Researchers Assess If Increased Protein Intake Affects Oral Health and Microbiota Composition

Oral health and nutrition are closely related. This relationship is most evident in older adults who often suffer from a decline in both oral health and nutritional status. Multiple studies have identified low protein intake among older adults as associated with poor oral health.¹

Poor oral health in older adults is identified as a high caries rate, periodontal disease, edentulism, and xerostomia. Most of these conditions are microbiota-associated diseases, and new evidence suggests that protein intake is associated with oral microbiota composition.¹

A randomized controlled trial evaluated physical function outcomes when protein intake was increased. Additionally, in a subgroup of the trial participants, the researchers assessed the effects on oral health outcomes and oral microbiota composition when protein intake was increased.¹

The Study

This study was performed from November 2018 through July 2022 at the University of Helsinki and the Vrije Universiteit Amsterdam. A total of 276 individuals participated in the clinical trial.¹

Participants were randomized into three groups:¹

• Group 1: Received dietary advice aimed at increasing protein intake (n=96)
• Group 2: Received dietary advice to increase protein intake and were advised to consume their protein just before or after physical exercise (n=89)
• Group 3: Received no intervention (n=91)

The groups receiving advice on protein intake were provided guidance via verbal and written instructions. The goal was to increase protein intake to >1.2 g/kg of adjusted body weight daily, with at least one meal containing >35 g of protein.¹

Clinical assessment took place at baseline and 3-month and 6-month follow-ups. Clinical assessment included a collection of unstimulated saliva and tongue swabs of the posterior dorsum of the tongue. Participants were asked not to brush their teeth before sampling to ensure the oral environment was not manipulated.¹

The Results

The results of this trial indicated that increased protein intake did not affect self-reported oral health status in older adults. In the subgroup, the microbiota results showed a moderate effect on overall microbiota composition based on alpha and beta diversity measures. However, no individual bacterial taxa were found to be affected.¹

It is important to consider that compared to other body sites, the oral microbiota displays high levels of intra-individual diversity and temporal stability. This indicates the oral microbiota may be resilient to dietary interventions.¹

There were no differences in oral health outcomes from baseline to the 6-month follow-up. There was also no effect on the salivary flow rate.¹

Previous cross-sectional studies have shown an association between protein intake and oral health outcomes, but this trial did not result in the same findings. Some limitations could have contributed to the results, including self-reported oral health outcomes, a short follow-up period of six months, and the advised increase in protein intake, which was modest.¹

Additionally, though the participants had a low protein intake at the start of the trial, they were not necessarily deficient. Therefore, increasing protein intake may get different results for older adults with a true protein deficiency.¹

In Conclusion

This study shows that dietary guidance that boosted protein intake to at least 1.2 g/kg of adjusted body weight per day in older adults with low protein consumption did not significantly enhance self-reported oral health. While the intervention had a modest impact on overall microbiota composition, as reflected in alpha- and beta-diversity measures, it did not significantly change individual taxa.¹

Future research with a more substantial or prolonged increase in dietary protein, particularly in older adults with more severe protein deficiencies, may result in more noticeable effects on oral health and microbiota.¹

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Reference

1. Fluitman, K.S., van den Broek, T., Reinders, I., et al. The Effect of Dietary Advice Aimed at Increasing Protein Intake on Oral Health and Oral Microbiota in Older Adults: A Randomized Controlled Trial. Nutrients. 2023; 15(21): 4567. https://pmc.ncbi.nlm.nih.gov/articles/PMC10647493/