Background: Dietary fibre consists of non-digestible forms of carbohydrate, usually as polysaccharides that originate from plant-based foods. Over recent decades, our diet within Westernised societies has changed radically from that of our hominid ancestors, with implications for our co-evolved gut microbiota. This includes increased ingestion of ultra-processed foods that are typically impoverished of dietary fibre, and associated reduction in the intake of fibre-replete plant-based foods. Over recent decades, there has been a transformation in our understanding of the health benefits of dietary fibre. Objective: To explore the current medical literature on the health benefits of dietary fibre, with a focus on overall metabolic health. Data Sources: We performed a narrative review, based on relevant articles written in English from a PubMed search, using the terms ‘dietary fibre and metabolic health’. Results: In the Western world, our diets are impoverished of fibre. Dietary fibre intake associates with overall metabolic health (through key pathways that include insulin sensitivity) and a variety of other pathologies that include cardiovascular disease, colonic health, gut motility and risk for colorectal carcinoma. Dietary fibre intake also correlates with mortality. The gut microflora functions as an important mediator of the beneficial effects of dietary fibre, including the regulation of appetite, metabolic processes and chronic inflammatory pathways. Conclusions: Multiple factors contribute to our fibre-impoverished modern diet. Given the plethora of scientific evidence that corroborate the multiple and varied health benefits of dietary fibre, and the risks associated with a diet that lacks fibre, the optimization of fibre within our diets represents an important public health strategy to improve both metabolic and overall health. If implemented successfully, this strategy would likely result in substantial future health benefits for the population.

Polycystic ovary syndrome (PCOS) is a common, highly heritable complex disorder of unknown aetiology characterized by hyperandrogenism, chronic anovulation and defects in glucose homeostasis. Increased luteinizing hormone relative to follicle-stimulating hormone secretion, insulin resistance and developmental exposure to androgens are hypothesized to play a causal role in PCOS. Here we map common genetic susceptibility loci in European ancestry women for the National Institutes of Health PCOS phenotype, which confers the highest risk for metabolic morbidities, as well as reproductive hormone levels. Three loci reach genome-wide significance in the case–control meta-analysis, two novel loci mapping to chr 8p32.1 and chr 11p14.1, and a chr 9q22.32 locus previously found in Chinese PCOS. The same chr 11p14.1 SNP, rs11031006, in the region of the follicle-stimulating hormone B polypeptide (FSHB) gene strongly associates with PCOS diagnosis and luteinizing hormone levels. These findings implicate neuroendocrine changes in disease pathogenesis.

BACKGROUND-Epidemiologic and genetic evidence links type 2 diabetes, obesity, and cancer. The tumor-suppressor phosphatase and tensin homologue (PTEN) has roles in both cellular growth and metabolic signaling. Germline PTEN mutations cause a cancer-predisposition syndrome, providing an opportunity to study the effect of PTEN haploinsufficiency in humans.

SummaryObjective Application of the newly introduced Rotterdam criteria for polycystic ovary syndrome (PCOS) generates four phenotypic subgroups, defined by the presence/absence of three diagnostic elements: polycystic ovarian (PCO) morphology (P); hyperandrogenism (H); and oligo-amenorrhoea (O). Whilst PCOS is associated with adverse metabolic features, the strength of the association within individual subgroups is not established. We characterized the metabolic and endocrine profiles of PCOS women who are oligomenorrhoeic but normoandrogenaemic, and compared these to other PCOS women and controls. Design Retrospective dataset analyses. Patients A total of 309 Europid PCOS women, all with PCO morphology, of whom 191 were also hyperandrogenaemic and oligomenorrhoeic (PHO), 76 hyperandrogenaemic with normal menses (PH) and 42 oligomenorrhoeic but normoandrogenaemic (PO); plus 76 Europid control women without PCOS. Measurements Metabolic parameters: fasting insulin, lipids, homeostasis model assessment (HOMA) measures of insulin sensitivity; endocrine variables: LH, FSH; prevalence of metabolic syndrome. Results Insulin sensitivity: PO women were indistinguishable from controls, and markedly less insulin-resistant than PHO women ( vs. controls, P = 0·38 after adjustment for BMI and age; vs. PHO, P = 0·003). Metabolic syndrome: the prevalence in PO women (7·1%) was similar to that in controls (3·9%), and lower than in PHO women (29·3%, P < 0·0001). LH levels: PO women were intermediate between controls ( vs. controls, P = 0·008) and PHO women ( vs. PHO, P = 0·06).Conclusions Normoandrogenaemic, oligomenorrhoeic women with PCOS are metabolically similar to control women with significantly fewer metabolic features than PCOS women who are also hyperandrogenaemic. However, higher than normal LH and lower sex hormone-binding globulin (SHBG) concentrations in the PO women support the view that they form part of the spectrum of PCOS.

Background National and global recommendations for BMI cutoffs to trigger action to prevent obesity-related complications like type 2 diabetes among non-White populations are questionable. We aimed to prospectively identify ethnicity-specific BMI cutoffs for obesity based on the risk of type 2 diabetes that are risk-equivalent to the BMI cutoff for obesity among White populations (≥30 kg/m²).Methods In this population-based cohort study, we used electronic health records across primary care (Clinical Practice Research Datalink) linked to secondary care records (Hospital Episodes Statistics) from a network of general practitioner practices in England. Eligible participants were aged 18 years or older, without any past or current diagnosis of type 2 diabetes, had a BMI of 15•0-50•0 kg/m² and complete ethnicity data, were registered with a general practitioner practice in England at any point between Sept 1, 1990, and Dec 1, 2018, and had at least 1 year of follow-up data. Patients with type 2 diabetes were identified by use of a CALIBER phenotyping algorithm. Self-reported ethnicity was collapsed into five main categories. Age-adjusted and sex-adjusted negative binomial regression models, with fractional polynomials for BMI, were fitted with incident type 2 diabetes and ethnicity data. Findings 1 472 819 people were included in our study, of whom 1 333 816 (90•6%) were White, 75 956 (5•2%) were south Asian, 49 349 (3•4%) were Black, 10 934 (0•7%) were Chinese, and 2764 (0•2%) were Arab. After a median follow-up of 6•5 years (IQR 3•2-11•2), 97 823 (6•6%) of 1 472 819 individuals were diagnosed with type 2 diabetes. For the equivalent age-adjusted and sex-adjusted incidence of type 2 diabetes at a BMI of 30•0 kg/m² in White populations, the BMI cutoffs were 23•9 kg/m² (95% CI 23•6-24•0) in south Asian populations, 28•1 kg/m² (28•0-28•4) in Black populations, 26•9 kg/m² (26•7-27•2) in Chinese populations, and 26•6 kg/m² (26•5-27•0) in Arab populations.Interpretation Revisions of ethnicity-specific BMI cutoffs are needed to ensure that minority ethnic populations are provided with appropriate clinical surveillance to optimise the prevention, early diagnosis, and timely management of type 2 diabetes.

Aims/hypothesis Variants in the fat-mass and obesityassociated gene (FTO) influence susceptibility to type 2 diabetes via an effect on adiposity/obesity. Given the important role of obesity in the aetiology of both polycystic ovary syndrome (PCOS) and type 2 diabetes mellitus, our aim was to establish whether FTO variants are also implicated in PCOS susceptibility. MethodsWe performed a genetic association study of FTO variant rs9939609 using case-control analyses, conducted in 463 PCOS patients (geometric mean BMI 27.5 kg/m 2 ) and 1,336 female controls (geometric mean BMI 25.3 kg/ m 2 ) of UK British/Irish origin. We also sought evidence for associations between FTO variation and circulating testosterone levels in 324 UK PCOS patients and 1,000 women from the Northern Finland Birth Cohort of 1966. Outcome Diabetologia (2008) [adjusted]). This association was most evident in obese PCOS patients (PCOS patients below median BMI vs UK controls, p=0.11; above median BMI vs controls, p=2.9× 10 −4 ). No relationship between FTO genotype and androgen levels was seen. Conclusions/interpretation We provide the first evidence that variants that predispose to common obesity also result in altered susceptibility to PCOS, confirming the mechanistic link between these conditions. The predominant effect of FTO variants on PCOS susceptibility is probably mediated through adiposity.

Polycystic ovary syndrome (PCOS) is a common female condition typified by reproductive, hyperandrogenic, and metabolic features. Polycystic ovary syndrome is a genetic condition, exacerbated by obesity. There is a close link between obesity and PCOS based on epidemiological data, and more recently corroborated through genetic studies. There are many mechanisms mediating the effects of weight-gain and obesity on the development of PCOS. The metabolic effects of insulin resistance and steroidogenic and reproductive effects of hyperinsulinaemia are important mechanisms. Adipokine production by subcutaneous and visceral fat appears to play a part in metabolic function. However, given the complexity of PCOS pathogenesis, it is important also to consider possible effects of PCOS on further weight-gain, or at least on hampering attempts at weight-loss and maintenance through lifestyle changes. Possible mediators of these effects include changes in energy expenditure, mental ill health, or physical inactivity. In this brief review, we discuss the main mechanisms that underlie the association between obesity and PCOS, from divergent perspectives of weight-gain contributing to development of PCOS and vice versa. We also consider novel management options for women with obesity and PCOS.

eral action of irisin improves glucose homeostasis and increases energy expenditure, with no data on a central role of irisin in metabolism. These studies sought to examine 1) presence of irisin in human cerebrospinal fluid (CSF) and banked human hypothalamic tissue, 2) serum irisin in maternal subjects across varying adiposities with or without gestational diabetes (GDM), and 3) their respective neonate offspring. CSF, serum, and neonatal cord serum were collected from 91 pregnant women with and without GDM attending for an elective cesarean section [body mass index (BMI): 37.7 Ϯ 7.6 kg/m 2 ; age: 32 Ϯ 8.3 yr]. Irisin was assessed by ELISA and correlated with biochemical and anthropometric data. Irisin expression was examined in human hypothalamus by immunohistochemical staining. Serum irisin in pregnant women was significantly lower in nonobese compared with obese and GDM subjects, after adjusting for BMI, lipids, and glucose. Irisin was present in neonatal cord serum (237 Ϯ 8 ng/ml) and maternal CSF (32 Ϯ 1.5 ng/ml). CSF irisin correlated positively with serum irisin levels from nonobese and obese pregnant women (P Ͻ 0.01), with CSF irisin significantly raised in GDM subjects (P Ͻ 0.05). Irisin was present in human hypothalamic sections in the paraventricular neurons, colocalized with neuropeptide Y. Irisin was detectable in CSF and in paraventricular neurons. Maternal serum irisin was lower in nonobese pregnant women after adjusting for BMI and a number of metabolic parameters. These studies indicate that irisin may have a central role in metabolism in addition to the known peripheral role. Further studies investigating the central action of irisin in human metabolic disease are required.irisin; obesity; gestational diabetes mellitus; leptin EMERGING DATA SUGGEST THAT a newly discovered polypeptide hormone, irisin, a cleaved secreted form of fibronectin type III domain containing 5 (FNDC5), has the potential to increase energy expenditure and improve glucose homeostasis in humans (4,16,31,34). This is particularly significant, since irisin can induce the transformation of white adipocytes into "beige" or "brite" adipocytes, which can ultimately lead to increased mitochondrial respiration (4, 34), with implications for weight loss. Therefore, such studies suggest the potential therapeutic applications of irisin not only in use for weight loss but also to improve glucose metabolism (4). Subsequent research has also revealed that the function of irisin appears to fall beyond its original role noted in muscle (4,9,13,21,23), and the administration of exogenous irisin could theoretically increase energy expenditure during or after weight loss. Recent studies have shown that irisin may also act as an adipokine (21, 25) as well as a potential "neurokine" (9, 12). Although the role of irisin in the brain is unclear, analysis has revealed that FNDC5 knockdown in murine embryonic stem cells reduces neurogenesis (11), whereas pharmacological doses of irisin increase proliferation of mouse hippocampal neuronal cells (20...