Healthy diet means a healthy planet, study shows – The Guardian

Eating healthy food is almost always also best for the environment, according to the most sophisticated analysis to date.

The researchers said poor diets threaten society by seriously harming people and the planet, but the latest research can inform better choices.

The analysis assessed the health and environmental impacts of 15 foods common in western diets and found fruit, vegetables, beans and wholegrains were best for both avoiding disease and protecting the climate and water resources. Conversely, eating more red and processed meat causes the most ill health and pollution.

Timeline

Half a century of dither and denial – a climate crisis timeline

Fossil fuel companies have been aware of their impact on the planet since at least the 1950s

The physicist Edward Teller tells the American Petroleum Institute (API) a 10% increase in CO2 will be sufficient to melt the icecap and submerge New York. “I think that this chemical contamination is more serious than most people tend to believe.”

Lyndon Johnson’s President’s Science Advisory Committee states that “pollutants have altered on a global scale the carbon dioxide content of the air”, with effects that “could be deleterious from the point of view of human beings”. Summarising the findings, the head of the API warned the industry: “Time is running out.”

Shell and BP begin funding scientific research in Britain this decade to examine climate impacts from greenhouse gases.

A recently filed lawsuit claims Exxon scientists told management in 1977 there was an “overwhelming” consensus that fossil fuels were responsible for atmospheric carbon dioxide increases.

An internal Exxon memo warns “it is distinctly possible” that CO2 emissions from the company’s 50-year plan “will later produce effects which will indeed be catastrophic (at least for a substantial fraction of the Earth’s population)”.

The Nasa scientist James Hansen testifies to the US Senate that “the greenhouse effect has been detected, and it is changing our climate now”. In the US presidential campaign, George Bush Sr says: “Those who think we are powerless to do anything about the greenhouse effect forget about the White House effect … As president, I intend to do something about it.”

confidential report prepared for Shell’s environmental conservation committee finds CO2 could raise temperatures by 1C to 2C over the next 40 years with changes that may be “the greatest in recorded history”. It urges rapid action by the energy industry. “By the time the global warming becomes detectable it could be too late to take effective countermeasures to reduce the effects or even stabilise the situation,” it states.

Exxon, Shell, BP and other fossil fuel companies establish the Global Climate Coalition (GCC), a lobbying group that challenges the science on global warming and delays action to reduce emissions.

Exxon funds two researchers, Dr Fred Seitz and Dr Fred Singer, who dispute the mainstream consensus on climate science. Seitz and Singer were previously paid by the tobacco industry and questioned the hazards of smoking. Singer, who has denied being on the payroll of the tobacco or energy industry, has said his financial relationships do not influence his research.

Shell’s public information film Climate of Concern acknowledges there is a “possibility of change faster than at any time since the end of the ice age, change too fast, perhaps, for life to adapt without severe dislocation”.

At the Rio Earth summit, countries sign up to the world’s first international agreement to stabilise greenhouse gases and prevent dangerous manmade interference with the climate system. This establishes the UN framework convention on climate change. Bush Sr says: “The US fully intends to be the pre-eminent world leader in protecting the global environment.”

Two month’s before the Kyoto climate conference, Mobil (later merged with Exxon) takes out an ad in The New York Times titled Reset the Alarm, which says: “Let’s face it: the science of climate change is too uncertain to mandate a plan of action that could plunge economies into turmoil.”

The US refuses to ratify the Kyoto protocol after intense opposition from oil companies and the GCC.

The US senator Jim Inhofe, whose main donors are in the oil and gas industry, leads the “Climategate” misinformation attack on scientists on the opening day of the crucial UN climate conference in Copenhagen, which ends in disarray.

A study by Richard Heede, published in the journal Climatic Change, reveals 90 companies are responsible for producing two-thirds of the carbon that has entered the atmosphere since the start of the industrial age in the mid-18th century.

The API removes a claim on its website that the human contribution to climate change is “uncertain”, after an outcry.

Mohammed Barkindo, secretary general of Opec, which represents Saudi Arabia, Kuwait, Algeria, Iran and several other oil states, says climate campaigners are the biggest threat to the industry and claims they are misleading the public with unscientific warnings about global warming.

Jonathan WattsGarry Blight and Pablo Gutiérrez

There were a small number of foods that bucked the trend. Fish is generally a healthy choice but has a bigger environmental footprint on average than plant-based diets. High-sugar foods, such as biscuits and fizzy drinks, have a low impact on the planet but are bad for health.

The effect of bad diets on health in rich nations is well known, as is the need to slash western meat consumption in order to tackle the climate breakdown and other environmental crises. But this is the first study to consider both together in detail.

Michael Clark at the University of Oxford, who led the research, said: “Continuing to eat the way we do threatens societies, through chronic ill health and degradation of Earth’s climate, ecosystems and water resources.

“Choosing better, more sustainable diets is one of the main ways people can improve their health and help protect the environment.”

Some farming groups argue only intensively produced meat is seriously damaging to the environment. But Clark said replacing any meat with plant-based food makes the biggest difference. “How and where a food is produced affects its environmental impact, but to a much smaller extent than food choice,” he said.

Marco Springmann, also at Oxford and part of the study team, said: “We now know pretty well that predominantly plant-based diets are much healthier and more sustainable than meat-heavy diets. But sometimes there is still confusion among people about what foods to choose.”

The scientists hope more detailed information will help consumers, policymakers and food companies make better choices. The researchers are currently working on new types of food labels to see if information on health and environmental impacts changes people’s selection of food.

The research, published in the journal Proceedings of the National Academy of Sciences, assessed plant-based foods including fruits, vegetables, legumes, nuts, potatoes, refined grains and wholegrain cereals, and sugar-sweetened beverages, and animal-based foods such as raw and processed red meat, chicken, dairy products, eggs and fish.

Chart showing foods and their environmental impact

Using data from other studies on the diets and health outcomes of tens of millions of people, mostly in developed western nations, they calculated the health impact of eating one extra portion of each food on heart disease, stroke, type 2 diabetes and colorectal cancer.

The environmental harm for each food, from greenhouse gases to water use to pollution, was calculated relative to a portion of vegetables. Producing unprocessed red meat had the highest impact for all environmental indicators and was many times worse than pulses.

The researchers said foods with medium environmental impacts or not significantly associated with ill health, such as refined grain cereals, dairy, eggs and chicken, could help improve health and reduce environmental harm if they replaced foods such as red meat.

Prof Tim Benton at the Chatham House thinktank, who was not part of the team, said: “The [new research] is the most sophisticated analysis to date that brings health and environment together.

“If we can produce reasonable guidelines of what a healthy and sustainable diet is, and were those guidelines to be adopted, the world and its people would be in a much better place.”

According to Benton, strictly controlling people’s diets over many years for scientific research is impractical and it is therefore difficult to study the direct effects on health of eating specific foods, as the continuing debate over red meat shows. But he said the weight of evidence from epidemiological studies was now significant.

“The global ill-health costs from diabetes alone are the same order of magnitude as the total value of farming to the global economy,” he said. “Our existing agricultural economy is destroying our ability to deal with climate change and also destroying our public health.”

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