The Great Salt Lake on the Utah-Nevada border registers 30% salinity in the northern reaches and 6% to 27% in the southern areas. Only brine shrimp and some algae thrive in such environments.

In the Middle East, the Dead Sea is so salty that some say it doesn't even feel like water — more like olive oil mixed with sand. Its only inhabitants are minuscule bacteria and microbial fungi.

These natural wonders are a testimony to how hard excess salt can be on plants and animals. And a new study in the journal Science Translational Medicine offers more evidence.

The researchers found that people who took in an extra 6 grams of salt (that's 1 teaspoon daily) showed pronounced immune deficiencies.

The Centers for Disease Control and Prevention recommends adults limit sodium intake to a total of 2.3 grams (2,300 mg) daily. That comes out to about a third of a teaspoon of salt.

But the average American takes in 3.4 grams (3,400 mg), and many people eat far more salt.

Along with making sure you get 30 minutes of physical activity daily, eat a plant-centric diet, take a multivitamin, and get seven to eight hours of quality sleep nightly, reducing excess salt intake is one more way to keep your immune system strong.

That's something you definitely want to do as you protect yourself and others from the spread of COVID-19.