A DNA-sequencing workflow has used municipal wastewater to track community dietary patterns, revealing signals linked to income, immigration, seasonality, and coastal food access across North Carolina.
Traditional dietary surveillance relies on food diaries, recall surveys, or purchase records, which can be slow, expensive, and vulnerable to reporting bias. To move beyond self-reported intake, researchers at Duke University School of Medicine and the University of North Carolina at Chapel Hill developed FoodSeq-FLOW, a wastewater adaptation of a dietary DNA sequencing platform previously applied to stool samples.
The workflow extracts DNA from municipal wastewater and uses metabarcoding to target plant chloroplast trnL and animal mitochondrial 12SV5 regions, allowing food-derived taxa to be identified from mixed community samples.
“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 David in the team’s press release. “This study helps fill that gap so we can better connect diet to health.”
The team analyzed wastewater from North Carolina treatment plants during 2020 and 2021. Across the samples, the workflow detected hundreds of plant and animal food markers, with wastewater-derived plant profiles closely matching dietary DNA patterns from stool samples collected in Durham during the same period.
The same data captured seasonal produce signals and geographic differences in seafood consumption, with inland urban areas showing stronger signals from widely distributed species such as Atlantic salmon and tilapia, and coastal communities showing greater evidence of locally available Atlantic and freshwater fish.
To interpret the mixed sequencing data, the team compared food-taxa profiles across sampling sites and linked plant and animal DNA patterns with demographic and geographic variables. Multivariate analysis separated seasonal, socioeconomic, and cultural dietary signatures. Hops and barley, ingredients associated with beer, were linked to higher-income communities, while areas with larger foreign-born populations showed stronger signals from tropical plants and pulses, including mango, palm or coconut, mung bean, black gram, chickpeas, and pigeon peas.
“Wastewater offers an objective way to monitor dietary patterns across entire communities and could help guide more targeted nutrition and food security programs,” said lead author Mengyi Dong. “Food security isn’t just about whether enough food is available. It’s also about ensuring communities can access healthy, nutritious options.”
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