Three studies have come out that suggest an antidepressant potential for the humble blueberry. All three studies hail from a single group lead by Claire Williams at the University of Reading, England. They tested the effect of a powdered blueberry drink—equivalent to one cup of fresh blueberries—on mood in 144 children, adolescents, and young adults through three randomized, placebo-controlled trials. The placebo drink had the same sugar and vitamin C content as the blueberry juice, and both drinks were made to look the same by mixing them with concentrated orange juice.
The first two studies examined mood 2 hours after a single drink, and the third looked at longer term effects of a daily drink over 4 weeks. All three studies were positive, with effect sizes that ranged from small to medium.
However, it is not all smooth sailing. The main limitation is the fact that the studies were small and came from a single research group. Also, they all enrolled healthy participants, so we don’t know if blueberries actually treat clinical depression. No risks were identified, though one might wonder if blueberries can trigger mania.
These findings are supported in part by a Canadian study where blueberry juice prevented postpartum depression (i.e., the brief lability seen after delivery) in healthy pregnant women, but the juice in that small controlled trial also contained tryptophan and tyrosine. In contrast, two other independent groups that tested blueberries in healthy older patients did not find any mood benefits.
This does not mean blueberries are only helpful in the young. It means more research has to be done. Blueberries sound like a brain super-food, but super-foods are not what nutritional psychiatry is all about.
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