Poor-quality diet, regarded as an important contributor to health inequalities, is linked to adverse health outcomes. We investigated sociodemographic and lifestyle predictors of poor-quality diet in a population sample.

A cross-sectional analysis of the Survey of Lifestyle, Attitudes and Nutrition (SLÁN). Diet was assessed using an FFQ (n 9223, response rate = 89 %), from which a dietary score (the DASH (Dietary Approaches to Stop Hypertension) score) was constructed.

General population of the Republic of Ireland.

The SLÁN survey is a two-stage clustered sample of 10 364 individuals aged 18 years.

Adjusting for age and gender, a number of sociodemographic, lifestyle and health-related variables were associated with poor-quality diet: social class, education, marital status, social support, food poverty (FP), smoking status, alcohol consumption, underweight and self-perceived general health. These associations persisted when adjusted for age, gender and social class. They were not significantly altered in the multivariate analysis, although the association with social support was attenuated and that with FP was borderline significant (OR = 1·2, 95 % CI 1·03, 1·45). A classical U-shaped relationship between alcohol consumption and dietary quality was observed. Dietary quality was associated with social class, educational attainment, FP and related core determinants of health.

The extent to which social inequalities in health can be explained by socially determined differences in dietary intake is probably underestimated. The use of composite dietary quality scores such as the DASH score to address the issue of confounding by diet in the relationship between alcohol consumption and health merits further study.

To estimate the extent of under- and over-reporting, to examine associations with misreporting and sociodemographic and lifestyle characteristics and mental health status and to identify differential reporting in micro- and macronutrient intake and quality of diet.

A health and lifestyle questionnaire and a semi-quantitative FFQ were completed as part of the 2007 Survey of Lifestyle, Attitudes and Nutrition. Energy intake (EI) and intake of micro- and macronutrients were determined by applying locally adapted conversion software. A dietary score was constructed to identify healthier diets. Accuracy of reported EI was estimated using the Goldberg method. ANOVA, χ2 tests and logistic regression were used to examine associations.

Residential households in Ireland.

A nationally representative sample of 7521 adults aged 18 years or older.

Overall, 33·2 % of participants were under-reporters while 11·9 % were over-reporters. After adjustment, there was an increased odds of under-reporting among obese men (OR = 2·01, 95 % CI 1·46, 2·77) and women (OR = 1·68, 95 % CI 1·23, 2·30) compared to participants with a healthy BMI. Older age, low socio-economic status and overweight/obesity reduced the odds of over-reporting. Among under-reporters, the percentage of EI from fat was lower and overall diet was healthier compared to accurate and over-reporters. The reported usage of salt, fried food consumption and snacking varied significantly by levels of misreporting.

Patterns in differential reporting were evident across sociodemographic, lifestyle and mental health factors and diet quality. Consideration should be given to how misreporting affects nutrient analysis to ensure sound nutritional policy.