Why eating less protein could be good for the environment

From spirulina to soy, chia seeds and squash, alternatives to meat are popular because they offer a new way to fill up on protein. But if you’ve decided to choose these options to reduce the environmental impact of your diet, bear in mind that eating too much of these foods might not be so wise either. In fact, it could contribute to nitrogen pollution.

We get protein from rib-eye, but also from fried eggs, a bowl of lentils or a salad of beansprouts. Protein is an essential part of our diet, helping the body to build muscle tissue and to renew cells in bones, hair and nails.

Whether of animal or vegetable origin, this macronutrient family should represent between 10 and 27% of the daily energy intake of an adult under 60 years of age, according to France’s National Agency for Food Safety (ANSES). More concretely, 100 to 150 grams of meat, fish or eggs largely cover these needs.

When we consume too much protein, the excess is filtered out by the kidneys and eliminated in urine. As such, urea is formed, a kind of waste product that is characterized by its nitrogen-rich compounds. So, beyond any nutritional dimension, another previously little-considered issue associated with excess protein consumption is that of nitrogen pollution of the environment.

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The Scientific American journal reports that nitrogen can break down to form gases of oxidized nitrogen, which can end up in the atmosphere. This process contributes to global warming by supporting the presence of greenhouse gases.

In the end, our excessive protein consumption — which is eliminated via urine — ends up being detected as nitrogen compounds in wastewater, and therefore potentially also in drinking water. This is how scientists have established the impact of the proteins we eat on the environment.

Indeed, they conclude that 67 to 100% of the nitrogen pollution found in wastewater is produced by what humans consume.

The good news is that there are means available to reduce the amount of nitrogen that is polluting our soils and atmosphere. According to an American study from the University of California, Davis, published in the journal Frontiers in Ecology and the Environment, if the US population consumed the right amount of protein at the recommended levels, nitrogen excretion rates in 2055 could be 27% lower than today, even if the number of people in the country increases. 

Technology could also help remove nitrogen from wastewater, by up to 90%. Although already developed, it is, unfortunately, expensive to implement. Only 1% of wastewater in North America benefits from this treatment.

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