Plant-based foods are good for both health and the environment

Foods associated with improved health (whole grain cereals, fruits, vegetables, legumes, nuts and some vegetable oils high in unsaturated fats, such as olive oil) have among the lowest environmental impacts, they found. Foods with the largest negative environmental impacts—unprocessed and processed red meat—were consistently associated with the largest increases in disease risk.

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. Red meat (pork, beef, mutton, and goat) and processed meat had the highest environmental impacts of all foods and were also associated with the largest increases in disease risk. Other animal-source foods, such as dairy and poultry meat, had moderate environmental impacts and a small impact on disease risk compared to other foods.

Lead author Dr Michael Clark, of the Livestock, Environment and People (LEAP) project at the Oxford Martin School, and the Nuffield Department of Population Health, University of Oxford, says the findings could help consumers make better choices by equipping them with an understanding of the health and environmental impacts of different foods, and enable policymakers to issue more effective dietary guidelines.

'Diets are a leading source of poor health and environmental harm,' said Dr Clark. '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. How and where a food is produced also affects its environmental impact, but to a much smaller extent than food choice.'

Using a comparison of an additional serving per day of 15 different foods, the researchers 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. The health and environmental analyses each incorporated five outcomes (total mortality, heart disease, stroke, type II diabetes, and colorectal cancer for health; and greenhouse gas emissions, land use, water use, water pollution, and acidification potential for environment), and the results were consistent when applied across nearly all combinations of health and environmental outcomes.

'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, of the LEAP project and Oxford’s Nuffield Department of Population Health.

The full paper, 'Multiple health and environmental impacts of foods,' is published in the Proceedings of the National Academy of Sciences.