U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            PAUL, DAVID - NIHitem
                                            Rhodes, Donnaitem
                                            Kramer, Matthewitem
                                            Baer, Daviditem
                                            Rumpler, William
  Submitted to: American Journal of Epidemiology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 5/25/2005
                                    Publication  Date: 8/24/2005
                                    Citation: Paul, D.R., Rhodes, D.G., Kramer, M.H., Baer, D.J., Rumpler, W.V. 2005. Validation of a food frequency questionnaire by direct measurement of habitual ad libitum food intake. American Journal of Epidemiology 162:1-9Interpretive Summary: The Food Frequency Questionnaires (FFQ) is one method commonly used to assess habitual food intake.  One limitation with them is the known measurement error that is commonly reported.  In order to reduce measurement error, investigators apply correction factors based on total energy intake or expenditure.  The problem with that approach is that the "true" habitual intake is generally not known, so the degree of measurement error and the effect of the correction is difficult to understand.  In this study, we allowed 12 men to consume meals ad libitum for 16 weeks, then asked them to report what they ate based on the FFQ.  As expected, there was significant measurement error.  The application of correction factors did not improve the measurement in all cases.  It appears as though the best way to correct FFQ data in this population is to use an individualized correction factor based on energy expenditure for carbohydrate and protein intake, and an individualized correction factor based on energy expenditure and body weight for fat intake.  Scientists will benefit from this study because it will provide the basis for research focusing on correction factors that improve the interpretation of food intake data.  Once the appropriate correction factors have been developed, nutritionists and the public will benefit from the improved data gleaned from FFQs.
                                Technical Abstract: Background: Food Frequency Questionnaires (FFQ) are a common technique used to assess habitual food intake.  Although FFQs are thought to be susceptible to measurement error, the amount of error and the effectiveness of correction factors are unknown.
Objective: To detect measurement error in FFQ predicted macronutrient intakes, and quantify the effectiveness of correction factors based on energy expenditure and/or body weight.
Design: Twelve men consumed an ad libitum, cafeteria-style diet for 16 weeks.  At the end of the study period, subjects reported their food intakes with a FFQ (Block 98).  Subjects were also dosed with doubly labeled water (DLW) and maintained physical activity logs (PA).
Results: Absolute and relative macronutrient intakes were not well predicted by the FFQ.  Although not statistically significant, the application of single, group mean correction factors (for DLW or PA) tended to reduce the variance in carbohydrate intake and increase the variance in fat and protein intakes (all P > 0.05).  The application of individual subject corrections reduced the variance for carbohydrate and protein intakes (P < 0.05).  The only procedure that significantly reduced the variance in fat intake was the combination of body weight and DLW (P < 0.05).  
Conclusions: Although the results of this study may only be applicable this relatively small and heterogeneous group of subjects, absolute and relative macronutrient intakes were not well predicted by the FFQ.  However, the application of different correction factors based on energy expenditure and/or body weight tend to reduce measurement error.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov