Study Finds Daily Blueberry Consumption Affects Gut Microbiome in Older Adults with Mild Depression

Despite the reductions in depressive symptoms observed in those consuming blueberries compared to a placebo group, these differences were not statistically significant. Nonetheless, the initial findings suggest a need for further investigation into the connections between blueberry intake, gut microbiota, and mood among older adults.

Lead author Courtney L. Millar, Ph.D., from the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife and an assistant professor of medicine at Beth Israel Deaconess Medical Center and Harvard Medical School, stated, "Fiber and anthocyanins in blueberries have the potential to modify the gut microbiome and metabolites that are relevant to depression in older adults." The study aimed to preliminarily explore the effects of blueberry consumption on gut health, metabolites, and depressive symptoms.

The randomized, double-blind, placebo-controlled trial involved sedentary participants aged 65 and older with mild depressive symptoms. Over three months, subjects either consumed 48 grams (approximately two cups) of blueberry powder daily or a placebo.

The study, which involved 18 participants (8 in the placebo group with a mean age of 75, and 10 in the blueberry group with a mean age of 71), utilized metagenomic sequencing to assess gut microbiota composition, along with liquid chromatography/mass spectrometry to analyze gut-derived fecal short-chain fatty acids. It also employed validated questionnaires to evaluate depressive symptoms pre- and post-intervention.

While overall measures of gut microbe species abundance and metabolites did not significantly change, noteworthy differences emerged within the blueberry group. Specifically, there were statistically significant alterations in gene abundance related to several enzyme commissions of the gut microbiome, including EC 3.6.3.31 Polyamine Transporting ATPase, which is linked to gamma-aminobutyric acid (GABA) production.

The findings were detailed in the study titled "A pilot study of daily blueberry intake modulates the gut microbiota enzyme commissions in older, sedentary adults with mild depressive symptoms," published in The Journal of Nutrition, Health and Aging.