A 2025 randomized trial of 1,201 US adults found that suggesting simple food swaps during online grocery shopping significantly improved the healthfulness of purchases, with health-focused swaps improving nutrition scores by 4.7 points on a 100-point scale. According to Gram Research analysis, climate-focused swaps reduced the carbon footprint of purchases by 3.3 kg of CO2 per kilogram of food. These suggestions worked equally well across different age groups and regardless of how much people cared about health or the environment.
A new study tested whether suggesting healthier food choices actually works when people shop online. Researchers had over 1,200 people shop in a fake grocery store and gave some groups suggestions to swap unhealthy foods for better options—either for health reasons, environmental reasons, or both. The results were encouraging: people who received swap suggestions bought noticeably healthier groceries. Those who got climate-focused swaps also reduced their carbon footprint. This shows that simple nudges during shopping can help people make choices that are better for both their bodies and the planet.
Key Statistics
A 2025 randomized controlled trial of 1,201 US adults found that health-focused food swap suggestions improved the nutritional quality of online grocery purchases by 4.7 points on a 100-point healthfulness scale compared to no suggestions.
Climate-focused food swap recommendations reduced the carbon footprint of online grocery selections by 3.3 kg of CO2 equivalents per kilogram of food in a 2025 trial of over 1,200 shoppers.
In a 2025 study published in PLoS Medicine, combined health-and-climate food swap suggestions improved nutrition scores by 4.0 points while reducing carbon emissions by 2.8 kg CO2-eq per kilogram, showing that dual-benefit recommendations can address both health and environmental goals.
A 2025 randomized trial found that food swap suggestions worked equally well across all age groups and regardless of participants’ baseline health or environmental consciousness, suggesting these nudges have broad appeal.
The Quick Take
- What they studied: Whether suggesting simple food swaps (like replacing one unhealthy item with a healthier one) actually changes what people buy when shopping online, and whether these changes help the environment too.
- Who participated: 1,201 adults in the United States, ages 18 and older, who completed three shopping sessions in a realistic online grocery store over two weeks in May-June 2025.
- Key finding: All three types of swap suggestions improved how healthy people’s grocery choices were. Health-focused swaps worked best for nutrition (improving healthfulness by 4.7 points on a 100-point scale), while climate-focused swaps were best for reducing environmental impact (cutting carbon emissions by 3.3 kg per kilogram of food).
- What it means for you: If you shop online for groceries, simple suggestions to swap one food for another could help you eat better and reduce your environmental impact. This works best when the suggestions match what you care about most—whether that’s your health or the planet.
The Research Details
This was a randomized controlled trial, which is one of the strongest types of research studies. Researchers recruited 1,201 people and had them shop in a realistic online grocery store three times over two weeks. The first shopping trip had no suggestions—this was the baseline. Then people were randomly divided into four groups: one group got suggestions to swap foods that were better for the climate, one got suggestions for healthier foods, one got both types of suggestions, and one group (the control) got no suggestions at all. The second and third shopping trips included the assigned suggestions for three of the groups.
Researchers measured two main things: how healthy the foods people chose were (using a standard nutrition scoring system that goes from 1 to 100) and how much carbon dioxide was produced to make the foods people selected. They compared how these scores changed from the first trip (no suggestions) to the later trips (with suggestions) between the groups that got suggestions and the control group that didn’t.
This approach is strong because it lets researchers see whether the suggestions actually caused people to change their choices, rather than just noticing that some people buy healthier foods anyway.
Testing whether suggestions actually work in a realistic shopping environment is important because computer models can predict that swaps would help, but real people don’t always follow predictions. This study shows that when people are actually shopping, they do respond to suggestions—they’re not just ignoring them. This matters for grocery stores, apps, and health programs that want to help people make better choices.
This study has several strengths: it used a randomized design (the gold standard for testing whether something causes a change), it had a large sample size (over 1,200 people), and it used a realistic shopping environment rather than just asking people hypothetical questions. The main limitations are that the online shoppers in the study weren’t perfectly representative of all Americans, and results from online shopping might not apply to traditional brick-and-mortar grocery stores where people shop differently. The study was published in PLoS Medicine, a highly respected peer-reviewed journal.
What the Results Show
All three types of swap suggestions improved the healthfulness of people’s grocery selections compared to the control group. The health-focused swaps worked best, improving the nutrition score by 4.7 points on the 100-point scale. The climate-plus-health swaps improved it by 4.0 points, and even the climate-only swaps improved it by 2.4 points. All of these improvements were statistically significant, meaning they’re very unlikely to have happened by chance.
For environmental impact, the climate-focused swaps were most effective, reducing the carbon footprint by 3.3 kg of CO2 per kilogram of food. The combined climate-plus-health swaps also worked well, reducing it by 2.8 kg. Interestingly, the health-only swaps didn’t significantly reduce carbon footprint—they focused on nutrition without considering environmental impact.
The researchers also tested whether the suggestions worked differently for different types of people. They found that age, how much someone cares about health, and how much someone cares about the environment didn’t change how well the suggestions worked. This means the swaps helped almost everyone equally, regardless of their background or values.
The study found that health-focused and climate-plus-health swaps worked equally well for improving nutrition (both around 4-4.7 points improvement), but climate-focused swaps were noticeably less effective for health. Similarly, climate-focused and climate-plus-health swaps worked equally well for reducing carbon footprint, but health-focused swaps alone didn’t reduce environmental impact. This suggests that the type of suggestion matters for what outcome you’re trying to achieve.
Previous research using computer models predicted that food swaps could improve both health and environmental outcomes, but this is one of the first studies to test whether real people actually make these swaps when shopping. According to Gram Research analysis, this study confirms that the theoretical benefits predicted by modeling studies actually happen in practice. It also shows that people respond to suggestions in realistic shopping environments, which wasn’t certain before.
The study was conducted in an online grocery store, which is becoming more common but still doesn’t represent how most Americans shop. People who shop online might be different from those who shop in regular stores in ways that could affect the results. The study also only lasted two weeks, so we don’t know if people would keep making these swaps over months or years. Additionally, the sample of online shoppers was somewhat different from the overall US population, though the researchers tried to recruit a diverse group.
The Bottom Line
If you shop online for groceries, look for or ask for swap suggestions that match your priorities. If you want to eat healthier, focus on suggestions that highlight nutritional improvements. If you care about environmental impact, look for suggestions about lower-carbon foods. If you care about both, look for combined suggestions. These suggestions appear to work well for most people regardless of age or background. Confidence level: High (based on a large randomized trial in a realistic setting).
Online grocery shoppers who want to improve their diet, reduce their environmental impact, or both should pay attention to swap suggestions. This is particularly relevant for people using grocery delivery apps or online shopping platforms. People who shop primarily in physical stores may find these results less directly applicable, though the underlying principle might still work. Anyone interested in sustainable eating or improving their diet should find this encouraging.
The study showed changes happening within just two shopping trips over one week, so you might notice improvements in your grocery selections fairly quickly if you follow swap suggestions. However, the long-term effects on your actual health or weight would take weeks to months to become noticeable.
Frequently Asked Questions
Do food swap suggestions actually change what people buy at the grocery store?
Yes. A 2025 trial of 1,201 shoppers found that swap suggestions improved nutrition scores by 2.4 to 4.7 points depending on the type of suggestion. People responded to the recommendations even though they weren’t required to follow them.
What’s the best type of food swap suggestion for reducing my carbon footprint?
Climate-focused swaps work best, reducing carbon emissions by 3.3 kg per kilogram of food. Combined health-and-climate swaps also work well (2.8 kg reduction), but health-only swaps don’t significantly reduce environmental impact.
Do food swap suggestions work better for some people than others?
No. A 2025 study found that swap suggestions worked equally well regardless of age, how much someone cares about health, or how much they care about the environment. The suggestions benefited almost everyone equally.
Can I use these food swaps to eat healthier and help the environment at the same time?
Yes. Combined health-and-climate swap suggestions improved nutrition scores by 4.0 points and reduced carbon emissions by 2.8 kg per kilogram, making them effective for both goals simultaneously.
How long do the benefits of food swaps last?
This study only tracked shopping for two weeks, so we don’t know about long-term effects. However, the improvements appeared quickly—within just one week of receiving suggestions—suggesting the approach could work over longer periods if people continue following recommendations.
Want to Apply This Research?
- Track the number of swaps you make per shopping trip and monitor your grocery nutrition score (if your app provides one) or the carbon footprint of your purchases. Set a goal like ‘make at least 2 healthy swaps per shopping trip’ and log which swaps you chose.
- When your grocery app suggests a food swap, pause before dismissing it. Read the reason (health or environmental benefit) and try at least one suggested swap per shopping session. Start with swaps for foods you buy regularly, as these will have the biggest impact.
- Review your shopping history monthly to see if your nutrition scores are improving and your carbon footprint is decreasing. Compare your current shopping cart to your baseline from a month ago. Share your progress with friends or family to stay motivated, or set monthly challenges to increase the number of swaps you make.
This research shows that food swap suggestions can improve the healthfulness and environmental impact of grocery purchases in online shopping environments. However, this study was conducted in a simulated online store and may not fully apply to traditional brick-and-mortar grocery shopping. Results are based on short-term shopping behavior (two weeks) and may not reflect long-term dietary changes or health outcomes. Individual results may vary based on personal preferences, dietary needs, and access to different foods. Consult with a healthcare provider or registered dietitian before making significant dietary changes, especially if you have specific health conditions, allergies, or nutritional requirements. This research does not replace professional medical or nutritional advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.