The present report summarises key insights from a recent symposium focusing on the impact of the intestinal microbiota on health and disease. A more appropriate definition of health was proposed since health maintenance is a dynamic process better assessed in terms of ability to adapt to stress and maintain physiological homeostasis. Biomarkers specifically for health are needed; use of challenge models and subjects with suboptimal health or specific disease risk were advised. The complexity of interactions between external factors, the intestinal epithelium, intestinal microbiota, the immune system and health was exemplified by describing the effects of antibiotics, the Western diet and non-digestible carbohydrates on the microbiota. The association of certain bacteria with different states of health or disease was acknowledged but also that is not always clear whether this is a cause or effect. Recent identification of three robust faecal metagenome clusters may advance this understanding. It was speculated that knowledge of the intestinal microbiota profile may eventually help in the diagnosis of health risks and choice of therapy. It was agreed that beneficial manipulation of the commensal microbiota can improve health outcome. For this purpose, three areas were reviewed. Firstly, research into probiotics as vaccine adjuvants was considered useful for substantiation of immune function claims. Secondly, positive results with certain probiotics and synbiotics for colorectal cancer are emerging, mostly from in vitro and animal studies. Finally, studies in endurance athletes have shown strain-specific probiotic benefit in terms of maintenance of immune function and, for certain strains, reduction of episodes of respiratory and/or gastrointestinal tract infections.

Studies in animals and human subjects indicate that gut-derived bacterial endotoxins may play a critical role in the development of non-alcoholic fatty liver disease (NAFLD). In the present study, we investigated if the liver is also sensitised by other microbial components during the onset of fructose-induced steatosis in a mouse model. C57BL/6 mice were either fed with 30 % fructose solution or tap water (control) with or without antibiotics for 8 weeks. Expression of toll-like receptors (TLR)1–9, TNF-α, inducible NO synthase (iNOS), myeloid differentiation factor 88 (MyD88) and number of F4/80 positive cells in the liver were assessed. Occludin protein, DNA of microbiota in the small and large intestine and retinol binding protein 4 (RBP4) in plasma were analysed using Western blot, DNA fingerprinting and ELISA, respectively. F4/80 positive cells were determined by immunohistochemistry. The accumulation of TAG found in the livers of fructose-fed mice was associated with a significant induction of TLR 1–4 and 6–8. Plasma RBP4 concentration and hepatic mRNA expression levels of TNF-α, iNOS, MyD88 and number of F4/80 positive cells of fructose-fed animals were significantly higher than those of controls; however, these effects of fructose were attenuated in antibiotic-treated mice. Whereas protein concentration of occludin was lower in the duodenum of fructose-treated mice, no systematic alterations of microbiota were found in this part of the intestine. Taken together, these data support the hypothesis that (1) an increased intestinal translocation of microbial components and (2) an increased number of F4/80 positive cells and induction of several TLR and dependent pathways (e.g. MyD88 and iNOS) may be involved in the onset of fructose-induced NAFLD.

Foods that have a low glycaemic index or foods that contain slowly digestible starch are beneficial in controlling fluctuations in blood glucose and insulin levels. The study hypothesis is that gelatinisation of starch in structured casein networks provides a method for decreasing the digestion rate of the starch and, hence, minimising postprandial glucose fluctuations. This study examined the effect of starch gelatinisation with or without casein on (1) gene expression and peptide secretion levels of the incretin hormones glucagon-like peptide 1 and glucose-independent insulinotropic polypeptide and (2) gene expression of the sodium–glucose cotransporter and GLUT-2 in intestinal cell culture systems. The intestinal epithelial cell line, STC-1, and the enteroendocrine colonic cell line, Caco-2, were exposed to in vitro digested foods (starch gelatinised with α-casein, starch gelatinised with β-casein and gelatinised starch alone). The encapsulation of starch with casein before in vitro digestion lowers levels of incretin hormone secretion. Digestion of starch gelatinised with casein also releases less glucose than starch alone as indicated by significantly (P < 0·05) lower levels of glucose transporter mRNA transcripts. Some subtle cellular response differences were observed following exposure to starch gelatinised with α- compared to β-casein. Fractionation of α-casein and β-casein by reverse-phase HPLC identified that fractions that differed in hydrophobicity differed significantly (P < 0·05) in their ability to promote secretion of the incretin hormones. Evidence suggests that gelatinisation of starch with casein may be a functional food ingredient that minimises blood glucose fluctuations.

The impact of dietary n-3 PUFA on behavioural outcomes has been widely researched; however, very little attention has been given to their impact on brain functioning in physiological terms. A total of twenty-two healthy adults took part in this double-blind, placebo-controlled study, wherein the cerebral haemodynamic effects of 12 weeks of daily dietary supplementation with either 1 g DHA-rich or 1 g EPA-rich fish oil (FO) or placebo (1 g olive oil) were assessed. Relative changes in the concentration of oxygenated Hb (oxy-Hb) and deoxygenated Hb were assessed in the prefrontal cortex using near IR spectroscopy (NIRS) during the performance of four computerised cognitive tasks. Supplementation with DHA-rich FO, in comparison with placebo, resulted in a significant increase in the concentrations of oxy-Hb and total levels of Hb, indicative of increased cerebral blood flow (CBF), during the cognitive tasks. In comparison, no effect on CBF was observed following supplementation with EPA-rich FO, where concentration changes in the chromophores followed the same pattern as placebo. These encouraging pilot data warrant further application of NIRS in this area.

Fibroblast growth factor 21 (FGF21) is a PPAR-α-regulated metabolic regulator that plays critical roles in glucose homoeostasis, lipid metabolism, insulin sensitivity and obesity. Conjugated linoleic acids (CLA), especially trans-10 (t-10), cis-12 (c-12), have shown anti-obesity properties. In addition, CLA is reported as a high-affinity ligand and activator of PPAR-α. This raises the possibility that FGF21 might be involved in the anti-obesity effect of CLA. In the present study, we tested the hypothesis that FGF21 expression in the liver could be induced by t-10, c-12-CLA through PPAR-α. HepG2 cells were treated with 100 μm-bovine serum albumin, 10 μm-t-10, c-12-CLA or 100 μm-t-10, c-12-CLA for 8 h. A total of ten adult C57BL/6J mice were fed with the diets containing 1 % soya oil or t-10, c-12-CLA for 5 d. t-10, c-12-CLA stimulated hepatic FGF21 mRNA abundance as determined by real-time RT-PCR. t-10, c-12-CLA also increased serum FGF21 concentrations as measured by an ELISA. Co-transfection analysis indicated that reporter gene expression from the mouse FGF21 promoter was induced by t-10, c-12-CLA in a PPAR-α-dependent manner. Taken together, these results suggest that t-10, c-12-CLA induces hepatic FGF21 expression through PPAR-α. This FGF21 and PPAR-α linkage may provide another potential explanation for the anti-obesity effect of t-10, c-12-CLA.

To assess the impact of prebiotic supplementation during gestation and fetal and early neonatal life, gestating BALB/cj dam mice were fed either a control or a prebiotic (galacto-oligosaccharides–inulin, 9:1 ratio)-enriched diet throughout pregnancy and lactation, and allowed to nurse their pups until weaning. At the time of weaning, male offspring mice were separated from their mothers, weaned to the same solid diet as their dam and their growth was monitored until killed 48 d after weaning. Prebiotic treatment affected neither the body-weight gain nor the food intake of pregnant mice. In contrast, at the time of weaning, pups that had been nursed by prebiotic-fed dams had a higher body weight (11·0 (se 1·2) g) than pups born from control dams (9·8 (se 0·9) g). At 48 d after weaning, significantly higher values were observed for colon length and muscle mass in the offspring of prebiotic-fed dams (1·2 (se 0·1) cm/cm and 5·7 (se 1·8) mg/g, respectively), compared with control offspring (1·1 (se 0·1) cm/cm and 2·9 (se 0·9) mg/g, respectively), without any difference in spleen and stomach weight, or serum leptin concentration. The present preliminary study suggests that altering the fibre content of the maternal diet during both pregnancy and lactation enhances offspring growth, through an effect on intestinal and muscle mass rather than fat mass accretion.

The main dietary guidelines recommend restricting total and saturated fat intake in the management of high blood cholesterol levels for cardiovascular risk. These recommendations are usually oversimplified by considering that all red meats should be limited and replaced by white meats. However, lean red meat can be as low in fat as white meat. We examined the effects of red meat (lean breed lamb) and lean white meat (chicken) intake on the lipid profile of a group of women with stable life conditions (nuns living in convents). An open-label, randomised, cross-over study was carried out in thirty-six nuns who consumed either lamb or chicken three times per week for 5-week periods with their usual diet. Clinical, dietary and biochemical variables were evaluated at baseline and the end of each diet period. A validated FFQ was used to assess nutrient intake and monitor compliance. The results showed neither between-diet differences in lipid responses nor differences from baseline in total cholesterol, LDL-cholesterol or TAG for any diet period. In conclusion, consumption of lean red meat (lamb) or lean white meat (chicken) as part of the usual diet is associated with a similar lipid response. These two foods can be exchanged in a healthy diet to increase palatability.

Iodine is required for adequate thyroid hormone production, which is essential for brain development, particularly in the first trimester of pregnancy. Milk is the principal source of iodine in UK diets, and while small studies in Europe have shown organic milk to have a lower iodine concentration than conventional milk, no such study has been conducted in Britain. In view of the increasing popularity of organic milk in the UK, we aimed to compare the iodine concentration of retail organic and conventional milk and to evaluate regional influences in iodine levels. Samples of organic milk (n 92) and conventional milk (n 80), purchased from retail outlets in sixteen areas of the UK (southern England, Wales and Northern Ireland), were analysed for iodine using inductively coupled plasma MS. The region of origin of the milk was determined from information on the label. Organic milk was 42·1 % lower in iodine content than conventional milk (median iodine concentration 144·5 v. 249·5 ng/g; P < 0·001). There was no difference in the iodine concentration of either conventional or organic milk by area of purchase. However, a difference was seen in iodine concentration of organic milk by region of origin (P < 0·001). The lower iodine concentration of organic milk has public-health implications, particularly in view of emerging evidence of iodine deficiency in UK population sub-groups, including pregnant women. Individuals who choose organic milk should be aware that their iodine intake may be compromised and should ensure adequate iodine intake from alternative sources.

Vascular dysfunction is recognised as an integrative marker of CVD. While dietary strategies aimed at reducing CVD risk include reductions in the intake of SFA, there are currently no clear guidelines on what should replace SFA. The purpose of this review was to assess the evidence for the effects of total dietary fat and individual fatty acids (SFA, MUFA and n-6 PUFA) on vascular function, cellular microparticles and endothelial progenitor cells. Medline was systematically searched from 1966 until November 2010. A total of fifty-nine peer-reviewed publications (covering fifty-six studies), which included five epidemiological, eighteen dietary intervention and thirty-three test meal studies, were identified. The findings from the epidemiological studies were inconclusive. The limited data available from dietary intervention studies suggested a beneficial effect of low-fat diets on vascular reactivity, which was strongest when the comparator diet was high in SFA, with a modest improvement in measures of vascular reactivity when high-fat, MUFA-rich diets were compared with SFA-rich diets. There was consistent evidence from the test meal studies that high-fat meals have a detrimental effect on postprandial vascular function. However, the evidence for the comparative effects of test meals rich in MUFA or n-6 PUFA with SFA on postprandial vascular function was limited and inconclusive. The lack of studies with comparable within-study dietary fatty acid targets, a variety of different study designs and different methods for determining vascular function all confound any clear conclusions on the impact of dietary fat and individual fatty acids on vascular function.

In the present study, we sought to conduct a literature review of randomised, double-blind, placebo-controlled trials, which assessed the impact of probiotics intake during pregnancy on the development of eczema in children. A meta-analysis was conducted for comparison of the development of atopic eczema in children whose mothers took probiotics during pregnancy v. placebo. Study selection, quality appraisal and data extraction were performed independently and in duplicate. The studies were rated according to their size in order to calculate the influence of individual studies on the meta-analysis. A total of seven randomised, double-blind, placebo-controlled trials, published between 2001 and 2009, were selected from the PubMed and Ovid databases for the meta-analysis. The meta-analysis was performed with statistical software Stata/SE11.0. The completed meta-analysis of the seven studies shows a significant risk reduction for atopic eczema in children aged 2–7 years by the administration of probiotics during pregnancy (reduction 5·7 %; P = 0·022). However, this effect was only significant for lactobacilli (reduction 10·6 %; P = 0·045), but not for a mixture of various bacterial strains as probiotics (difference 3·06 %, P = 0·204). In conclusion, the meta-analysis shows that the administration of lactobacilli during pregnancy prevents atopic eczema in children aged from 2 to 7 years. However, a mixture of various bacterial strains does not affect the development of atopic eczema, independent of whether they contain lactobacilli or not.

Within a neonatal vitamin A supplementation (VAS) trial, we investigated the effect of VAS on TNF-α, IL-10, IL-5 and IL-13 production after lipopolysaccharide, purified protein derivative (PPD) of Mycobacterium tuberculosis and phytohaemagglutinin stimulation using a whole blood culture protocol. We found that VAS recipients had lower unstimulated TNF-α concentrations than placebo recipients. In the present paper, we investigated whether the SNP TNF-α − 308, TNF-α − 238, IL-10 − 592, IL-10 − 1082 and toll-like receptor 4 (TLR4)+896 modified the effect of VAS on cytokine production. DNA and cytokine concentrations were available from 291 children. We found a significant interaction between TNF-α − 308 genotype and VAS for the unstimulated TNF-α production (Pinteraction = 0·04); among G homozygotes, TNF-α concentrations were significantly lower after VAS compared with placebo, whereas for A carriers, VAS did not appear to have any effect. For TNF-α − 238, there was a tendency towards an increase in PPD-stimulated TNF-α production after VAS for the G homozygotes, but the opposite tendency for A allele carriers (Pinteraction = 0·07). Stratification by sex revealed a significant VAS–genotype interaction for boys for TNF-α − 238. There was a borderline-significant three-way interaction (P = 0·05) between sex, VAS and TLR4+896 genotype. Although the present study had very limited representation of the genetic variation with potential for modification of the response to VAS, it adds to the efforts of untangling the diverse effects and impact of VAS.

Catechins, compounds derived from green tea, have been shown to improve cholesterol metabolism in animal studies, but the molecular mechanisms underlying this function have not been fully understood. We performed DNA microarray analysis in order to clarify the effects of epigallocatechin gallate (EGCG), the dominant catechin in green tea, on cholesterol metabolism in HepG2 hepatocytes. This revealed that the expression levels of several genes related to cholesterol metabolism, including the LDL receptor, were changed by EGCG treatment. Using a real-time PCR technique, we confirmed that EGCG treatment up-regulated mRNA expression level of the LDL receptor. Moreover, EGCG decreased extracellular apoB levels. These findings indicated that EGCG improves cholesterol metabolism through the up-regulation of LDL receptor and also reduces extracellular apoB levels.

The declining inflammatory immune competence of acute (i.e. wasting) pre-pubescent protein–energy malnutrition has been regarded as reflecting an unregulated immunological disintegration. Recent evidence, however, suggests that malnutrition stimulates a regulated immunological reconfiguration to achieve a non-inflammatory form of competence, perhaps offering protection against autoimmune reactions – the ‘Tolerance Model’. Our objective was to determine the influence of acute pre-pubescent malnutrition on the expression of genes critical to tolerogenic regulation. Male and female C57BL/6J mice, initially 19 d old, consumed a complete purified diet either ad libitum (age-matched controls) or in restricted daily quantities (mimicking marasmus), or consumed an isoenergetic low-protein diet ad libitum (mimicking incipient kwashiorkor) for 14 d (six animals per dietary group). Gene expression in the spleen, typically an inflammatory organ, and in the small intestine, a site designed for non-inflammatory defence, was assessed by real-time quantitative RT-PCR, and normalised to β-actin. In the spleen of the malnourished groups, both IL-10 and transforming growth factor-β1 mRNA expression increased compared with controls (P < 0·05), whereas mRNA expression of IL-12p40 decreased (P < 0·05). Conversely, malnutrition exerted no influence on the expression of mRNA for these cytokines in the small intestine (P>0·05). Moreover, forkhead box P3 mRNA expression, indicative of cell-based tolerogenic potential, was sustained in both the spleen and intestine of the malnourished groups (P>0·05). Thus, despite limited supplies of energy and substrates, the spleen shifted towards a non-inflammatory character and the intestine was sustained in this mode in advanced pre-pubescent weight loss. These findings provide the first support for the Tolerance Model at the level of mRNA transcript expression.

d-Fagomine is an iminosugar originally isolated from seeds of buckwheat (Fagopyrum sculentum Moench), present in the human diet and now available as a pure crystalline product. We tested d-fagomine for activities connected to a reduction in the risk of developing insulin resistance, becoming overweight and suffering from an excess of potentially pathogenic bacteria. The activities were: intestinal sucrase inhibition in vitro (rat mucosa and everted intestine sleeves), modulation of postprandial blood glucose in rats, bacterial agglutination and bacterial adhesion to pig intestinal mucosa. When ingested together with sucrose or starch, d-fagomine lowered blood glucose in a dose-dependent manner without stimulating insulin secretion. d-Fagomine reduced the area under the curve (0–120 min) by 20 % (P < 0·01) and shifted the time to maximum blood glucose concentration (Tmax) by 15 min at doses of 1–2 mg/kg body weight when administered together with 1 g sucrose/kg body weight. Moreover, d-fagomine (0·14 mm) agglutinated 60 % of Enterobacteriaceae (Escherichia coli, Salmonella enterica serovar Typhimurium) populations (P < 0·01), while it did not show this effect on Bifidobacterium spp. or Lactobacillus spp. At the same concentration, d-fagomine significantly (P < 0·001) inhibited the adhesion of Enterobacteriaceae (95–99 % cells in the supernatant) and promoted the adhesion of Lactobacillus acidophilus (56 % cells in the supernatant) to intestinal mucosa. d-Fagomine did not show any effect on bacterial cell viability. Based on all this evidence, d-fagomine may be used as a dietary ingredient or functional food component to reduce the health risks associated with an excessive intake of fast-digestible carbohydrates, or an excess of potentially pathogenic bacteria.

Taurine has an important role in numerous physiological processes, including many aspects of fetal development such as development of the pancreas and brain, and requirements increase during pregnancy. Periconceptional undernutrition has long-term effects on pancreas and brain function of the offspring, but the effects on maternal taurine economy are unknown. We, therefore, studied the effects of different periods of periconceptional undernutrition on maternal plasma and urine taurine concentrations before and during pregnancy. Four groups of singleton-bearing ewes were studied (n 10–11): controls fed ad libitum, and groups undernourished from 60 d before until mating (PreC), from 2 d before mating until 30 d after mating (PostC) or from 60 d before until 30 d after mating (Pre+PostC). In PreC ewes, plasma taurine concentrations remained at control levels for the first 30 d, and then decreased through the remainder of undernutrition, but recovered by 30 d after mating; urinary taurine excretion was low at mating, but recovered similarly. In PostC ewes, plasma taurine concentrations recovered after 2 weeks despite ongoing undernutrition; urinary taurine excretion had recovered by 30 d after mating. Pre+PostC ewes followed the same pattern as PreC for the first 60 d, but plasma taurine concentrations and urinary excretion recovered slowly, and did not reach the control levels until 97 d. These data suggest that different periods of mild periconceptional undernutrition in sheep have different but substantial effects on maternal taurine homoeostasis. These effects may be one mechanism by which maternal periconceptional undernutrition alters development of the offspring with implications for adult health.

Choline is an important component of the human diet and is required for the endogenous synthesis of choline-containing phospholipids, acetylcholine and betaine. Choline can also be synthesised de novo by the sequential methylation of phosphatidylethanolamine to phosphatidylcholine. Vitamins B6, B12 and folate can enhance methylation capacity and therefore could influence choline availability not only by increasing endogenous choline synthesis but also by reducing choline utilisation. In the present experiment, we determined whether combined supplementation of these B vitamins affects plasma choline concentration in a rat model of mild B vitamin deficiency which shows moderate increases in plasma homocysteine. To this end, we measured plasma choline and homocysteine concentrations in rats that had consumed a B vitamin-poor diet for 4 weeks after which they were either continued on the B vitamin-poor diet or switched to a B vitamin-enriched diet for another 4 weeks. Both diets contained recommended amounts of choline. Rats receiving the B vitamin-enriched diet showed higher plasma choline and lower plasma homocysteine concentrations as compared to rats that were continued on the B vitamin-poor diet. These data underline the interdependence between dietary B vitamins and plasma choline concentration, possibly via the combined effects of the three B vitamins on methylation capacity.

Formation of advanced glycation end products (AGE) plays a key role in the several pathophysiologies associated with ageing and diabetes, such as arthritis, atherosclerosis, chronic renal insufficiency, Alzheimer's disease, nephropathy, neuropathy and cataract. This raises the possibility of inhibition of AGE formation as one of the approaches to prevent or arrest the progression of diabetic complications. Previously, we have reported that some common dietary sources such as fruits, vegetables, herbs and spices have the potential to inhibit AGE formation. Flavonoids are abundantly found in fruits, vegetables, herbs and spices, and rutin is one of the commonly found dietary flavonols. In the present study, we have demonstrated the antiglycating potential and mechanism of action of rutin using goat eye lens proteins as model proteins. Under in vitro conditions, rutin inhibited glycation as assessed by SDS-PAGE, AGE-fluorescence, boronate affinity chromatography and immunodetection of specific AGE. Further, we provided insight into the mechanism of inhibition of protein glycation that rutin not only scavenges free-radicals directly but also chelates the metal ions by forming complexes with them and thereby partly inhibiting post-Amadori formation. These findings indicate the potential of rutin to prevent and/or inhibit protein glycation and the prospects for controlling AGE-mediated diabetic pathological conditions in vivo.

Maternal low-protein (LP) diets programme β-cell secretion, potentially altering the emergence of ageing of offspring pancreatic function. We hypothesised that isolated pancreatic islet β-cell secretory responses are blunted in offspring exposed to LP during development and age-related reduction is influenced by the developmental stage of exposure to decreased nutrition. We studied male offspring of rats fed control (C) or LP protein (R) diets in pregnancy, first letter and/or lactation second letter of CC, RR, CR or RC groups. Serum glucose, insulin and homeostatic model assessment (HOMA) were measured. Pancreatic islets were isolated and in vitro insulin secretion quantified in low (LG – 5 mm) or high glucose (HG – 11 mm). Body weight and serum values between groups were similar at all ages. Insulin and HOMA rose with age and were highest at postnatal day (PND) 450 in all groups. At PND 36, insulin secretion was greatest in RR and RC. Only CC increased insulin secretion to HG. By PND 110, restricted groups responded less to LG but increased secretion to HG. By PND 450, CC offspring alone increased secretion to HG. Despite minimal differences in circulating insulin and glucose, reduced maternal protein intake affected insulin secretion at all ages. In addition, ageing reduced function in all R groups compared with CC by PND 110 and further by PND 450 most markedly in RC. We conclude that maternal LP diet during pregnancy and/or lactation impairs offspring insulin secretory response to a glucose challenge and alters the trajectory of ageing of pancreatic insulin secretion.