Observing Diets in Communities

What we eat has a big impact on our health. Knowing what people in different communities eat can help scientists identify where help is needed and guide nutrition programs. A new study showed that scientists can learn about a community’s eating habits by studying its wastewater.

Usually, scientists study what people eat through food diaries and surveys. These are slow, costly, and depend on people remembering what they consumed.

Our food carries the DNA of the plants and animals it is made of. After we eat, small amounts of this DNA pass through our bodies and end up in wastewater. To see if they could track diets through wastewater, an NIH-funded research team tested 183 wastewater samples from 21 treatment plants in North Carolina. These treatment plants serve more than 2 million people.

The team found DNA from hundreds of foods. Their analysis cost less than 1 cent per person.

The study revealed interesting patterns. Certain fruits and vegetables showed up more when they were in season. Certain communities ate more tropical fruits and legumes. This included wealthier areas and areas with more foreign-born residents. Coastal communities ate more locally caught fish, while inland cities ate more farmed fish.

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