Chewing well may help protect health later in life

Have you ever noticed that crunchy rice crackers are harder to chew, bread sometimes feels stuck in your throat, or your mouth feels too dry to speak comfortably? Small changes like these may actually be connected to overall health.

Among older adults, weight loss caused by poor nutrition is known to contribute to physical and mental decline and increase the risk of needing long-term care or even death. Previous studies have also shown that specific problems—such as having fewer teeth, difficulty chewing or swallowing, and dry mouth—are related to weight loss.

These kinds of overall declines in oral function are known as oral frailty. However, scientists have not fully understood how oral frailty influences weight loss. Earlier studies often examined factors such as teeth or chewing ability separately and did not fully consider how these factors interact with one another, making it difficult to see the whole picture.

To address this issue, a research team led by Professor Jun Aida at Institute of Science Tokyo (Science Tokyo) developed a new analytical approach that considers five elements together: number of teeth, chewing ability, swallowing ability, dry mouth, and speech clarity. The team followed older Japanese adults living independently for six years and carefully examined how these factors were associated with changes in weight over time.

One of the biggest challenges for the researchers was how to measure the invisible condition of “declining oral function.” Simply adding up scores for the five elements or assuming that they are unrelated may not fully capture their true relationships.

To overcome this challenge, the team introduced a statistical method called structural equation modeling, which allows multiple related factors to be analyzed at the same time. Their analysis showed that people with oral frailty were more likely to lose more than 10% of their body weight over the six-year period.

The study also revealed that the five elements are connected. For example, having fewer teeth can lead to difficulty chewing and even problems with pronunciation. Among the five factors, difficulty chewing showed the strongest association, suggesting that reduced chewing ability lies at the core of oral frailty.

The encouraging news is that oral frailty can often be improved if detected early. Adjusting or replacing ill-fitting dentures, restoring missing teeth, performing exercises to strengthen the tongue and cheek muscles, and training to improve swallowing may help prevent poor nutrition and weight loss.

This research supports the idea of including oral function checks in regular health examinations and highlights the importance of collaboration between medical and dental professionals in caring for older adults. Maintaining oral health may ultimately help people live longer, healthier lives.

In a sense, our study confirmed something that may seem obvious: having fewer teeth can make it harder to chew or speak, and these difficulties can lead to weight loss. Many people assume that eating less is simply a natural part of aging. However, the real issue may be that people cannot chew properly. Noticing small changes in your mouth early may be the first step toward protecting your future health.
（Jun Aida, Professor, Department of Dental Public Health, Graduate School of Medical and Dental Sciences, Institute of Science Tokyo）

Department of Dental Public Health (Japanese)

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