A study of thousands of twins has suggested what your grandmother preached all along: eating more fruits and vegetables is associated with a lower risk of depressive symptoms.
Scientists led by a team at UNSW Sydney looked at 3,483 twins (all aged over 45) from Australia, Denmark, Sweden, and the US to see how their fruit and vegetable intake compared with the extent of their depressive symptoms.
Within the pairs of twins, the individuals who had higher intakes of both fruit and vegetables tended to report fewer symptoms of depression, leading the paper to conclude that “higher fruit and vegetable intakes may protect against depressive symptoms.”
“The findings present another argument for increasing fruit and vegetable intake in adults over 45 years of age,” Dr Annabel Matison, lead study author and postdoctoral fellow at UNSW Sydney, said in a statement.
Bear in mind that the relationship is a correlation, not causal. In other words, the study found a link between fruit and vegetable consumption and certain aspects of depression, but it did not determine whether the dietary differences were directly responsible for the outcomes.
For instance, the twin who ate more vegetables might also exercise more, drink less alcohol, and maintain a healthier lifestyle overall, all of which can promote improved well-being.
With the caveat in mind, twin studies are fairly effective at reducing other factors that can skew the results, like genetics and upbringing.
“Twin pairs share 50-100 percent of their genetic background and when raised together share the same family environment. One of the advantages of the twin design is that it can help address the issue of unwanted factors, such as socioeconomic status early in life, influencing the results,” added Dr Karen Mather, co-author on the research and Leader of the Centre for Healthy Brain Ageing’s Genomics and Epigenomics Group.
It’s also hardly controversial to say that a diet rich in fruit and vegetables is good for your health, including your mental health.
With their abundance in dietary fiber, vitamins, and micronutrients, it’s apparent that fruit and vegetables are likely to help the gut microbiome and protect against oxidative damage to the brain, which could potentially improve mental well-being.
“The importance of the gut microbiome and its potential influence on depression as a result of inflammation, both systemic and neuroinflammation, is becoming increasingly well understood,” explained Dr Matison.
Not all vegetables are created equal, though. The study found that higher potato intake does not have a beneficial association with depressive symptoms. This might be because potatoes are often eaten in their delicious (albeit not highly nutritious) deep-fried form, although the researchers note that “further research is required to understand the relationship between potato intake and depression.”
Another interesting, albeit hardly surprising, insight for the study was people in Europe, Australia, and North America aren’t eating enough fruit and vegetables. This is especially true in Scandinavia, where studies have shown the average person eats less than half the World Health Organization’s recommended of at least five servings per day.
Could we see a reduction in depression if servings were increased to the recommended levels? The study’s findings seem to point in that direction, although Matison said it was still “unclear.”
The study is published in the journal Scientific Reports.
