U.S – Researchers from the University of Houston have established that Houstonians living in low-income and urban neighborhoods are at a higher risk of contracting gastrointestinal illnesses, possibly linked to the lettuce they purchase from grocery stores in their community.

The findings, published in the Journal of Food Protection, focus on loose-leaf romaine lettuce. According to the study, loose-leaf romaine lettuce, when purchased from supermarkets in low-income communities in Houston, was found to be contaminated with disease-causing microorganisms.

Researchers said the discovery raises questions about quality and safety.

“Looking at all these empirical studies, there are a few questions we can ask. At what point do these disparities arise? So, for example, we look at the food supply chain. Is it different in any way? And if it’s not different in any way, what are the changes in, say time and temperature or potential cross-contamination that occurs, and what stage do they occur?”

Sujata Sirsat,Associate Professor, University of Houston


Researchers purchased lettuce from an even number of stores in two communities — one in a low-income neighborhood and the other in a high-income neighborhood. The neighborhoods were chosen based on the U.S. Department of Agriculture Economic Research Service Food Access Research Atlas and U.S. Census Bureau definition of low and high socioeconomic status neighborhoods.

Professor Sirsat said the findings gave clarity that loose-leaf romaine lettuce obtained from these low-income neighborhoods, registered an increased number of bacteria, including bacterial pathogens.

Among the findings, 87% of samples purchased from stores in the low-income neighborhood tested positive for staphylococcus aureus. Sirsat said Staph isn’t typically life-threatening but can cause skin infections.  She stressed the pathogen could prove life-threatening for the immunosuppressed.

Fifty-three percent tested positive for salmonella, while 13% were contaminated with listeria monocytogenes. Four percent of samples purchased in a low-income neighborhood tested positive for E. coli.

Sirsat said none of the lettuce purchased from stores in the high-income neighborhood tested positive for the pathogens. Staph was the sole exception, with 38% of the lettuce purchased testing positive.

She noted that the study does not provide a solution, but rather, it establishes a problem by providing a data-based correlation between access to nutrient-rich, quality produce, and health disparities based on socioeconomic status.

“I think there are a lot of things to investigate to provide some historical context. There have been studies that demonstrate nutritional disparities, but there have been very few studies that identify the food safety and quality disparities in low versus high-income neighborhoods.”

Sujata Sirsat,Associate Professor, University of Houston


Sirsat concluded the study allows for a conversation to begin about how to implement change.  She said among the suggestions was changing food supply, with a stronger focus on locally grown produce.

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