In 18 sedentary adults ages 65 and older, three months of blueberry powder did not beat placebo on mood

What the research found

Study (small randomized pilot). Courtney L. Millar and colleagues at Hebrew SeniorLife report in The Journal of Nutrition, Health and Aging (2026; 30(10):100958; DOI 10.1016/j.jnha.2026.100958). ScienceDaily carried it on 18 Oct 2026. Eighteen sedentary adults ages 65 and older with mild depressive symptoms finished a three-month trial. Ten ate 48 grams of blueberry powder a day, about two cups of fresh berries. Eight took a matching placebo. Most participants were women, and the group was predominantly white. Mean age was about 71 in the blueberry group and about 75 in the placebo group. Depressive symptoms fell more steadily on the blueberry powder, but the difference versus placebo was not statistically significant. Overall microbial species, metabolic pathways, and short-chain fatty acids did not change. Genes tied to a few gut microbial enzymes did change inside the blueberry group, including one linked to polyamine transport and GABA. A pilot this small cannot show that a blueberry diet treats depression. Not medical advice.

Evidence level: Clinical trial. This is among the stronger kinds of evidence, but one study rarely settles a question.

Read the original at The Journal of Nutrition, Health and Aging