Topics » Food Sustainability » Do We Need Animal Foods to Meet Global Protein Requirements?
T. Colin Campbell Center for Nutrition Studies

We have a bad habit of persistently conflating protein with animal foods. It’s on the restaurant menus. When it’s not at the forefront of our thoughts, it’s in the back of our minds. The idea is so deeply entrenched that one of the first questions a non-meat-eater must confront from friends and family is, inevitably, where will you get your protein?

The same thinking is frequently applied on a larger scale when discussing the environmental impact of livestock-based agricultural systems. Many acknowledge that these systems are responsible for resource depletion, habitat loss, and greenhouse gas emissions, among other potentially existential threats, yet repeatedly emphasize how important it is to be mindful of satisfying global protein requirements. If we aren’t eating meat—or so the story goes—then we at least need to plan carefully, and we might struggle.

But this story doesn’t stand up to scrutiny. Protein deficiency is rare in populations consuming a calorie-sufficient diet. According to the National Health and Nutrition Examination Survey (NHANES), the average American adult has consistently obtained almost 16% of their calories from protein for several decades.[1] That’s nearly twice the required amount to meet or exceed the needs of 97.5% of adults.

Okay, but what about those who abstain from the standard American diet’s high level of meat consumption? In a review published in 2019, authors compared the protein intake of meat-eaters with lacto-ovo-vegetarians and vegans using data from the EPIC-Oxford study.[2] They found that both groups of non-meat-eaters consumed significantly more than the RDA. The authors put it well in their conclusion: “We recommend that further study on protein in vegetarian diets shift away from unnecessary questions about protein adequacy, to a comparison of overall nutrition quality and implications for long-term health.”

Numerous authoritative public health agencies have reiterated the plant-based diet’s ability to provide more-than-adequate protein levels, including the Academy of Nutrition and Dietetics (AND).[3] In a 2016 position statement on vegetarian diets, AND authors cite several research studies from previous decades, reaching the following stance:

Vegetarian, including vegan, diets typically meet or exceed recommended protein intakes, when caloric intakes are adequate. The terms complete and incomplete are misleading in relation to plant protein. Protein from a variety of plant foods, eaten during the course of the day, supplies enough of all indispensable (essential) amino acids when caloric requirements are met [. . . ] Protein needs at all ages, including for athletes, are well achieved.

But even these relatively definitive statements understate the case for shifting away from animal-based foods as our preferred source of protein. We need to revise our thinking. Rather than defending the plant-based diet’s ability to provide protein, we should pounce on the unsuitability of animal-based foods.

We only need to look at where most of the world’s protein comes from. Despite requiring 77% of the currently available agricultural land for its production, livestock only accounts for 37% of the world’s protein supply.[4]

That’s right—not only are livestock-based agricultural systems responsible for resource depletion, habitat loss, and greenhouse gas emissions, among other potentially existential threats, but they’re also less efficient.


  1. National Center for Health Statistics, National Health and Nutrition Examination Survey. See Sources and Definitions, National Health and Nutrition Examination Survey (NHANES) and Health, United States, 2020–2021 Table McrNutr.
  2. Mariotti F, Gardner CD. Dietary Protein and Amino Acids in Vegetarian Diets-A Review. Nutrients. 2019;11(11):2661. Published 2019 Nov 4. doi:10.3390/nu11112661
  3. Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116(12):1970-1980. doi:10.1016/j.jand.2016.09.025
  4. Ritchie H, Roser M. Land use. Published online at September 2019. Accessed January 3, 2023.

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