Eating an orange a day could reduce your risk of depression
A well-established benefit of running – and exercise as a whole – is the positive impact that it has on your mental health. If you move your body, you really can improve your mind.
But running isn’t the only thing that you can do to influence your mental health. Indeed, research has shown that your gut and brain also like to talk to each other, to the point where they can even influence the health of one another. What you eat – and the bacteria that it creates in your gut – can have a big impact on how you think and feel, with new a study suggesting that this connection could affect your entire mental health.
The study in question, which was published in the journal BMC Microbiome, explored the link between the consumption of citrus and the onset of depression. The findings? Doing something as simple as including oranges in your daily diet could help to lower your risk of developing depression.
It’s important to stress that many factors contribute to depression, so it is unfair to assume that just eating an orange a day will dramatically alter your mental health. However, if you want to learn more about the things that you can do to lower your risk of depressions, these findings are worth paying attention to.
Here’s what the researchers found – plus, what a dietitian and psychologist want you to keep in mind when interpreting the study’s results.
What did the study find?
The study analysed data from almost 32,500 women who were involved in the longitudinal Nurses’ Health Study 2, which aimed to investigate chronic disease risk factors for women, as well as data from more than 300 men. They then used this data, along with faecal samples, to learn more about the participants’ gut microbiomes.
The researchers found that those who had a daily serving of citrus lowered their risk of developing depression by about 20%. This was unique to citrus – meaning that the data didn’t establish the same link with other fruits or vegetables.
On closer examination, the researchers discovered that the bacteria Faecalibacterium prausnitzii (F. prausnitzii), which is found in the gut of people who eat citrus fruits, was more abundant in people who weren’t depressed.
‘These data underscore the role of diet in the prevention of depression and offer a plausible explanation for how the intestinal microbiome modulates the influence of citrus on mental health,’ wrote the researchers in their conclusion.
How does gut bacteria influence your mental health?
According to registered dietitian Scott Keatley, co-owner of Keatley Medical Nutrition Therapy, the bacteria in your gut – otherwise known as your gut microbiome – play a ‘crucial role’ in your mental health by influencing the production of neurotransmitters (chemical messengers that help cells ‘talk’ to each other), bodily inflammation and the integrity of your gut barrier.
‘Certain gut bacteria, like F. prausnitzii, contribute to the gut-brain axis, a bi-directional communication system between the gut and the brain,’ says Keatley, who explains that this type of bacteria is especially important because it can help to reduce inflammation. ‘Since chronic inflammation has been linked to depression, increasing F. prausnitzii in the gut [by way of consuming citrus] may help to regulate mood by reducing inflammatory markers,’ he adds.
Although the gut-brain relationship is has already been established, the way that this pathway actually functions on a cellular level is still being explored. ‘We don’t fully understand the pathways between gut health and depression,’ says Thea Gallagher, a clinical associate professor at NYU Langone Health in the US. ‘But we do know that there’s something there.’
How many oranges should you eat to see the benefits?
This particular study found that eating one medium orange a day could help to lower your risk of depression. However, the researchers consider all citrus fruits equal in this regard. So, if you’re a grapefruit fan, having a daily serving can still give your mental health the same boost.
Why is citrus so special?
There are a few things about citrus that seem to give it an edge when it comes to improving mental health.
‘The real game-changer in citrus is its high concentration of flavonoids, such as naringenin and formononetin,’ says Keatley, who adds that these flavonoids help to support the growth of the essential bacteria F. prausnitzii. Flavanoids may also regulate processes in the gut that help to increase the availability of our ‘feel-good’ neurotransmitters, serotonin and dopamine, in the body.
Keep in mind, though, that the study’s findings don’t actually prove that consuming citrus influences your mental health – they just establish a link.
What’s more, the study only looks at one aspect of citrus’ impact on the gut – and, specifically, the bacterial link. ‘Citrus may impact the gut biome, but it also has other features, such as high vitamin C, which could figure into this story,’ says Gail Saltz, associate professor of psychiatry at the NY Presbyterian Hospital Weill-Cornell School of Medicine in the US.
Can other foods lower your risk of depression?
Possibly. Research has found a link between eating a lot of ultra-processed foods and a higher risk of depression, which suggests that eating whole, unprocessed foods may be better for your mental and physical health, says Gallagher.
Gallagher adds that focusing on fruits, vegetables, whole grains and foods that don’t contain lots of ingredients is the ‘safe route’ when it comes to eating for mental health. But she also suggests focusing on an 80/20 style of eating, where you try to eat healthily for 80% of the time and are more lenient with what you eat for the other 20% of the time.
Keatley also suggests consuming fermented foods like yogurt, kimchi and kefir, which have probiotics that can help to regulate neurotransmitter levels in the brain, along with nuts and seeds, which provide omega-3 fatty acids that reduce inflammation and enhance gut-brain communication.
Legumes, fatty fish and leafy green vegetables may also help. ‘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,’ notes Keatley.
How does this impact the treatment of depression?
This study looked specifically at preventing depression – not treating it. So, if you already have depression, it’s unclear, based on these findings, whether eating oranges may impact your symptoms or treatment plan.
Either way, Gallagher is keen to emphasise that you shouldn’t simply replace any medications you’re taking with oranges – and Saltz agrees. ‘I would not advise anyone, based on this study, to in any way consider oranges a treatment for clinical depression,’ she says.
Gallagher still calls the findings ‘exciting’ for mental health. ‘This is something that you could easily implement in your diet and probably should regardless,’ she says. ‘It’s accessible and that’s always a good thing.’
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