‘Planet-friendly diet’ cuts cancer and heart disease risk

Scientists found that people with a mainly plant-based diet of whole grains, fruit, vegetables and nuts were less likely to die over the course of three decades compared with those who ate less environmentally-friendly meals.

The findings, presented at Nutrition 2023 – an international conference of experts in food, diet, and health – comes days after a separate study estimated that cutting down on meat consumption in the UK could be like “taking eight million cars off the road” in terms of the reduced carbon footprint.

Researchers at Nutrition 2023, which is being held in Boston, unveiled a new diet score incorporating scientific evidence that shows the effects of food on human health as well as the environment.

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Known as the Planetary Health Diet Index (PHDI), it looks at existing evidence to give scores for foods, taking into account the risk of chronic diseases such as heart disease, bowel cancer, diabetes and stroke, as well as environmental impacts such as water use, land use, nutrient pollution and greenhouse gas emissions.

The researchers said their work builds on existing research which has shown that plant-based foods such as whole grains, fruit, non-starchy vegetables, nuts, and unsaturated oils were healthier and less harmful to the environment than red and processed meats.


In 2019, the Eat-Lancet Commission – a three-year project by 37 international experts – warned that worldwide intakes of red meat and sugar would have to be halved by 2050 to avoid “potentially catastrophic” damage to the planet, and recommended that humans switch to a largely plant-based diet. 

The team behind the PHDI score hopes that its tool will help policymakers and public health bodies develop strategies to improve public health while also addressing the climate crisis.

READ MORE: Annual sandwich consumption ‘has same environmental impact as eight million cars’ 

Linh Bui, a PhD student in the department of nutrition at Harvard University’s TH Chan School of Public Health, in the US, said: “We proposed a new diet score that incorporates the best current scientific evidence of food effects on both health and the environment.

“The results confirmed our hypothesis that a higher Planetary Health Diet score was associated with a lower risk of mortality.”

She added: “As a millennial, I have always been concerned about mitigating human impacts on the environment.

“A sustainable dietary pattern should not only be healthy but also consistent within planetary boundaries for greenhouse gas emissions and other environmental parameters.”

After developing their tool, the researchers used it to determine the outcomes of more than 100,000 people in the US, from 1986 to 2018.

More than 47,000 died during the follow-up period of more than 30 years.

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The team found that higher PHDI scores were associated with a 15% lower risk of death from cancer or heart diseases, a 20% lower risk of death from neurodegenerative diseases, and a 50% lower risk of death from respiratory diseases.

Ms Bui said that the PHDI may need to be adapted for different countries, depending on their culture or religion.

She said: “We hope that researchers can adapt this index to specific food cultures and validate how it is associated with chronic diseases and environmental impacts such as carbon footprint, water footprint, and land use in other populations.”

It comes days after a study led by Oxford University compared the greenhouse gas emissions associated with different types of UK diet, ranging from high or low meat diets to non-meat diets containing fish and vegetarian or vegan diets. 

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It concluded that the heaviest meat consumers’ diet is equivalent to an average carbon dioxide output each day of 10.24 kg, to a low of 2.47kg a day for vegans.

The researchers estimated that if the UK’s biggest meat eaters were to cut down it would have the same environmental impact as taking eight million cars off the road.

Professor Peter Scarborough, who led the new research, said: ”Our results show that if everyone in the UK who is a big meat-eater reduced the amount of meat they ate, it would make a really big difference.”

“You don’t need to completely eradicate meat from your diet.”

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