A study has revealed the link between gut health, eating certain fruit and the risk of depression.
We’re told to eat fruit and veg because it’s good for our physical health, but – much like learning the gym is just as much for your mind as it is body – what could be the link between fruit and mental health?
A study published in BMC dives into the possibility of diet being a ‘promising avenue for depression prevention and management’ opposed to using antidepressant medications.
It reflects on how Mediterranean-style diets ‘have been associated with a nearly 35 percent reduced risk of depression’ and ‘although the specific food groups that underlie these findings remain unclear, citrus, including oranges and grapefruits, have recently been linked with lower depression risk’.
And ‘increasing data’ shows the microbiome of the gut may impact the development of mental illness
So, it decided to put this to the test.
Looking at over 32,427 participants, the study ‘analyzed the interplay between citrus consumption, the gut microbiome, and risk of depression’ – ‘one of the first and most in-depth investigations’ to do so.
The study was built off another study first formed in 1989 which consisted of 116,429 female registered nurses who were sent questionnaires after every two years collecting data on their medical history and lifetstyles.
Semi-quantitative food frequency questionnaires were then sent out in 1991 and continued every four years.
In 2003, information specifically about depression began to be collected.
Excluding those who skipped any data, the study then focused in on 32,427 middle-aged women who were followed up with from 2003’s baseline until 2017.
The food questionnaire saw participants asked how often they consumed a ‘standard serving’ of certain food items – 130 to be precise.
“For citrus consumption, participants were asked how often (never to six or more servings per day) they consumed grapefruit, oranges, grapefruit juice, and orange juice over the preceding year,” the study details. “Total citrus intake was calculated by combining the consumption of each individual product.”
Alongside taking other dietary factors into account, the study also asked participants if they’d ever been diagnosed with depression every two years, alongside any use of antidepressants.
The study worked out the effects of a higher intake of citrus on the microbiome of the gut – specifically which microbial species were more present – and then looked at how certain microbial species linked to depression.
The study resolves: “From 2003 through 2017, we identified 2173 cases of depression among 32,427 women free of self-reported physician/clinician-diagnosed depression and regular use of antidepressants at baseline.
“Over 222,923 person-years of follow-up, compared to participants in the lowest quintile of citrus consumption, those in the highest quintile had a 22 percent lower risk of depression.”
The study then checked whether the risk of depression was lowered simply by ‘total fruit’ and ‘total vegetable’ rather than simply citrus fruit.
However, Harvard Medical School instructor and Massachusetts General Hospital physician Raaj Mehta – who led the study – told The Harvard Gazette: “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.”
And the effect can be from as little as ‘eating one medium orange a day’.
In two cohorts of data overall, the study shows ‘citrus intake is prospectively associated with a greater abundance of F. prausnitzii, which in turn, is associated with a lower risk of depression’.
While Mehta notes ‘more research is needed’ to compare citrus to traditional antidepressants, the study resolves: “This finding supports the notion that dietary interventions can mitigate or prevent depression symptoms, and, importantly, offers new avenues for therapeutic and/or biomarker development.”