According to a large cross-sectional study published today in the Journal of Neuropsychiatry and Clinical Neurosciences, the answer appears to be no.
Researchers from the Department of Epidemiology at Janssen Research and Development in Titusville, New Jersey, assessed 18,019 adults who participated in the National Health and Nutrition Examination Survey (NHANES). As part of this survey, participants were asked to estimate the types and amounts of foods and beverages consumed during the 24-hour period prior to the interview. Depression was measured with the Patient Health Questionnaire (PHQ-9). (Participants were classified as having moderate or more severe depressive symptoms if PHQ-9 scores were 10 or greater and a score of 5 or greater was used to classify subjects with mild to more severe depressive symptoms.)
About 14% of the participants reported consuming probiotics, primarily through their diet. When making an unadjusted comparison, the probiotic users did have about half the odds of depression as non-users (odds ratio of 0.58); however, this did not factor in that people in the probiotic group were more likely to be white, older, women, healthier, and to have higher family income.
When the analysis was adjusted, the association between probiotic exposure and depression disappeared, irrespective of how depression was defined. Excluding the small subset of people who took probiotics via supplements also did not affect the results.
“These findings suggest that it is not the probiotic exposure itself, but the attributes of subjects who consume probiotics, which lessen the odds of depression,” the authors wrote. “Although these data can provide insight, information on usual dietary practices collected over time would be expected to provide a stronger indication of associations between dietary factors and health outcomes.”
For related information, see the Psychiatric News article “Food May Be a Tool to Consider When Helping Psychiatric Patients,” by Drew Ramsey, M.D.