Food Swaps to Improve the Healthfulness and Reduce the Carbon Footprint of Grocery Purchases

The study will asses healthfulness of participants' selections as the average Ofcom Nutrient Profiling Model score of the products the participants select in the shopping task. The score ranges from 0 to 100, where higher scores are healthier. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the carbon footprint of participants' selections, operationalized as the average carbon footprint (in CO2-equivalents) of the products the participants select in the shopping task. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, the non-missing value was used.

The study will assess the average calorie density of participants' grocery selections, calculated as the average kcal per 100g of the selected products. Higher values will indicate higher calorie density. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the average sugar density of participants' grocery selections, calculated as the average grams of sugar per 100g of the selected products. Higher values will indicate higher sugar density. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the average sodium density of participants' grocery selections, calculated as the average milligrams of sodium per 100g of the selected products. Higher values will indicate higher sodium density. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the average saturated fat density of participants' grocery selections, calculated as the average grams of saturated fat per 100g of the selected products. Higher values will indicate higher saturated fat density. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the average fiber density of participants' grocery selections, calculated as the average grams of fiber per 100g of the selected products. Higher values will indicate higher fiber density. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the average protein density of participants' grocery selections, calculated as the average grams of protein per 100g of the selected products. Higher values will indicate higher protein density. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess the total amount participants spent on their grocery selections in United States dollars. Higher values will indicate greater spending. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess thinking about health using 1 item: "We are interested in how you selected products while you were grocery shopping. When you selected foods, how much did you think about each of the following characteristics? ... health." Response options range from "Not at all" (1) to "A great deal" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess thinking about climate impact using 1 item: "We are interested in how you selected products while you were grocery shopping. When you selected foods, how much did you think about each of the following characteristics? ... climate impact." Response options range from "Not at all" (1) to "A great deal" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess thinking about taste using 1 item: "We are interested in how you selected products while you were grocery shopping. When you selected foods, how much did you think about each of the following characteristics? ... taste." Response options range from "Not at all" (1) to "A great deal" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess negative emotional reactions using 3 items: "While you were shopping, how much did you feel…" "worried", "guilty," "ashamed"? Response options range from "Not at all" (1) to "Extremely" (5). The investigators will average the 3 items; higher average scores indicate stronger negative emotional reactions. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess positive emotional reactions using 3 items: "While you were shopping, how much did you feel…" "inspired", "proud," "reassured"? Response options range from "Not at all" (1) to "Extremely" (5). The investigators will average the 3 items; higher average scores indicate stronger positive emotional reactions. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess injunctive norms to buy healthy foods with 1 item: "People who are important to me think I should buy healthy foods." Response options range from "Strongly disagree" (1) to "Strongly agree" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess descriptive norms to buy healthy foods with 1 item: "Most shoppers buy healthy foods when they are shopping for groceries." Response options range from "Strongly disagree" (1) to "Strongly agree" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess injunctive norms to buy foods with low climate impact with 1 item: "People who are important to me think I should buy foods with low climate impact." Response options range from "Strongly disagree" (1) to "Strongly agree" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess descriptive norms to buy foods with lower climate impact with 1 item: "Most shoppers buy foods with low climate impact when they are shopping for groceries." Response options range from "Strongly disagree" (1) to "Strongly agree" (5). Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.

The study will assess perceived helpfulness of nutrition labels with 1 item: "These labels would help me choose healthier foods." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess perceived helpfulness of climate labels with 1 item: "These labels would help me choose foods with lower climate impact." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess perceived helpfulness of health swap recommendations with 1 item: "This type of recommendation would help me choose healthier foods." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess perceived helpfulness of climate swap recommendations with 1 item: "This type of recommendation would help me choose more foods with lower climate impact." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess liking of nutrition labels with 1 item: "I like these labels." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess liking of climate labels with 1 item: "I like these labels." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess liking health swap recommendations with 1 item: "I like these recommendations." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess liking climate swap recommendations with 1 item: "I like these recommendations." Response options range from "Not at all" (1) to "A great deal" (5).

The study will assess acceptability of the nutrition labels with 1 item: "How much would you approve or disapprove of these labels being displayed on foods sold in grocery stores?" Response options range from "Strongly disapprove" (1) to "Strongly approve" (5).

The study will assess acceptability of the climate labels with 1 item: "How much would you approve or disapprove of these labels being displayed on foods sold in grocery stores?" Response options range from "Strongly disapprove" (1) to "Strongly approve" (5).

The study will assess acceptability of the health swap recommendations with 1 item: "How much would you approve or disapprove of these recommendations being offered by grocery stores?" Response options range from "Strongly disapprove" (1) to "Strongly approve" (5).

The study will assess acceptability of the climate swap recommendations 1 item: "How much would you approve or disapprove of these recommendations being offered by grocery stores?" Response options range from "Strongly disapprove" (1) to "Strongly approve" (5).