Social position and nutrition: a gradient relationship in Canada and the USA

[corrected] To study the existence of a graded relationship between the nutrient content of the diet and some measures of social position.

The graded relationship hypothesis was verified by secondary analysis performed on two different nutrition surveys: the Quebec Nutrition Survey (QNS) and the NHANES III, both based on a single 24 h recall. The data of these surveys were collected on a representative sample of two different populations, the first (n=2103) in the province of Quebec (Canada) in 1990 (QNS) and the second in the US population (n=14 877) between 1988 and 1994 (NHANES III).

The social gradient hypothesis was tested with four different social position indicators. The analyses were performed separately for men and women aged from 18 to 74 y, for all the nutrients available in the databanks. For the USA, the graded relationship for the total population, for the non-Hispanic white population and for respondents sometimes or often experiencing a lack of food was also measured.

A graded relationship between almost all nutrients and the studied social position measurements is observed for the consumption of total calorie-adjusted nutrients, for the proportion of people eating in accordance with dietary guidelines and for the proportion of individual not meeting 75% of the respective Recommended Dietary Allowances for their country. The direction of these relationships (positive or negative) is mainly in accordance with the clinical known impacts of nutrients on chronic diseases.

It is possible that nutrition plays a role in the graded distribution of social health inequalities in North America even in the magnitude of this contribution remains to be evaluated.