*4.1. The Role of Oral Health in Nutrition and Hypertension*

The findings of this study revealed that the risk of hypertension increased with age, which was consistent with previous reports [5,16]. The study also revealed that in older adults, the absence of posterior occlusal contact increased the risk of hypertension by 1.7 times. The loss of occlusal contact results in a decrease in mastication ability [17]. Thus, this study postulates that the participants in the History of hypertension group were found to have a lower masticatory performance because they had lower oral moisture count, decreased occlusal force, no posterior occlusal contact, and a lesser number of remaining teeth. Tooth loss can lead to hyperactivity of the masticatory system, leading to unhealthy diet patterns and reduced nutrient intake that can negatively influence the general health [58]. Studies have reported that tooth loss was directly related to reduced oral function [17]. Hence, the Japan Ministry of Health, Labor, and Welfare continuously promotes preserving ≥ 20 natural teeth until the age of 80 [58] because tooth loss can decrease posterior occlusal contact, consequently influencing the occlusal force [59]. Reduced occlusal force affects saliva secretion, which is necessary for oral functions such as mastication and swallowing. Other factors such as systemic diseases and medications can influence saliva secretion [17,60]. Hasegawa et al., found that the patients taking antihypertensive drugs have decreased saliva secretion [60]. Dry mouth is a common side effect of antihypertensive medication, which could deteriorate teeth and periodontal condition [49], eventually leading to tooth loss if not addressed properly. In this study, the participants were found to be taking calcium channel blockers (CCBs), renin–angiotensin system inhibitors (angiotensin II receptor blockers (ARBs), angiotensin-converting enzyme (ACE) inhibitors), aldosterone receptor antagonists, β-blockers, and α-blockers. Moreover, there were several participants who took two combinations of medication. It was reported that the masticatory ability

was influenced by the number of natural teeth, occlusal support, muscular weakness, and occlusal force [23].

Mastication is a necessary function for nutrition-ingestion, and an impaired mastication ability leads to many functional declines, including malnutrition [17]. Several observational studies have revealed that tooth loss, particularly in older adults, was associated with dietary intake of fruits and vegetables and a low intake of antioxidative vitamins. Furthermore, the low occlusal force has been linked to a decrease in vegetable, fruit, antioxidant, and dietary fiber intake [23]. The present study presumed that the individuals without posterior occlusal contact prefer foods that are easy to chew and avoid vegetables high in potassium, which was consistent with a study finding that Japanese older adults with <19 teeth had a significantly lower intake of vegetables than those with ≥20 [61]. This was also consistent with the findings of our study that the participants in the History of hypertension group had the lowest intake of potassium. According to the JSH 2019 guidelines, improving dietary patterns, such as increasing fruit and vegetable intakes (to 350 g/day), can reduce the risk of hypertension because potassium antagonizes the hypertensive activity of the sodium [5]. It was also pointed out that balanced ingestion of fruits and vegetables (especially green and yellow vegetables) may be necessary for improved general health [17].
