Footnotes to food tables: 1. Differences in nutrient intakes of dietitians as calculated from the DHSS food tables and the fourth edition of McCance and Widdowson's 'The composition of foods'

Abstract

The differences in nutrient intakes as calculated by two British food composition tables (those compiled by the Department of Health and Social Security in 1963 [DHSS] and the 4th edition of McCance and Widdowson's 'The composition of Foods' [MW4] were examined. Intakes of 43 dietitians who kept weighed diet records every sixth day for 3 to 12 months with 11 to 75 (mean 40) days' records per subject were calculated from each food table and compared in a loge tranformation. Mean per cent differences between intakes (delta x 100) were vitamin A, +23.3; vitamin D, + 21.1; riboflavin, + 16.0;calcium, +6.3; thiamin +4.8; niacin, +3.2 (MW4 higher) and protein, -1.7; fat, -3.5; energy, -3.6; carbohydrate, -6.0; vitamin C, -6.1; iron, -11.3; vitamin B6, -14.4 (MW4 lower). Correlation coefficients were: nicotinic acid, 0.84; vitamin B6, 0.86; other nutrients 0.90 to 0.99; thus differences between the two food tables in classifying individuals as high or low consumers were small. Mean intakes compared by paired t-test were significantly different (P less than 0.001) for all nutrients except nicotinic acid, indicating consistent differences in the food tables when applied to foods eaten by different individuals (nicotinic acid excepted). Mean intakes compared by one-tailed t-test -- as if the data came from independent surveys -- were significantly different/only for riboflavin/and vitamin/B6 (P less than 0.01), vitamin A and iron (P less than 0.05). For these nutrients, significant differences in intakes could be found between two surveyed populations due solely to the use of different food tables and not to differences in foods eaten. For the other nutrients studied, differences between the food tables were of little practical importance. Differences were due primarily to new analytical values in MW4 for riboflavin in milk, retinol in liver, iron in meats, vitamin B6 in many foods, and the use of margarine fortified with vitamins A and D in recipes. Major differences in the (high) nicotinic acid content of beer, instant coffee and specific breakfast cereals resulted in unpredictable differences in intakes of individuals.