The saying ‘gut instinct’ originates from the influence our stomach has on our brain, and our gut is often said to be our second brain. This means what we eat, and the bacteria that form in our gut, can have a big impact on how we think and feel and it is claimed it can influence our mental health.

A study published in the journal BMC Microbiome has found a link between eating citrus and a lowered risk of depression .

The study included 32,427 participants and looked at the connection between citrus consumption, the gut microbiome, and risk of depression.

It asked participants how often they consumed a serving of 130 food items.

They were asked how often – from never to six or more servings per day –  they consumed grapefruit, oranges, grapefruit juice, and orange juice over the preceding year.

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 and then examined the microbial species linked to depression.

The study found that from 2003 through 2017, there were 2173 cases of depression among the 32,427 women.

It found that compared to participants who had lower levels of citrus consumption, those who ate the most 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.

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’.

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.”