Since current evidence on the link between dietary fibre intake and the risk of depression is inconsistent, the researchers conducted a study to further investigate the association and hopefully, provide more definitive answers.
Findings on fibre
They used data from the National Health and Nutrition Examination Survey 2007 — 2014 for a cross-sectional study involving 16,807 adults aged 20 and above, and obtained dietary information using two 24-hour dietary recall interviews.
They also assessed depressive symptoms with the Patient Health Questionnaire, and evaluated the relationship between depressive symptoms and dietary intakes of total, cereal, fruit and vegetable fibre.
Subsequently, the researchers observed that greater dietary intakes of total, cereal, fruit and vegetable fibre were correlated with less severe depressive symptoms.
In addition, dose-response analyses revealed that while greater cereal, fruit and vegetable fibre intake was likely to alleviate depressive symptoms, the same was not always true when it came to total fibre intake.
The researchers noted dietary fibre's ability to alter the composition of intestinal microbiota, which may regulate inflammation and oxidative stress, saying fibre consumption "communicates with the central nervous system and influences brain function".
Additionally, the fermentation of dietary fibre produced short-chain fatty acids, which were said to regulate inflammatory responses, and "underlying mediating pathway" in depression.
At the same time, dietary fibre was said to lower postprandial hyperglycaemia, inhibiting inflammation and preventing the overproduction of oxidative stress
The link between dietary fibre intake and depression has been studied in the past, with a high-fibre diet said to help lower the risk of depression.
More recently, the lead researcher behind an Australian study said a high-fibre diet is the 'key to a healthy mind'.
The future of fibre
The researchers behind the current study said one of its limitations was its cross-sectional design, which made causality difficult to determine.
They also wrote that the Patient Health Questionnaire "is an interviewer-administered screening tool for depressive symptoms, not a diagnostic instrument for clinical depression; thus, it may suffer from misclassification bias".
Furthermore, the study's reliance on participants self-reporting their depressive symptoms could have skewed the results.
They concluded: "Our study suggested that intakes of total fibre, vegetable fibre, and fruit fibre were inversely associated with depressive symptoms. Further larger prospective studies are needed to confirm our findings."
"Exploration of the association between dietary fiber intake and depressive symptoms in adults"
Authors: Hui Xu, et al.