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An Orange A Day Keeps Depression Away? Here’s What Researchers Found
Can a simple citrus fruit brighten your mood?
According to a study published in Microbiome, eating an orange a day may lower a person’s risk of depression by 20%. The link between citrus consumption and mental health appears to be mediated by the gut microbiome—specifically, a key player known as Faecalibacterium prausnitzii (F. prausnitzii).
The gut-brain connection
Your gut is home to trillions of bacteria, many of which play critical roles in digestion, immune function, and even brain health. Scientists have long suspected that diet influences mental well-being, but pinpointing exactly how certain foods interact with our brain chemistry has been challenging.
This new research provides compelling evidence that citrus fruits, such as oranges and grapefruits, may positively influence mental health through their impact on the gut microbiome.
The study: Citrus & mood
The study analyzed data from the Nurses' Health Study II, which has tracked the health habits of over 100,000 women since 1989.
Researchers found that participants who consumed at least one medium orange per day had a significantly lower risk of developing depression compared to those who ate little to no citrus. Importantly, this effect was specific to citrus fruits—other fruits like apples and bananas showed no such correlation.
To explore the underlying mechanism, the researchers analyzed stool samples from a subset of participants. They discovered that individuals with high citrus intake had an increased abundance of F. prausnitzii, a beneficial gut bacterium previously linked to lower levels of inflammation and improved gut health. This bacterium was significantly less abundant in those with depression, suggesting it may play a role in mood regulation.
The role of F. prausnitzii
So why does F. prausnitzii matter? The researchers found that this bacterium influences the production of neurotransmitters like serotonin and dopamine—key molecules involved in mood regulation.
One potential mechanism is its role in the S-adenosyl-L-methionine (SAMe) cycle, which affects serotonin synthesis in the gut. Low SAMe production is associated with higher depression risk, and boosting F. prausnitzii levels through diet may help counteract this effect.
Interestingly, the study’s findings were validated in an independent cohort of men, strengthening the evidence that the citrus-microbiome connection is not gender-specific.
The takeaway
While this study does not suggest that eating an orange is a cure for depression, it does highlight the potential of diet as a tool for mental health.
Given that 70% of individuals with depression do not fully respond to antidepressants, dietary strategies that support gut health could offer additional benefits. Future research will be needed to confirm whether directly increasing F. prausnitzii—through probiotics or targeted dietary interventions—could be an effective strategy for preventing or managing depression.
For now, adding more citrus to your diet might be a simple, natural way to support your mental well-being. So the next time you're debating between a snack, consider reaching for an orange—not just for its vitamin C, but for the potential mood boost, too.