 en% originating from either meat, dairy products or grain. We used a two-step approach to identify biomarkers in urine and plasma. With principal component discriminant analysis, we identified amino acids (AA) from the plasma or urinary AA profile that were distinctive between diets. Subsequently, after pooling total study data, we applied mixed models to estimate the predictive value of those AA for intake of protein types. A very good prediction could be made for the intake of meat protein by a regression model that included urinary carnosine, 1-methylhistidine and 3-methylhistidine (98 % of variation in intake explained). Furthermore, for dietary grain protein, a model that included seven AA (plasma lysine, valine, threonine, α-aminobutyric acid, proline, ornithine and arginine) made a good prediction (75 % of variation explained). We could not identify biomarkers for dairy protein intake. In conclusion, specific combinations of urinary and plasma AA may be potentially useful biomarkers for meat and grain protein intake, respectively. These findings need to be cross-validated in other dietary intervention studies.

The present randomised parallel study assessed the impact of adding MUFA to a dietary portfolio of cholesterol-lowering foods on the intravascular kinetics of apoAI- and apoB-containing lipoproteins in subjects with dyslipidaemia. A sample of sixteen men and postmenopausal women consumed a run-in stabilisation diet for 4 weeks. Subjects were then randomly assigned to an experimental dietary portfolio either high or low in MUFA for another 4 weeks. MUFA substituted 13·0 % of total energy from carbohydrate (CHO) in the high-MUFA dietary portfolio. Lipoprotein kinetics were assessed after the run-in and portfolio diets using a primed, constant infusion of [2H3]leucine and multicompartmental modelling. The high-MUFA dietary portfolio resulted in higher apoAI pool size (PS) compared with the low-MUFA dietary portfolio (15·9 % between-diet difference, P= 0·03). This difference appeared to be mainly attributable to a reduction in apoAI fractional catabolic rate (FCR) after the high-MUFA diet ( − 5·6 %, P= 0·02 v. pre-diet values), with no significant change in production rate. The high-MUFA dietary portfolio tended to reduce LDL apoB100 PS compared with the low-MUFA dietary portfolio ( − 28·5 % between-diet difference, P= 0·09), predominantly through an increase in LDL apoB100 FCR (23·2 % between-diet difference, P= 0·04). These data suggest that adding MUFA to a dietary portfolio of cholesterol-lowering foods provides the added advantage of raising HDL primarily through a reduction in HDL clearance rate. Replacing CHO with MUFA in a dietary portfolio may also lead to reductions in LDL apoB100 concentrations primarily by increasing LDL clearance rate, thus potentiating further the well-known cholesterol-lowering effect of this diet.

Hypophosphataemia is frequently encountered in dairy cows during early lactation. Although supplementation of P is generally recommended, controversy exists over the suitability of oral P supplementation in animals with decreased or absent rumen motility. Since the effects of transruminal P absorption and the reticular groove reflex on the absorption kinetics of P are not well understood, it is unclear in how far treatment efficacy of oral P supplementation is affected by decreased rumen motility. Phosphate absorption was studied in six phosphate-depleted dairy cows fitted with rumen cannulas and treated with test solutions containing either NaH2PO4 or CaHPO4 with acetaminophen. Each animal was treated orally, intraruminally and intra-abomasally in randomised order. Absorption kinetics of P were studied and compared with the absorption kinetics of acetaminophen, a marker substance only absorbed from the small intestine. Intra-abomasal treatment with NaH2PO4 resulted in the most rapid and highest peaks in plasma inorganic P (Pi) concentration. Oral and intraruminal administration of NaH2PO4 resulted in similar increases in plasma Pi concentration from 4 to 7 h in both groups. Treatment with NaH2PO4 caused more pronounced peaks in plasma Pi concentration compared with CaHPO4. Neither transruminal P absorption nor the reticular groove reflex affected P absorption kinetics as determined by comparing plasma concentration–time curves of P and acetaminophen after administration of 1 m-phosphate salt solutions. It is concluded that oral treatment with NaH2PO4 but not CaHPO4 is effective in supplementing P in hypophosphataemic cows with adequate rumen motility. Decreased rumen motility is likely to hamper the efficacy of oral phosphate treatment.