From pp. 45 - 49, The Salt Solution (Herb Boynton, Mark F. McCarty, Richard D. Moore MD. PhD. 2001) (taken from an earlier topic):
"... clearly, salt is a risk factor for stroke even when blood pressure is normal. Louis Tobian and colleagues demonstrated this last point dramatically (see: L. Tobian and S. Hanlon, "High Sodium-Chloride Diets Injure Arteries and Raise Mortality Without Changing Blood Pressure".* Still more evidence of the stroke-salt connection comes from primitive cultures throughout the world, including the Yanomano Indians of Brazil, the Solomon Islanders, and the Kalahari Bushmen. Among these people, who eat almost no salt, stroke is remarkably rare. Conversely, in cultures switching from low-salt to high-salt diets, stroke rates - like hypertension rates - climb steadily.
How does salt cause stroke? Weve already noted that salt increases blood pressure, putting more strain on the blood vessels. But this damage doesnt account for all or even most strokes. Salt affects your bodys production of certain hormones, called natriuretic factors. . . These hormones, produced when you eat too much salt, flush sodium from your body. They do this by slowing down your kidney cells Na/K pumps that normally recycle up to 99 percent of the sodium filtered through your kidneys. By making these pumps work less efficiently and thus recycle less salt, natriuretic hormones quickly lower the sodium in your body. However, if you keep eating too much salt day after day, as most Americans do, your body pumps out a chronic excess of natriuretic hormones and thats not good. The problem is that all of your [~50 trillion] cells, not just your kidney cells, have Na/K pumps. Although its a good idea to slow down the pumps in your kidneys during a salt overload, its not a good idea to impair the performance of Na/K pumps in other cells.
The Na/K pumps normally work hard to maintain a healthy balance of sodium, potassium, calcium, and other substances inside and outside your cells. Thats particularly important for the delicate cells that line the insides of your blood vessels. Blood vessel cells with sluggish Na/K pumps are unhealthy cells and, if theyre chronically exposed to an overload of pump-slowing hormones, theyre chronically unhealthy cells. Research indicates that natriuretic hormones, by making the Na/K pumps in your vessels work sluggishly, can initiate cellular changes that cause your blood vessels to constrict and become less elastic. This makes them easier prey for atherosclerosis, a condition in which plaque buildup in the arterial walls causes narrowing of the arteries diameter.
In summary, a high-salt diet causes your body to crank out excess levels of natriuretic hormones that, while lowering your salt levels, damage your blood vessels in a variety of ways. . .
Its no wonder that salt is so strongly linked to both stroke and heart attacks. Clearly, everyone who wants to avoid a stroke should cut down on excess salt whether they suffer from hypertension or not. Salt reduction leads to lower blood pressure, eliminating a huge risk factor for stroke. But even when blood pressure is already normal, less salt translates into healthier blood vessels and brain cells, and thus to a decreased risk of stroke."
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hyper.ahajournals.org]
Hypertension, Vol 15, 900-903, Copyright © 1990 by American Heart Association
High sodium chloride diets injure arteries and raise mortality without changing blood pressure
L Tobian and S Hanlon
Department of Medicine, University of Minnesota Hospital, Minneapolis 55455.