High Salt Consumption Linked to Growing Autoimmune Disease Rates in Western Societies

The frequency of autoimmune diseases in Western societies, such as multiple sclerosis and type 1 diabetes, has risen in recent decades. In three research papers published Wednesday, high-salt consumption was attributed as a risk factor for causing the spike in these diseases.

In three studies published in Nature, researchers said that salt may activate a part of the immune system that can target the body. Experts quickly cautioned that although the findings were interesting and plausible, avoiding salt altogether is a not cure for people with multiple sclerosis.

The three studies were done by teams of researchers at the Brigham and Women's Hospital and the Broad Institute of MIT and Harvard. In two of the studies in mice and human cells, scientists saw that salt boosted the development of a type of immune cell known as T helper 17, or Th17, that has been implicated in diseases like MS, psoriasis and rheumatoid arthritis.

Autoimmune diseases develop when the immune system attacks rather than protects the host.

Other researchers found they could induce more severe forms of autoimmune diseases, and at higher rates, in mice fed a diet higher in salt than others.

"It's premature to say: 'You shouldn't eat salt because you'll get an autoimmune disease'," says one of the study authors, Dr Aviv Regev from the Massachusetts Institute of Technology.

"We're putting forth an interesting hypothesis - a connection between salt and autoimmunity - that must now be tested through careful epidemiological studies in humans."

Dr David Hafler, a professor of immunobiology at Yale University in New Haven, Connecticut, and senior author of one of the three papers, says the findings now need to be studied in people.

"It's not bad genes. It's not bad environment. It's a bad interaction between genes and the environment," said Dr. Hafler.

 "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," Haffler said.  He added that the exact amount of salt considered to be "too much" is still unknown.