4. Discussion
FOP, WL
SHOP
Consistent with prior evidence, we found that both the modified Nutri-Score (NS) and the Chilean warning labels (WL) promoted healthier food and beverage choices relative to the no-label control arm. However, the effectiveness of the two labels varied depending on which outcome we focused on. Consistent with our hypothesis, the NS improved the overall diet quality of shopping baskets as measured by the weighted (by the number of servings) average NS point, whereas the WL did not. However, again, as hypothesized, the WL is generally more effective at reducing targeted nutritional attributes. Compared with the no-label control, these labels were more effective at decreasing per-serving energy (kcal) and saturated fat (g) intake. However, contrary to expectations, the reduction in sugar intake per serving was greater with the NS. This finding may be due to our modification of the NS to explicitly show the sugar percentage per serving, thus minimizing the difference between the two labels for this nutrient.Although cross-study comparisons may be confounded by differences in participant and store characteristics, the effect size of the two labels in our study appears reasonable. A study testing the standard NS label with 290 products with 691 French subjects showed the NS score of a grocery basket (normalized by 100 kcal) in the NS arm was better by 2.65 points relative to the no-label arm [We further show that both labels improved overall diet quality and reduced per-serving intakes of sugar and calories from beverages purchased. We also found no evidence that either label induced shoppers to purchase more The heterogeneous effect of the two labels on different outcomes is an important finding. The choice of one label over another should depend on the public health goal. Our results suggest that, if the goal is to improve overall diet quality while targeting one factor to emphasize (sugar in our case), then a modified NS label as applied here should be considered. If the goal is to reduce intake of a small number of negative factors, then warning labels targeting these factors may be the optimal approach, in which case focusing on those nutrients as the primary outcomes would be appropriate. However, if there are too many nutrients targeted, efforts to avoid one nutrient could inadvertently increase the consumption of another. Our study also showed that not only did the modified NS label improve overall diet quality, but that, compared to shoppers in the WL arm, shoppers in the NS arm purchased healthier non-WL products (i.e., products that did not have a warning label in the WL arm had higher average NS points in a grocery cart) and bought a smaller percentage of WL products (products that had a warning label in the WL arm). This is consistent with the NS label providing additional information that is not available to those in the warning label arm.None of the labels statistically reduced sodium (mg) per serving, which contrasts with our hypothesis about the effectiveness of the high-in-sodium warning label. Although few papers reported nutrient-specific effects of the Chilean warning-type labels, one study with Mexican adults found that the labels led to a reduction in sodium purchases per 100 g/mL relative to the GDA label (56). As noted above, the sodium warning label might not have the intended effect if it is displayed with other warning labels. Prior studies showed that multiple claims increase information costs [Our findings come with the following limitations: First, our two cart criteria (i.e., a minimum expenditure and a minimum number of food categories in which to shop) probably reduced biases associated with hypothetical shopping, but the data for this study still represent hypothetical purchases, which may not represent actual purchases. Second, even if it provides an accurate reflection of purchases from a single shopping trip online, this study does not address the long-term effects of the FOP labels or the effects of the labels on offline grocery shopping patterns. Third, we modified the NS label, assuming that this change would increase its effectiveness for the targeted nutrient. Our results suggest this may be the case, but we did not conduct a formal test of this hypothesis because funding and other constraints did not allow for a four-arm trial. Fourth, although our primary outcome has been shown to be a valid measure of overall diet quality [As managing risks for NCDs requires long-term behavior change, future studies should extend these results to test the labels over repeated shopping trips with actual purchases, both in online and in-store settings, and extend the analysis to measure clinical outcomes such as body mass index and blood pressure. In the real world, food purchase channels for home consumption are a mix of online and offline grocery shopping trips, where the effects of FOP labels may differ. Our results are applicable to similar online grocery shops where individuals make grocery purchases for future consumption, but the extent to which the labels improve diet quality may differ for other online shopping for more immediate consumption and when the range of products is more limited (e.g., online convenience store vs. grocery store). The results may also differ for in-store purchases, where visceral factors (sounds, smells, placement, and lighting) may attenuate the effects of the label. Future efforts should also formally test different variants of these labels to identify which is most beneficial for a given target population. For instance, given that Arabic is read from right to left, KSA shoppers may respond to the NS labels differently than those in other countries, as they read the sugar percentage before the grade for overall diet quality.In conclusion, this study showed that both the modified NS labels and Chilean warning labels positively influenced food and beverage choices among KSA participants, but that there were differential effects across the two labels. The modified NS label with the sugar per serving tagline increased overall diet quality and decreased sugar per serving to a greater extent than the warning labels. By contrast, the warning labels were more effective at reducing calories and saturated fat per serving. Policymakers should consider these findings, along with their stated objectives, when determining which strategy may be best for their target population.