Dr. David Tilman at the University of Minnesota has been at this for a while. He traced urbanization and income growth around the world between 1961 and 2009 and linked it with increased consumption of refined sugars and refined fats brought about people adopting more meat intensive western-style diets. In 2014 he published research in Nature showing how a shift away from that trajectory in favor of a more traditional Mediterranean diets that included fish or vegetarian diets “could not only boost human lifespan and quality of life, but also slash greenhouse gas emissions and save habitat for endangered species.” 1, 2 At that time food production, especially livestock farming, was estimated to account for 25% of global greenhouse-gas emissions. 3
In discussing that research, Dr. Tilman said, “We showed that the same dietary changes that can add about a decade to our lives can also prevent massive environmental damage…In particular, if the world were to adopt variations on three common diets, health would be greatly increased at the same time global greenhouse gas emissions were reduced by an amount equal to the current greenhouse gas emissions of al all cars, trucks, planes trains and ships. In addition, this dietary shift would prevent the destruction of an area of tropical forests and savannas as large as half of the United States.” 1
Tilman and his team have followed up that work with a more recent paper published in the prestigious Proceedings of the National Academy of Sciences that offers more specifics about the health impacts of certain foods with their impact on the planet. 4 A University of Minnesota press release summarized the work nicely for us: 5
“The researchers explored how consuming 15 different food groups is, on average, associated with five different health outcomes and five aspects of environmental degradation. Their results show that:
-Almost all foods associated with improved health outcomes (e.g., whole grain cereals, fruits, vegetables, legumes, nuts and olive oil) have the lowest environmental impacts;
-Likewise, foods with the largest increases in disease risks — primarily unprocessed and processed red meat such as pork, beef, mutton and goat — are consistently associated with the largest negative environmental impacts;
-The two notable exceptions are fish, a generally healthier food with moderate environmental impacts, and sugar-sweetened beverages, which pose health risks but have a low environmental impact.
Researchers concluded that transitioning diets toward greater consumption of healthier foods would also improve environmental sustainability.”4, 5
Without adopting a healthier diet, Tilman’s team warns, “By 2050 these dietary trends, if unchecked, would be a major contributor to an estimated 80 per cent increase in global agricultural greenhouse gas emissions from food production and to global land clearing. Moreover, these dietary shifts are greatly increasing the incidence of type II diabetes, coronary heart disease and other chronic non-communicable diseases that lower global life expectancies.” 2
In the video below, Dr. Tilman states that “agriculture is the major threat of extinction for species on earth” and describes how a shift toward more people adopting Mediterranean pescatarian or vegetarian diets could significantly lower CO2 emissions that are now slightly more than all C02 emissions from transportation worldwide. 6
International health advocates hope that Tilman’s work can be used to help people make better food choices. That is a complicated issue, as Elke Stehfest of the Netherlands Environmental Assessment Agency observed about Tilman’s earlier work, “Individual choices are strongly influenced by the ‘food environment’ — factors such as shop proximity, food prices, food and nutrition programmes, labelling schemes and community characteristics. Governments and other agencies play a part in shaping these environments to support healthier and more-sustainable food choices, and increased efforts to include both health and environmental factors in dietary guidelines will be key to promoting behavioural change.” 3
We hope that sharing Dr. Tilman’s work here will add some food for thought as you plan your next meals.
– R.A. Kroft
1University of Minnesota. Live Longer? Save the Planet? Better Diet Could Nail Both. Press Release. 12 November 2014.
2Tilman D and Clark M. Global diets link environmental sustainability and human health. Nature 2014: 515;518-522. 12 November 2014.
3Stehfest E. Food choices for health and planet. Nature 2014:515;501-502.
4Clark MA, Springmann M, Hill J, Tilman D. Multiple health and environmental impacts of foods. Proceedings of the National Academy of Sciences 2019: 116(46); 23357-23362
5University of Minnesota. Nutritious foods have lower environmental impact than unhealthy foods. Press Release. 28 October 2019.
6VIDEO: Diets, Human Health and the Environment. David Tilman College of Biological Sciences University of Minnesota. Presented at NASEM Health and Medicine Division. 10 August 2018.
R.A. Kroft writes about her day-to-day journey in living a smaller, more sustainable life and other topics that interest her.
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