30 years of supporting nutrition research

Researchers in Penn State’s Diet Assessment Center help accurately measure what people are eating

Collecting dietary recall data by phone is one of the center's areas of expertise.   Credit: kali9All Rights Reserved.

A person’s diet affects almost every aspect of their health, from heart disease to mood regulation. For 30 years, Penn State’s Diet Assessment Center has collected and analyzed high-quality dietary data in order to help researchers clearly understand what, how, and when people are eating.

Measuring what people eat in the course of their normal lives is notoriously difficult. When asked, people often fail to report their intake accurately. Remembering every food and beverage consumed and estimating the amount of food consumed can be a daunting task for many. 

Despite the challenges, understanding diet is critical. The Diet Assessment Center, housed within Penn State’s Department of Nutritional Sciences, has been providing expert data collection to address this need for decades. It has developed a reputation as one of the best resources for researchers who need to plan, collect data, or analyze data in the field of nutrition.

“The Diet Assessment Center provides data collection and research expertise that is central to understanding nutrient intake and to analyzing the behavioral aspects of what, when, and how people eat. A lot of training and experience is required to be able to query adults and children about their diet and get reliable information from them. Diet assessment is a cornerstone of nutrition research and many other types of studies, for example of the microbiome or metabolic diseases. It is well established that diet underlies about half of the risk of many chronic diseases, so learning what people -- individuals and groups -- actually consume is essential to public health science.” said A. Catharine Ross, professor of nutrition and physiology, and Dorothy Foehr Huck Chair in the Nutritional Sciences department.

Researchers in the Diet Assessment Center collaborate with nutrition researchers, government agencies, and private companies to collect and analyze data. The researchers in the center have worked on dozens of studies, large and small.

Collaborating for a healthier population

Credit: Penn State / Penn StateCreative Commons

“The Geisinger Rural Aging Study has been one of the hallmark studies of the Diet Assessment Center,” said Diane Mitchell, associate research professor of nutritional sciences and director of the Diet Assessment Center. “The original principal investigator was Gordon Jensen, former head of Penn State’s Nutritional Sciences department. Currently, Christopher Still at Geisinger is the principal investigator. Under their leadership, the study has investigated a broad array of topics that can improve the health of rural Americans.

“In many ways, the Geisinger Rural Aging Study has served as the bread and butter of the center, allowing us to continually improve our methods,” Mitchell continued. “Funded through a cooperative agreement with the United States Department of Agriculture and Geisinger Health System, it has provided resources to develop and test dietary methods to assess nutrition risk and diet quality.”   

According to Mitchell, the study has collected and analyzed dietary and other health-related data for more than 21 years on over 20,000 older adults in Central Pennsylvania. It is the longest running study conducted in the Diet Assessment Center. The study has helped researchers better understand how diet affects health as people age and has led to dozens of scientific publications.

Recently, the investigators uncovered new insights about the connection between diet quality and mortality. In the next several years, the project will focus on other neurological outcomes such as Parkinson’s disease and dementia. This work is being guided by Xiang Gao, professor of nutritional sciences.

Data collection, instrument validation, and more

Over the life of the Diet Assessment Center, researchers have collected more than 75,000 dietary recalls. During a dietary recall, researchers call study participants at random times on select days over the course of the study, which prevents participants from consciously or subconsciously editing their responses in advance. The participants explain what they ate during the 24 hours before they received the call. For most dietary recall studies, the center uses the Nutrition Data System for Research (NDSR), a software program developed by the University of Minnesota. The NDSR database allows for automatic calculation of over 150 nutrients and food components participants are consuming such as fat, protein, calories, vitamins and minerals.

Though the center is best known for collecting dietary recalls, the Diet Assessment Center also provides research support for studies involving the collection and analysis of food records; the development, validation, and collection of food frequency questionnaires; and the collection of a variety of other types of telephone or self-administered questionnaires including physical activity, functional status, and health history.

“We recently wrapped up a collaboration with the American Cancer Society on the modification and validation of a food frequency questionnaire,” Mitchell explained. “We used detailed food data to modify an existing food frequency questionnaire to reflect the diets of the Cancer Prevention Study-3 participants. The American Cancer Society uses dietary data collected via food frequency questionnaires to study the effect of diet on the development of cancer in over 300,000 Americans, so it is important that these data represent the population being studied.”    

Promoting undergraduate research

One unique aspect of the Diet Assessment Center is that they train undergraduate students to collect data. This gives students a unique opportunity to be involved in research collecting high-quality dietary data for ground breaking nutritional studies. It prepares the students for graduate school and employment by grounding them in rigorous research protocols while enhancing communication skills. For the investigators who collaborate with the Diet Assessment Center, employing a highly trained student staff results in a more efficient and cost-effective approach to data collection.

Looking forward

Thirty years into its existence, the Diet Assessment Center shows no signs of slowing down.

“I’m very excited about the future,” Mitchell said. “Advances in nutritional sciences require that we continue to develop and refine approaches to better capture diet, and this is a top priority for government-sponsored nutrition research.  This aligns very well with the expertise of the Diet Assessment Center.”

Researchers who are interested in collaborating with the Diet Assessment Center are encouraged to visit the center’s website or email Diane Mitchell at

Last Updated October 26, 2020