Wastewater DNA Reveals Community Nutrition Patterns in North Carolina

Community wastewater is proving to be an unexpected source of nutrition information. Scientists have found that they can assess the diets of whole neighbourhoods without depending on surveys or food diaries.

In a recent study, researchers examined DNA fragments in sewage from communities across North Carolina, showing that material washed down drains closely corresponds with income, immigration patterns and location.

Researchers from Duke University School of Medicine and the University of North Carolina at Chapel Hill led the study.

The team studied wastewater samples from 19 North Carolina communities, covering 2.1 million people. By extracting minute pieces of plant and animal DNA, they mapped broad dietary patterns within each population.

Beer, fruit, and fish reveal distinct patterns

The resulting patterns closely reflected demographic and economic differences among the communities.

More affluent neighbourhoods were likelier to contain traces of hops, a principal beer ingredient. Communities with larger foreign-born populations showed signs of tropical fruit and bean consumption.

In coastal areas, wastewater showed strong evidence of seafood-rich diets, including locally caught species such as drum, Spanish mackerel and triggerfish.

“Poor diet is one of the world’s biggest drivers of chronic disease, but we’ve never had a fast objective way to measure what people eat,” said senior author Lawrence A. David, a member of the Duke Microbiome Center.

“This study helps fill that gap so we can better connect diet to health.”

A missing measure in nutrition research

For decades, nutrition scientists have used food diaries and surveys to monitor diets. These approaches are widely known to be costly, time-intensive and unreliable.

People may forget what they consumed, fail to report less healthy choices or never be included in a survey at all.

Moreover, communities most affected by diet-related illness are often those that are most difficult to assess through these conventional methods.

To address these shortcomings, Duke researchers created FoodSeq-FLOW, a DNA sequencing platform intended to search wastewater for evidence of the food communities are eating and preparing.

Lead author Mengyi Dong conducted the genomic analysis during her time at Duke, converting raw DNA sequences into recognisable plant and animal species.

COVID-era wastewater surveillance

The method directly builds on wastewater surveillance systems that grew rapidly during COVID-19.

Viral fragments released in human waste enabled public health officials to identify and follow outbreaks in real time.

That infrastructure now monitors various infectious and respiratory illnesses, while researchers continue extending its use beyond disease detection.

With their new sequencing platform, the researchers assessed wastewater samples obtained from eight treatment plants in three North Carolina regions during two study periods: June to December 2020 and June 2021.

“Wastewater offers an objective way to monitor dietary patterns across entire communities and could help guide more targeted nutrition and food security programs,” said Dong, now an associate professor at Virginia Tech’s Seafood Agricultural Research and Extension Center.

“Food security isn’t just about whether enough food is available. It’s also about ensuring communities can access healthy, nutritious options.”

A FoodSeq-FLOW tool for practical use

Potential uses for the method are already attracting attention from local communities.

In Durham’s historic Hayti neighbourhood, local leaders are seeking to establish a Black-owned full-service grocery store.

They believe these data could demonstrate the measurable difference such a shop might make in an area described as a food desert.

“It would allow us to eat healthier foods more regularly because we wouldn’t have to travel so far to get them,” said Erin Dooley, co-founder of BLK South and resident of the Grant Street Community.

“What’s unique about Dr. David’s research is that it’s not just hard facts and data, but it supports our lived experiences.”

Confirming the method

To verify that the wastewater findings were dependable, researchers compared the DNA patterns with dietary data from 14 stool samples collected in Durham in June 2021.

The two sources closely aligned, indicating that sewage-based monitoring can accurately represent local diets rather than merely providing a broad estimate.

Crucially, the researchers stress that the purpose is not to track individuals, but to assess wider patterns at community level.

By gathering dietary data from entire populations without identifying individual people, wastewater analysis could address real shortfalls in public health data while protecting personal privacy.

“The result is a snapshot of the community that helps understand where resources are needed,” said co-author Rachel T. Noble, a professor of marine sciences at UNC-Chapel Hill.

What wastewater data means for local food communities

Noble said the DNA markers developed at Duke can identify food sources with notable precision.

For instance, the findings indicated that inland communities depend largely on only a small number of seafood types, especially farmed fish such as Atlantic salmon, instead of using the wider selection of local or regional options available elsewhere in the state.

“Could we be doing more to support local fisheries and make their seafood more available? It looks like we certainly could,” Noble concluded.