A small pilot trial has explored whether daily blueberries might influence mood and gut bacteria in older adults, according to research from the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife reported by ScienceDaily. Published in The Journal of Nutrition, Health and Aging, the randomized, double-blind, placebo-controlled study gave inactive adults aged 65 and over with mild depressive symptoms either blueberry powder, equivalent to about two cups of fresh berries, or a matching placebo every day for three months.
Among the 18 participants who completed the study, the blueberry group showed a larger and more consistent drop in depressive symptoms, although the difference from placebo was not statistically significant. Overall gut bacteria levels did not change, but several microbial enzyme genes shifted in the blueberry group, including one linked to GABA production.
The researchers describe the work as preliminary and say larger studies are needed to determine whether these gut changes are connected to mood.