Lack of efficacy of a food-frequency questionnaire in assessing dietary macronutrient intakes in subjects consuming diets of known composition.
BACKGROUND
We compared the validity of a semiquantitative food-frequency questionnaire in assessing intakes of macronutrients (absolute amounts and percentages of energy) by 19 subjects fed natural-food diets of known composition. In small subsets (n = 5 or 6), we also tested 3-d diet records.


OBJECTIVE
The objective of this study was to investigate the efficacy of food-frequency questionnaires and diet records in subjects fed natural-food diets of known composition.


METHODS
Each subject consumed 3 different diets for >/=6 wk and self-reported his or her food intake by using a food-frequency questionnaire and a diet record. The diets varied in their chemically analyzed contents of fat (15-35% energy), saturated fat (5-14%), monounsaturated fat (5-14.5%), polyunsaturated fat (2.5-10.5%), carbohydrate (49-68%), and cholesterol (108-348 mg/d).


RESULTS
The food-frequency questionnaire significantly underestimated fat, saturated fat, monounsaturated fat, and protein intakes and significantly overestimated carbohydrate intake with the high-fat diet. The percentage of energy from fat was significantly underestimated for the high-fat diet and significantly overestimated for the very-low-fat diet. Estimates from the food-frequency questionnaire differed significantly from actual intakes for fat (absolute and percentage), saturated fat (absolute and percentage), monounsaturated fat (absolute and percentage), and protein (percentage) in the high-fat diet and for polyunsaturated fat (absolute and percentage), saturated fat (percentage), fiber (absolute), and cholesterol (daily absolute; in mg/d) in the lower-fat diet. Estimates from the diet records better agreed with actual intakes than did estimates from the food-frequency questionnaire except for monounsaturated fat (absolute and percentage) in the high-fat diet and polyunsaturated fat (percentage) in the lower-fat diet and the very-low-fat diet.


CONCLUSIONS
Our data indicated that the food-frequency questionnaire did not provide reliable estimates of absolute amounts of dietary fats or cholesterol.
Schaefer
E J
EJ
Lipid Metabolism Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
Augustin
J L
JL
Schaefer
M M
MM
Rasmussen
H
H
Ordovas
J M
JM
Dallal
G E
GE
Dwyer
J T
JT
D000328:Adult; D000368:Aged; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D015930:Diet Records; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011795:Surveys and Questionnaires
D002791:Cholesterol, Dietary; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004042:Dietary Fats, Unsaturated; D004043:Dietary Fiber; D004044:Dietary Proteins