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NHANES Study Flawed?

by Sandy Todd Webster on Dec 19, 2013

Food for Thought

Researchers from the Arnold School of Public Health at the University of South Carolina reported recently in PLoS ONE (2013; 8 [10], e76632) that 40 years of nutrition information from the National Health and Nutrition Examination Survey—the gold-standard database for such information—may be fatally flawed.

The methodology that NHANES uses to collect the data—widely and regularly cited as the most comprehensive compilation of information on child and adult health in the U.S.—is not “physiologically plausible,” according to lead study author and exercise epidemiologist Edward Archer, PhD, in a press release. Archer observed that the results of the research suggest that without valid population-level data, speculations regarding the role of energy in increasing obesity prevalence are without empirical support.

In short, the authors said that it would be nearly impossible to survive on most of the energy intakes— the “calories in” and “calories out”—that participants reported. This misreporting of energy intake varied among participants; it was greatest in obese men and obese women, who underreported their intake by an average of 25% and 41% (716 and 856 calories per day), respectively.

To assess the health and nutritional status of the U.S. population, the survey involved interviews of self-reported food and beverage consumption over 24 hours followed by physical examinations. Conducted by the Centers for Disease Control and Prevention and the U.S. Department of Agriculture, the NHANES is the primary source of data for researchers studying the impact of nutrition and diet on health.

“Throughout its history, the NHANES 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.”

IDEA contributing editor Natalie Digate Muth, MD, MPH, RD, observed that “while this article appears to signal alarm bells that our nutrition research is flawed, the truth is that it is well-known and widely accepted that self-reported nutrition intake is a gross underestimation. We also know that this is especially the case for obese individuals, exactly as this study (and many before it) reported.”

Muth also says that while it would be helpful if researchers could collect truly valid and accurate nutrition-intake information on a population level, logistical and financial issues can make it prohibitive to do so. “As such, in the thinking that some information is better than none, NHANES collects self-reported nutrition information. This information ends up a closer indication of norms of what should be eaten rather than what actually is eaten.”

Her conclusion: “There are continual efforts to try to improve accuracy of the data collected, and this study is another reminder that innovation is needed in making it easier and less expensive to collect truly accurate dietary intake information.”

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About the Author

Sandy Todd Webster

Sandy Todd Webster IDEA Author/Presenter

Sandy Todd Webster is Editor in Chief of IDEA's publications, including the award-winning IDEA FITNESS JOURNAL and IDEA FOOD & NUTRITION TIPS, the industry's leading resources for fitness, wellness and nutrition professionals worldwide. Sandy joined IDEA in 2001 as executive editor of IDEA PERSONAL TRAINER and IDEA FITNESS MANAGER magazines and was promoted to lead the editorial team in 2003. More than 20 years in magazine publishing, marketing communications and creative services have shaped her straightforward approach to multi-channel communication. Early experience in Los Angeles as a sports writer/reporter, and then enriching years as a managing editor in allied health care publishing have pulled her across a spectrum of stimulating subject matter. Fitness, health and nutrition reside at the perfect center of this content continuum, she feels. A Chicago native, Sandy grew up fully engaged in various competitive sports. Her drive and dedication as an athlete translate to a disciplined work ethic and unwavering approach to challenge in her career. Shortly after graduating journalism school from Southern Illinois University-Carbondale, she was recruited to L.A. for her first post in magazine publishing. After two decades of working on magazines--and now in the throes of applying the unbelieveable multi-media content delivery options available in the magazine 2.0 world--she is still "completely in love" with the creative process it takes to deliver meaningful, inspirational content to end users. She is an accomplished home cook and gardner who would love to combine those skills and passions with her health and fitness background to continue educating readers about a well-balanced, healthy lifestyle.