Selected Intakes as Ratios of Energy Intake, US Population, 2001-04
The NCI method provides the capability, for the first time, to estimate the
distribution of usual intake of a nutrient expressed as a ratio of usual energy
intake in the US population. This greatly enhances our ability to monitor diets
relative to those recommendations that are expressed as ratios of energy intake
and to assess the scope of dietary deficiencies and excesses in these cases. An
example is the ratio of usual saturated fat intake (expressed in terms of energy
value) to usual energy intake.
We have applied the NCI method to data from two recent cycles of the National
Health and Nutrition Examination Survey (NHANES), a nationally representative
sample, to estimate means and percentiles of the distributions of the ratio of
usual food or nutrient intake to usual energy intake for a range of sex-age
groups in the US population.
Methods
Dietary data were obtained from the 2001-2004 NHANES. The data were
collected via two 24-hour recalls from 17,889 persons 1 year of age and older.
Further information regarding the design and methodology used in the
2001-04 NHANES is available from the CDC.
Intakes of macronutrients are available in the NHANES datasets. In addition,
intakes reported on the recalls were translated into quantities of solid fats,
alcoholic beverages, and added sugars using the MyPyramid Equivalents Database
(MPED) 1.0, which was developed for the 2001-02 survey, and MPED 2.0 which was
developed for the 2003-04 survey. This analysis does not account for the
differences in data collection and processing procedures during the 2001-2004
time period.
An extension of the NCI method of estimating
usual dietary intake distributions was used. The model postulates a joint
bivariate model for the nutrient/food in question and energy intake. The method
deals with ratios of usual intake of nutrients or foods that are consumed almost
every day by everyone in the population. That is, this is an extension of NCI's
method of estimating usual intake of nutrients, and episodically consumed foods
are not considered here.
Each reported nutrient intake was first mathematically transformed to
approximate normality using a Box-Cox (power) transformation. Dietary recalls
tend to be different depending on whether they are the first or second report
from an individual (the "sequence") and whether the reported day was a weekday
or weekend. For each nutrient, the joint distribution of the Box-Cox
transformed reported nutrient and energy was modeled, correcting for sequence
and weekend/weekday effects and based on sex/age group. Means and percentiles
of the distribution of the ratio of usual nutrient intake to usual energy intake
were then estimated. Analyses were conducted for the entire population and for
a range of sex-age subgroups. The method uses the survey sampling weights to
adjust estimates for the complex sampling design and nonresponse.
[Return to top]
Results
Results from the NCI Method using 2001-2004 NHANES data are presented in the
tables below. There are separate tables for each of the following ratios, all
of which are expressed as percentages: total fat (kcal) to energy (%); saturated
fat (kcal) to energy (%); polyunsaturated fat (kcal) to energy (%); and
monounsaturated fat (kcal) to energy (%); and solid fats, alcoholic beverages,
and added sugars (kcal) to energy (%). These tables show the mean, standard
error of the mean, and percentiles of the distribution of intake for each
percentage, by sex/age group. Additionally, each table has a corresponding
Appendix table (denoted with an "a") that provides percentile values and their
standard errors.
[Return to top]
Selected Findings
- The 2005 Dietary Guidelines for Americans recommend that saturated fat
intakes be less than 10 percent of calories. Over half the population consumed
in excess of that, as the usual intake at the 50th percentile was 11% of energy
for the entire population among most sex-age groups.
- The Dietary Guidelines for Americans recommend that total fat intake be
kept between 20 to 35 percent of calories. Most Americans' dietary fat intake
fell within this range. The usual intake at the 5th percentile was 25% of
energy for the total population, and the value 35% of energy fell between the
50th and 75th percentiles.
- There is no explicit recommendation for the percentage of calories coming
from solid fats, alcohol and added sugars (SoFAAS). These sources of energy
count against the discretionary calorie allowance, as do intakes in excess of
the recommended amounts of any of the food groups. Discretionary calorie
allowances in MyPyramid range from 8% to 20% of energy. Even at the 5th
percentile, all sex/age subgroups had SoFAAS intakes at or above 20% of energy.
Median intakes were about 32% of energy, and across nearly all subgroups, at the
tail end of the distribution, intakes of SoFAAS exceeded half the energy intake!
[Return to top]
Acknowledgements
The following individuals represent the team who developed the NCI Method and produced this analysis:
- Laurence S. Freedman1
- Susan M. Krebs-Smith2
- Douglas Midthune2
- Patricia M. Guenther3
- Dennis W. Buckman4
- Raymond J. Carroll5
- Victor Kipnis2
- Amy F. Subar2
- Janet A. Tooze6
- Kevin W. Dodd2
1 Gertner Institute for Epidemiology
2 National Cancer Institute
3 USDA Center for Nutrition Policy and Promotion
4 Information Management Services, Inc.
5 Texas A&M University
6 Wake Forest University School of Medicine
[Return to top]
|
