A recent article in the scientific journal Nature has drawn a correlative link between increased salt intake and autoimmune diseases such as multiple sclerosis and rheumatoid arthritis.
This is a change from the previous understanding that these conditions were largely genetic, and not influenced by diet.
“It’s not bad genes. It’s not bad environment. It’s a bad interaction between genes and the environment,” said Dr. David Hafler, senior author of one of the three papers.
While high salt intake has long been known to be related to things like heart disease and hypertension, this is the first link between salt and autoimmune diseases, which may change the way that doctors interact with their patients’ diets.
This study is a very preliminary work on a connection that will need to be thoroughly investigated over many years, and salt is far from the only contributor to autoimmune disease.
“It can’t be just salt. We know vitamin D probably plays a small component. We know smoking is a risk factor. This now suggests that salt is also a risk factor,” Hafler said. “How much? We don’t know.”
The idea for the study came about almost by accident, when Hafler and his team were studying the gut biome, which is the bacteria that live in our stomachs and intestines. Hafler began to notice that nearly every patient in the study who visited a fast-food restaurant more than once a week had higher levels of inflammatory cells, which are responsible for attacking healthy cells in a person with an autoimmune disease.
These findings fit into research being done at Harvard Medical School regarding what caused activity in T helper 17 cells, or Th17, which is a type of autoimmune cell. Together, they hope to develop a thorough understanding of these cells, including how to turn them back off.
“Once we have a more nuanced understanding of the development of the pathogenic Th17 cells, we may be able to pursue ways to regulate them or their function,” said Vijay Kuchroo of the Harvard-affiliated Brigham and Women’s Hospital.
It is important to note that these results were found in mice, as human trials have not yet begun. Salt is a healthy part of the human diet, and while low-salt diets can be useful in some circumstances, it is dangerous to eliminate salt from the diet altogether.
Still, Hafler suggests that if you are genetically at risk for developing an autoimmune disease, cutting back on your salt as a prevention may be a good idea!