Dietary acid exposure and intake phenotypes in young adults: a 4-year longitudinal study with implications for...

To characterise the longitudinal behaviour in diet-related attitudes and frequency-based dietary acid exposure over four-year period, and to evaluate the concordance between attitudes and self-reported intake within the context of erosive tooth wear research.

Ninety-one dental students (mean age 20.9 ± 2.2 years) were followed annually from baseline to year 4, with four follow-up assessments. A self-administered questionnaire captured frequencies of acidic food and beverage consumption as well as seven diet-related attitude items. Consumption frequencies were converted into estimated daily dietary acid exposure events. Statistical analyses included participant-clustered linear models, Friedman sensitivity tests, Cronbach's alpha, exploratory k-means clustering, Kruskal-Wallis tests, and Spearman correlations.

Group-level dietary acid exposure and diet-related attitudes remained broadly stable over time, with no robust longitudinal effects observed. However, substantial within-person variability in acid exposure was evident. Attitude items showed predominantly stable responses or minor adjacent-wave shifts, alongside low internal consistency. Total dietary acid exposure was driven primarily by fruit- and juice-related sources rather than by soft drink. Four baseline intake phenotypes were identified: lower-intake/low-acid, fruit-juice, wine-vinegar, and soft-drink. Persistence of phenotypes over time was moderate. Person-level profiling revealed fluctuating total acid exposure in 45.1% of participants and consistently high exposure in 8.8%. Associations between attitudes and behaviour were modest.

The longitudinal questionnaire data did not support a one-dimensional interpretation of dietary acid exposure. Instead, acid-exposure magnitude, temporal variability, source-specific intake patterns, and diet-related attitudes emerged as partly distinct layers of dietary behaviour.

In the context of erosive tooth wear, dietary history-taking may be more informative when it considers not only the frequency of dietary acid exposure, but also its temporal variability and broader source-specific intake patterns, rather than relying solely on global questions about dietary acid intake.