Associations of individual beverage types and substitution with dementia risk

To the Editor,

We carefully read the article by Kim et al. published in The Journal of Nutrition, Health & Aging, entitled “Associations of Individual Beverage Types and Substitution with Dementia Risk: A UK Biobank Cohort Study” [1]. Using the large prospective UK Biobank cohort, the authors systematically evaluated the associations between multiple beverage types and their substitution patterns with dementia risk, and further applied substitution models to enhance the clinical interpretability of their findings. Overall, this study focuses on modifiable lifestyle factors and provides evidence of practical relevance for dementia prevention, which is highly commendable. While acknowledging the overall value of this work, several methodological and interpretative issues merit further discussion.

Beverage intake was assessed using the Oxford WebQ 24 -h dietary recall questionnaire, with a subset of participants completing repeated assessments. Although this tool is feasible for large-scale population studies, single-day dietary recalls remain susceptible to within-person variability, particularly for beverages that are not consumed on a daily basis, and may therefore inadequately reflect long-term habitual intake. Clarification of how repeated dietary assessments were handled (e.g., use of the first assessment only or averaging across multiple measurements) would help readers better understand the stability and robustness of exposure assessment. In addition, given the typically long prodromal period of dementia, lifestyle changes occurring during the early stages of the disease may themselves influence beverage choices [2,3]. In this context, conducting sensitivity analyses that exclude dementia cases occurring early during follow-up could further reduce the potential for reverse causation.

The substitution analysis represents an important strength of this study; however, the assumption of isocaloric substitution may not always be fully met in real-world dietary behaviors [4]. Moreover, in the setting of long follow-up durations and an older study population, death constitutes an important competing event that may affect estimates of dementia incidence [5]. Applying competing-risk models to further validate the findings could therefore enhance the robustness of the results.

The authors report that beverage substitution effects were more pronounced among individuals with obesity, hypertension, depression, or dyslipidemia, suggesting the potential value of personalized nutritional interventions. Future studies incorporating repeated dietary assessments, more detailed characterization of beverage composition, and indicators related to underlying biological mechanisms may further deepen our understanding of these associations.

In summary, this study provides important evidence linking beverage consumption and substitution patterns with dementia risk. The methodological and interpretative considerations raised herein are intended to further strengthen the robustness, interpretability, and clinical and public health relevance of the findings. We are grateful for the opportunity to comment on this valuable work and look forward to future investigations that further advance this line of research.

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Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.