30.10.2019 |

Healthy diets also benefit the environment, study shows

Plant-based foods benefit both the health of people and the planet (Photo: CC0)

Eating wholesome food is not only good for your health, it also benefits the environment, new research has confirmed. According to a study published in the journal “Proceedings of the National Academy of Sciences”, the same dietary changes that could help reduce the risk of diet-related non-communicable diseases could also help meet internationally agreed sustainability goals. The scientists from the University of Oxford and the University of Minnesota analysed how consuming 15 different food groups is associated with health outcomes and aspects of environmental degradation. They found that foods associated with improved health, such as whole grain cereals, fruits, vegetables, legumes, nuts and some vegetable oils high in unsaturated fats like olive oil, also have among the lowest environmental impacts. However, foods with the largest negative environmental impacts, such as red meat, were linked to the largest increases in disease risk. “The study adds to the growing body of evidence that stresses that replacing meat and dairy with a variety of plant-based foods can improve both your health and the health of the planet,” said co-author Dr Marco Springmann from the University of Oxford.

The researchers 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. Using a comparison of an additional serving per day of those foods, they analysed collections of large epidemiological cohort studies – which follow populations of individuals through time – and life cycle assessments, which are used to estimate the environmental impacts per unit of food produced. With respect to health, the researchers looked at five outcomes – total mortality, heart disease, stroke, type II diabetes, and colorectal cancer. The aspects incorporated in the environmental analysis were greenhouse gas emissions, land use, water use, water pollution (eutrophication) and acidification.

The largest health benefits were found for nuts, minimally processed whole grains, fruits, vegetables, legumes, olive oil, and fish, which are associated with significantly reduced mortality and/or reduced risk for one or more diseases. On the contrary, “consumption of sugar-sweetened beverages, unprocessed red meat, and processed red meat are consistently associated with increased disease risk,” the authors write. “Of all of the foods examined, a daily serving of processed red meat is associated with the largest mean increase in risk of mortality and incidences of coronary heart disease, type II diabetes, and stroke.” When only environmental aspects were considered, minimally processed plant-based foods, olive oil, and sugar-sweetened beverages consistently have among the lowest environmental impacts. Producing a serving of unprocessed red meat has the highest impact for all five environmental indicators. The combination of health and environmental outcomes showed that foods associated with improved adult health also have the lowest environmental impacts. The exceptions were fish, which is a healthy food but has moderate environmental impacts, and processed foods high in sugars, which can be harmful to health but have a relatively low environmental impact.

“Diets are a leading source of poor health and environmental harm,” said lead author Dr Michael Clark from the University of Oxford. “Continuing to eat the way we do threatens societies, through chronic ill health and degradation of Earth’s climate, ecosystems, and water resources.” He hopes the findings will help consumers to make better choices and enable policymakers to issue more effective dietary guidelines. “Choosing better, more sustainable diets is one of the main ways people can improve their health and help protect the environment. How and where a food is produced also affects its environmental impact, but to a much smaller extent than food choice,” Dr. Clark added. Eating those foods that are best for human health and the environment would have the greatest impact. But the researchers also stressed that foods with intermediate environmental impacts or which are not significantly associated with health outcomes, such as refined grain cereals, dairy, eggs, and chicken, could also contribute to meeting sustainability targets if they are used to replace foods that are less healthy or worse for the environment such as red meat. (ab)

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