Diet Quality, Dieting, Attitudes and Nutrition Knowledge: Their Relationship in Polish Young Adults—A Cross-Sectional Study

The purpose of this study was to examine the relationships between diet quality, dieting, nutrition knowledge and attitudes in a group of Polish young adults. A cross-sectional survey was conducted in 2018 amongst 638 students of food and nutrition-related majors. Based on the frequency of consumption of 24 food groups, the “Pro-Healthy Diet Index” (pHDI) and “Non-Healthy Diet Index” (nHDI) were calculated. To assess the nutrition knowledge, the “GAROTA” test was used. The k-means clustering method was used to identify clusters-attitudes towards food and nutrition. The relationships between pHDI and nHDI indices, dieting, nutrition knowledge (NK), and attitudes towards food and nutrition were verified, using multiple linear regression analysis. The results confirmed some relationships between the variables. Higher nHDI characterized males (p < 0.0001) and people with more unfavorable attitudes towards food and nutrition (p < 0.0001), and those not using a diet (p < 0.0001). Higher nutrition knowledge (p < 0.0001) and higher BMI (p = 0.0370) were correlated with lower nHDI. Higher pHDI characterized people with more favorable attitudes (p < 0.0001) and those using a diet (p = 0.0002). Nutrition knowledge showed an adverse association with nHDI (r = −0.172, p < 0.05) and no association with pHDI. Thus, declarative nutrition knowledge does not seem to be a good indicator of healthy dietary behavior. Nutrition education programs that concentrate only on knowledge of facts, and neglect the development of favorable attitudes towards food and nutrition, may not be efficient enough to develop adequate dietary behavior of students.