HEALTHY DIETS FOR PEOPLE AND THE PLANET - Nature
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Feature
ILLUSTRATION BY PAWEŁ JOŃCA
HEALTHY DIETS
FOR PEOPLE AND
THE PLANET
The ideal diet should be nutritious without threatening natural
resources. Researchers are trying to decide what’s best for countries
from Kenya to Sweden. By Gayathri Vaidyanathan
22 | Nature | Vol 600 | 2 December 2021
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.A
clutch of fishing villages dot the of freshwater use and 40% of land coverage, changes in urbanization and population
coast near Kilifi, north of Mombasa and relies on fertilizers that disrupt the cycling growth globally between 2010 and 2050
in Kenya. The waters are home to of nitrogen and phosphorus and are respon- would cause an 80% increase in food-related
parrot fish, octopus and other edi- sible for much of the pollution in rivers and emissions6.
ble species. But despite living on the coasts3. But if everyone, on average, ate a more
shores, the children in the villages In 2019, a consortium of 37 nutritionists, plant-based diet, and emissions from all
rarely eat seafood. Their staple ecologists and other experts from 16 coun- other sectors were halted, the world would
meal is ugali, maize (corn) flour tries— the EAT–Lancet Commission on Food, have a 50% chance of meeting the 1.5 °C cli-
mixed with water, and most of their nutrition Planet, Health — released a report4 that called mate-change target5. And if diets improved
comes from plants. Almost half the kids here for a broad dietary change that would take into alongside broader changes in the food system,
have stunted growth — twice the national rate. account both nutrition and the environment. such as cutting down waste, the chance of hit-
In 2020, Lora Iannotti, a public-health A person following the EAT–Lancet reference ting the target would rise to 67%.
researcher at Washington University in St. diet would be ‘flexitarian’, eating plants on Such findings are not popular with the meat
Louis, and her Kenyan colleagues asked people most days and occasionally a small amount industry. For example, when in 2015, the US
in the villages why the children weren’t eating of meat or fish. Department of Agriculture was revising its
seafood, even though all the parents fish for The report provoked a flurry of attention dietary guidelines, which happens every
a living; studies show that fish and other ani- towards sustainable diets, and some criticism five years, it briefly considered factoring in
mal-source foods can improve growth1. The about whether it was practical for everyone. the environment after researchers lobbied
parents said it made more financial sense for Some scientists are now trying to test environ- the advisory committee. But the idea was
them to sell their catch than to eat it. mentally sustainable diets in local contexts, overruled, allegedly in response to industry
So, Iannotti and her team are running a without compromising nutrition or damaging pressure, says Timothy Griffin, a food-systems
controlled experiment. They have given fish- livelihoods. scientist at Tufts University in Boston, who was
ers modified traps that have small openings “We need to make progress toward eating involved in the lobbying effort7. Nonetheless,
that allow young fish to escape. This should diets that have dramatically lower ecological people took notice of the attempt. “The big-
improve spawning and the health of the over- footprints, or it’ll be a matter of a few decades gest accomplishment is it brought a lot of
fished ocean and reef areas over time, and before we start to see global collapses of biodi- attention to the issue of sustainability,” he says.
eventually increase incomes, Iannotti says. versity, land use and all of it,” says Sam Myers, The EAT–Lancet Commission, which was
Then, for half the families, community health director of the Planetary Health Alliance, a funded by Wellcome, a UK-based charity,
workers are using home visits, cooking demon- global consortium in Boston, Massachusetts, helped to build a stronger case. Nutritionists
strations and messaging to encourage parents that studies the health impacts of environmen- reviewed the literature to craft a basic healthy
to feed their children more fish, especially tal change. diet composed of whole foods. Then the team
plentiful and fast-growing local species such set environmental limits for the diet, including
as ‘tafi’, or white spotted rabbitfish (Siganus Emissions on the menu carbon emissions, biodiversity loss and the use
canaliculatus) and octopus. The scientists will Producing food generates so much green- of fresh water, land, nitrogen and phosphorus.
track whether children from these families eat house-gas pollution5 that at the current rate, Breaching such environmental limits could
better and are growing taller than ones who even if nations cut all non-food emissions to make the planet inhospitable to humans8.
don’t receive the messaging. zero, they still wouldn’t be able to limit tem- They ended up with a diverse and mainly
The aim of the experiment, says Iannotti, is perature rise to 1.5 °C — the climate target in plant-based meal plan (see ‘Healthy eating’).
to understand “which sea foods can we choose the Paris agreement. A large proportion of The maximum red meat the 2,500-calorie per
that are healthy for the ecosystem as well as emissions from the food system — 30–50%, day diet allows in a week for an average-weight
healthy in the diet”. The proposed diet should according to some estimates — comes from 30-year-old is 100 grams, or one serving of red
also be culturally acceptable and affordable, the livestock supply chain, because animals are meat. That’s less than one-quarter of what a
she says. inefficient at converting feed to food. typical American consumes. Ultra-processed
Iannotti is wrestling with questions that In 2014, David Tilman, an ecologist at the foods, such as soft drinks, frozen dinners
are a major focus of researchers, the United University of Minnesota in Saint Paul, and and reconstituted meats, sugars and fats are
Nations, international funders and many Michael Clark, a food-systems scientist at mostly avoided.
nations looking for diets that are good for the University of Oxford, UK, estimated that This diet would save the lives of about 11 mil-
both people and the planet. More than 2 bil- lion people every year, the commission esti-
lion people are overweight or obese, mostly in mated4. “It is possible to feed 10 billion people
the Western world. At the same time, 811 mil- healthily, without destroying ecosystems fur-
lion people are not getting enough calories or ther,” says Tim Lang, food-policy researcher at
nutrition, mostly in low- and middle-income the City University of London and a co-author
nations. Unhealthy diets contributed to more
IT IS POSSIBLE of the EAT–Lancet report. “Whether the hard-
TO FEED 10
deaths globally in 2017 than any other factor, liners of the cattle and dairy industry like it or
including smoking2. As the world’s population not, they are really on the back foot. Change
BILLION PEOPLE
continues to rise and more people start to eat is now inevitable.”
like Westerners do, the production of meat, Many scientists say the EAT–Lancet diet
HEALTHILY, WITHOUT
dairy and eggs will need to rise by about 44% is excellent for wealthy nations, where the
by 2050, according to the UN Food and Agri- average person eats 2.6 times more meat
DESTROYING
culture Organization (FAO). than their counterpart in low-income coun-
That poses an environmental problem tries, and whose eating habits are unsustain-
alongside the health concerns. Our current
industrialized food system already emits ECOSYSTEMS able. But others question whether the diet is
nutritious enough for those in lower-resource
about one-quarter of the world’s green-
house-gas emissions. It also accounts for 70% FURTHER.” settings. Ty Beal, a scientist based in Washing-
ton DC with the Global Alliance for Improved
Nature | Vol 600 | 2 December 2021 | 23
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.Feature
Vegetables
HEALTHY EATING
300g
North Europe and Region
Dairy Whole grains America Central Asia key
250g 232g
A commission of food researchers
devised a ‘planetary health’ diet —
meant to be nutritious and sustainable Fruits
— and compared its composition with 200g
Animal Latin South
the average diets in different regions. protein America Asia
Further studies showed that, in many 84g and the
regions, following the proposed diet Caribbean
would be prohibitively expensive. Starchy Plant Middle East East Asia
vegetables protein and North and Pacific
By Kerri Smith 50g 125g Africa
Sub-Saharan
Design by Jasiek Krzysztofiak Africa
Planetary health diet
grams per day
Dietary intakes
Healthy diet cost
2016 300 g
(daily income per person)
41% 4% 28% 10%
Healthy diet
200 g
Over- Under-
consumed consumed
100 g
Global average North America Latin America Europe and
and Caribbean Central Asia
300 g
32% 65% 73% 27%
200 g
SOURCES: INTAKES, REF. 4; COSTS, REF. 12
100 g
East Asia and Pacific South Asia Sub-Saharan Africa Middle East and
North Africa
Health risks Type 2 diabetes Environmental Greenhouse-gas emissions
16% costs 2010
The planetary health
diet could save around Between 2010 and 2050, 2050
SOURCES: RISKS, REF. 6; ENVIRONMENTAL COSTS, M. SPRINGMANN
25%
11 million lives, according predicted growth in
to its designers. Similarly, 42% population and income Cropland use
a 2014 analysis showed could drive a 50–90%
2010
that diets that are lower in increase in environmental
Cancer 2050
fat, meat and sugar pressures exerted by
reduce the relative risk of 7% food systems, such as
several health conditions climate impacts and Water use
when compared with an 13% freshwater use. 2010
omnivorous diet such
10% Staple crops 2050
ET AL. NATURE 562, 519–525 (2018)
as the global average
(above). Plant proteins
Coronary-disease mortality
Fruits and vegetables Nitrogen application
Mediterranean 26% Vegetable oils 2010
Pescatarian
20% Sugars 2050
Vegetarian
Other crops
20% Animal products 0 50 100 150
Reduction in relative risk (%) Environmental pressure (% of present impact)
24 | Nature | Vol 600 | 2 December 2021
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.Nutrition, has analysed the diet in unpublished Across the Atlantic, some academics of $2.84 per day, about 1.6 times higher on aver-
calculations and found that it provides 78% and restaurateurs are trialling the diet in age than the cost of a basic nutritious meal12.
of the recommended zinc intake and 86% of low-income settings. In Baltimore, Maryland, There are other impracticalities. Take
calcium for those over 25 years old, and only a collaboration between a catering business restrictions on meat, for instance. In places
55% of the iron requirement for women of and a restaurant, both forced to close during with nutrient deficiencies and where the
reproductive age. the COVID-19 pandemic, started taking dona- diet’s prescribed foods are not available,
Despite these critiques, the diet has put tions and providing free meals based on the animal-source products are a crucial source
environmental concerns front and centre.“Un- EAT-Lancet diet to families who live in ‘food of easily bioavailable nutrients in addition
til EAT–Lancet, I don’t think it had been at the deserts’ — areas where there is little access to plants, Iannotti says. In many places in
top of policymakers’ minds that sustainability to affordable, nutritious food. One meal had low-income nations, farming systems are
should be integrated into this global conver- salmon cakes with mixed seasonal vegetables, small-scale and include both crops and domes-
sation about dietary change,” says Anne Elise Israeli couscous and creamy pesto sauce. ticated animals, which can be sold in times of
Stratton, a food-systems scientist at the Uni- Researchers at the Johns Hopkins University family need, says Jimmy Smith, director-gen-
versity of Michigan in Ann Arbor. School of Medicine in Baltimore surveyed 500 eral of the International Livestock Research
The diet is not a one-size-fits-all recommen- people who tried the meals and found that 93% Institute in Nairobi.
dation, stresses Marco Springmann, a food of the 242 people who completed the survey “The farmer in the highlands of Ethiopia
scientist at the University of Oxford who was said they either loved or liked it10. The down- doing dairy has three or four animals in his or
part of the EAT–Lancet core modelling team. side? Each donation-funded meal cost US$10 her backyard, and each of these animals is a
Since the report was published, pub- — five times the amount currently provided by member of the family, they have names,” he
lic-health scientists around the world have the US food-stamp programme. says.
been studying how to make the diet realistic “It’s very clear that if you have a huge shift in Menon says that for now, scientists in
for people the world over, whether an over- diets, you could swing the environment impact low- and middle-income regions are more
weight adult or an under-nourished child. for the better, but there’s cultural barriers and concerned about delivering nutrition than
economic barriers to that,” says Griffin. preserving the environment. The FAO has
Rich diets organized a committee to do a much more
Nutrition researchers know that most con- Hard to stomach comprehensive analysis than EAT–Lancet’s.
sumers do not follow dietary guidelines. So For researchers exploring future diets in some The new analysis will be more globally inclu-
some scientists are exploring ways to convince low- or middle-income nations, one hurdle is sive and include topics such as food security
people to adopt healthy, sustainable diets. finding out what people are eating in the first and sustainability of the livestock sector, says
In Sweden, Patricia Eustachio Colombo, a place. “It’s literally like a black box to me right Iannotti, who is part of the committee. It will be
nutrition scientist at the Karolinska Institute now,” says Purnima Menon at the International published in 2024. “They don’t feel as if it was
in Stockholm, and her colleagues are quietly Food Policy Research Institute in Delhi, who entirely balanced or holistic in its review of the
testing a sustainable diet in schools. Their has been studying diets in India. The data on evidence,” she says. “Let’s go further and make
work piggybacks on a social movement that what people are eating are a decade old, she sure we have evidence from around the world.”
began in Scandinavian countries called the says. The way to find sustainable diets in poor
New Nordic Diet, which promotes consump- Getting that information is crucial, because nations is by working closely with commu-
tion of traditional, sustainable foods such as India ranks 101 out of 116 countries in the nities and farmers, as in Kilifi, scientists say.
seasonal vegetables and free-range meat. Global Hunger Index and has the greatest Clark, having mapped out diet at a global scale
Eustachio Colombo and her colleagues number of children who are too thin for their using model-based projections, thinks that
used a computer algorithm to analyse existing height. food-system scientists now need to find the
school lunches at a primary school with about Using what’s available, Abhishek Chaudhary, local adjustments and fixes to get people to
2,000 students. The algorithm suggested a food-systems scientist at the Indian Insti- eat better.
ways to make them more nutritious and cli- tute of Technology Kanpur, who was part “People working in food sustainability need
mate-friendly, such as reducing the amount of of the EAT–Lancet team, and his colleague to go into communities and ask, ‘hey, what’s
meat in a typical stew and adding more beans Vaibhav Krishna at the Swiss Federal Institute good for you?’” he says. “And then, given that
and vegetables. The children and parents were of Technology in Zurich used a computer pro- baseline, how can we start working towards
informed that lunches were being improved, gram and local environmental data on water, outcomes that those communities are inter-
but did not know details, Eustachio Colombo emissions, land use and phosphorus and nitro- ested in.”
says. Most kids did not notice, and there was no gen use to design diets for all of India’s states.
more food waste than earlier9. The same exper- The algorithm suggested diets that would Gayathri Vaidyanathan is a freelance science
iment is now being re-run in 2,800 children. meet nutritional requirements, cut food-re- writer based in Bangalore, India.
“School meals are a near unique opportu- lated emissions by 35% and wouldn’t stress 1. Iannotti, L. L. et al. Pediatrics 140, e20163459 (2017).
nity to foster sustainable dietary habits. The other environmental resources. But to grow 2. GBD 2017 Diet Collaborators. Lancet 393, 1958–1972
dietary habits we develop as children, we tend the required amount of food would require (2019).
3. Springmann, M. et al. Lancet Planet. Health 2, e451–e461
to stick to them into adulthood,” Eustachio 35% more land — which is impractical in the (2018).
Colombo says. overcrowded nation — or higher yields. And 4. Willett, W. et al. Lancet 393, 447–492 (2019).
The diet is very different from the EAT–Lan- food costs would be 50% higher11. 5. Clark, M. A. et al. Science 370, 705–708 (2020).
6. Tilman, D. & Clark, M. Nature 515, 518–522 (2014).
cet one, she says. It is cheaper and includes Healthy, sustainable diets are expensive 7. Merrigan, K. et al. Science 350, 165–166 (2015).
more starchy foods such as potatoes, which elsewhere, too. The dietary diversity advised 8. Steffen, W. et al. Science 347, 1259855 (2015).
are a staple of Swedish cuisine. It is also more by EAT–Lancet — nuts, fish, eggs, dairy and 9. Elinder, L. S., Eustachio Colombo, P., Patterson, E.,
Parlesak, A. & Lindroos, A. K. Sustainability 12, 8475
nutritious and culturally acceptable, she says. more — is impossible to access for millions of (2020).
“This highlights the importance of tailoring people, says Iannotti. 10. Semba, R. D., Ramsing, R., Rahman, N. & Bloem, M.
J. Agric. Food Syst. Communi. Dev. 10, 205–213 (2020).
the EAT-Lancet diet to the local circumstances In fact, for the average person to eat the diet
11. Chaudhary, A. & Krishna, V. One Earth 4, 531–544 (2021).
in each country or even within countries,” she in 2011 — the most recent data set available on 12. Hirvonen, K., Bai, Y., Headey, D. & Masters, W. A.
says. food prices — would have cost a global average Lancet Glob. Health 8, e59–e66 (2020).
Clarified 21 December 2021 | Nature | Vol 600 | 2 December 2021 | 25
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.Correction
This News feature misquoted Iannotti’s
explanation of how the FAO committee
would improve on the EAT–Lancet analysis.
The committee is not redoing the study, but
rather doing a separate analysis that might
overlap with the original work.
Clarified 21 December 2021
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