ByWALLA! HEALTH
A new study found a significant link between citrus fruit consumption and a reduced risk of depression, through its influence on gut bacteria and brain neurotransmitters.
If you're looking for a natural way to combat depression, the answer might be in the fruit section. A new study recently published in the scientific journal Microbiome points to a surprising connection between the consumption of oranges and other citrus fruits and a significant reduction in the risk of developing depression.
The researchers, led by Dr. Raaj Mehta from Harvard Medical School and Massachusetts General Hospital, analyzed data from over 32,000 middle-aged women who participated in the Nurses' Health Study II. Over approximately 14 years (2003–2017), the participants filled out periodic questionnaires about their diets and depression status.
Through DNA sequencing of stool samples collected from the participants, the researchers discovered a link between citrus fruit consumption and the abundance of 15 species of gut microbiome bacteria, particularly a bacterium named Faecalibacterium prausnitzii.
“We found that eating one medium orange a day may reduce the risk of developing depression by about 20%,” said Dr. Mehta. “And the effect seems specific to citrus. When we look at overall fruit or vegetable consumption, or other fruits like apples or bananas, we don’t see a connection between intake and risk of depression.”
Microbiome and Mental Health
Previous studies have shown that the bacterium F. prausnitzii is beneficial to the body because it helps reduce inflammation and supports the immune system. It may also help with inflammatory bowel diseases, obesity, and even type 2 diabetes, according to animal studies.
The new study found a lower amount of F. prausnitzii in the microbiomes of the participants who suffered from depression. The researchers validated their findings among men as well, using data from the Men’s Lifestyle Validation Study, which also showed a decrease in F. prausnitzii in relation to depression.
The researchers believe that F. prausnitzii may help reduce depression by affecting the levels of the neurotransmitters serotonin and dopamine through a metabolic pathway known as the S-adenosyl-L-methionine cycle I. This pathway plays an important role in the production of neurotransmitters.
“These neurotransmitters regulate food transit through the digestive system, but they can also travel to the brain, where they elevate mood,” explained Dr. Mehta.
Fascinating Links Between Gut Microbiome and Mood
Professor Gary Small, Head of the Psychiatry Department at Hackensack University Medical Center in New Jersey, commented on the study: “Recent research has shown fascinating connections between the gut microbiome, brain health, and mood. Consuming citrus fruits can stimulate the growth of certain types of bacteria in the human gut that affect the production of brain neurotransmitters that can elevate mood.”
Dr. Rudolph Bedford, a certified gastroenterologist at Providence Saint John's Health Center in Santa Monica, California, added: “We know that the microbiome regulates many aspects of the body, from the immune system to the brain, so it’s not surprising to find a lack or surplus of certain bacteria that may regulate brain function, depression, and other neurological issues.”
The study provides additional evidence supporting the saying “you are what you eat” and offers a simple and natural preventive strategy against depression. Clinical depression affects about 15% of people at some point in their lives, and traditional treatments like psychotherapy and antidepressant medications, while effective, are costly and not accessible to everyone.
According to Dr. Bedford, it is important for researchers to continue to find new ways to prevent depression through natural means like diet. “It keeps us from relying on various medications to treat or prevent conditions like depression, and I’m sure there are also keys to addressing anxiety and other psychological behaviors,” he noted.
However, the experts emphasize that a randomized and controlled study is needed to confirm a causal relationship between citrus consumption and depression risk, and that there is still a long way to go in understanding the full impact of the microbiome on mental health.
In the meantime, adding a medium orange a day may be a tasty and simple way to support your mental health—and that’s definitely a good reason to smile.
