May 16, 2013
Is salt turning your own cells against you? Could be, according to a new study suggesting that salt may overstimulate the immune system, paving the way for autoimmune diseases.We already know that some forms of autoimmunity are associated with an overproduction of a particular type of cell—TH17—that produces inflammatory, infection-fighting cells. Normally, having those infection-fighting cells is a good thing. Our immune system relies on them to fight off bacteria, viruses and other disease-causing agents.
But too much of a good thing is a bad thing. When a person’s immune system is on overdrive, it begins to attack healthy tissues…and autoimmune diseases develop.
In the past 50 years, the number of people being diagnosed with autoimmune diseases has been soaring, making scientists worry that some environmental factor is at play. Since the average American consumes more than twice the 1,500 mg of salt that the American Heart Association recommends as the daily maximum, salt is a possible culprit. Here’s the connection…
WHY SALT IS A SUSPECT
Other studies showed that an overgrowth of TH17 cells causes mice to develop the mouse equivalent of multiple sclerosis, a condition called experimental autoimmune encephalomyelitis. The triggers that provoke the overproduction of TH17, however, were not known.
While looking for keys to the production of TH17 cells, researchers identified a protein central to sensing salt intake. They went on to show that mouse cells cultured in a high-salt solution (in a petri dish) produced more TH17 cells than those growing in normal conditions. Then the same thing happened to human cells in a petri dish.
The researchers then began to look for the same effect in living mice, not just in mouse cells. To that end, they fed a high-salt diet to laboratory mice that were genetically susceptible to autoimmune problems. In human terms, the saltiness of the mice’s diet was approximately equal to “the upper end of a high-salt diet,” researchers said—but not far beyond what any human would normally consume, the way some animal studies are. Results: The mice overproduced the TH17 cells…and they went on to develop experimental autoimmune encephalomyelitis.
SHAKE OFF THE SALT
This study shows that salt increases the production of TH17 cells and that it can induce one type of autoimmune disease in mice. Granted, that is a long way from proving that excessive quantities of salt could trigger autoimmune diseases in people. We need more research on this.
In the meantime, though, the new study does ring alarms about a potential danger of salt that few people consider when they wield the saltshaker or gobble high-salt fast food and packaged processed foods. Given the proven cardiovascular risks that come from consuming excess salt—not to mention the increased risk for kidney disease, asthma, osteoporosis and stomach cancer, too—it just makes sense to talk to your doctor about cutting back, particularly if you have or are at risk for autoimmune problems.
Passing up the saltshaker and saying no to junky, high-salt foods will help…but salt also is overabundant in some foods you probably don’t suspect. Click to read “Hidden Salt In Six Favorite Foods”—so you won’t unwittingly eat more salt than you want.
Source: David Hafler, MD, professor of neurology and immunobiology, chair, department of neurology, Yale School of Medicine, New Haven, Connecticut. His study was published in Nature.
http://www.bottomlinepublications.com/content/article/diet-a-exercise/salt-linked-to-multiple-sclerosis-rheumatoid-arthritis-and-other-autoimmune-diseases
