The research is based on a correlation between diet and people’s self-assessed mental-health scores, relating to a U.K. general health questionnaire and life-satisfaction scoring system. The researchers also show by drawing upon Australian data, that a similar result may also stand for actual clinical diagnosis of depression and anxiety. The conclusion drawn is that there is an indication of accumulating evidence for the psychological relevance of a diet rich in fruit and vegetables. This was an inverse relationship, that is the more fruit and vegetables people ate the less likely they were to be diagnosed with a mental illness in later periods.
The research found that eating four extra portions of fruit and vegetables each day seems to raise people’s mental health to the level that this can offset half the negative psychological impact of a major life event, like divorce. Moreover, this level of fruit and vegetable consumption could off-set a quarter of the psychological damage caused by unemployment.
Whereas earlier research has based a diet and mental health connection based on people’s subjective responses (limited by cross-sectional correlations, convenience samples, and lack of adequate controls), the new study uses objective evidence, based on longitudinal data, about the association between fruit and vegetables and overall psychological health. An advantage connected with the longitudinal nature of the dataset was that the researchers were able to relate changes in fruit and vegetable consumption with changes in self-reported well-being for the same individual over a sustained period of time.
The research was led by Redzo Mujcic, Assistant Professor of Behavioural Science, and Andrew Oswald, Professor of Economics and Behavioural Science (both based at the University of Warwick, U.K.). The research findings have been published in the journal Social Science Medicine, with the research paper titled “Does eating fruit and vegetables also reduce the longitudinal risk of depression and anxiety? A commentary on ‘Lettuce be happy'”.
