Blueberries can modify the gut microbiome in older adults with mild depression
· Medical Xpressby Hinda and Arthur Marcus Institute for Aging Research
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A new pilot study found that older, sedentary adults who consumed blueberries daily showed a greater, more consistent reduction in depressive symptoms, along with minor changes in markers of gut microbial enzymes.
The differences in depressive symptoms between the blueberry and placebo groups were not statistically significant. Still, the preliminary data warrant further research into the link between blueberries, the gut microbiome and mood in older adults.
"Fiber and anthocyanins in blueberries have potential to modify the gut microbiome and metabolites that are relevant to depression in older adults," said lead author Courtney L. Millar, Ph.D., assistant scientist II at Hebrew SeniorLife's Hinda and Arthur Marcus Institute for Aging Research and assistant professor of medicine at Beth Israel Deaconess Medical Center and Harvard Medical School. "Our objective was to preliminarily determine the effect of blueberry consumption on the gut microbiome, metabolites, and depressive symptoms."
Study design
Sedentary adults 65 and older with mild depressive symptoms were enrolled in a randomized, double-blind, parallel-arm, placebo-controlled pilot study. Participants consumed 48 grams (1.7 ounces) of blueberry powder per day (approximately two cups, or 475 milliliters, of fresh berries) or a matched placebo powder for three months.
Metagenomic sequencing measured the abundance of gut microbiota species and genes, liquid chromatography/mass spectrometry evaluated gut-derived fecal short-chain fatty acids, and validated questionnaires evaluated depressive symptoms before and after the intervention.
Study participants
Eighteen participants, predominantly female and white, completed the intervention (placebo group, n = 8; mean age: 75 ± 6; blueberry group, n = 10; mean age: 71 ± 4).
Measures of gut microbe species abundance, MetaCyc pathways and short-chain fatty acid metabolites did not change. Within the blueberry group, there were statistically significant differences in the gene abundance of several enzyme commissions of the gut microbiome—including EC 3.6.3.31 Polyamine Transporting ATPase, which is involved in the production of the neurotransmitter gamma-aminobutyric acid (GABA).
The study, "A pilot study of daily blueberry intake modulates the gut microbiota enzyme commissions in older, sedentary adults with mild depressive symptoms," was published in The Journal of Nutrition, Health and Aging.
More information
Courtney L. Millar et al, A pilot study of daily blueberry intake modulates the gut microbiota enzyme commissions in older, sedentary adults with mild depressive symptoms, The Journal of Nutrition, Health and Aging (2026). DOI: 10.1016/j.jnha.2026.100958
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Nutrition & Healthy eatingPsychology & Mental healthHealthy aging Provided by Hinda and Arthur Marcus Institute for Aging Research Who's behind this story?
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