One Orange a Day May Help Keep Depression Away: Harvard Study Finds Gut Microbiome Link

New Delhi: An orange a day may do more than enhancing the immunity; it could also support mental well-being. Citrus fruits, rich in essential nutrients and gut-friendly compounds, are now being studied for their potential role in reducing depression risk.

A study from Harvard Medical School and Massachusetts General Hospital suggests that regular citrus consumption is linked to a 20 to 22 percent lower risk of depression, possibly due to its effects on gut microbiota.

The study, published in Microbiome, analyzed 32,427 women over 14 years and found that citrus intake promotes the growth of Faecalibacterium prausnitzii, a gut bacterium associated with improved mental health.

Dr. Raaj S. Mehta, the study’s lead researcher, emphasized the broader significance:"Our study demonstrates a potential protective role of citrus fruit in preventing depression, offering new insights into how diet can influence mental health through the gut microbiome."

He also highlighted the specificity of this effect:"The effect seems to be specific to citrus. When we look at people's total fruit or vegetable consumption, or at other individual fruits such as apples or bananas, we don't see any relationship between intake and risk of depression."

The research suggests that citrus enhances the abundance of F. prausnitzii, which plays a role in producing S-adenosyl-L-methionine (SAM)—a compound involved in serotonin and dopamine synthesis.

"Lower SAM production by F. prausnitzii may reduce intestinal monoamine oxidase A (MAOA) gene expression, which is directly implicated in serotonin and dopamine regulation," noted Dr. Andrew T. Chan, senior author of the study.

The study utilized data from the Nurses’ Health Study II, an ongoing Harvard-led cohort that tracks the diet, lifestyle, and health of over 100,000 women since 1989. Researchers found that consuming one medium orange daily was associated with a lower risk of depression.

To validate their findings, the researchers analyzed an independent cohort of 307 men and observed similar associations between citrus intake, F. prausnitzii, and depression biomarkers.

Dr. Curtis Huttenhower, co-author of the study, emphasized the implications:"This research underscores the role of diet in mental health and suggests that targeted dietary strategies could complement existing treatments for depression."

While these findings highlight the potential of citrus as part of a preventive approach, Dr. Mehta cautioned against direct comparisons with traditional antidepressants.

"Citrus consumption should be seen as part of a broader strategy for managing depression, alongside conventional treatments," he said.

With 280 million people worldwide affected by depression, the study supports the growing evidence that diet influences mental health through gut microbiota. It opens potential avenues for preventive strategies and biomarker development.

"Given the limitations of current antidepressants, our study highlights the potential of gut microbiome-targeted dietary interventions to improve mental health outcomes," Dr. Mehta concluded.

As research continues, citrus fruits may emerge as a natural, accessible tool to promote mental well-being.