The authors conducted a dietary methodology study in 1984 in Finnish men aged 55-69 years in order to validate two dietary assessment instruments being used in the US-Finland Alpha-Tocopherol, Beta-Carotene Lung Cancer Prevention Trial. Twelve 2-day food records collected from 162 men over a 6-month period, including every day of the week, served as the reference measure. This report focuses on three important questions for investigating diet and disease relations: 1) How many days are necessary to classify "usual" intake? 2) Is there loss as a result of using consecutive days? 3) Which days are necessary for assessment and classification of "usual" diet? A repeated-measures regression model was used to estimate the variance components and the effects of consecutive days, weekday (weekday vs. weekend), and season. Correlations between the averages of different numbers of days of food records and "true" usual intake were examined along with the resulting attenuations in relative risk. Results suggest that 7-14 days are required to adequately classify most individuals into categories of intake for most nutrients and some foods. There appears to be some loss of information from using consecutive days rather than days further apart. Weekday/weekend differences in mean intakes are slight, and the rank ordering of individuals appears to be preserved. A moderate seasonal effect is shown for classification of fruits, but only a slight one is seen for micronutrients and berries. Implications for the design of epidemiologic and validation studies are discussed.
A dietary survey concerning 1348 persons aged 25-64 was carried out in connection with the first FINMONICA risk factor survey in the three monitoring areas, North Karelia and Kuopio in the east, and Turku-Loimaa in the south-west in 1982. Three-day food records were used in the dietary assessment. The fat content of the diet in men was 38-39% of energy in all areas, whereas in women it was about 36% in the east compared to 38% in the south-west. The ratio of polyunsaturated to saturated fat of the diet was lower in the east than in the south-west in both sexes (0.25 vs. 0.31). This seemed to be the result of higher milk and butter consumption in the east. The regional differences in the quality of dietary fats seemed to be the result of both different occupational structures and different dietary habits within each occupational group, especially among women.
The reproducibility and validity of a food frequency questionnaire designed to measure intakes of total fat, saturated and polyunsaturated fats, vitamins A, C, and E, selenium, and dietary fiber were tested from March to October 1984 among 297 Finnish men aged 55-69 years. The questionnaire asked about consumption of 44 food items. In the reproducibility study, 107 subjects filled in the questionnaire three times, at three-month intervals. Intraclass correlations varied from 0.52 for vitamin A to 0.85 for polyunsaturated fat. In the validity study, 190 subjects kept food consumption records for 12 two-day periods distributed evenly over a period of six months and filled in the questionnaire both before and after this period. Correlations between the nutrient intake values from the food records and those from the food frequency questionnaires ranged from 0.33 for selenium to 0.68 for polyunsaturated fat. On the average, 40-45% of the subjects in the lowest and highest quintiles based on food records were in the same respective quintiles when assessed by the food frequency questionnaire, and 70-75% were in the two lowest and two highest questionnaire quintiles, respectively. The food frequency questionnaire and a quantitative food use questionnaire tested in the same study were compared. Use of these two instruments in large-scale epidemiologic studies is discussed.
This study examines social structural and family status factors as determinants of food behaviour. The data were derived from the FINMONICA Risk Factor Survey, collected in Finland in spring 1992. A multidimensional framework of the determinants of food behaviour was used, including social structural position, family status and gender. The associations between the determinants of food behaviour were estimated by multivariate logistic regression models, adjusted for age and regional differences. Food behaviour was measured by an index including six food items which were chosen based on Finnish dietary guidelines. In general, women's food behaviour was more in accordance with the dietary guidelines than that of men. The pattern of association between educational level and food behaviour was similar for both genders, but slightly stronger for men than women. Employment status was associated only with women's food behaviour, but the tendency was the same for men. Marital status was associated with men's as well as women's food behaviour. The food behaviour of married men and women was more in line with the dietary guidelines than the food behaviour of those who had been previously married. Parental status, however, was only associated with women's food behaviour, that is, the food behaviour of women with young children was more closely in line with the dietary guidelines than that of the rest of the women.