Higher fiber intake may be associated with decreased risk of depression in premenopausal women, new research suggests.
Nic_Ol/Thinkstock
Investigators analyzed data from close to 6,000 pre- and postmenopausal women. They found that, in premenopausal women, dietary fiber intake was higher among those without depression versus their counterparts with the disorder in a dose-dependent manner. However, there appeared to be no relationship between higher fiber intake and depression risk in postmenopausal women.
“We think the most important finding of our study is that dietary fiber intake was inversely associated with depression in premenopausal but not postmenopausal women,” lead author Yunsun Kim, MD, resident, department of family medicine, Chung-Ang University Hospital, Seoul, South Korea, said in an interview.
“We hope that the findings of this study could form the basis of future investigations to determine the causal relationship between dietary fiber intake and depression,” she added.
The study was published online Dec. 21, 2020, in Menopause.
Gut-brain interaction
The prevalence of depression is twice as high in women, compared with men, which may be attributable to a number of factors, including hormonal status – especially during menstruation and menopause, the authors wrote.
Previous research suggests a potential association between dietary fiber and depression in premenopausal women and between estrogen and gut microbiota. Fiber intake has an impact on gut microbiota, Dr. Kim said.
“We are motivated by the fact that depression provokes disease burden internationally and we would like to find modifiable factors that could prevent depression, especially in women, who are more vulnerable to depression,” she noted.
To investigate, the researchers drew on data from the Korea National Health and Nutrition Examination Survey for 2014, 2016, and 2018. Of the total number of women who met inclusion criteria (n = 5807; mean age, 47.11), roughly half were premenopausal and half were postmenopausal (n = 2,949 [mean age, 36.23 years] and n = 2,868 [mean age, 62.73], respectively).
Dietary fiber intake was assessed using the 24-hour dietary recall method, while depression was assessed using the Patient Health Questionnaire-9. The researchers used the Dietary Reference Intakes for Koreans to define a sufficient intake of dietary fiber (i.e., 12 g/1,000 kcal).
Covariates included chronic diseases, body mass index, medications, smoking status, alcohol use, physical activity, and sociodemographic factors.
When the researchers looked at all participants, they found that the estimated mean dietary fiber intake was significantly higher in women without depression, compared with those with depression (14.07 g/1,000 kcal/d; 95% confidence interval, 13.85-14.29 vs. 12.67 g/1,000 kcal/d; 95% CI, 11.79-13.55; P = .003).
Although the relationship remained significant in premenopausal women, it lost significance in postmenopausal women.
A 5% decrease in the prevalence of depression in premenopausal (but not postmenopausal) women was found in those with an increased intake of dietary fiber – i..e, there was a 1-g increase for every 1,000 kcal of daily energy intake, after adjusting for potential confounders in premenopausal women (OR, 0.949; 95% CI, 0.906-0.993]).
“The inverse relationship between dietary fiber intake and depression could be explained by the gut-brain interactions,” said Dr. Kim.
“Changes in the gut microbiota composition may affect neurotransmission and various neuropsychiatric phenomena in the brain,” she said, noting that previous studies have suggested that dietary fiber intake “may modulate the richness and diversity of the gut microbiota, and this change may promote brain health by affecting neurotransmission.”
Because postmenopausal women experience estrogen depletion, “the decreased interaction between estrogen and the gut microbiota may be related to the insignificant association between dietary fiber intake and depression in postmenopausal women,” she said.
Despite the lack of a significant association between postmenopausal depression and fiber intake, Dr. Kim said she “advises middle-aged women to have dietary fiber–rich diets, regardless of their menopausal status.”