Positive relationships between masticatory function, blood lipids, and complement components in Chinese oldest-old and centenarian population

Abstract

Nowadays, oral health has become a global academic consensus. A major threat to the oral health of the elderly population is the loss of teeth. In many countries, the rate of total teeth loss in people over 65 years old is between 7% and 45%.1 Recessionary masticatory ability in edentulous populations leads to lacked food diversity, changes the dietary structure and insufficient nutritional intake, whichmay further lead to decreased blood lipids and body resistance.2 Meanwhile, lipid metabolism also plays an important role in immune cell function.3 It is closely related to liver physiology and pathology and is also involved in regulating macrophage biology.4 Abnormal blood lipids may affect the basic life activities of cells and lead to an imbalance of immune function. A recent study has found that blood lipids were correlated with immune function.5 The change inmasticatory function could affect the metabolism of blood lipids and the risk of immune abnormality. The evaluation of immune function is of great significance in the elderly population. Complement components, produced partly in the liver and secreted partly by the macrophages, are essential to immune system.6 Complement components play an important role in body resistance through immunoconditioning and interfere with the release of cytokines involved in immune responses.7 Whether masticatory function affects the alteration in blood lipids and complement levels has not yet been determined, especially in Chinese elderly population. This study investigated the relationships between masticatory function, blood lipids, and complement components in Chinese oldest-old and centenarians (Figure S1A). Based on the China Hainan Centenarian Cohort Study (CHCCS), this survey was carried out in 18 cities and counties of Hainan, China. All 1712 oldest-old and centenarian participants with complete data and had no diagnosed rheumatoid arthritis and other autoimmune diseases. Home interviews and physical checkups were conducted following standard procedures by our strictly trained investigator.8 A portable ultrasound machine (Philips CX50, Philips Medical Systems, Andover, MA, USA) was used to measure the periumbilical fat thickness (PFT) by experienced radiologists. In the oral examination of each participant, professional dentists were arranged to record the number of remaining teeth, missing teeth, tooth position, and denture restoration using mouth mirror and probe. Edentulous participants without dentures were assigned to the group without masticatory function,