Inverse Associations of Acetic Acid Intake with Carbohydrate, Sugar, and Saturated Fat Intakes Among Japanese Adults Aged 20 to 69 Years

<b>Background:</b> Acetic acid has been suggested to have health benefits. Our previous exploratory study linked acetic acid intake to higher protein and vitamin consumption, but relationships with age and sex remained unclear. <b>Objective:</b> This study examined associations between acetic acid intake, age, and sex, and explored nutrient correlates after adjusting for age, sex, and energy intake. <b>Methods:</b> Dietary data from 12,074 Japanese adults aged 20-69 years, collected via the Asken food-tracking app, were analyzed. Two-way ANOVA assessed effects of age, sex, and their interaction on acetic acid intake. Multiple linear regressions examined associations between acetic acid intake and nutrient intakes. Model 1 adjusted for age and sex; Model 2 additionally adjusted for total energy intake. <b>Results:</b> Participants included 3038 men (47.8 ± 11.9 y) and 9036 women (42.4 ± 11.8 y). Acetic acid intake was higher among men and older participants (sex: F = 11.0, <i>p</i> < 0.001; age: F = 9.1, <i>p</i> < 0.001). In Model 1, acetic acid intake correlated positively with most nutrients. After adjusting for energy (Model 2), negative associations were found with carbohydrates, sugars, starches, saturated fat, and butyric acid (all <i>p</i> < 0.05). <b>Conclusions:</b> Individuals with higher acetic acid intake tended to consume fewer carbohydrates and saturated fats, even at equivalent energy intake. These findings suggest that acetic acid-containing diets may reduce the intake of starches and saturated fatty acids, potentially contributing to obesity prevention.