For decades now, the U.S. Centers for Disease Control and Prevention (CDC) has been funding research on the nutritional habits of Americans. A new study, however, is claiming that those studies could all be invalid due to seriously flawed data collection methods.
The study, published in the journal PLOS ONE, claims that the data gathering in the CDC's National Health and Nutrition Examination Survey (NHANES) makes the studies taken from it not "physiologically credible. The NHANES is a joint project between the CDC and the U.S. Department of Agriculture. For 40 years the survey has taken Americans' food and beverage habits, cross-referencing them with physical examinations.
The new study points out, however, that the food and drink data was provided by patients themselves, making it extremely unreliable. The study looked at decades of NHANES data on over 63,000 men and women ages 20 to 74. It compared the caloric intake reported by study participants to their average energy expenditure based on their physical attributes. The study found that it would be "impossible" to survive on the number of calories self-reported by most study participants.
"Throughout its history, the NHANES survey has failed to provide accurate estimates of the habitual caloric consumption of the U.S. population," said Edward Archer, lead author of the study and an epidemiologist at the University of South Carolina. "Although improvements were made to the NHANES measurement protocol after 1980, there was little improvement to the validity of U.S. nutritional surveillance."
Though the misreporting varied among study participants, those who were obese were found to give the most inaccurate reporting of their eating habits. Obese men were found to underreport their caloric intake by an average of 25%, while obese women underreported their calories by an average of 41%.
Archer and his colleagues concluded that the misreporting of caloric intake makes it extremely difficult to estimate American nutritional habits. Given this conclusion, the study also states that basing public policy decisions on NHANES research could be problematic at best.
"The nation's major surveillance tool for studying the relationships between nutrition and health is not valid," said Archer. "It is time to stop spending tens of millions of health research dollars collecting invalid data and find more accurate measures."