A recent PLOS ONE study investigates the impact of the coronavirus disease 2019 (COVID-19) pandemic on food quality and diversity in households in the United States of America.

Study: Pandemic-induced changes in household-level food diversity and diet quality in the U.S. Image Credit: ANRproduction / Shutterstock.com

Did the COVID-19 pandemic affect diet quality?

The rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the COVID-19 pandemic. In addition to its direct effects on human health and the global economy, the COVID-19 pandemic also disrupted normal food acquisition and consumption patterns due to nationwide lockdowns implemented to prevent viral transmission.

Approximately 50% of the budget for food items is spent on food away-from-home (FAFH) options in the U.S. Therefore, pandemic-induced closures of restaurants, cafeterias, and lockdowns caused a significant shift from FAFH establishments to supermarkets. This shift disrupted agricultural supply chains, which subsequently led to the inability to access various essential items.

Before the pandemic, the average American diet was described as unhealthy, with high consumption of processed food and FAFH. According to the Dietary Guidelines for Americans, eating patterns in the United States have remained far below dietary recommendations.

Mixed findings have been documented regarding overall improvements in diet quality due to pandemic-induced restaurant closures and reduced sales. A United Kingdom-based study indicated that some individuals shifted from consuming low-calorie food from dine-in restaurants to purchasing high-calorie food from grocery stores.

About the study

The current study investigates the overall dietary changes that occurred due to the COVID-19 pandemic using household-level purchase data from the NielsenIQ consumer panel. Two diet quality indicators, including the Berry Index and USDAScore, were used to measure changes in food diversity and adherence to dietary guidelines, respectively, after the pandemic.

The Berry Index, which ranges between zero for the least diverse and one for the most diverse, is based on household-level expenditure shares for the 24 food categories used by the Center for Nutrition Policy and Promotion (CNPP).

The USDAScore system also uses household-level expenditure shares for the same CNPP food categories. Each share is a portion of category expenditure relative to total household food purchase expenditures. In contrast to the Berry Index, the USDAScore system involves comparing each household’s expenditure share to the recommended expenditure shares of the USDA Thrifty Food Plan.

Based on the two indicators, event-study differences were constructed. Events that occurred when the American schools were closed were considered as pandemic-induced events.

Event-scale differences were assessed using the two indicators for one month, which was extended to six months before (leads) and after (lags) the school closure date in each household’s state. The seasonality factor in the diet was considered by comparing the purchasing behavior of the current study month with exactly one year earlier for the same household.

Study findings

Consistent with previous reports, the current study confirmed that the COVID-19 pandemic significantly influenced the food-purchasing behavior of American households. The Berry Index data observed modest temporary increases in food diversity of up to 2.6% compared to the previous year.

USDAScore data indicated temporary increases in diet quality of up to 8.5% compared to the previous year’s estimates. These findings were based on 41,579 households.

Even after six months of school closure, higher scores above normal levels were observed, which implied overall good maintenance of dietary diversity and quality.

Although households with different demographic characteristics had similar dietary patterns, minor changes were observed in certain households. For example, households with young children, households that did not own a vehicle, and low-income households exhibited smaller increases in USDAScore and Berry Index scores.

Study limitations

The current study has several limitations; for example, the diet quality score, particularly the USDAScore system, showed an unrealistic increase. In the future, this increasing trend should be validated using a more robust healthy eating index (HEI) score system. The potential stockpiling by households and food price inflation during the pandemic could also cause bias and lead to the generation of inaccurate Berry Index and USDAScore scores.

The study findings are exclusively based on the food-at-home purchase dataset rather than out-of-home food intake data. Thus, considering both datasets would have reflected true food changes during the pandemic.

Conclusions

The current study highlights an increase in household-level food diversity and healthfulness during the lag phase, which occurs six months after the pandemic.

Based on the Berry Index, food diversity increased for a few months during the school closure period, followed by a marginal increase that eventually stabilized. Food healthfulness measured by the USDAScore indicated a rise of 8.5% in the first months of the closure period, followed by a steady decline.