Eating blueberries every day may have a surprising effect on your mood
Eating blueberries every day could have surprising effects on mood, according to a small study that found greater reductions in depressive symptoms among older adults who consumed the fruit for three months. Researchers also detected changes in gut microbial enzymes, suggesting a possible gut-brain connection, although the mood benefits were not statistically significant compared with a placebo.
Key points
- A small pilot study found daily blueberry powder did not significantly improve depressive symptoms versus placebo.
- Researchers saw significant gene changes tied to gut microbial enzymes in the blueberry group.
- Eighteen adults aged 65 and older with mild depressive symptoms completed the three-month study.
A small pilot study suggests that eating blueberries daily may affect gut bacteria and possibly mood in older adults, though the mood improvements were not statistically significant compared with a placebo group. The research, published in the Journal of Nutrition, Health and Aging, does not show that blueberries relieve depression, but offers early clues about links between blueberry intake, the gut microbiome and mental health.
Researchers recruited physically inactive adults aged 65 and older with mild depressive symptoms for a randomized, double-blind, placebo-controlled trial. Over three months, participants took either 48 grams of blueberry powder daily, about two cups of fresh berries, or a matching placebo powder.
What the study found
Eighteen participants completed the study: 10 in the blueberry group (mean age 71) and eight in the placebo group (mean age 75). Most were women, and the group was predominantly white.
The blueberry group showed a greater and more consistent reduction in depressive symptoms, but the difference from placebo was not statistically significant. Overall microbial species, metabolic pathways and short-chain fatty acid metabolites were unchanged, though the blueberry group had significant shifts in genes linked to several gut microbial enzymes, including one involved in producing GABA, a neurotransmitter.
Fiber and anthocyanins in blueberries have potential to modify the gut microbiome and metabolites that are relevant to depression in older adults
— Courtney L. Millar, PhD
Researcher comments and next steps
Lead author Courtney L. Millar, PhD, of Hebrew SeniorLife's Hinda and Arthur Marcus Institute for Aging Research, said fiber and anthocyanins in blueberries "have potential to modify the gut microbiome and metabolites that are relevant to depression in older adults."
The authors say larger studies are needed to determine whether these changes are connected to meaningful improvements in mood or depressive symptoms.
