Which fruit in Australia is underestimated

Vegetables for the psyche

Leeds / Warwick (Great Britain) - Diet affects not only physical well-being, but could also affect psyche. This is what British researchers conclude from a follow-up study in which the participants repeatedly provided information about their eating habits and their mental well-being over a longer period of time. There was an astonishingly close relationship between the extent of fruit and vegetable consumption and self-assessed mental health. Another study with data from Australia confirms a possibly positive effect of the plant-based diet. Instead of self-disclosure by those involved, these researchers documented medically proven depression and anxiety disorders. According to both research groups, the results published in the journal “Social Science and Medicine” suggest that increased consumption of fruit and vegetables can improve mental health.

“The effects of fruits and vegetables may have been underestimated so far,” write Redzo Mujcica and Andrew Oswald from the University of Warwick. They used data from 7,108 people aged 15 or over from two surveys in Australia two years apart. Among other things, respondents indicated whether they had ever been diagnosed with depression or anxiety disorder that lasted for at least six months. That was the case for a total of 17 percent. The probability of developing such a mental disorder for the first time between the two interview dates was greater, the lower the consumption of fruit and vegetables. Influencing factors such as age, school education and income were taken into account in the statistical analysis. This suggests that a fortified plant-based diet could have a protective effect.

The researchers also examined the possibility of a reverse causality: In this case, people with current or past illness should have reduced their fruit and vegetable consumption by the time of the first survey by the second survey. However, there was no evidence of this. The negative psychological impact of inadequate consumption of plant-based foods could reach levels comparable to experiencing unemployment or divorce, the authors write.

The much larger study by Neel Ocean and his colleagues at the University of Leeds lasted seven years. They evaluated data from around 50,000 British people who were at least 15 years old. Between 2009 and 2017, the participants were asked annually on how many days per week and in what quantities they ate fruit and vegetables. A standardized test with twelve questions was used to measure psychological well-being. The respondents rated their feelings of joy, happiness, fear, stress, worry and dejection on a scale from 0 to 3. The researchers used subjective information on the degree of life satisfaction as an alternative measure of mental well-being. They considered age, gender, income, school education, marital status, chronic illnesses, tobacco consumption and physical activity as influencing factors.

The more frequently fruit and vegetables were consumed per week and the greater the amounts consumed per day, the better the scores for mental health and satisfaction. Assuming a causal relationship that has not yet been established, the results indicate that even a slight increase in plant-based food can have a positive effect on the psyche, the researchers write. It has not yet been clarified how a causal relationship could be explained. Plant-based ingredients such as vitamins or antioxidants and breakdown products of complex carbohydrates could act on the brain and improve mood. It is also conceivable that heavy consumption of fruit and vegetables would reduce the consumption of more harmful foods and thereby indirectly promote health. Incidentally, only one in five participants in the larger study consumed the generally recommended five servings of fruit and vegetables per day. According to the World Health Organization (WHO), 400 grams of it should be consumed daily to prevent chronic diseases and malnutrition.

© Wissenschaft aktuell