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- Protein consumption rates in the United States are about 40 percent higher than recommended levels.
- This excess protein results in excess amino acids, which transform into nitrogen.
- Excreted nitrogen finds its way into drinking water, posing a risk for human and animal life.
Americans consume some of the highest total and per capita amounts of protein in the world. New research shows the country’s water quality might suffer as a result.
Balancing individual protein consumption can reduce the level of nitrogen pollution in U.S. aquatic systems by 12 percent, according to new research published in Frontiers in Ecology and the Environment. This could also lead to a 4 percent overall reduction in nitrogen in air and water.
“When protein consumption outpaces physiologic protein demands, excess amino acids are degraded in the human body and nitrogen is excreted and released to the environment, mainly in the form of urea,” researchers at the University of California, Davis explained.
Elevated nitrogen levels in water can lead to eutrophication, or excessive nutrient richness, which contributes to high plant life growth and decreased animal life, due to a lack of oxygen. Excess nitrogen can also contribute to toxic algal blooms and have negative effects on drinking water supplies.
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To estimate nitrogen excretion rates, investigators assessed current U.S. protein consumption rates and recommended consumption rates, along with population demographic data. Based on previous studies, they estimated protein has a 16 percent nitrogen content, 80 percent is excreted in urine and 10 percent in feces.
Models showed that if Americans adjusted their protein intake to recommended amounts, nitrogen excretion rates would be 27 percent lower in 2055 than they are today, despite projected population growth.
However, should current levels of consumption continue, nitrogen rates will increase by 20 percent from 2016 to 2055. This is due in part to a growing aging population that requires more protein to build muscle mass and combat frailty.
Authors also found coastal cities have the greatest potential to reduce this pollutant on track to enter their watersheds. In particular, the Chesapeake Bay and Great Lakes areas, along with the mouth of the Mississippi River are all regions with high concentrations of land-based nitrogen pollution.
In addition, although technologies that can remove 90 percent of nitrogen from wastewater exist, less than 1 percent of sewage is treated with these technologies due to their high cost.
“It’s interesting to think about possible ways to cut into those nitrogen losses beyond expensive technology,” said lead study author Maya Almaraz in a statement. “Dietary changes are a healthy and cheap way to do it.”
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