Influence of dietary knowledge, attitude and preference on psychological wellbeing among middle-aged and older people in China: a longitudinal study

Background The study aims to explore the influence of dietary knowledge, attitude and preference (KAP) on psychological wellbeing among middle-aged and older people in China. Methods Data from 12,418 middle-aged and older people (aged ≥55 years) in the 2006, 2009, 2011 and 2015 China Health and Nutrition Survey (CHNS) were analysed. A set of questions were used to assess the dietary KAP during face-to-face interviews. The psychological wellbeing score was constructed by summing up the scores of three psychological wellbeing related questions. Comparison of dietary KAP in urban and rural residents was conducted using chi-square test. Multilevel mixed-effects linear regression models were used to identify the association between dietary KAP and psychological wellbeing. Results The mean psychological wellbeing score of the participants decreased from 10.2 in 2006 to 9.6 in 2015. Among the participants, 37.2% had low dietary knowledge score, 95.3% held positive attitude toward healthy eating, and most of them preferred vegetables (88.0%) and fruits (73.2%), and did not like fast food (90.3%), salty snacks (85.5%) and soft drinks (66.8%). Chi-square test indicated that rural residents experienced poorer dietary KAP than urban residents (all p -values < 0.01). Participants who had medium ( β = 0.38, 95% CI = 0.30–0.47) or high ( β = 0.52, 95% CI = 0.42–0.62) dietary knowledge score, held positive attitude toward healthy eating ( β = 0.58, 95% CI = 0.41–0.76), preferred salty snacks ( β = 0.25, 95% CI = 0.04–0.45), fruits ( β = 0.36, 95% CI = 0.27–0.46) and vegetables ( β = 0.56, 95% CI = 0.43–0.68) had significantly better psychological wellbeing. Conclusion The middle-aged and older people with better dietary knowledge, holding positive attitude toward healthy eating, preferring salty snacks, fruits and vegetables were positively associated with psychological wellbeing. The positive associations might reflect a common underlying mechanism that these participants may have better capacity to derive pleasure from eating. Improving dietary knowledge and attitude, promoting preferring fruits and vegetables, and improving the capacity to derive pleasure from various food may help to protect the psychological wellbeing of Chinese middle-aged and older people.