Relative validity of a FFQ in measuring carbohydrate fractions, dietary glycaemic index and load: exploring the effects of subject characteristics

Abstract

FFQ require validation as part of epidemiological research of diet -disease relationships. Studies exploring associations between carbohydrate type and chronic diseases are rapidly increasing, but information on the validity of carbohydrate fractions, dietary glycaemic index (GI) and the glycaemic load (GL) estimated by FFQ is scarce. Likewise, the effects of subject characteristics on FFQ validity have been poorly documented. The present study evaluates the relative validity of an 131-item FFQ in relation to two 3 d food records (FR) performed 6 months apart focusing on the intake of carbohydrate fractions, dietary GI and the GL. Furthermore, we assessed the extent to which subjects' age, education and BMI explain differences between these methods. The study sample comprised 218 men and 292 women aged 25-74 years participating in a large population-based survey in Finland. Energy-adjusted Spearman's rank correlations ranged from 0·27 (sugars) to 0·70 (lactose) for men and from 0·37 (sugars) to 0·69 (lactose) for women. On average, 73 % of the subjects were categorised into the same or adjacent distribution quintile based on the two methods. In general, the FFQ overestimated the intakes compared with FR. Especially in women, FFQ validity for some nutrients was associated with the level of intake, subjects' age and, to a lesser extent, education but not BMI. In conclusion, the FFQ appears to be reasonably valid in the assessment of carbohydrate exposure variables, but the findings show a need for adjustment of diet -disease relationships for subjects' age and education.

The Baltic Sea Diet Score: a tool for assessing healthy eating in Nordic countries

“…Our FFQ has been found to overestimate the consumption of vegetables, longchain n-3 fatty acids, carotenoids and vitamin C, and underestimate alcohol and margarine consumption (48) . Since the FFQ has good ability to rank individuals according to relative nutrient intakes, the misreporting may not be problematic in the present study (21,22) . Vitamin and mineral supplement usage was not taken into account; but this may not influence the results however, since supplement users are likely also to have higher vitamin intakes from foods and thus be classified correctly (50)(51)(52) .…”

A diet following Finnish nutrition recommendations does not contribute to the current epidemic of obesity

“…Since the study design was cross-sectional, we could examine the associations between diet and obesity but not the causal effects. We used a validated FFQ and various internationally standardized anthropometric measurements (15)(16)(17)22) . The FFQ might have influenced the exposure assessment because the questionnaire was filled in during a certain period of the year (spring), which means that some foods are remembered and reported more accurately than others.…”

“…Dietary intake Participants filled in a validated 131-item FFQ, which was designed to measure the habitual diet over the previous 12 months (15)(16)(17) . The participants were asked to indicate the average consumption frequency of each FFQ item by using nine frequency categories ranging from never or seldom to six or more times daily.…”

Naturally occurring and added sugar in relation to macronutrient intake and food consumption: results from a population-based study in adults

“…Food consumption was measured using a comprehensive 131-item semi-quantitative FFQ inquiring into the average use frequencies of central food groups during the previous 12 months ( 17 ) . Based on the National FINDIET 2007 Survey data ( 18 ) , each FFQ item was aggregated from 1–8 most commonly consumed foods (encoded in the food composition database) and the portion sizes were fixed sex-specifically.…”