Citrus fruits prevent and reduce depression: here is the one you should eat more

Depression is a widespread and debilitating condition that affects more than 280 million people worldwide. It has complex causes, some of which remain unclear. The effectiveness of its treatment often leaves much to be desired.

Seventy percent of patients with depression do not respond to initial treatment with antidepressants and/or experience side effects. Nutrition can be a promising way to prevent and treat depression.

The Mediterranean diet has been associated with a nearly 35% reduction in the risk of depression and has also been shown to reduce symptoms of mood disorders. Although the specific food groups that influence these results have not been identified, citrus fruits, including oranges and grapefruits, have recently been linked to a reduced risk of depression.

WHAT THE DATA ANALYSIS SHOWED

In a new study, a team of researchers from Harvard Medical School and Massachusetts General Hospital analyzed the relationship between citrus consumption, gut microbiome, and risk of depression in more than 32,427 participants. The prospective study examined how long-term citrus consumption correlates with depression and the diversity of intestinal microorganisms, as well as the relationship between the dominance of certain bacterial species and their metabolic potential with depression.

The researchers reviewed data from the Nurses' Health Study II, which began in 1989 to identify risk factors for major chronic diseases in women. More than 100,000 nurses participated in the study, and approximately every two years they provided researchers with detailed information about their lifestyle, diet, medication use, and health status.

The authors used this data to look for evidence that nurses who ate a lot of citrus fruits had lower rates of depression in the future than those who did not. They found that eating one medium orange a day could reduce the risk of depression by about 20%.

Some of the participants provided the researchers with several samples of their stool over the course of a year. Using the results of DNA sequencing from these samples, the researchers looked for a link between citrus consumption and certain types of bacteria in the gut microbiome.

Among them, one species of bacteria stood out, Faecalibacterium prausnitzii. It was more prevalent in people who did not suffer from depression than in those who did, and consumption of large amounts of citrus fruits was also associated with high levels of Faecalibacterium prausnitzii. Therefore, scientists believe that this bacterium links citrus consumption to better mental health.

To confirm this link for men, they looked at data from the Men's Lifestyle Validation Study, where they also found that higher levels of Faecalibacterium prausnitzii were inversely correlated with depression risk.

The results of the study were published in the journal Microbiome.

HOW CITRUS FRUITS AFFECT MOOD

Then the question arose: how does Faecalibacterium prausnitzii improve people's well-being? One answer, according to the authors of the study, is that these bacteria use a metabolic pathway known as S-adenosyl-L-methionine cycle I to affect the levels of two neurotransmitters, serotonin and dopamine, which are produced by human gut cells. These neurotransmitters regulate the passage of food through the digestive tract, but they can also reach the brain, improving mood and overall mental health.

The researchers hope that their findings will inspire other researchers to study the link between nutrition and mental health. They believe that people intuitively know that certain foods affect mood. And some foods help people feel better in the short term. However, this requires further study.