Excess dietary salt identified as autoimmune trigger

For the past few decades, health officials have been reporting increases in the incidence of autoimmune diseases such as multiple sclerosis (MS). Now researchers at Yale School of Medicine, Harvard Medical School and the Broad Institute have identified a prime suspect in the mystery—dietary salt.

In the March 6 issue of the journal Nature, Yale researchers showed that can induce and worsen pathogenic immune system responses in mice and that the response is regulated by genes already implicated in a variety of autoimmune diseases.

In accompanying papers in the same issue of Nature, researchers from Brigham and Women's Hospital and Harvard identified the key molecular pathway involved in the response to salt, and the Broad Institute sketched out the of genes that governs this .

"These are not diseases of bad genes alone or diseases caused by the environment, but diseases of a bad interaction between genes and the environment," said David Hafler, the Gilbert H. Glaser Professor of Neurology, professor of immunobiology, chair of the Department of Neurology, and senior author of the Yale paper.

The research was inspired, in part, by an observation that eating at fast-food restaurants tended to trigger an increase in production of , which are mobilized by the immune system to respond to injury or pathogens but which, in autoimmune diseases, attack healthy tissue. Researchers at Yale and colleagues in Germany led by Dominik Mueller wanted to know whether high in diet might induce the destructive that is the hallmark of autoimmunity.

They found that adding salt to the diet of mice induced production of a type of previously associated with autoimmune diseases and that mice on salt diets developed a more severe form of an MS animal model, experimental autoimmune encephalomyelitis.

The research at the Broad Institute, Brigham and Women's Hospital, Harvard University, and Yale University expands the understanding of how one type of immune cell—known as a T helper 17 or Th17 cell—develops, and how its growth influences the development of other kinds of cells involved in the . Reconstruction of this molecular circuitry confirmed the surprising role of salt, said the researchers.

"The question we wanted to pursue was: How does this highly pathogenic, pro-inflammatory T cell develop?" said Vijay Kuchroo, a senior scientist at Brigham and Women's Hospital and a Broad Institute associate member. Kuchroo is also the Wasserstrom Professor of Neurology at Harvard Medical School and co-director of the Center for Infection and Immunity at Biomedical Research Institutes. "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."

"Humans were genetically selected for conditions in sub-Saharan Africa, where there was no salt," Hafler said. "Today, Western diets all have high salt content and that has led to increase in hypertension and perhaps autoimmune disease as well."

Hafler noted that all test-tube cell biology is performed based on the salt levels found in blood and not in the tissues where immune cell ultimately travel to fight infections. That may have been a reason salt's role in autoimmunity has gone undetected.

"We may have been using the wrong concentrations of salt in our experiments for the past half-century," Hafler said. "Nature did not want immune cells to become turned on in the pipeline, so perhaps blood salt levels are inhibitory."

Patient trials to assess affects of salt on are being planned.

"The value in doing an unbiased analysis is that we're able to understand a lot more about the molecular biology at play and put forth a completely novel process," said Aviv Regev, a Broad Institute core member and an associate professor of biology at MIT. Regev is also an Early Career Scientist at Howard Hughes Medical Institute and the director of the Klarman Cell Observatory at the Broad.

Hafler is not waiting with his own patients.

"I already recommend that my patients use a low-salt, low-fat diet," he said

Markus Kleinewietfeld was lead author of the Yale-led study.

More information: Nature, doi: dx.doi.org/10.1038/nature11868

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NikFromNYC
1 / 5 (5) Mar 06, 2013
"Humans were genetically selected for conditions in sub-Saharan Africa, where there was no salt...."

Black humans that is, explaining why fast food ruins their health.
Lurker2358
1 / 5 (3) Mar 06, 2013
Did they do these experiments only for Sodium salts, or did they also test potassium salts?

Maybe the FDA should pass a law so that all commercially packaged or prepared food should have no more Sodium than the RDA as a percentage recommended daily food calories, so that high sodium foods would be functionally illegal.

People would still use salt shakers if they want, but prepared foods would be required to be below the limit.
DruidDrudge
2.4 / 5 (8) Mar 06, 2013
so... non-blacks came from?? Mars perhaps??
ScooterG
1 / 5 (5) Mar 06, 2013
This half-assed study implies all salt is the same. Nothing could be further from the truth.

Reduce it too much and you will suffer. Cut salt from your diet entirely and you will die.
kochevnik
1 / 5 (1) Mar 06, 2013
Use Celtic sea salt. The chemical refined crap from mines will kill you fast
arq
not rated yet Mar 07, 2013
@scooter, If a person is eating too much, then reducing it too much means bringing the consumption down to normal levels.Thats whats important....'normal level'
JRi
1 / 5 (1) Mar 07, 2013
I'm sure the link between excessive salt consumption and MS-disease would have already been discovered from existing MS-patients, if it was that clear. After all, high blood pressure has been known to be caused by high salt intake for a long time.
roldor
not rated yet Mar 07, 2013
There exists no "Dietary Salts"! There are only existing mixtures of certain salts NaCl with MgCl CaCl and KCl to reduce Na takein. This is here not spacified. These mixtures are sometimes called "Dietary Salt" or "Light Salt". So this is such a scientifically incorrect statement as "radiation kills you" without announcing that an oven is also radiating and under which cirumstances it could kill one.

Read more at: http://medicalxpr...html#jCp
88HUX88
5 / 5 (1) Mar 07, 2013
Use Celtic sea salt. The chemical refined crap from mines will kill you fast

you subscribe to Mercola's thinking then? What besides the sodium and the chlorine do you think is in conventional table salt, and in what quantities?
88HUX88
not rated yet Mar 07, 2013
There exists no "Dietary Salts"! There are only existing mixtures of certain salts NaCl with MgCl CaCl and KCl to reduce Na takein. This is here not spacified. These mixtures are sometimes called "Dietary Salt" or "Light Salt". So this is such a scientifically incorrect statement as "radiation kills you" without announcing that an oven is also radiating and under which cirumstances it could kill one.

they mean salt in your diet, that's all, and excess dietary salt means too much salt in your diet - oh and diet means what you eat
kochevnik
1 / 5 (1) Mar 11, 2013
Use Celtic sea salt. The chemical refined crap from mines will kill you fast

you subscribe to Mercola's thinking then? What besides the sodium and the chlorine do you think is in conventional table salt, and in what quantities?
Nothing, and that imbalance is the problem. Celtic salt has all the trace elements necessary for your body to make it's own vitamins. People are starving due to stipping themselves of essential elements found in nature