Food for Thought

By James Badham, University of California, Santa Barbara
Nov. 12, 2014

The world is gaining weight and becoming less healthy, and global dietary choices are harming the environment.

Those are among the findings of a paper co-authored by David Tilman, a professor in the Bren School of Environmental Science & Management, and Michael Clark, a graduate student at the University of Minnesota, where Tilman also is a professor. In “Global Diets Link Environmental Sustainability and Human Health,” published today in the journal Nature, the researchers find that rising incomes and urbanization around the world are driving a global dietary transition that is, in turn, diminishing the health of both people and the planet.

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The links between urbanization, increased wealth and unhealthful diets are clear, Tilman explains. When a country industrializes, the transition from a traditional rural diet to one that includes more processed meats and more empty calories can occur quickly. “People move to cities, leaving behind their own gardens where they grew fruits and vegetables,” Tilman said. “They’re working in a factory 12 hours a day, six or seven days a week, so they need food that’s cheap and fast. The cheapest, fastest food you can get is filled with starch, sugar, fat and salt. Almost overnight, they go from a healthy diet to one that has way too many calories and leads to diabetes and heart disease.”

Also, because people tend to eat more meat as they become wealthier, much of the expected 100-percent increase in crop production that will be required by 2050 would be used to feed not humans but livestock. To do that, much more land will need to be cleared, with the result that more habitat will be lost, more species will likely become extinct and increased runoff of agricultural fertilizers and pesticides will degrade streams, rivers, lakes, groundwater and oceans.

Tilman suggests that hope — and help — lie in the widespread adoption of alternative diets that offer substantial health benefits and could reduce global agricultural greenhouse gas emissions, reduce land clearing and resultant species extinctions and help prevent a variety of diet-related chronic noncommunicable diseases.

Comparing conventional American omnivorous diets to the Mediterranean diet, a pescetarian diet (in which fish is the only animal protein) and a vegetarian diet, the compiled research showed that the three alternatives to the omnivorous diet decreased Type 2 diabetes by 16 to 41 percent, cancer by 7 to 13 percent and morality rates from coronary heart disease by 20 to 26 percent. Moreover, the authors show that these alternative diets could reduce global greenhouse gas emissions from food production by about 40 percent below what they would be if dietary trends continued.

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Twenty servings of vegetables have fewer greenhouse gas emissions than one serving of beef.

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And among cereal grains, rice has five times the emissions per gram of protein as wheat.

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