Resilience, perceived danger and work attendance of Sudanese healthcare workers in war zones: the April 2023 armed conflict.

A healthy gastrointestinal environment supports nutrient digestion and absorption, and also contributes to aspects of immune, metabolic, and mental health (Bischoff, ). While lacking a clear definition, gut health can be referred to as a state where the gastrointestinal system functions in the absence of (i) gastrointestinal complaints (e.g., abdominal pain, bloating, diarrhoea); (ii) indications of bowel disease, for example, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD); and (iii) confirmed bowel disease (Bischoff, ). Gastrointestinal complaints are widely experienced in most populations, with approximately 40% of the global population experiencing ≥1 symptom associated with functional gastrointestinal disorders (FGIDs) (Sperber et al., ), symptom-based conditions without identifiable structural or biochemical abnormalities that explain their clinical features (Drossman and Hasler, ). They are characterised by symptoms such as abdominal pain and discomfort, bloating, diarrhoea, and constipation, with IBS and functional dyspepsia being the most common presentations (Drossman and Hasler, ), which can disrupt gastrointestinal functioning and can cause emotional distress and negatively impact quality of life (QoL) (Farndale and Roberts, ). FGIDs affect a substantial proportion of the population and are associated with considerable socioeconomic consequences, with the annual cost per person with IBS in Europe estimated at €3,000 (Flacco et al., ; Sperber et al., ). FGIDs can be managed through pharmacological therapies, although lifestyle adjustments are also highly important, with a growing interest in the role of dietary intake in this context (Sayuk and Gyawali, ; Marasco et al., ). Fermented foods are of particular interest, due to their potential to positively impact the gastrointestinal environment and improve symptoms of dysfunction (Leeuwendaal et al., ). A variety of fermented dairy foods are commonly produced through the desirable action of microorganisms including yoghurt, kefir, fermented milk, and cheese (Marco et al., ). Animal and human studies show that some fermented milks, yoghurts, and kefirs can benefit those with functional gastrointestinal symptoms (Ní Chonnacháin et al., ). While research shows fermented dairy foods offer a potential solution to improve gastrointestinal parameters in cohorts with gastrointestinal dysfunction, the majority of studies have focused on fermented milks (liquid food matrix) and yoghurts (gel-viscoelastic food matrix), which often contain live microorganisms (Ní Chonnacháin et al., ). An alternative method for delivering health benefits associated with fermentation is via a dried fermented product, known as a fermentate (Mathur et al., ). A fermentate is typically a dried powder formulation derived from a fermented product (e.g., fermented milk) that can contain the fermenting microorganisms (e.g., lactic acid bacteria (LAB)), components of these microorganisms, culture supernatants, fermented substrates, and a range of metabolites and bioactive components with potential health benefits (Mathur et al., ). Dried dairy fermentates are commonly produced using LAB that undergo a heat-killing phase during processing prior to drying by either freeze-drying or spray drying, the purpose of which is to inactivate the microbes present (Mathur et al., ). As fresh fermented foods containing live microorganisms have a short shelf life, fermentates offer the potential for increased food safety and stability during processing, transport, and storage (Wei et al. ; Kaya et al. ), with the possibility for use as a food ingredient to enhance the nutritional profile of a variety of foods. Emerging evidence highlights the efficacy of fermentates in managing gastrointestinal disorders, reducing inflammation, and improving overall gut health (Żółkiewicz et al., ). Specifically, LAB have been investigated for their effects on human health, including the gut (Pasolli and Ercolini, ), with subsp. gaining interest recently (Wang et al., ). Fermentation of dairy via LAB can produce bioactive substances such as peptides with angiotensin-converting enzyme-inhibitory activity (Gobbetti et al., ; Regazzo et al., ), which has been linked with inflammation and immunity (Oosthuizen and Sturrock, ). Cell-line work has shown subsp. to eliminate modulated cytotoxicity in addition to reducing colonisation of cells in colorectal cells (Banerjee et al., ). Extracellular polysaccharides are produced by LAB during fermentation and have been shown to have immunomodulatory effects in mouse models (Makino et al., ; Nagai et al., ) and further confirmed in a human study to increase natural killer cell activity and reduce the risk of catching the common cold in elderly individuals (Makino et al., ). Trials in porcine cells suggest expression of IL-6 and proinflammatory chemokines may be implicated here (Kanmani et al., ). Few studies consider the effect of fermented dairy, includi