Changing dynamics of high-sodium item purchases from restaurant chains in New York

By Pooja Toshniwal PahariaReviewed by Aimee MolineuxAug 29 2022

In a recent study posted to the medRxiv* preprint server, researchers investigated if implementing the sodium warning regulation by New York City (NYC) restaurants changed consumer purchasing.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

A sodium warning rule was enforced in NYC in 2016, which required chain restaurants (with ≥15 national locations) to display icons representative of high-sodium content (containing ≥2,300 mg sodium) for items on the menu and furnish a statement mentioning the potential health risks. Nutrient-content warnings foster transparency about the content of food items and thereby may contribute to the promotion of improved public health. Reducing the intake of dietary sodium has been linked to a lower risk of cardiovascular disorders and hypertension.

About the study

In the present survey-based study, researchers evaluated changes in consumer purchasing at chains of quick-service restaurants (QSR) and full-service restaurants (FSR) in NYC and Yonkers (control) before and post- enforcement of the sodium warning rule.

Consumer purchases, verified by purchase receipts, were assessed at two QSR (Popeyes and Subway) and two FSR (IHOP and TGI Friday’s) chain restaurants in NYC and Yonkers between October 2015 and 2016 (baseline) and between April and June 2017 (follow-up). Baseline information obtained at Applebee’s (FSR) was excluded due to advanced enforcement of the sodium warning rule.

McDonald’s (QSR) and Burger King (QSR) were excluded since negligible/no menu items were eligible for the sodium warning icon. The prime study outcomes were the number of high-sodium item purchases and the calorie and sodium content of the purchases. Interviewers conducted surveys between 5 pm and 9 pm at FSR on any day and between 12 pm and 3 pm at QSR on weekdays.

Adults that visited the chosen locations were given an incentive of $5 to participate in the study. Items purchased for personal consumption and were enlisted on the purchase receipt were included, and their calorie and sodium contents were obtained from the MenuStat database. Individuals without purchase receipts or missing nutritional data for their purchases were excluded from the analysis. Further, individuals were excluded if their purchases were not verifiable or if individuals only purchased beverages. Purchases of items containing >12,000 mg of sodium (extreme outliers) were also excluded. Regression modeling was used for the analysis.

Results

In total, 738 and 923 participants were evaluated at NYC FSR at baseline and follow-up, respectively. The corresponding counts for Yonkers FSR were 419 and 544, respectively. Baseline and follow-up respondent counts at NYC QSR were 341 and 379 individuals, respectively, and the corresponding numbers at Yonkers QSR were 317 and 331 participants, respectively.

In the NYC FSR participant group, a significant drop in the average purchases of items containing high sodium was observed (baseline vs follow-up values were 0.8 vs 0.7 items purchased/respondent) and in the fraction of participants who purchased ≥2 such items (15% versus three percent). However, there was no statistically significant difference from baseline (67%) to follow-up (65%) in fractions of participants buying ≥1 item with high sodium content. In the Yonkers FSR participant group, a significant drop was observed in the fraction of individuals who bought ≥2 such items at baseline versus follow-up (6% versus 2%). However, the average purchases of items with high sodium content by Yonkers city FSR participants showed no difference at baseline versus follow-up.

Likewise, the fraction of individuals who bought ≥1 item with high sodium content did not significantly change (59% versus 62%). For FSR, no significant changes at follow-up were observed in NYC compared to Yonkers in the average purchases of items with a high-sodium content or the fraction of participants buying ≥1 or ≥2 such items. The results were similar for the NYC QSR participants.

Contrastingly, in the Yonkers QSR participant group, the fraction of individuals who bought ≥1 item with high sodium content significantly increased from baseline (25%) to follow-up (37%). However, the average purchases of such items didn’t show significant changes. At QSR, the team observed no difference-in-difference between the two cities in the average purchases of items with high sodium content or the fraction of participants buying ≥1 such item. However, the average sodium content in items purchased significantly reduced between baseline and follow-up in Yonkers FSR (2696 mg versus 2254 mg) and NYC FSR (3245 mg versus 2279 mg).

The drop in NYC purchases was significantly higher than Yonkers purchases. Similar trends were noted for the average caloric content of purchased items, with reductions at NYC (baseline versus follow-up 1524 kcal versus 1055 kcal) and Yonkers (1259 kcal versus 1009 kcal). Concerning Yonkers, the fraction of NYC participants who bought ≥1 item with high sodium content did not differ significantly at follow-up (difference-in-difference for FSR and QSR were -4.6% and -8.9%, respectively).

In the NYC FSR participant group, the average sodium quantity purchased significantly reduced (-524 mg difference-in-difference); however, such significant changes were not observed among QSR participants (258 mg difference-in-difference). At QSR, the average sodium quantity of purchased items didn’t differ significantly from baseline to follow-up in New York (1977 mg versus 1777 mg) or Yonkers city (2193 mg versus 1735 mg). The average caloric purchase decreased from baseline to follow-up in New York (946 kcal versus 794 kcal) and Yonkers city (1047 kcal versus 836 kcal).

Overall, the study findings showed that the decrease in the average quantity of sodium bought from NYC FSR after the implementation of the sodium warning regulation was encouraging; however, a corresponding decrease in the fraction of individuals buying items with high sodium content was not observed.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources