A comparison of two methods of measuring food group intake: grams vs servings

Different measurements can be used to quantify food group intake, such as servings, cups, or grams. Dietary recommendations are given in terms of servings (recently expressed as cup and ounce measurements), but research on disease risks often uses grams as the intake measure. Because serving sizes vary among foods within a food group, the method of expressing food group intake (grams vs servings) may impact disease risk analyses. Daily consumption of eight food groups was calculated as both Food Guide Pyramid servings and grams for 206,721 participants in the Multiethnic Cohort Study who completed a quantitative food frequency questionnaire between 1993 and 1996. Mean grams per serving ranged from 25 g for red meat to 172 g for dairy products. Spearman correlation coefficients between intakes as grams per day and servings per day were 0.85 for grains, 0.97 for vegetables, 0.99 for fruit, 0.95 for dairy products, 0.98 for red meat, 0.93 for processed meat, 1.00 for poultry, and 1.00 for fish. Because there was little effect on the ranking of study participants' intakes due to the method of calculating food group consumption, the two measures are interchangeable in disease risk models.