Guiding Principles for Developing Dietary Reference Intakes Based on Chronic Disease (2017) / Chapter Skim
Currently Skimming:
4 Methodological Considerations Related to Assessing Intake of Nutrients or Other Food Substances
4 Methodological Considerations Related to Assessing Intake of Nutrients or Other Food Substances
Pages 89-106
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 89... ...
Accuracy in the NOFS intake methodology is essential because the quantitative relationship between the nutrient and the chronic disease must be characterized with considerable certainty in order to establish a chronic disease Dietary Reference Intake (DRI)
|
From page 90... ...
Calibration of a self-reported dietary intake method: Calibration is the process of using a suitable intake biomarker in an attempt to correct a self-reported intake assessment for measurement error. Calibration equations are typically developed by regressing biomarker intake values on corresponding self-reported values and possibly other study participant characteristics.
|
From page 91... ...
. METHODS TO ASSESS NUTRIENTS OR OTHER FOOD SUBSTANCES Self-Reported Measures of Dietary Intake Self-report of NOFSs has been the primary intake assessment method for most cohort studies and randomized controlled trials with chronic disease endpoints.
|
From page 92... ...
The use of repeated and updated dietary assessments by validated food frequency questionnaires has been found to reduce measurement errors and represent long-term dietary habits, which are most relevant to chronic disease etiology and prevention. Some studies have analyzed changes in dietary exposures over time and subsequent risk of chronic diseases.
|
From page 93... ...
A biomarker that substantially meets this classical measurement model criterion will have the greatest utility when the biomarker measurement error variance is small relative to the variance of the targeted nutritional variable in the study population. However, it is important to note that some nutrition-related biomarkers, useful for other purposes, do not reflect intake but, rather, NOFS status.
|
From page 94... ...
thus it may not represent usual intake (systematic error)
|
From page 95... ...
This may introduce systematic bias associated with obesity, race/ethnicity, social class, or unusual dietary lifestyle. Brief Instruments for Limited questions The questionnaire Highly feasible, Strengths: Provides qualitative or general specific nutrients or about usual intake of may be completed by low respondent ranking data on specific foods or nutrients.
|
From page 96... ...
Limitations, however, do exist. Importantly, only a few true recovery biomarkers are available, namely doubly labeled water, which estimates total energy expenditure and is used to approximate total energy intake in weight-stable individuals; urinary nitrogen (from 24-hour urine collections)
|
From page 97... ...
Furthermore, for many concentration biomarkers, metabolic and physiological factors will influence concentrations. For example, phospholipid fatty acids are influenced by both dietary intake and endogenous fatty acid synthesis.
|
From page 98... ...
. Validity and Utility in Assessing Dietary Intake with Biomarkers of Intake The measurement error associated with dietary self-report may be a significant impediment for DRI committees, whose task will be focused on establishing optimal NOFS intake values for chronic disease risk reduction.
|
From page 99... ...
, plus random noise that does not depend on the targeted intake, or on other study participant characteristics that are pertinent to the disease under study (e.g., established disease risk factors, other dietary intakes, physical activity patterns)
|
From page 100... ...
. The committee concluded that biomarkers meeting an R≥0.6 criterion relate to actual intake about as closely as those established biomarkers and may be used to obtain calibrated intake values and provide useful objective measures of intake in the population from which feeding study participants were drawn.
|
From page 101... ...
The committee developed a decision guide (see Figure 4-2) for use in considering dietary intake methodological issues in studies on diet and chronic disease and in incorporating questions in the risk-of-bias assessment.
|
From page 102... ...
In the long term, research agendas should include accel erated efforts to improve NOFS exposure assessments for application in studies of chronic disease risk. Specifically, based on a systematic search of the scientific literature related to validation of dietary assessment methods, DRI committees will select a priori criteria to define the most accurate dietary intake methods, such as those that use validation and calibration methods to minimize bias.
|
From page 103... ...
using a standardized risk of bias tool risk of bias on the outcomes and incorporate in risk-of-bias = a decision point; assessment = an action FIGURE 4-2 Decision guide for use in considering dietary intake methodological issues in studies on diet and chronic disease and in incorporating questions in the risk-of-bias assessment. NOTE: FFQ = food frequency questionnaire; HR = hour.
|
From page 104... ...
? • Were intake data based on one or more days of the week?
|
From page 105... ...
2017. Dietary long-chain fatty acids and carbohydrate biomarker evaluation in a controlled feeding study in participants from the Women's Health Initiative cohort.
|
From page 106... ...
1985. Reproducibility and validity of a semiquantitative food frequency questionnaire.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.