Eating citrus fruit like oranges tied to 20% lower depression risk

An estimated 280 million people around the world live with clinical depression — a mental health condition that impacts a person’s mood and sense of self.

There are a number of risk factors for depression, including family history, hormonal changes, other chronic diseases, and constant stress.

Past studies show that certain lifestyle changes can help lower a person’s risk of developing depression. These include physical activity, proper sleep, stress management, and eating a healthy diet.

In regards to diet, previous research even shows that eating healthy foods may help lower a person’s risk for depression.

Now a study recently published in the journal Microbiome has identified oranges as another food that may help decrease depression risk.

Larger amount of beneficial bacteria linked with eating citrus

For this study, researchers analyzed data from more than 32,000 middle-aged women who had participated in the Nurses’ Health Study II. Between 2003 to 2017, questionnaires were periodically sent to study participants to ask them about their diet and depression status.

By using DNA sequencing results from stool samples that had previously been collected by participants, the researchers found a correlation between eating citrus fruits and an abundance of 15 species in the gut microbiome, including a bacterium called Faecalibacterium prausnitzii.

Past research shows that Faecalibacterium prausnitzii is beneficial to the body as it helps lower inflammation and support the immune system.

It may also help with gastrointestinal diseases such as irritable bowel disease (IBD), as well as obesity, and even type 2 diabetes, according to some animal studies.

Depression linked to lower amount of F. prausnitzii in microbiome

Additionally, scientists found a lower amount of F. prausnitzii in the microbiome of study participants with depression.

“We found that eating one medium orange a day may lower the risk of developing depression by about 20%,” Raaj Mehta, MD, MPH, an instructor in medicine at Harvard Medical School, a physician at Massachusetts General Hospital, and lead author of this study said in a press release.

“And 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,” he further explained.

Scientists further validated their findings in men with participants of the Men’s Lifestyle Validation StudyTrusted Source, which also showed a decrease of F. prausnitzii in the microbiomes correlated to depression.

Researchers believe F. prausnitzii may help with depression by influencing levels of the neurotransmitters serotonin and dopamine via a metabolic pathway called the S-adenosyl-L-methionine cycle I pathway. This pathway plays a large role in the production of neurotransmittersTrusted Source.

“These neurotransmitters regulate how food passes through the digestive tract, but they can also travel to the brain, where they elevate mood,” Mehta said in an interview with The Harvard Gazette.

More evidence in support of ‘you are what you eat’

Medical News Today had the opportunity to speak with Gary Small, MD, chair of psychiatry at Hackensack University Medical Center in New Jersey and author of more than a dozen books on behavioral health, about this study.

“Recent research has shown intriguing links between the gut microbiome, brain health, and mood,” Small, who was not involved in this research, told us.

“Consumption of citrus fruits can stimulate growth in the human gut of certain types of bacteria that influence production of brain neurotransmitters that can elevate mood. This study offers a possible explanation for how eating oranges might lower future risk for depression and certainly supports the old adage: ‘You are what you eat’.”– Gary Small, MD

“Clinical depression that disrupts a person’s functioning afflicts an estimated 15% of people at some point in their life,” he continued. “Psychotherapy, antidepressant medications, and other treatments are effective but costly and not accessible to everyone.“

“Prevention strategies that work can have an important impact on public health since untreated or inadequately treated depression increases a person’s risk of death, not just from suicide but from medical comorbidities,” explained Small.

“People who are more likely to consume fresh fruits are also more likely to exercise regularly and engage in other healthy lifestyle habits that will lower depression risk,” he added. “A randomized, controlled clinical trial would be needed to confirm a causal relationship between citrus consumption and depression risk.”