Adoption of a plant-rich “planetary health diet” could prevent 40,000 early deaths a day across the world, according to a landmark report.

The diet – which allows moderate meat consumption – and related measures would also slash the food-related emissions driving global heating by half by 2050. Today, a third of greenhouse gas emissions come from the global food system and taming the climate crisis is impossible without changing how the world eats, the researchers said. Food production is also the biggest cause of the destruction of wildlife and forests and the pollution of water.

The planetary health diet (PHD) sets out how the world can simultaneously improve the health of people and the planet, and provide enough food for an expected global population of 9.6 billion people by 2050.

The diet is flexible, allowing it to be adapted to local tastes, and can include some animal products or be vegetarian or vegan. However, all versions advise eating more vegetables, fruits, nuts, legumes and whole grains than most people in the world currently eat. In many places, today’s diets are unhealthy and unsustainable due to too much meat, milk and cheese, animal fats and sugar.

People in the US and Canada eat more than seven times the PHD’s recommended amount of red meat, while it is five times more in Europe and Latin America, and four times more in China. However, in some regions where people’s diets are heavily reliant on starchy foods, such as sub-Saharan Africa, a small increase in chicken, dairy and eggs would be beneficial to health, the report found.

Severe inequalities in the food system must also be ended to achieve healthy and sustainable diets, the researchers said. The wealthiest 30% of the world’s population generates more than 70% of food-related environmental damage, it found. Furthermore, 2.8 billion people cannot afford a healthy diet and 1 billion are undernourished, despite enough food being produced globally. The food system is also failing the 1 billion people living with obesity, the report said.

The report recommends shifting taxes to make unhealthy food more costly and healthy food cheaper, regulating the advertising of unhealthy food and using warning labels, and the shifting of today’s massive agricultural subsidies to healthier and more sustainable foods.

The report recommends shifting taxes to make healthy food cheaper. Photograph: Wu Hao/EPA

“What we put on our plates can save millions of lives, cut billions of tonnes of emissions, halt the loss of biodiversity, and create a fairer food system,” said Prof Johan Rockström, who co-chaired the EAT-Lancet Commission that produced the report. “The evidence is undeniable: transforming food systems is not only possible, it’s essential to securing a safe, just, and sustainable future for all.”

“This is not a deprivation diet,” said Prof Walter Willett of the Harvard TH Chan school of public health, and another commission co-chair. “This is something that could be delicious, aspirational and healthy. It also allows for cultural diversity and individual preferences, providing flexibility.”

The report, published in the Lancet, was produced by 70 leading experts from 35 countries and six continents. It builds on the 2019 report that introduced the PHD, but includes new evidence of the health benefits of the diet.

“We have been able to look at this diet in relation to health outcomes such as total mortality, diabetes, respiratory diseases, heart disease, stroke, etc and we found very strong inverse relationships” said Willett. The diet was also linked to reduced cancer and neurodegenerative diseases.

Overall, the researchers estimated global adoption of the PHD could prevent 15m early deaths a year in adults. The estimate did not include the impact of the diet reducing obesity, meaning it is probably an underestimate.

The PHD recommends plant-rich, flexible diets, including:

• Fruits and vegetables – at least five portions a day

• Whole grains – three to four portions a day

• Nuts – one portion per day

• Legumes (beans, peas, lentils) – one portion per day

• Dairy – one serving of milk, yoghurt or cheese portions a day

• Eggs – three to four a week

• Chicken – two portions a week

• Fish – two portions a week

• Red meat – one portion a week

Dr Marco Springmann from UCL in the UK and an author of the report said the differences between the PHD and current diets vary: “What needs to be reduced differs a lot. In low income countries, it’s the starchy foods and grains, whereas in high income countries it is animal-sourced foods, sugar, saturated fats, and dairy. It’s insane how much dairy is consumed in Europe and North America.”

The data underlying the report is available online and can be used to tailor different planetary health diets for the tastes of people in specific countries and of different ages. The website also shows how much the diets reduce deaths, improve nutrition, and cut environmental impacts. “Hopefully this will lead to more science-based policymaking,” said Springmann.

‘What needs to be reduced differs a lot [from country to country]. In low income countries, it’s the starchy foods and grains.’ Photograph: eFesenko/Alamy

The PHD is better than current average diets for many nutrients, including fatty acids, fibre, folate, magnesium and zinc. Adequate iron and vitamin B12 could be provided by green leafy vegetables, fermented soy foods and algae, the researchers said.

Moving diets towards the PHD could be achieved by helping consumers make better everyday choices, said Prof Line Gordon, director of the Stockholm Resilience Centre, for example by shifting taxes to make healthy foods cheaper, and putting warning labels on unhealthy foods. “But it is not just about getting prices lower, it’s also about bringing purchasing power up so that people can afford a healthier diet” she said.

“Our recommendations are grounded in scientific evidence and real-world experience,” Gordon said. “Changes are already under way, from school meal programmes to regenerative agriculture and food waste reduction initiatives.” England banned price promotions on unhealthy foods on Wednesday and will ban advertising such foods online.

The report estimates that food-related ill health and environmental damage costs society about $15tn a year. It said investments to transform the food system would cost $200bn to $500bn a year, but save $5tn.

Alongside a shift in diets, the report calls for other changes to the food system, including cutting the loss and waste of food, greener farming practices, and decent working conditions, as a third of food workers earn below living wages.

The launch of the PHD in 2019 led to attacks from meat industry interests. Rockström said: “The [new report] is a landmark achievement. It is a state-of-the-art scientific assessment that quantifies healthy diets for all human beings in the world and the environmental boundaries all food systems need to meet to stay safe. So we have a really rigorous foundation for our [results]. We are ready to meet that assault.”