Global study finds healthy diets can cut emissions without raising costs

A global study has found that eating healthy can reduce costs and greenhouse gas (GHG) emissions. It shows that choosing less expensive healthy food options generally leads to lower dietary emissions, while also underlining compromises in animal-source foods and starchy staples.

The publication in Nature Food challenges the popular belief that eating healthy is expensive. Tufts University, US, researchers found that cheaper food options actually had lower emissions.

In 2021, the average daily CO2-equivalent emissions from typical diets were 2.44 kg at US$9.96 per day, while a healthy diet planned to minimize emissions would emit 0.67 kg at US$6.95. 

When focusing on minimizing expenses over emissions, a healthy diet would cost US$3.68 with 1.65 kg emissions. Meanwhile, a healthy diet that combines the most commonly consumed products with lower-cost healthy choices would cost US$6.33 and produce 1.86 kg of emissions.

The researchers hope to guide consumers and policymakers toward more sustainable food choices.

Growing global population

The study points out that governments and international organizations are exploring how to cut food system emissions without making food insecurity worse. 

The team examined foods in groups based on the Healthy Diet Basket targets, which are also used for global monitoring by UN agencies and governments worldwide.

Choosing lower-cost foods within each food group is often linked to reduced dietary emissions, with some key exceptions.“People can’t see or taste the emissions caused by each food, but everyone can see the item’s price — and within each food group, less expensive options generally cause less emissions,” says senior author Wiliam Masters, professor at the Friedman School of Tufts University.

Modelling diets per country 

The team analyzed food data based on availability and price in 171 countries, how much of each country’s food supply it accounted for, and the global average GHG emissions tied to the food.

Based on this, they created five diets for each country, which included the healthiest diet with the lowest emissions, the healthiest diet at the lowest cost, and three versions of diets based on the most commonly consumed foods.

“In general, choosing less expensive options in each food group is a reliable way to lower the climate footprint of one’s diet,” comments study co-lead author Elena Martinez, who completed the work as a doctoral student and postdoc at the Friedman School. 

“This new study extends that to the extremes, asking which items could meet health needs with the smallest possible climate footprint,” she adds.

Costs versus emissions

The researchers explain that the cheapest options are also the least emitting because they use less fossil fuel and require less land-use change.

However, there are tradeoffs between the extreme end of low costs and low emissions in animal-source foods and starchy staples.

For instance, milk is the cheapest option in animal-sourced food, with CO2-equivalent emissions lower than beef and other meats. But fish like sardines and mackerel have lower emissions at the middle level of cost per calorie.

Moreover, rice is the cheapest option in starchy staples in countries where wheat or corn are the lowest-emission products, note researchers. But rice emissions are slightly higher than more expensive corn or wheat, because rice paddies emit more methane.

“There are situations where reducing emissions costs money, because it involves investment in new equipment and power sources,” says Masters. 

“But at the grocery store, frugality is a helpful guide to sustainability. Most people can reduce emissions by choosing less expensive options from each food group, with important exceptions at the extremes of low-cost diets due to methane from dairy and rice.”

Healthy diets for people and the planet

According to the latest Planetary Health Diet (PHD) update, food production is driving 30% of global GHG emissions. However, it suggests that following its dietary recommendations could prevent millions of premature deaths and cut food-related emissions by more than half.

Nutrition Insight spoke with the European Food Information Council, which promotes the PHD, about the importance of planning a nutritious transition when switching to more plant-based diets and promoting flexitarian approaches to food transitions.

Last December, researchers at the University of Oxford, UK, explained how replacing meat and dairy with plant-based food alternatives might reduce nutritional imbalances, mortality and disease risks, environmental resource use, and pollution.