North Carolina researchers are turning an unlikely source into a new kind of nutrition report card: the state’s sewer system. By studying food DNA flushed down drains, scientists say they may be able to track broad community eating patterns faster and more objectively than traditional surveys.
The next step is getting much more local. Researchers are piloting neighborhood-level sampling in Durham by collecting wastewater directly from manholes, according to Axios, after an earlier analysis examined sewage from communities representing more than 2 million North Carolinians, with much of the sampling concentrated in the Triangle and Charlotte.
How FoodSeq-FLOW Reads A Community’s Diet
The peer-reviewed study, published in the Proceedings of the National Academy of Sciences, used a genomic platform called FoodSeq-FLOW to identify fragments of plant and animal DNA in wastewater. The researchers analyzed 183 samples from 21 treatment plants serving roughly 2.1 million people and detected 184 plant food taxa and 116 animal food taxa at a cost of less than a penny per person, according to the study’s abstract on PubMed.
The method looks for genetic material associated with food rather than asking residents to remember every meal they ate. A report from Duke University School of Medicine says the wastewater results closely matched dietary information from stool samples collected in Durham, while the researchers stress that the system is intended to measure community patterns, not identify individual people.
What North Carolina’s Wastewater Revealed
The study found that food signatures varied with geography, income, education and the size of foreign-born populations. Beer-related ingredients were associated with greater discretionary income, while tropical fruits and pulses appeared more often in places with larger immigrant communities, according to the findings summarized by the study authors.
Coastal and rural communities showed stronger traces of local and freshwater fish, while inland communities consumed more nationally distributed seafood such as salmon. The research also found North Carolina food staples were negatively associated with per-capita income, and communities with larger South Asian populations showed more evidence of mango consumption, Axios reported.
Why Durham Is Getting A Closer Look
Sampling at the treatment-plant level can reveal broad trends, but manhole samples could provide a sharper neighborhood view. Researchers told Axios they are avoiding populations smaller than 500 people and excluding communities that rely on septic tanks, while hoping to eventually expand the approach to other U.S. communities.
That could give policymakers a quicker way to evaluate changes to SNAP benefits, school lunch programs and the effects of economic downturns. The researchers also see potential for measuring food-access disparities without waiting for expensive surveys that can miss the communities most affected by diet-related disease.
The Sewer Data Still Has Limits
The technique is promising, but it is not a perfect window into anyone’s kitchen. Food DNA can degrade with temperature, and industrial or agricultural wastewater may complicate the results, limitations the researchers identified in the reporting by Axios.
North Carolina already has a statewide wastewater-monitoring infrastructure built around tracking respiratory viruses, creating a ready-made foundation for this kind of research. The North Carolina Department of Health and Human Services says its wastewater network works with treatment plants, University of North Carolina researchers, the CDC and local communities to monitor population-level health trends, according to the agency’s wastewater dashboard.
If the Durham pilot holds up, the humble sewer could become something more than a destination for yesterday’s leftovers. It could offer public-health researchers a near-real-time way to see how communities eat, where food access is falling short and whether nutrition policies are changing what ends up on the plate.
