The Interplay between Metabolic Syndrome and Oral Health – A Possible Unexpected Link with Cognitive Dysfunction

Abstract

Metabolic syndrome (MetS) is not a single disease but a cluster of conditions that significantly increase medical risks. It is typically defined by the presence of five metabolic risk factors: atherogenic dyslipidaemia, high blood pressure, hyperglycaemia, a prothrombotic state, and a proinflammatory state. MetS is a global pandemic that involves chronic inflammation and insulin resistance, leading to higher risks of heart disease, diabetes, stroke, and other disabilities. It also includes visceral adiposity, dyslipidaemia, endothelial dysfunction, genetic susceptibility, and hypertension. The connections between MetS, cognition, and oral health are complex and multifaceted. This narrative review aims to describe the relationships between each pair of conditions and a broader interconnection among all three. MetS has a bidirectional relationship with oral health, influenced by insulin resistance and local inflammation, impacting both masticatory function and glycaemic control. Additionally, there is a significant link between oral health and cognition, involving various aspects of daily life, such as poor oral hygiene practices, nutritional deficiencies, and intricate biological mechanisms, including inflammatory and immunological responses. Nutrition plays a crucial role in influencing all three areas. Essential nutrients such as proteins, carbohydrates, fats, minerals, and vitamins are vital for maintaining and improving metabolic health, cognitive function, and oral health. The nutritional factors affecting MetS, cognition, and oral health are interrelated. Poor nutrition can lead to MetS, which can impair cognitive function and increase the risk of oral health issues. Furthermore, inflammation and oxidative stress, common in MetS, are also involved in cognitive decline and periodontal disease. Among the different nutritional factors, malnutrition, antioxidants, omega-3 fatty acids, and dietary fibers are especially crucial, as they collectively aid metabolic processes, prevent cognitive decline, and support oral health. Healthcare professionals must understand the mechanisms linking MetS, cognition, and oral health to develop effective preventive and therapeutic strategies.