A study in Australia in 2016 revealed improvement in psychological well-being after increasing the consumption of fruits and vegetables. We would like to know if this conclusion was really used, using a larger sample (more than 40,000 participants) from a UK longitudinal study.
Our analysis has shown that an increase in the consumption of fruits and vegetables is associated with an increase in the self-esteem of the welfare psyche and life satisfaction with data covering the age of one, even after taking into account other determinants of mental well-being such as physical well-being, Revenue, and consumption of other products.
The benefits of physical activity for mental health are well established. Estimates of our work show that adding one portion to your daily ration may be just as beneficial to mental well-being as a walk for an additional seven to eight days a month. One serving is one cup of raw vegetables (fist size), half a cup of cooked vegetables or chopped fruits or one piece of whole fruit. This result is encouraging as it means that one of the possible ways to improve mental health may be something as simple as taking an extra piece of fruit daily or a salad with food.
It is important to emphasize that our findings alone can not reveal the causal relationship between the consumption of fruits and vegetables to increased psychological well-being. And we can not exclude the so-called "substitution effects". People can eat so much a day, so that someone eats more fruits and vegetables can just have fewer places to eat for unhealthy food. Although in our study we took into account bread and dairy products, ideally, future studies should track all other consumed products to exclude alternative explanations
. For example, a randomized study in New Zealand found that in a treatment group where young people were asked to eat two additional portions of fruit and vegetables per day for two weeks, various mental well-being measures such as motivation and vitality improved.
Although our own Research can not exclude that people with a higher level of mental well-being can Eat more fruits and vegetables, as a result of which the last comment of our work by the authors of the Australian study in 2016 sheds light on this. The authors show that the amount of fruits and vegetables consumed per day can predict whether someone will diagnose depression or anxiety in two years. But the reverse does not seem true. The diagnosis of depression does not appear to be a strong predictor of fruit and vegetable consumption in two years. This suggests that it may be more likely that the use of fruits and vegetables affects the mood, and not vice versa.
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Seeking the cause
 Although several studies, including our own, have found a link between the consumption of fruits and vegetables and mental well-being, we need great trials to provide strong evidence that the link is causal. However, randomized controlled trials are expensive, so another way of identifying cause-and-effect is to focus on biological mechanisms that detect the chemicals that are commonly found in fruits and vegetables to the physical changes in the body. For example, it has been shown that vitamins C and E reduce inflammatory markers associated with depressive mood.
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Although additional research is needed, our work adds weight to the growing volume of evidence that the use of fruits and vegetables and a higher level of mental well-being is positively correlated and signs of causation. It is encouraging with other recent studies. We do not offer fruits and vegetables by replacing drug treatment, but an easy way to improve your mental health is to add a little more fruit and vegetables to your daily diet.
Neel Ocean is a research researcher on behavioral economics and Peter Hawley is an associate professor of economics at Leeds University. They receive funding from the Food Security Program of the United Kingdom's Global Food Security Program with the support of the BBSRC, the ESRC, the NERC and the Scottish Government.