A medical paper clarifying the relationship between hypertension and oral function in elderly people through dietary habits has been published in the international medical journal "Nutrients"

A paper by Professor Ken Niimura, Chief of Department of General Internal Medicine, and Part-time Lecturer Yoko Hasegawa Department of Oral and Maxillofacial Surgery was published in the international medical academic journal Nutrients (4th February 2022).

In a joint study with Hyogo Medical University, Niigata University Graduate School of Medical and Dental Sciences, and Tanba Sasayama City, a cohort study was conducted on elderly people living in the Tanba Sasayama area of Hyogo Prefecture, and the relationship between hypertension and oral function in the elderly was clarified from their dietary habits. For details, please see below.

The Association of Dietary Intake, Oral Health, and Blood Pressure in Older Adults: A Cross-sectional Observational Study

Pinta Marito, Yoko Hasegawa, Kayoko Tamaki, Ma Therese Sta. Maria, Yu Zenmoto, Hiroshi Kusunoki, Shotaro Tsuji, Yosuke Wada, Takahiro Ono, Takashi Sawada, Hiromitsu Kishimoto, and Ken Niimura

This research is a collaborative study with Hyogo Medical University, Niigata University Graduate School of Medical and Dental Sciences, and Tamba Sasayama City.
It is known that high blood pressure in the elderly is related to daily dietary habits such as salt intake. In addition, the Suita Study (a cohort study of the general population of Suita City, Osaka Prefecture) in Japan has reported a relationship between high blood pressure and oral function in the elderly. This paper shows that oral function is related to changes in blood pressure in the elderly, and that "a high ability to chew food is extremely important in maintaining a diet that is preventive against high blood pressure." In particular, evidence was obtained that a lack of bite alignment in the back teeth "increases the risk of high blood pressure by 1.7 times."
In order to reduce the risk of hypertension in the elderly, it is important to reduce salt intake and increase fruit and vegetable intake, but it is difficult to continue such a diet if the oral function is poor. Therefore, it is considered important for the elderly to extend their healthy lifespan by providing appropriate dietary guidance while maintaining the oral function through cooperation between medical and dental departments.

Hypertension is said to be one of the leading causes of death among non-communicable diseases in Japanese people. Approximately 70% of Japanese people over the age of 75 are said to have hypertension, and various lifestyle habits are related to the onset of hypertension. In the field of dental and oral surgery, it has been reported that periodontal disease and the number of teeth are related to hypertension.
The mouth is an important organ for absorbing nutrients and is said to be involved in the development of various diseases. When the oral cavity and overall condition change due to aging or disease, food choices and eating habits change. According to the 2018 National Health and Nutrition Survey in Japan, about 25% of people over 60 years old complain of a decrease in masticatory function and are unable to chew a variety of foods. People who have lost teeth also tend to prefer soft, easy-to-chew foods and avoid foods that are rich in dietary fiber and high in nutrients. Chewing is the first step in the digestive process, which involves breaking down food into small pieces and swallowing it, and it makes it easier to absorb nutrients, which is essential for maintaining health, especially in the elderly.
The relationship between dietary intake and high blood pressure is widely known, but there is little research on "what role oral health plays in the relationship between dietary intake and high blood pressure." Therefore, in this study, we investigated and analyzed the relationship between "blood pressure, dietary intake" and "oral function."

This cross-sectional study was conducted as part of the cohort study "Frail elderly study in the Tamba Sasayama-Area (FESTA)" conducted in Tamba Sasayama City, Hyogo Prefecture. The study subjects were "independent community-dwelling elderly people aged 65 years or older (894 people)" who voluntarily participated in a joint medical and dental research study between April 2016 and December 2019 and provided written informed consent.
Hypertension was classified according to the guidelines of the Japanese Society of Hypertension. The condition of the oral cavity was evaluated based on the number of remaining teeth, occlusal force (chewing force), posterior occlusal support (occlusion of the molars), chewing ability, oral moisture content, and oral bacterial count.
Dietary intake was assessed using a short-form self-administered dietary history questionnaire (BDQH). Health information, including exercise habits, smoking habits, diabetes, dyslipidemia, chronic kidney disease, cardiovascular disease, and stroke, was collected from participants through a questionnaire survey.
As a result of the analysis, the following patient background factors were identified as related to hypertension: age, body mass index (calculated as weight (kg) ÷ (height (m) squared)), state of molar occlusal support area, and sodium/potassium ratio in ingested foods. In particular, it was revealed that the odds ratio of hypertension was significantly higher at 1.72 for elderly people who had lost molar occlusal support area.

・Hyogo Prefecture Dental Association
・8020 Foundation
・Mitsui Sumitomo Insurance Welfare Foundation
・Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (Kakenhi) (Ken Niimura 2016-2018 Grant number 16KT0012)

Because this study was a cross-sectional study, the causal relationship between "high blood pressure in the elderly," "oral function," and "dietary habits" is unclear. In the future, we would like to follow up changes in blood pressure in the elderly over time to clarify in detail "how maintaining good oral function plays a preventive role against high blood pressure."