A new cross-sectional study investigating the relationship between the number of teeth, self-reported gum condition and intake of food and nutrition has demonstrated that people with type 2 diabetes are more likely to lack key nutrients such as dietary fibre, vitamins, and minerals due to a decrease in the number of teeth and deterioration of the condition of their gums.

With a link between nutrition and oral health identified, the results released during Diabetes Awareness Month in November indicate that it is important for patients with type 2 diabetes to receive dietary advice according to their oral health condition.

The joint study by the Clinic Masae Minami/Minami Diabetes Clinical Research Center and international oral healthcare company Sunstar investigated oral health factors, such as number of teeth, condition of gums, and food and nutrient intake through a brief self-reported questionnaire, as well as physical indicators, including HbA1c and BMI.

The study confirms that there is a strong relationship between oral health and nutrient and food intake in patients with type 2 diabetes. The results identified that individuals with fewer teeth had lower consumption of plant protein and carotenes and were older. And poor gum condition was associated with lower intake of B vitamins (vitamin B1, vitamin B2, vitamin B6, folic acid, and pantothenic acid), vitamin C, total dietary fibre, soluble dietary fibre, and insoluble dietary fibre.

The results also showed a significant correlation between the number of teeth and dietary fibre intake after age and sex adjustment - particularly for those with HbA1c levels of seven per cent or higher, where patients with fewer teeth showed lower dietary fibre intake. Similarly, the relationship was observed for individuals with a BMI less than 25, while those with a BMI of 25 or higher had consistently low dietary fibre intake regardless of the number of teeth.

While the results of this study alone do not reveal a causal relationship, it is expected that the quality of life for people with diabetes will be improved by receiving dietary advice according to their oral health condition and supporting them to chew and eat.

Key research results

1. Relationship between number of teeth and condition of gums to intake of food and nutrients (Spearman's ρ)

Lower intakes of green leafy vegetables, carrots/ squash, as well as vegetable proteins and carotene, were in correlation to fewer teeth.

People with self-reported poor gum health consumed less fish with bones, carrots/squash, and alcoholic beverages, as well as vegetable proteins, minerals including potassium, calcium, magnesium, carotenes, B vitamins (vitamin B1, vitamin B2, vitamin B6, folic acid, and pantothenic acid), vitamin C, and soluble, insoluble, and total dietary fibre.

2. Investigating the relationship between the number of teeth and dietary fibre intake considering other factors (generalised linear model)

When analysing the intake of dietary fibre - which is considered crucial in dietary therapy for diabetic patients - a significant correlation was shown. Specifically, more teeth meant a greater intake of total dietary fibre, soluble dietary fibre, and insoluble dietary fibre. This data was adjusted for the effects of gender and age.

In addition, subjects were clustered based on their metabolic control (measured as HbA1c) and number of teeth and compared for total dietary fibre intake, again adjusting for gender and age. In the group with HbA1c of less than seven per cent, there was no association between the amount of total dietary fibre and the number of teeth. However, in the group with poor metabolic control (HbA1c ≥ seven per cent), total daily dietary fibre intake was significantly lower in the group with substantial tooth loss (fewer than 24 teeth), compared to the group with 24 or more teeth. (Figure 1: Upper row)

Subjects were also clustered according to their BMI. Surprisingly, in the group with a BMI lower than 25 (considered as healthy), it was shown that the total dietary fibre intake was significantly lower in patients with substantial tooth loss (fewer than 24 teeth), compared to those with 24 or more teeth. In the cluster of patients with a BMI of 25 or higher (considered as obese), the values were low in both groups, and there was no difference between the groups. (Figure 1: Lower row)

Research background and purpose

Figure 1. Stratified analysis of number of teeth (24 or more) and total dietary fibre content (Generalised linear model).

Dietary therapy for diabetes is based on optimising energy intake and nutrient composition, and from the perspective of preventing complications, consumption of dietary fibre- rich foods is recommended.

It is often reported that the decrease in the number of teeth affects the amount and diversity of food intake and nutrients. Patients with type 2 diabetes have a high risk of developing periodontal disease and are prone to tooth loss, and there is concern that a subsequent decline in oral function could make appropriate dietary therapy difficult. However, the relationship between oral health and nutrition and food intake in diabetic patients is not well understood.

Study methodology

The cross-sectional study involved 104 patients with type 2 diabetes who had 15 or more natural teeth, attending clinics. Indicators related to oral health, including number of teeth and self-reported condition of gums (ranging from very good to poor), were considered. A brief self-administered dietary history questionnaire was used to calculate crude daily intake to investigate food and nutrients. Additionally, physical indicators included HbA1c and BMI.

References available on request.

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