Older adults who consumed blueberries every day for three months experienced a surprising change: Their depressive symptoms declined more consistently than those of participants taking a placebo. But the researchers also discovered something unexpected happening inside their guts .

The study, highlighted by ScienceDaily , suggests blueberries may influence microbial processes connected to mood. However, the improvements were not statistically significant compared with placebo, meaning the findings don’t establish blueberries as a depression treatment.

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Scientists Found an Unexpected Gut-Brain Connection

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Researchers recruited adults 65 and older who were physically inactive and experiencing mild depressive symptoms.

For three months, participants consumed either 48 grams of blueberry powder daily—equivalent to approximately two cups of fresh blueberries—or a placebo.

According to the 2026 study…