Citrus fruits are in peak season during the winter, a time when many of us suffer from seasonal depression or plain old cabin fever—and according to new research, that timing may be more advantageous than we realize. Doctors and scientists say that eating an orange a day could lower your risk of depression by 20 percent, attributing the positive effect to the gut-brain connection.
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Citrus fruits can stave off depression, new research finds.
The study, which was published in the journal Microbiome, was led by Raaj Mehta, MD, MPH, an instructor in medicine at Harvard Medical School and a physician at Massachusetts General Hospital.
He told The Harvard Gazette that he was inspired to undertake this research by a 2016 study that found a potential link between a higher intake of flavonoids (plant compounds that give fruits and vegetables their colors), specifically those of citrus fruits, and a lower depression risk among older women.
The new study expanded the data set to include over 100,000 women who participated in the Nurses’ Health Study II (NHS2). This research program began in 1989, with nurses reporting lifestyle, diet, medication use, and health information every two years.
Mehta and his team found that nurses who ate roughly one medium orange per day had a 20 percent lower risk of developing depression. He noted that he and his researchers did not observe similar trends in consuming other fruits or vegetables.
The gut-brain connection is likely at play.
How do citrus fruits protect against depression? Mehta believes it’s due to the fact that oranges, lemons, and the like stimulate the growth of the gut bacteria Faecalibacterium prausnitzii (F. prausnitzii). This bacteria influences the production of serotonin and dopamine, two neurotransmitters that regulate mood and are often referred to as “happy hormones.”
By analyzing stool samples, the study found that women who ate more citrus fruits had more F. prausnitzii in their guts. Mehta also looked at data from a large sample of men and found the same to be true. Moreover, it was observed that participants with depression had lower levels of F. prausnitzii.
“There’s so much evidence now suggesting a strong link between the gut and the brain that I was not surprised to find more,” Mehta told The Harvard Gazette. “At the same time, I had not associated citrus with the brain before we got these results. You often hear that fish is ‘brain food,’ but nobody says that oranges are brain food.”
“Similarly, F. prausnitzii has been linked to good health in lots of ways, like by lowering the risk of developing inflammatory bowel disease. But I wasn’t aware of a link between F. prausnitzii and mental health,” he added.
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Is there a place for citrus in depression treatment?
As Mehta clarified, “It’s hard to compare the effectiveness of citrus to traditional antidepressants, such as selective serotonin reuptake inhibitors [SSRIs], because we’re talking about preventing depression, and those drugs are usually used to treat depression once a person is already experiencing it.”
“In the future, eating citrus could perhaps be part of a strategy for managing depression that also involves these more traditional pharmaceuticals,” he added. “But more research is needed before we can conclude that.”
To that point, Mehta said that he would next like to see a clinical trial that specifically studies the role of citrus fruits and depression. He also hopes his research will create more of a dialogue around diet and mental health.
Citrus fruits offer other important health benefits, too.
In addition to helping with mental health, there is much research to support how citrus fruits can benefit your physical health.
For example, their flavonoids help to relax blood vessels, which can lead to lower blood pressure. And a medium-sized orange packs roughly 69 mg of vitamin C, helping to boost your immune system.
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The takeaway:
New research found that eating a medium-sized orange daily stimulated the growth of a specific gut bacteria that increased the production of serotonin and dopamine, two neurotransmitters that positively affect mood. Therefore, the researchers concluded that regular consumption of citrus fruits could lower depression risk by 20 percent.
