Assessing the Effects of a Daily Prebiotic Fibre Blend on Inflammation, the Gut Microbiome, and Self-Report Measures of Mental Health in Individuals With Metabolic Syndrome

Metabolic syndrome is not a chronic disease, but a cluster of metabolic abnormalities including central obesity, insulin resistance, hyperglycemia, hypertension, and dyslipidemia. In the UK, it's estimated that 1 in 3 adults aged 50 years or over meets the criteria of metabolic syndrome. Emerging evidence suggests that metabolic syndrome is associated with low-grade systemic inflammation, which is thought to play a critical role in the subsequent pathogenesis of various metabolic and cardiovascular diseases. In fact, the inflammatory biomarker, high-sensitivity (hs)-CRP, has been shown to be predictive of whether metabolic syndrome progresses to a chronic disease, including cardiovascular disease (CVD), type 2 diabetes (T2D), and cancer mortality. Alongside metabolic disturbances, recent studies have shown that repeated (or long-term) exposure to systemic inflammation is also associated with an increased risk of future depressive and anxiety symptoms, potentially acting via the blood-brain barrier (BBB) interface.

From both a physical and mental health standpoint, it's clear that novel interventions, beyond pharmacotherapy, are needed to reverse the progression of metabolic syndrome, and reduce the risk of developing a long-term chronic disease, and poor mental health.

It is well established that dietary fibre plays a critical role in reducing symptoms of metabolic syndrome, including improvements in insulin sensitivity, glucose metabolism, lipid profile, and blood pressure. Specifically, dietary fibre has been shown to reduce cholesterol levels by binding to bile acids and promoting their excretion, as well as by decreasing the absorption of dietary cholesterol. Additionally, dietary fibre can slow the absorption of carbohydrates and reduce post-prandial glucose spikes, which may contribute to improvements in insulin sensitivity and metabolic health.

Growing evidence also suggests that the mechanisms underlying the benefits of fibre are thought to be mediated, at least in part, by the gut microbiota and their metabolites, such as short-chain fatty acids (SCFAs). A recent systematic review and meta-analysis of 10 randomised controlled trials found that increased intake of dietary fibre was associated with significant improvements in fasting glucose, insulin resistance, total cholesterol, and low-density lipoprotein (LDL) cholesterol levels in individuals with type 2 diabetes. Furthermore, a randomised controlled trial in individuals with metabolic syndrome found that supplementation with a prebiotic fibre blend led to significant reductions in fasting glucose, insulin resistance, and inflammatory markers. Therefore, increasing prebiotic fibre intake may represent a promising strategy for the prevention and management of metabolic symptoms, but remains poorly understood.

Prebiotics are specific types of fibres found in foods like onion, garlic, artichokes, asparagus, leeks, and chicory root. However, to reap the benefits of prebiotics for given health indications, this requires someone to consume roughly 5-10 onions a day. Prebiotic fibre blends (in powder form) are derived from a diversity of plant-based sources, and allows for the study of prebiotic-based benefits in a feasible, easy, measurable, and controlled way.