Daily Blueberries Shift Gut Enzymes in Older Adults, Pilot Study Finds — SkimNews
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- Courtney L. Millar, PhD led a randomized, double-blind, placebo-controlled pilot study at Hebrew SeniorLife's Marcus Institute in which 18 adults aged 65 and older consumed 48 grams of blueberry powder daily (roughly two cups of fresh berries) or a matching placebo for three months.
- Mood outcomes favored the blueberry group with greater reductions in depressive symptoms, but the difference versus placebo was not statistically significant, and researchers cautioned the findings do not establish that blueberries relieve depression.
- Gut microbiome composition showed no overall change in microbial species, MetaCyc metabolic pathways, or short-chain fatty acid metabolites, yet the blueberry group did exhibit statistically significant shifts in genes tied to several microbial enzymes.
- One enzyme flagged was EC 3.6.3.31 Polyamine Transporting ATPase, which participates in producing GABA, a neurotransmitter with a role in brain signaling, suggesting a possible biochemical bridge between blueberry intake and neural function.
- Millar said fiber and anthocyanins in blueberries have potential to modify the gut microbiome and metabolites relevant to depression in older adults, framing the work as preliminary.
- The study, published in The Journal of Nutrition, Health and Aging, was small (placebo n=8, blueberry n=10), predominantly female and white, and authors concluded larger trials are needed before any causal mood claims can be made.
- Co-investigators spanned Harvard Medical School, Harvard T.H. Chan School of Public Health, UMass Chan Medical School, the Broad Institute of MIT and Harvard, and the University of Connecticut's Department of Nutritional Sciences.
Why it matters: For roughly one in three older adults who experience depressive symptoms, any non-pharmaceutical lead matters — and this trial offers a mechanistic breadcrumb (GABA-related gut enzyme genes shifted) rather than a clinical result, meaning dietary guidance for mood is not changing yet but the gut-brain pathway hypothesis now has a specific biochemical target worth probing in larger trials.
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