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Association between dietary fibre intake and depressive symptoms before and during the COVID-19 pandemic
The relationship between dietary fibre and mental health has gained attention, particularly concerning how it may interact with the gut-brain axis. Despite this, there is a scarcity of population-level studies that specifically address the effects of dietary fibre on depressive symptoms during the unique circumstances of the COVID-19 pandemic. This research aimed to explore the correlations between both energy-adjusted and energy-unadjusted dietary fibre consumption and depressive symptoms in the periods preceding and during the pandemic.
Utilizing data from the National Health and Nutrition Examination Survey (NHANES), which included 7,513 participants from January 2017 to March 2020 and 4,680 participants from August 2021 to August 2023, the study assessed depressive symptoms through the Patient Health Questionnaire-9, categorizing scores of 10 or higher as indicative of depression. Dietary fibre intake was monitored via a 24-hour dietary recall, with energy-adjusted fibre intake calculated using the residual method to ensure independent evaluation from overall caloric intake. Statistical relationships between fibre intake and depressive symptoms were estimated with modified Poisson regression models, accounting for relevant sociodemographic factors.
Results indicated a noticeable increase in depression prevalence, from 8.0% before the pandemic to 10.1% during it. Simultaneously, average dietary fibre intake declined from 16.52 g/day to 15.95 g/day. Notably, an increase of 5 g in energy-adjusted dietary fibre was linked to a 14% reduction in depressive symptoms prior to the pandemic (adjusted prevalence ratio (aPR) = 0.86; 95% CI: 0.81, 0.92), while this link weakened during the pandemic (aPR = 0.98; 95% CI: 0.91, 1.05). In terms of energy-unadjusted fibre, a rise of 1 g/day was correlated with a 2% drop in prevalence pre-pandemic (aPR = 0.98; 95% CI: 0.97, 0.99), but this effect became statistically insignificant during the pandemic (aPR = 0.99; 95% CI: 0.98, 1.00).
Gender-specific analyses revealed that, prior to the pandemic, increased energy-adjusted dietary fibre intake correlated with decreased depressive symptoms in both men (aPR = 0.79; 95% CI: 0.71, 0.88) and women (aPR = 0.91; 95% CI: 0.84, 0.99). Conversely, during the pandemic, this association diminished among men (aPR = 1.04; 95% CI: 0.92, 1.17), but a modest protective effect persisted in women (aPR = 0.90; 95% CI: 0.81, 0.99).
Overall, the findings highlight that greater energy-adjusted dietary fibre intake was linked to reduced depressive symptoms prior to the pandemic in both genders. However, during the pandemic, the association remained significant solely for women. These results imply that dietary fibre might deliver ongoing mental health advantages for women amidst societal challenges, suggesting its potential role as a targeted nutritional strategy for the prevention of depression. [NPID: Fiber, depression, dietary, pandemic, population-level]
Year: 2026
