With new dietary guidelines set to be announced later this year, consumers may be wondering what approach the U.S. Department of Agriculture and the Department of Health and Human Services, who jointly issue the Dietary Guidelines for Americans, will advocate for the next five years. How will the recommendations change and how will they be shared with the general public to incorporate into their daily lives? For many years, the Food Guide Pyramid served as the primary vehicle for providing consumer-friendly education about the guidelines to the public. In 2011, Choose My Plate replaced the pyramid. In addition, detailed healthy eating patterns (e.g., Mediterranean Diet, Dietary Approaches to Stop Hypertension, USDA Food Pattern) have emerged in recent years to help individuals understand the exact quantities, serving sizes, types of foods, etc. they should consume. But perhaps the specific pattern a person follows is less important than previously thought.
[Photo: Dr. Angela Liese]
Dr. Angela Liese’s research suggests this might just be the case. A professor in the department of epidemiology and biostatistics at the University of South Carolina’s Arnold School of Public Health, Dr. Liese is interested in behavioral influences on chronic diseases. She has a background in nutrition and has been studying dietary patterns for 15 years. “I believe there is a lot to be learned about how diet affects health if one focuses primarily on the foods and food groups,” she says. As such, Dr. Liese has conducted numerous studies examining eating patterns using statistical methods.
It was this expertise that led the USDA Nutrition Evidence Library to invite Dr. Liese to join a technical expert panel on dietary patterns. The Library organized this panel in 2011 to prepare for the 2015 set of updated guidelines by consulting on the latest scientific evidence from a range of studies. However, through their work the panel realized that there was a gap in the existing research. Previous studies had not established a relationship between eating patterns and mortality, because the methods used to define these patterns were not standardized across the studies.
Based on her research experience with dietary patterns, Dr. Liese spearheaded and defined the key research questions that needed to be examined to move the field forward and generated the group for what became the National Cancer Institute-led Dietary Patterns Methods Project. Using standardized types of data analyses, the team analyzed and then compared the data from three cohorts in order to produce three separate, yet parallel evaluations. Each cohort included studies that examined four types of healthy eating patterns that are popular in the U.S., including the Healthy Eating Index 2010, Alternative Healthy Eating Index 2010, Mediterranean Diet and Dietary Approaches to Stop Hypertension.
The researchers’ findings revealed that higher quality diets (i.e., adhering to the dietary recommendations within a given healthy eating pattern) were associated with reduced (11-28 percent) rate of mortality as well as cardiovascular disease and cancer when compared to lower quality diets. These linkages were consistent across all three cohorts and the four major types of eating patterns examined within each cohort. Moreover, the reductions in mortality risk became apparent at relatively lower levels of diet quality, suggesting that individuals with poor dietary habits can reduce this risk with even small improvements in diet quality.