Is the Association between Green Tea Consumption and the Number of Remaining Teeth Affected by Social Networks?: A Cross-Sectional Study from the Japan Gerontological Evaluation Study Project

Abstract

Consumption of green tea without sugar, as well as social networks, are associated with a lower risk of tooth loss. There is a possibility of confounding both factors because tea is often drunk with friends. Therefore, the present study aimed to examine whether green tea consumption is beneficially associated with the number of remaining teeth, while considering social networks. This cross-sectional study was based on the Japan Gerontological Evaluation Study (JAGES) in 2016. Self-administered questionnaires containing questions about green tea consumption were mailed to 34,567 community-dwelling residents aged ≥ 65 years. We used the number of remaining teeth as a dependent variable, and green tea consumption and the number of friends met over the past month (social network size) as independent variables. Linear regression models with multiple imputation were used. A total of 24,147 people responded (response rate = 69.9%), and 22,278 valid data were included into our analysis. Participants’ mean age was 74.2 years (standard deviation = 6.3), and 45.9% were men. Among the participants, 52.2% had ≥ 20 teeth, 34.2% drank 2–3 cups of green tea per day, and 32.6% met ≥ 10 people over the past month. After adjusting for all potential confounders, both higher green tea consumption and a larger social network size were associated with more remaining teeth (both p for trend < 0.001). The association of green tea was greater among those with smaller social networks (p for interaction < 0.05). The protective association of green tea was remarkable among people with smaller social networks.

The association between social isolation and oral health of community‐dwelling older adults—A systematic review

“…Two studies analyzed data from the 2012 Japan Gerontological Evaluation Study (JAGES) project (Aida et al, 2016; Yamamoto et al, 2014), which is a prospective cohort study investigating social and behavioral factors associated with health among individuals aged 65 years or older from >30 municipalities throughout Japan. Three studies analyzed data from the 2016 JAGES project (Hoshi et al, 2020; Igarashi et al, 2021; Koyama et al, 2021). One study (Morishita et al, 2020) targeted community‐dwelling older adults who participated in a preventive long‐term care project aimed at the maintenance or improvement of physical and mental functions, while other studies all investigated community‐dwelling older adults who were free of care facilities.…”

“…Based on the criteria of the JBI Critical Appraisal Checklist for Analytical Cross‐Sectional Studies, six (Aida et al, 2011; Aida et al, 2016; Burr & Lee, 2013; Igarashi et al, 2021; Koyama et al, 2021; Morishita et al, 2020) out of the 11 included studies scored higher than six points and were rated as high quality. The remaining five studies (Arcury et al, 2013; Avlund et al, 2003; Hoshi et al, 2020; Mikami et al, 2019; Yamamoto et al, 2014) received a score of four or five points and were rated as moderate quality. A summary of the risk of bias assessment is presented in Figure 2.…”

“…The self‐reported number of remaining teeth was the most frequently measured outcome. Three studies evaluated the association between the number of remaining teeth and objective social isolation, which included the friendship network (Aida et al, 2011), social network diversity (Aida et al, 2016), social network contact frequency (Aida et al, 2016), social network size (Aida et al, 2016; Hoshi et al, 2020), and frequency of meeting friends (Aida et al, 2016). Denture use was investigated to clarify the association with frequency of meeting friends and participation in social groups (Yamamoto et al, 2014).…”

“…There are several possible pathways to explain this association. First, people with extensive social contact may receive additional support from different social backgrounds, which may influence them to maintain or form oral health behaviors (Aida et al, 2011; Burr & Lee, 2013; Hoshi et al, 2020). People with significant others, such as spouses, are also likely to have available to them models of appropriate behavior and normative influences (Avlund et al, 2003).…”

“…In addition to these health conditions, limited studies have focused on the contribution of social isolation to oral health. Most studies showed that people who were socially isolated were more likely to have worse oral health in the older population (Aida et al, 2011; Aida et al, 2016; Arcury et al, 2013; Avlund et al, 2003; Burr & Lee, 2013; Hoshi et al, 2020; Yamamoto et al, 2014). In contrast, researchers also investigated the possible influence of oral health status on social isolation (Igarashi et al, 2021; Koyama et al, 2021; Mikami et al, 2019).…”