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Protein swap: Improve your health and the planet by eating fewer animals and more plants, researchers suggest

A new review of protein consumption recommends cutting back on overall protein consumption and shifting from meat-based proteins to plant-based proteins.

In the campus office of Christopher Gardner, PhD, a nutrition specialist, sits a sculpture of a chicken. It's no ordinary chicken sculpture — the body takes the shape of a curvy eggplant; the beak, a pointy carrot and from its rear sprouts a feathery tail of tomato vines.

It's purpose is more than just quirky decor; I think the veggie-chicken captures the core message of Gardner's latest review paper, which appears in Nutrition Reviews.

The paper takes a close look at protein consumption habits in the United States, and the big-picture effect it has on climate change and resource use. The long and short of it is, Americans eat the most meat (and protein) of any country in the world, and as a whole, we could stand to cut back.

In this review, Gardner breaks down what we really need to satisfy our protein needs, recommending a partial shift from meat-based protein to plant-based protein. After all, he says, both sources provide roughly the same quality of protein.

I chatted with Gardner about protein consumption on a national level, and asked him to explain how we can better align with protein eating "goals" for both our own health and for the health of the earth.

In an excerpt from the original Q&A, here's what he had to say:

The review estimates that the average person in the United States consumes about 200 pounds of meat in one year. How much protein does a person really need?

The data we cite from the Food and Agricultural Organization encompasses meat intake in more than 150 countries and concludes that more meat per person is consumed in the United States than in any other country. The United States government’s guidelines have a 'recommended daily allowance' that amounts to 0.36 grams of protein per pound of body weight per day. That equals 45 grams of protein for someone weighing 125 pounds, and 64 grams for someone weighing 175 pounds.

But what’s important to note is that this estimation already has a built-in buffer to account for variability across the population. The majority of people should interpret the recommended allowance as an amount with a buffer, not as a minimum requirement. If the entire population consumed the recommended daily allowance of protein, 97.5 percent would meet or exceed their requirement. And yet the average woman in the United States eats about 80 grams per day, and the average man about 100 grams per day. And that’s before adding protein bars, protein shakes and protein powders.

What’s the connection between meat consumption, greenhouse gas emissions and water use?

Over the last decade, concerns about greenhouse gasses and water usage have grown to states of urgency and emergency. There are now dozens of published analyses demonstrating that current agricultural practices are contributing substantially to accelerating global warming, and changes in agricultural practices will be essential to addressing climate change. This is particularly true of raising livestock, beef and dairy in particular, which is far more negatively impactful on resources than growing plant foods, which is relatively less resource-intensive and produces less greenhouse gas.

Do you recommend a cutback in protein? How would that help reduce the impact on natural resources?

Given that many, if not most, Americans eat twice the amount of protein they require, there is substantial room to consume less protein and still easily meet individual needs. Most people could choose a vegetarian or even a vegan diet and still meet their protein needs — but I don’t think that is realistic or necessary.

I would recommend two things: eating less protein in general and shifting the source of some protein from animal to plant foods. Keep in mind that, beyond protein, this shift to a more plant-based diet is now consistent with the recommendations of every public health organization regarding improving human health.

In our paper, we modeled the impact of individuals consuming 25 percent less protein, and also shifting 25 percent of the remaining protein that they consume from animal to plant protein. For the average American that would mean still getting most of their protein from animal foods, about a 60-40 split. By our estimates, that 25-percent-less-and-25-percent-shift recommendation would result in 40 percent lower carbon dioxide emissions from food production-related sources, which would be equivalent to about 8 percent of the greenhouse gas emissions reductions originally pledged by the United States under the Paris Climate Agreement. The shift would also equate to a 10 percent decrease in water consumption — about 3.1 trillion gallons — relative to current consumption. If the protein shifts were bigger, the impact would be even larger.

Photo by Christopher Gardner

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