Monday, December 12, 2016

Vegetarians and Sustainability

According to Dr. Vaclav Smil formerly of the University of Manitoba and author of Should We Eat Meat, homo sapiens are naturally omnivore with a high degree of preference for meat consumption. However, we are no longer hunter gatherers increasing density of populations created the need to abandon hunting and gathering and progressively increase permanent settlements with crop farming. The agrarian life was accompanied by cultural adaptions of meat restrictions and taboos turned meat into a relative rare foodstuff for the majority of the population in traditional agricultural societies. The return to more frequent meat eating has been a transition in affluent economies.

World food production has changed over the centuries and so, too, has population health. Food production capabilities and capacity has increased greatly; maternal and child nutrition in high-income groups has improved; health and life expectancies have increased, at least partly because of nutritional gains; and refrigeration, transport, and open markets have increased year-round access to healthy foods for many populations.

In this holiday season I have been thinking about what food means within families, the many different styles of eating, and food sustainability. Our family holidays have traditional dishes that tell the story of our family. We also have vegetarians in the family who consume a diet of fruits, vegetables, grains, legumes, eggs, and dairy. A diet limited to only plant based food is called veganism. Then there are Pescetarians (sometimes called pesco-vegetarians) who eat freshwater and saltwater fish and shellfish in addition to the fruits, vegetables, grains, legumes, eggs, and dairy of the vegetarian. Omnivores eat everything (hopefully in moderation) and on it goes.

A study published in JAMA in 2015 found that among over 77,000 Seventh-Day Aventists who have a high number of vegetarians found that when compared with non-vegetarians, pesco vegetarinan had a 43% lower risk, and vegetarians had a 22 % lower risk for colorectal cancer which remains the second leading cause of cancer mortality in the United States. Dietary choices are important sources of modifiable risk for colorectal cancer, as well as part of our identity. Our style of eating is part of who we are.

For most of the 20th Century agricultural science focused on increasing food production yield and efficiency. Only recently have scientists begun to include ecological impacts of farming but now nutritionists and agricultural scientists from Tufts University and Cornell have joined together to compare the per capita land requirements and potential carrying capacity of the land base of the continental United States (U.S.) under a diverse set of dietary scenarios. In other words they have looked at how much land resources are necessary to feed a person on various eating senarios.

Unsurprisingly, certain styles of eating require more land and water resources than others. The scientists found that diet composition greatly influences overall land footprint necessary to feed a person. The baseline scenario of how the U.S. eats on average today had the highest total land use, 1.08 hectares per person per year. Land requirements decreased steadily across the five “healthy” omnivorous diets with fewer calories and decreasing animal protein, from 0.93 to 0.25 hectares per person per year, and the total land requirements for the three vegetarian diets were all very low, 0.13 to 0.14 hectares per person per year.

The scientist found that diets including some meat can feed more people than vegan diets. As the amount of meat in the diet was reduced, the amount of land necessary to grow crops to feed livestock decreased until the crossover where more land was necessary to grow enough plant protein for human consumption. The scientist found that the vegetarian diet could provide adequate nutrition and feed almost 800 million people from the currently available agriculture land. However, differences in total per capita land requirements are only part of the story the scientists were telling.

While I initially thought the data was intended to be used only to maximize the number of people that could be feed by our nation’s agricultural lands. The scientists state: “Provision of food, while essential, is not the only important ecological service provided by land. Some of these services, such as carbon capture, may be compatible with grazing, at least in well-managed systems. Other services, such as wildlife habitat, may be impinged where domesticated species compete for biomass with wild ruminants and ungulates. Finally, the use of perennial cropland for grazing or hay production could conceivably compete with bioenergy production where biomass energy or draft animals are possible alternatives to fossil fuels.”

Changing the American diet could improve health, reduce the need for agricultural land and make biomass available to meet the new U.S Environmental Protection Agency mandated increase in renewable fuel volume requirements across all categories of biofuels under the Renewable Fuel Standard (RFS) program, fight increasing CO2 levels and support a healthier ecology. I thought the study was how to best feed the growing population of mankind, but it wasn’t. This is part of the pivot towards climate under Executive Order 13653, “Preparing the United States for the Impacts of Climate Change.”


  1. This is confusing. I infer that eating fish is healthy. Beyond that, it's hard to make an unbiased conclusion. If we paved over grazing land, that would not be good for the earth. So what is the point of using less grazing land?

    1. The current policy is to minimize carbon dioxide equivalents in the atmosphere and secondarily to maximize the number of people that can be feed from the earth's resources. Reducing enteric methane by reducing the meat content in the first world countries serves both goals. Ultimately, whether or not this change is made, the earth's forecast population will exceed the capacity to feed them and the climate will continue to change. So, Linda your inferred point is valid. Using less grazing land is a policy and value judgment by the scientists who did the study.