Is Too Much Causing Autoimmune Disease?

What comes crashing down with excessive salt? Dr Stephen Havas, Professor of Epidemiology at the University of Maryland says, “The number of deaths from excess salt is equivalent to a commuter jet crashing every day in the U.S.” During a recent visit to the Harvard Medical School, I also learned that too much salt may be causing autoimmune diseases such as Type 1 diabetes, multiple sclerosis, Crohn’s Disease and psoriasis.

For years doctors have linked excessive amounts of salt to high blood pressure and cardiovascular disease. Dietary guidelines suggest no more than 1,500 milligrams (mgs) of salt daily. But the majority of North Americans consume a whopping 4,000 mgs daily. Studies show that one in two North Americans over the age of 65 suffers from hypertension. Moreover, the massive Framingham study in the U.S. reported that, at age 75, nine out of ten people have high blood pressure. A high salt diet has also been linked to the risk of stomach cancer. Salty foods may affect the stomach lining making it easier for the bacterium, H pylori, a cause of stomach ulcers and cancer, to infect tissues. And too much salt has been proven to increase the amount of calcium excretion in the urine. Calcium is removed from bone and increases the risk of bone fractures.

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During an alumni meeting at The Harvard Medical School in Boston, Dr. Vijay K. Kuchroo, Professor of Neurology and an expert in immunology, reported that a high salt diet may increase the risk of autoimmune diseases such as multiple sclerosis, Type 1 diabetes and psoriasis. Autoimmune diseases occur when the body’s immune system, the TH17 cells that normally help the body clear infections, start to attack normal cells. It’s as if soldiers, rather that shooting the enemy, suddenly decided to shoot themselves. But the big question asked by Dr. Kuchroo is why there’s been such an increase in autoimmune disease. For instance, according to the American Diabetes Association, Type 1 diabetes increased 23 percent between 2001 and 2009. The incidence of psoriasis has also doubled. And according to Dr. Kuchroo pediatric multiple sclerosis, virtually unheard of 20 years ago, is now being seen more and more. So how could an increased intake of salt trigger autoimmune disease? Researchers discovered that mice, with the gene SGK1, were predisposed to developing a form of multiple sclerosis when fed a high salt diet. But mice without the gene, when fed the same diet, showed a lesser form of the disease. Other researchers at Yale University performed experiments on human immune cells and mice and found the same results. Dr. Kuchroo says more research is needed, but the solution may be due to the SGK1 gene present in the gastrointestinal tract and kidney, which helps to regulate absorption of salt. So will hiding the salt shaker on the table make a difference in developing rheumatoid arthritis, Crohn’s disease and other autoimmune problems? It may be that some people have a genetic susceptibility to these diseases so it’s prudent to limit salt intake. Remember what I’ve said in the past, that too much of anything is rarely a good idea. This is why one study showed that those who frequent fast food restaurants had elevated levels of TH17 cells, the ones that attack their own normal cells. Today excessive salt intake has become a way of life. Restaurant meals and packaged foods are loaded with salt. But don’t hold your breath waiting for TV ads to warn about the dangers of excessive salt. Pharmaceutical companies make billions warning us about the hazards of cholesterol. But there’s no pill to correct this salty problem. Rather, you have to be a smart shopper and read labels. Dr. Kuchroo’s talk brought back many memories for me. It was 68 years ago that I sat in the same amphitheater listening to my first lecture at The Harvard Medical School. What massive changes in surgery, medicine and immunology since that time! For instance, I learned that Harvard researchers have now cured cancer using immunological techniques. This means chemotherapy may become past history. It also necessitates another visit to my favourite city and HMS.