July 30, 2026

Tracking diets via wastewater

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Researchers analyzed samples from wastewater treatment facilities to understand dietary patterns across communities.

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Poor diet promotes chronic disease and contributes to global illness, death, and healthcare costs. Effective measures to improve food access and security depend on timely information on dietary trends. However, diet tracking typically relies on food diaries and surveys. These are only as reliable as participants’ memories. They can also be expensive and time-consuming.

An NIH-funded research team, led by Dr. Rachel Noble at the University of North Carolina at Chapel Hill and Dr. Lawrence David at Duke University, developed a method to survey communities’ food consumption using wastewater. The team developed a DNA sequencing platform to detect and identify residual plant and animal DNA from food in wastewater samples. Results from a test of the platform, called FoodSeq-FLOW, were published in the Proceedings of the National Academy of Science on July 20, 2026.

Networks for monitoring wastewater expanded during the COVID-19 pandemic to track SARS-CoV-2 outbreaks. The researchers sought to expand the application of wastewater monitoring from tracking virus outbreaks to understanding nutritional patterns across a community. The researchers analyzed 183 wastewater samples from 21 treatment facilities in North Carolina. Together, these facilities serve more than 2 million people. They identified 184 plant and 123 animal food types across the samples. The cost of the analysis amounted to less than one cent per person.

The team first wanted to confirm that the FoodSeq-FLOW technology worked properly. To do so, they compared wastewater from one treatment facility to 14 stool samples provided by residents of the facility’s service area. The abundances of food plants found in the wastewater correlated well with those found in the individual stool samples. Almost all the animal DNA found in the wastewater came from known food species. This suggests that FoodSeq-FLOW accurately captures human dietary patterns.

The researchers monitored wastewater from eight of the treatment facilities over seven months. The abundance of many food plants varied over this time. This variation reflected the plants’ seasonal availability. Species available in the spring and summer, such as asparagus, blueberries, and okra, were more abundant in the summer months. Species more commonly available later in the year, such as cabbage and citrus, were more abundant in the fall and winter months. This suggests that FoodSeq-FLOW could detect seasonal shifts in diet.

Across communities, dietary composition varied. Urban centers had higher plant-to-animal ratios, indicating more plant-rich diets. Dietary variety increased with per capita income and population density.

Variations in specific food species revealed economic and cultural dietary patterns. For example, higher income was associated with more consumption of barley and hops—primary ingredients in beer. Higher-income communities and those with larger foreign-born populations consumed more tropical fruits and legumes. Coastal communities consumed more locally caught fish species, such as triggerfish and bluefish. Inland urban areas consumed more farmed species like Atlantic salmon and tilapia.

The results suggest that this test could provide timely, adaptive diet tracking at a community scale and at low cost. This could help public health agencies respond to nutritional shortages and track the effectiveness of interventions. Policymakers could use the data to target resources where they’re most needed.

“Poor diet drives an enormous share of chronic disease, but measuring what a whole community eats has been slow, expensive, or indirect,” David says. “This study helps fill that gap so we can better connect diet to health.” 

—by Brian Doctrow, Ph.D.

Related Links

• Early-life nutrition
• Tracking diet from stool samples
• Early-life sugar intake affects chronic disease risk
• Tracking SARS-CoV-2 variants in wastewater
• Highly processed foods form bulk of U.S. youths' diets
• Dejunking your diet: the drawbacks of ultra-processed foods
• Breaking down food: a closer look at what you eat

References

Dietary DNA in municipal wastewater reveals signatures of wealth, immigration, and coastal proximity. Dong M, Clerkin TJ, Jiang S, Ives N, Osborne OW, Kirtley M, Bauer AE, Anderson KY, Smith MD, Noble RT, David LA. Proc Natl Acad Sci U S A. 2026 Aug 4;123(31):e2530704123. doi: 10.1073/pnas.2530704123. Epub 2026 Jul 20. PMID: 42475548.

Funding

NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and National Center for Advancing Translational Sciences (NCATS); National Science Foundation; Chan Zuckerberg Initiative; Schmidt Sciences; The Gerber Foundation; Springer Nature; Burroughs Wellcome Fund; Duke University.