Depression: Lower Your Risk by 20% With an Orange

A new study reveals that oranges are more than just a good source of juice and vitamin C. Research published in the journal BMC Microbiome suggests that eating one orange a day may reduce the risk of depression. The study suggests this is due to gut bacteria that impact certain chemicals in the brain.

Researchers at Harvard Medical School and Massachusetts General Hospital examined data from nearly 32,500 women participating in the Nurses’ Health Study 2, a long-running study that investigates the risk factors for chronic diseases in women. The research team also analyzed data from over 300 men. They took this information, along with fecal samples, to analyze the participants’ gut microbiomes—the microorganisms, such as bacteria and viruses, that live in the gut.

The research team also used DNA sequencing of stool samples to look for links between eating citrus fruits and particular species of bacteria in the gut microbiome. The species of bacteria that stood out was Faecalibacterium prausnitzii (F. prausnitzii), according to Dr. Raaj Mehta, the study’s lead researcher. The investigators observed that the people who were not depressed had more F. prausnitzii in their gut microbiomes.

“F. prausnitzii was more abundant in people who were not depressed than people who were, and consuming a lot of citrus was also associated with high levels of F. prausnitzii,” Dr. Mehta told The Harvard Gazette. “So we think the bacterium may link citrus consumption with good mental health.”

The research team found that a daily serving of citrus fruits, such as oranges and grapefruits, decreased the risk of depression by about 20 percent. In contrast, apples, bananas, and other fruits, along with vegetables—although considered healthy foods—did not have the same effect as citrus fruits, according to the study.

Dr. Mehta, who is also a physician at Massachusetts General Hospital, noted that citrus boosts the growth of F. prausnitzii, which in turn affects the production of serotonin and dopamine—two key neurotransmitters recognized for elevating mood. Neurotransmitters are chemicals that nerve cells use to talk to each other.
The new study does not prove that eating citrus fruits impacts mental health; it only establishes a link. Therefore, Dr. Mehta said he would like to see further evidence linking citrus fruits to depression.

“I would love to see a clinical trial done to definitively show that eating citrus can lower the risk of depression, or maybe even alleviate the condition in some cases,” Dr. Mehta told The Harvard Gazette. “There’s such a huge unmet need for depression treatments, and eating citrus doesn’t really have any major side effects, so it would be great to see how much this simple treatment can help.”

Citrus fruits are rich in flavonoids, which are compounds found in many plant products with antioxidant properties. Scott Keatley, a registered dietitian-nutritionist and co-owner of Keatley Medical Nutrition Therapy in New York, believes flavonoids are the “real game-changer” because they support the growth of F. prausnitzii. Keatley further noted that flavonoids might regulate gut processes that promote the production of the “feel-good” neurotransmitters serotonin and dopamine. The F. prausnitzii bacteria also help reduce inflammation, Keatley said.

“Since chronic inflammation has been linked to depression, increasing F. prausnitzii in the gut [by way of consuming citrus] may help regulate mood by reducing inflammatory markers,” Keatley told Women’s Health.

Dr. Gail Saltz, an associate professor of psychiatry at the NY Presbyterian Hospital Weill-Cornell School of Medicine, pointed out that the study only examined citrus’ bacterial link to the gut and not its other properties.

“Citrus may impact the gut biome, but it also has other features, such as high vitamin C, which could figure into this story,” Dr. Saltz told Women’s Health.

Although the gut-brain relationship has been established, researchers are still investigating how this pathway operates at the cellular level.

“We don’t fully understand the pathways between gut health and depression, but we do know there’s something there,” Thea Gallagher, a clinical associate professor at NYU Langone Health and co-host of the Mind in View podcast, told Women’s Health.

Will Eating Citrus Fruits Help People With Depression?

The Harvard-led study focused on preventing depression, but do citrus fruits have an effect on the symptoms or treatment of people who are already depressed? The study’s findings are unclear. So, neither Gallagher nor Dr. Saltz recommends that people who are depressed stop their current method of treatment.

“Don’t go off your medications and start eating oranges,” Gallagher told Women’s Health. Saltz told the outlet, “I would not advise anyone based on this study to in any way consider oranges a treatment for clinical major depression.”

Still, Gallagher describes the study’s findings as “exciting” for mental health. “This is something that you could easily implement in your diet and probably should, regardless,” Gallagher said. “It’s accessible, and that’s always a good thing.”

Are There Other Foods That Can Reduce the Risk of Depression?

There is already plenty of evidence that suggests consuming a lot of ultra-processed foods increases the risk of depression. Research also suggests that whole, unprocessed foods are better for mental and physical health, Gallagher said. So, Gallagher suggests taking the “safe route” by:

• Adopting an 80/20 style of eating by consuming healthy foods 80 percent of the time while being more flexible with your diet for the remaining 20 percent.

Keatley suggests:

• Eating nuts and seeds, which provide omega-3 fatty acids that reduce inflammation and improve gut-brain communication.

• Eating legumes, fatty fish, and leafy green vegetables.

“Together, these foods create a diet that supports gut health, reduces systemic inflammation, and enhances neurotransmitter balance, all of which contribute to lowering the risk of depression,” Keatley said.

Source Links:

https://www.womenshealthmag.com/health/a63917947/orange-citrus-depression-study/
https://news.harvard.edu/gazette/story/2025/02/eating-citrus-may-lower-depression-risk/