After 40 years fatal flaw found in federally funded nutrition research
A new study has found that 40 years of nutrition research funded by the Centers for Disease Control and Prevention (CDC) may be worthless due to the seriously flawed way the research data was collected.
The study by the Arnold School of Public Health at the University of South Carolina discovered major limitations in the measurement protocols used in the National Health and Nutrition Examination Survey (NHANES).
These findings, published in PLOS ONE, reveal that a majority of the nutrition data collected by the NHANES was not "physiologically credible," according to Arnold School exercise scientist and epidemiologist Edward Archer, who led the study.
Archer also said the results of the study suggest that without such credible data, any assumptions or conclusions drawn about the role of energy intake on rising obesity rates are without empirical support.
As the most complete accumulation of data on the health of children and adults in the U.S., the NHANES survey combines self-reported food and beverage consumption reports over 24 hours and physical exams that evaluate the health and nutritional status of Americans. The NHANES, conducted by the CDC and the U.S. Department of Agriculture, is the main source of data used by researchers studying the role of nutrition and diet on health.
Archer’s study examined data from 28,993 men and 34,369 women, between the ages of 20 and 74 years, from NHANES I (1971 - 1974) through NHANES (2009 - 2010), and looked at the number of calories participants reported taking in and how much energy they expended, predicted by height, weight, age and sex. Based on the participant’s self-reported intake of food and beverages, Archer said that the vast majority of the NHANES data "are physiologically implausible, and therefore invalid."
Put simply, this means that the participant’s recall of calories consumed, compared with the number of calories expended, could not be accurate because it would be impossible to survive on most of the caloric intakes reported by the participants. This misrepresentation of calories consumed varied among the participants, but the obese participants were most likely to inaccurately report their caloric intake by an average of 25 to 41 percent less than it really was.
"Throughout its history, the NHANES survey has failed to provide accurate estimates of the habitual caloric consumption of the U.S. population," Archer said. "Although improvements were made to the NHANES measurement protocol after 1980, there was little improvement to the validity of U.S. nutritional surveillance."
Archer said that these limitations "suggest that the ability to estimate population trends in caloric intake and generate public policy relevant to diet-health relationships is extremely limited."
He therefore concluded that the "nation's major surveillance tool for studying the relationships between nutrition and health is not valid,” adding that it’s “time to stop spending tens of millions of health research dollars collecting invalid data and find more accurate measures."
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