Edible Atlas: Mapping City Diets from Sewage DNA with Lawrence David

Overview

In this Science Friday episode, Flora Lichtman speaks with Dr. Lawrence David about the Edible Atlas project at Duke University. The team analyzes DNA in sewage to identify what people are eating across cities, offering a backend data source for understanding community nutrition beyond surveys and store data.

Key insights

• Wastewater DNA can capture a wide range of foods including staples, herbs, and even spices, providing a window into daily diet patterns.
• Certain items like coffee may be underrepresented, while tea and other infusion practices can be more detectable due to how the food leaves are processed.
• Privacy safeguards are built into the approach by sampling only at larger populations, and the team emphasizes openness and community input to mitigate concerns.
• The method has potential for rapid, city-level insights on food availability, seasonality, and equity, enabling data-driven nutrition policies.

Overview and goals

The podcast features Dr. Lawrence David, associate professor at Duke University, discussing the Edible Atlas project which uses genetic material from wastewater to profile community diets. The aim is to create a back-end nutrition metric for cities that complements store data and surveys, enabling researchers and policymakers to assess what people actually eat and how access may vary by neighborhood and season.

What foods show up

The conversation highlights the breadth of foods detected in wastewater. Researchers report seeing staples such as rice, bananas, wheat, and soy, but also a surprising array of herbs and spices like rosemary, sage, garlic, and ginger. They note that fish species detection is possible for around 50 different kinds, depending on genetic relatedness, while closely related plants such as broccoli and cauliflower can be difficult to distinguish. Not all foods are equally detectable; coffee often appears less in the data, while tea tends to show up reliably because of how leaves shed compounds during infusion.

How it works and its challenges

DNA is surprisingly resilient, with about 1% of dietary DNA passing through digestion and sewer systems, but the sheer volume of DNA eaten means millions of gene copies can be amplified and sequenced. Sampling can occur either at the entry point of a wastewater treatment plant or by deploying absorbent materials to collect material over a day. The team emphasizes permission, safety, and reproducibility. The pilot work even piggybacks on pandemic virus sampling techniques, demonstrating that food DNA can be tracked using similar workflows.

Granularity, diversity, and top line trends

Top-line results across cities show substantial diversity: more than 100 animal species and about 200 plant species show up in daily life, suggesting that urban diets remain surprisingly varied. This diversity challenges the notion that modern food systems are overly homogenized. The Edible Atlas is positioned as a tool to ask new questions about food availability, seasonality, and equity—such as who has access to fresh produce and how consumption patterns shift with weather and income disparities.

Privacy, ethics, and community engagement

Privacy is a central concern. The researchers commit to anonymizing data by avoiding sampling areas with populations smaller than 500 people and by engaging with communities to gather feedback on how the data could be useful. The host frames the discussion around responsible data use and the importance of transparent communication when monitoring what people eat from a communal source like wastewater.

Origins and future directions

Dr. David shares a personal anecdote about collecting stool samples during a microbiome study that inspired the approach to fecal DNA as a dietary record. The project name, Edible Atlas, evokes a city-scale food atlas drawn from the genome, providing a novel lens on nutrition research. Looking ahead, the team anticipates using this data to answer practical questions about fresh food availability, seasonal access, and urban nutrition policy, while continuing to refine detection for accuracy and privacy protection.