We can’t live well without a healthy diet. What we eat affects our growth, lifespan, mental health, and more. But for a third of the world’s population, even the least-expensive foods that meet nutritional requirements are out of reach. And the impact of poor nutrition is staggering – diet-related conditions claim millions of lives and cost trillions of dollars annually.
Food Economist and Bellagio Center Resident Dr. William Masters believes our global food system can bring healthy diets within reach of all people at all times. Through the Food Prices for Nutrition project at Tufts University, he and his team created a system of measurement to track access to healthy diets around the world. Combining data on retail prices and nutritional content of foods with nutritional requirements, the Cost of a Healthy Diet method identifies the lowest-priced foods sold in local markets that meet national and global nutritional targets, and it informs policies and approaches to improve food access.
This pioneering method has been embraced worldwide. Since 2020, the United Nations’ Food and Agriculture Organization (FAO) and the World Bank have published annual global Cost of a Healthy Diet estimates for all countries, and five national governments now share their own statistics on healthy diet costs. In recognition of that and other work on food economics, Masters was awarded the prestigious 2026 Georg and Greta Borgström Prize for Global Food Security by The Royal Swedish Academy of Forestry and Agriculture.
We spoke to Masters about how the project developed, what makes it unique, and how affordability data can help ensure everyone has access to healthy, affordable food.
Imagine a world where every local market offers an inexpensive assortment of vegetables, fruits, dairy products, eggs, and so forth, thanks to greater investment and innovation in farm production and supply chains.
Dr. William MastersPrincipal Investigator, Food Prices for Nutrition
What is unique about the Food Prices for Nutrition approach ?
We bring economic and nutritional data together on a large scale, using modern techniques to identify the least-expensive available foods being sold that meet each population’s health needs. Our team works closely with data analysts in national governments and global institutions, building partnerships so they can all run similar software tools on their computers. This provides a new way to distinguish causes of malnutrition, such as high costs, low household income, or other factors.
One big step has been translating national dietary guidelines into quantifiable targets. Anna Herforth, who has also done other pioneering researcb on how to collect data on what people eat, leads that work. Calculating the lowest possible cost of a healthy diet is most valuable when you can compare that mix of foods to actual consumption, so you can see where and how improvements could be made.
For international comparisons, we define a healthy diet using commonalities among national dietary guidelines. Anna’s work revealed how to capture these in a single set of Healthy Diet Basket targets, specifying the quantity needed from each of six food groups: vegetables; fruits; legumes, nuts and seeds; animal-source foods; oils and fats; and starchy stables.
When consumed in the required proportions, the lowest-cost options in each food group deliver enough of almost all essential nutrients and other compounds needed to avoid deficiencies while avoiding excesses that cause diet-related diseases.
Here’s an example of what this looks like. Nigeria’s National Bureau of Statistics publishes data on seasonal variation and differences by region. Their lowest-cost healthy diet might involve items like maize and cassava, served with a stew including tomatoes, okra and a green leafy vegetable, some beans and a small fish, plus milk or eggs, avocado and dried dates. Elsewhere, the foods selected would be very different, but they would still meet basic dietary requirements.
How has the project grown over the last 10 years?
The least-cost-diet approach to measuring food access has grown from the germ of an idea to global adoption. The key has been iterating, improving, and scaling gradually. We collaborate closely with local data analysts and government leaders to ensure our work meets their needs, and we have published dozens of scientific articles to share results with other researchers.
It started in 2016 with a pilot grant from the UK government for research in Ghana and Tanzania. The Gates Foundation then funded a project that expanded research across Africa and South Asia, in collaboration with the World Bank and others. Based on those results, the UK and Gates supported us to continue our research and help national governments to publish their own Cost of a Healthy Diet statistics. That work was led by Rachel Gilbert, who provided hands-on help to dozens of analysts around the world.
In our current project, we’re shifting the education and analysis work with governments to the FAO, so adoption can proceed on a larger scale. The Tufts team will continue researching new techniques of using food price data to guide decisions.
The whole thing runs on partnerships, working with the analysts who do day-to-day management of food price data. We also spend a lot of time on publication and dialogue with researchers, advancing scientific consensus on measurement methods and interpretation of results. Our goal is to publish every step for peer review and replicability, so that the methods and results can be challenged, improved, and used independently.
How have you seen data from the project being adopted and used?
Nigeria, Ethiopia, Malawi, Ghana, and Pakistan all publish regular bulletins of official statistics on food prices and the cost of a healthy diet. Local agencies then use the data to address their specific concerns. The FAO and World Bank continue to publish an annual average for all countries, focusing on people who cannot afford their country’s least-cost healthy diet.
Nigeria was the first to publish a monthly bulletin, starting in January 2024 during a period of rapid inflation and economic crisis. That coincided with periodic renegotiation of their minimum wage for government workers. These data enabled people to compare salaries against a benchmark level of spending and ask whether working full time at a government job made it possible to feed a family at an international standard of health.
Calculating diet costs can inform three major types of policy decisions. Determining the cost of the least-expensive locally available options in each food group helps set priorities for improving food supply and distribution. Even where the cost of a healthy diet is low, many people still might not have enough income available for food. In that case, these data can inform efforts to improve earnings, strengthen safety nets and lower the cost of nonfood essentials like housing, health and education. Finally, the consumption of low-cost, healthy options is often displaced by other foods, for reasons such as taste, convenience, preparation time, cultural needs, and aspirations shaped by marketing. Calculating the absolute lowest-cost healthy diet for each population helps people have these conversations using internationally comparable data.
How do you believe this program will improve systems and change people’s access to food?
The first step is making low-cost options in each food group more available, convenient, and desirable. Imagine a world where every local market offers an inexpensive assortment of vegetables, fruits, dairy products, eggs, and so forth, thanks to greater investment and innovation in farm production and supply chains.
Comparing diet costs to available income can help ensure people have access to decent jobs complemented by safety nets and targeted nutrition assistance. One example is SNAP in the United States, which gives people who can’t afford a healthy diet a debit card to buy food. Programs of this kind illustrate how diet-cost data can be used to target food assistance more precisely, drawing on up-to-date information about food prices and incomes. Data on the lowest cost of a healthy diet can help ensure that safety nets are well targeted and based on up-to-date information about food prices and incomes.
Finally, this new data could help people distinguish between monetary costs and other drivers of food choice. People can walk into local markets and just get the basics. In the U.S. that might be generic pasta or rice with frozen cut vegetables and tomatoes, onions and oil, bread and peanut butter or canned beans, tinned fish and milk, apples and bananas, or whatever. Almost anywhere in the world, you could meet your country’s national dietary guidelines or the global Healthy Diet Basket standard for less than $6 per person per day. But these basic meals are less attractive than other options, especially meat and fried foods, refined grain and sugar, or heavily advertised products. That’s why nutrition debates focus on how we regulate modern ingredients and processing methods, as well as the older issues around meat and saturated fats, refined grain and sugar. Avoiding those things can take a lot of effort and time, but knowing what is possible gives people a better sense of their options.
How did your 2023 residency impact your work?
It was an enormous boost. When you’re given a Bellagio Center residency, you’re being told you have enormous potential. It really changed my self-perception and pushed me to demand more from myself. I realized that I needed to be a better storyteller. In my cohort, I met social entrepreneurs who were great at explaining what they do and why it matters.
At the Bellagio Center, I did the first draft of a review article telling the story of these new methods. That and other writing helped connect a lot of dots, providing a stronger narrative about how these data help people solve problems. We’ll soon have 15 years of sustained funding and rapid adoption. I need to listen carefully to people and make the case for how and why this innovation continues to meet their needs, on their terms.
Masters is proud of what the project has achieved, and he credits its impact to the whole ecosystem around the work. “My job is to be a messenger between people,” he said. “Innovation is only possible because of deep collaboration between researchers, national governments, international organizations, and many others. It’s not something that anyone could do on their own.”
Learn More:
- Watch William Masters’ presentation on Food Prices for Nutrition at Tufts University’s Friedman School of Nutrition Science and Policy.
- Read an overview of Food Prices for Nutrition and the Healthy Diet Basket on the World Bank’s Data Blog.
- Listen to Dr. Masters discuss the value of the Cost of a Healthy Diet method on the Curious by Nature podcast.
The opinions expressed in this article are those of the author. The Rockefeller Foundation is not responsible for and does not endorse its content.