Globally, we are currently facing a rapid demographic shift leading to an increase in the proportion of older adults within the population. This raises concerns about the potential increase in age-related diseases and their impact on our ability to provide adequate health and end-of-life care. To apply appropriate interventions, understanding the changes that happen with ageing becomes essential. Ageing is often accompanied by a decrease in appetite and physical activity, which may lead to malnutrition, resulting in decreased muscle mass, physical capabilities and independence. To preserve muscle mass, older adults are advised to increase protein intake and physical activity. However, protein’s high satiating effect may cause reduced energy intake. Physical activity is also advised to maintain or enhance older adult’s appetite. This review paper aims to discuss appetite-related changes that occur with ageing and their consequences. In particular, it will focus on investigating the relationship between protein intake and physical activity and their impact on appetite and energy intake in the ageing population. Recent studies suggest that physical activity might contribute to maintaining or enhancing appetite in older adults. Nevertheless, establishing a definitive consensus on the satiating effect of protein in ageing remains a work in progress, despite some promising results in the existing literature.

Resistant starch (RS) has received increased attention due to its potential health benefits. This study was aimed to investigate the effects of dietary corn RS on immunological characteristics of broilers. A total of 320 broiler chicks were randomly allocated to five dietary treatments: normal corn–soyabean (NC) diet group, corn starch diet group, 4 %, 8 % and 12 % RS diet groups. This trial lasted for 42 d. The relative weights of spleen, thymus and bursa, the concentrations of nitric oxide (NO) and IL-4 in plasma at 21 d of age, as well as the activities of total nitric oxide synthase (TNOS) and inducible nitric oxide synthase (iNOS) in plasma at 21 and 42 d of age showed positive linear responses (P < 0·05) to the increasing dietary RS level. Meanwhile, compared with the birds from the NC group at 21 d of age, birds fed 4 % RS, 8 % RS and 12 % RS diets exhibited higher (P < 0·05) relative weight of bursa and concentrations of NO and interferon-γ in plasma. Birds fed 4 % RS and 8 % RS diets showed higher (P < 0·05) number of IgA-producing cells in the jejunum. While compared with birds from the NC group at 42 d of age, birds fed 12 % RS diet showed higher (P < 0·05) relative weight of spleen and activities of TNOS and iNOS in plasma. These findings suggested that dietary corn RS supplementation can improve immune function in broilers.

Mycoprotein is a food high in both dietary fibre and non-animal-derived protein. Global mycoprotein consumption is increasing, although its effect on human health has not yet been systematically reviewed. This study aims to systematically review the effects of mycoprotein on glycaemic control and energy intake in humans. A literature search of randomised controlled trials was performed in PubMed, Embase, Web of Science, Google Scholar and hand search. A total of twenty-one studies were identified of which only five studies, totalling 122 participants, met the inclusion criteria. All five studies were acute studies of which one reported outcomes on glycaemia and insulinaemia, two reported on energy intake and two reported on all of these outcomes. Data were extracted, and risk-of-bias assessment was then conducted. The results did not show a clear effect of acute mycoprotein on blood glucose levels, but it showed a decrease in insulin levels. Acute mycoprotein intake also showed to decrease energy intake at an ad libitum meal and post-24 h in healthy lean, overweight and obese humans. In conclusion, the acute ingestion of mycoprotein reduces energy intake and insulinaemia, whereas its impact on glycaemia is currently unclear. However, evidence comes from a very limited number of heterogeneous studies. Further well-controlled studies are needed to elucidate the short- and long-term effects of mycoprotein intake on glycaemic control and energy intake, as well as the mechanisms underpinning these effects.

Psychosocial stress, uncontrolled eating and obesity are three interrelated epidemiological phenomena already present during youth. This broad narrative conceptual review summarises main biological underpinnings of the stress–diet–obesity pathway and how new techniques can further knowledge. Cortisol seems the main biological factor from stress towards central adiposity; and diet, physical activity and sleep are the main behavioural pathways. Within stress–diet, the concepts of comfort food and emotional eating are highlighted, as cortisol affects reward pathways and appetite brain centres with a role for insulin, leptin, neuropeptide Y (NPY), endocannabinoids, orexin and gastrointestinal hormones. More recently researched biological underpinnings are microbiota, epigenetic modifications and metabolites. First, the gut microbiota reaches the stress-regulating and appetite-regulating brain centres via the gut–brain axis. Second, epigenetic analyses are recommended as diet, obesity, stress and gut microbiota can change gene expression which then affects appetite, energy homeostasis and stress reactivity. Finally, metabolomics would be a good technique to disentangle stress–diet–obesity interactions as multiple biological pathways are involved. Saliva might be an ideal biological matrix as it allows metagenomic (oral microbiota), epigenomic and metabolomic analyses. In conclusion, stress and diet/obesity research should be combined in interdisciplinary collaborations with implementation of several -omics analyses.

In recent years, there has been a renewed interest in the role of dietary fibre in obesity management. Much of this interest stems from animal and human studies which suggest that an increased intake of fermentable fibre can suppress appetite and improve weight management. A growing number of reports have demonstrated that the principal products of colonic fermentation of dietary fibre, SCFA, contribute to energy homeostasis via effects on multiple cellular metabolic pathways and receptor-mediated mechanisms. In particular, over the past decade it has been identified that a widespread receptor system exists for SCFA. These G-protein-coupled receptors, free fatty acid receptor (FFAR) 2 and FFAR3 are expressed in numerous tissue sites, including the gut epithelium and adipose tissue. Investigations using FFAR2- or FFAR3-deficient animal models suggest that SCFA-mediated stimulation of these receptors enhances the release of the anorectic hormones peptide tyrosine tyrosine and glucagon-like peptide-1 from colonic L cells and leptin from adipocytes. In addition, the SCFA acetate has recently been shown to have a direct role in central appetite regulation. Furthermore, the SCFA propionate is a known precursor for hepatic glucose production, which has been reported to suppress feeding behaviour in ruminant studies through the stimulation of hepatic vagal afferents. The present review therefore proposes that an elevated colonic production of SCFA could stimulate numerous hormonal and neural signals at different organ and tissue sites that would cumulatively suppress short-term appetite and energy intake.

Dietary regulation of appetite may contribute to the prevention and management of excess body weight. The present study examined the effect of consumption of individual dairy products as snacks on appetite and subsequent ad libitum lunch energy intake. In a randomised cross-over trial, forty overweight men (age 32 (sd 9) years; BMI 27 (sd 2) kg/m2) attended four sessions 1 week apart and received three isoenergetic (841 kJ) and isovolumetric (410 ml) servings of dairy snacks or water (control) 120 min after breakfast. Appetite profile was determined throughout the morning and ad libitum energy intake was assessed 90 min after the intake of snacks. Concentrations of amino acids, glucose, insulin, ghrelin and peptide tyrosine tyrosine were measured at baseline (0 min) and 80 min after the intake of snacks. Although the results showed that yogurt had the greatest suppressive effect on appetite, this could be confounded by the poor sensory ratings of yogurt. Hunger rating was 8, 10 and 24 % (P < 0·001) lower after the intake of yogurt than cheese, milk and water, respectively. Energy intake was 11, 9 and 12 % (P < 0·02) lower after the intake of yogurt, cheese and milk, respectively, compared with water (4312 (se 226) kJ). Although there was no difference in the postprandial responses of hormones, alanine and isoleucine concentrations were higher after the intake of yogurt than cheese and milk (P < 0·05). In conclusion, all dairy snacks reduced appetite and lunch intake compared with water. Yogurt had the greatest effect on suppressing subjective appetite ratings, but did not affect subsequent food intake compared with milk or cheese.

The localization and distribution of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica at different stages in the development of the adult fluke have been determined by an indirect immunofluorescence technique, using antisera to 19 vertebrate peptides and the invertebrate neuropeptide, FMRFamide. Positive immunoreactivity was obtained with antisera to pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), substance P (SP) and FMRFamide. Cell bodies and nerve fibres immunoreactive to the 4 peptides are present in the anterior ganglia and the 3 pairs of longitudinal nerve cords and their commissures in the central nervous system. In the peripheral nervous system, immunoreactivity occurs in the nerve plexuses supplying the subtegumental musculature, the oral and ventral suckers, and the muscular lining of the male and female reproductive ducts, including the ootype, uterus, cirrus pouch and gonopore. Cells displaying immunoreactivity to PYY and FMRFamide lie amongst the Mehlis' gland cells that surround the ootype. Processes from these cells extend into the wall of the ootype. One group of PP-immunoreactive cells occurs at the junction of the vitelline and ovovitelline ducts, whilst another group is situated at the entrance to the uterus from the ootype. The results are discussed in relation to the possible roles of the peptides in the neurophysiology and egg production of the fluke.