Japanese female nurses' characteristics and diet quality associated with their food intake patterns: The Japan Nurses’ Health Study

Japanese women have the longest life expectancy of any population of women in the world. Insights regarding the background factors behind their diets may provide helpful information for improving health globally. The present study aimed to examine Japanese female nurses' characteristics and the diet quality associated with their food intake patterns. This cross-sectional study included 11,164 female Japanese nurses. Participants completed a 98-item semi-quantitative food frequency questionnaire and provided information about their demographic characteristics. Latent class analysis was used to classify participants’ food intake patterns on the basis of energy contribution, and the Alternative Healthy Eating Index was used to score diet quality from 0 (worst) to 110 (best). Four patterns were identified: “Class 1: Convenient and highly processed food,” “Class 2: Traditional Japanese food,” “Class 3: Vegetable/fruit-oriented,” and “Class 4: Seafood and high snacking.” Alternative Healthy Eating Index scores were best (73) in Class 2 and worst (61) in Class 1. Prevalence ratios were significantly higher for Class 1 among younger nurses, those working night shifts, registered/licensed practical nurses and smokers; for Class 2 among older nurses, those working in public health or midwifery, and not working night shifts; for Class 3 among public health nurses/midwifes with children; and for Class 4 among registered/licensed practical nurses, smokers, those working night shifts, and those without children. Diet quality among Japanese female nurses was high, especially for those who ate a traditional Japanese diet. Younger nurses and those who smoked or worked night shifts were more likely to have a poorer quality diet.