A clutch of fishing villages dot the coast near Kilifi, north of Mombasa in Kenya. The waters are home to parrot fish, octopus and other edible species. But despite living on the shores, the children in the villages rarely eat seafood. Their staple meal is ugali, maize (corn) flour mixed with water, and most of their nutrition comes from plants. Almost half the kids here have stunted growth — twice the national rate.
In 2020, Lora Iannotti, a public-health researcher at Washington University in St. Louis, and her Kenyan colleagues asked people in the villages why the children weren’t eating seafood, even though all the parents fish for a living; studies show that fish and other animal-source foods can improve growth1. The parents said it made more financial sense for them to sell their catch than to eat it.
So, Iannotti and her team are running a controlled experiment. They have given fishers modified traps that have small openings that allow young fish to escape. This should improve spawning and the health of the overfished ocean and reef areas over time, and eventually increase incomes, Iannotti says. Then, for half the families, community health workers are using home visits, cooking demonstrations and messaging to encourage parents to feed their children more fish, especially plentiful and fast-growing local species such as ‘tafi’, or white spotted rabbitfish (Siganus canaliculatus) and octopus. The scientists will track whether children from these families eat better and are growing taller than ones who don’t receive the messaging.
The aim of the experiment, says Iannotti, is to understand “which sea foods can we choose that are healthy for the ecosystem as well as healthy in the diet”. The proposed diet should also be culturally acceptable and affordable, she says.
Iannotti is wrestling with questions that are a major focus of researchers, the United Nations, international funders and many nations looking for diets that are good for both people and the planet. More than 2 billion people are overweight or obese, mostly in the Western world. At the same time, 811 million people are not getting enough calories or nutrition, mostly in low- and middle-income nations. Unhealthy diets contributed to more deaths globally in 2017 than any other factor, including smoking2. As the world’s population continues to rise and more people start to eat like Westerners do, the production of meat, dairy and eggs will need to rise by about 44% by 2050, according to the UN Food and Agriculture Organization (FAO).
That poses an environmental problem alongside the health concerns. Our current industrialized food system already emits about one-quarter of the world’s greenhouse-gas emissions. It also accounts for 70% of freshwater use and 40% of land coverage, and relies on fertilizers that disrupt the cycling of nitrogen and phosphorus and are responsible for much of the pollution in rivers and coasts3.
A young child is weighed on some scales in a village in Kenya
A child is weighed as part of a study into sustainable fishing and child nutrition in a village near Kilifi Creek, Kenya.Credit: Lora Iannotti
In 2019, a consortium of 37 nutritionists, ecologists and other experts from 16 countries— the EAT–Lancet Commission on Food, Planet, Health — released a report4 that called for a broad dietary change that would take into account both nutrition and the environment. A person following the EAT–Lancet reference diet would be ‘flexitarian’, eating plants on most days and occasionally a small amount of meat or fish.
The report provoked a flurry of attention towards sustainable diets, and some criticism about whether it was practical for everyone. Some scientists are now trying to test environmentally sustainable diets in local contexts, without compromising nutrition or damaging livelihoods.
“We need to make progress toward eating diets that have dramatically lower ecological footprints, or it’ll be a matter of a few decades before we start to see global collapses of biodiversity, land use and all of it,” says Sam Myers, director of the Planetary Health Alliance, a global consortium in Boston, Massachusetts, that studies the health impacts of environmental change.
Emissions on the menu
Producing food generates so much greenhouse-gas pollution5 that at the current rate, even if nations cut all non-food emissions to zero, they still wouldn’t be able to limit temperature rise to 1.5 °C — the climate target in the Paris agreement. A large proportion of emissions from the food system — 30–50%, according to some estimates — comes from the livestock supply chain, because animals are inefficient at converting feed to food.
In 2014, David Tilman, an ecologist at the University of Minnesota in Saint Paul, and Michael Clark, a food-systems scientist at the University of Oxford, UK, estimated that changes in urbanization and population growth globally between 2010 and 2050 would cause an 80% increase in food-related emissions6.
Environmental costs. Chart showing how food systems will increase environmental pressures by 2050.
Source: M. Springmann et al. Nature 562, 519–525 (2018)
But if everyone, on average, ate a more plant-based diet, and emissions from all other sectors were halted, the world would have a 50% chance of meeting the 1.5 °C climate-change target5. And if diets improved alongside broader changes in the food system, such as cutting down waste, the chance of hitting the target would rise to 67%.
Such findings are not popular with the meat industry. For example, when in 2015, the US Department of Agriculture was revising its dietary guidelines, which happens every five years, it briefly considered factoring in the environment after researchers lobbied the advisory committee. But the idea was overruled, allegedly in response to industry pressure, says Timothy Griffin, a food-systems scientist at Tufts University in Boston, who was involved in the lobbying effort7. Nonetheless, people took notice of the attempt. “The biggest accomplishment is it brought a lot of attention to the issue of sustainability,” he says.
The EAT–Lancet Commission, which was funded by Wellcome, a UK-based charity, helped to build a stronger case. Nutritionists reviewed the literature to craft a basic healthy diet composed of whole foods. Then the team set environmental limits for the diet, including carbon emissions, biodiversity loss and the use of fresh water, land, nitrogen and phosphorus. Breaching such environmental limits could make the planet inhospitable to humans8.
They ended up with a diverse and mainly plant-based meal plan (see ‘Healthy eating’). The maximum red meat the 2,500-calorie per day diet allows in a week for an average-weight 30-year-old is 100 grams, or one serving of red meat. That’s less than one-quarter of what a typical American consumes. Ultra-processed foods, such as soft drinks, frozen dinners and reconstituted meats, sugars and fats are mostly avoided.
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