Stroke is the third leading cause of death in the United States, killing about 140,000 each year. It is also the leading cause of long-term disability. Each year, an estimated 795,000 people suffer a stroke. The risk of stroke rises with increasing age and elevated blood pressure. Older women are at a significantly increased risk of stroke relative to men, particularly if they have atrial fibrillation (1).
High blood pressure is due largely to excessive salt intake especially when accompanied by too little dietary potassium. There is clear evidence that excessive salt intake raises blood pressure and is the main reason most Americans sooner or later are diagnosed with hypertension. Each 20/10mmHg in blood pressure starting at a blood pressure of about 110/70mmHg is associated with a doubling of the risk of stroke and other cardiovascular events. The ability of the human body to rid itself?of excessive dietary salt diminishes with age. However, it is wrong to assume that all the adverse effects of salt intake on the cardiovascular system are mediated by its impact on blood pressure alone. Salt toxicity has been associated with an increased risk of stroke that was independent of increased blood pressure (2)
Another study examined the incidence of stroke in 2657 older New Yorkers who had their dietary sodium measured using food frequency questionnaires. Over the next 10 years they recorded 235 strokes in this group. These researchers found that the risk of stroke increased by 17% for each additional 500mg of sodium subjects consumed daily.
The 21% of subjects who consumed more than 4000mg of sodium were 2.6 times as likely to suffer a stroke as those consuming less than 1500mg of sodium daily. The authors stated, ?The association between sodium?consumption and stroke risk was independent of behavioral and vascular risk factors, including hypertension, at baseline, and was observed among those with and without hypertension and across age groups, suggesting that lowering sodium consumption can have beneficial effects on stroke risk for all? (3). Simply put, a diet high in salt and low in potassium-rich foods lead to elevated blood pressure and a dramatically increased risk of stroke.
Bottom Line: It appears that most of the 795,000 strokes that occur each year in the USA could be avoided if all Americans limited their salt intake to no more than 1500 mg per day and ate more potassium-rich fruits and vegetables.
By James J. Kenney, PhD, FACN
1. JAMA. 2012;307:1952-1958
2. Hypertens 1992;6:23-5
3. Stroke 2012;43:1200-5
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.