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                                              POTASSIUM and STROKE

Abstract:  Inadequate intake of Potassium can significantly increase the risk of stroke.  Increasing a typical value of 2300 mg per day by 2,000 mg reduces risk by about 30%.  This effect is appreciably larger than that forecast only from a change in blood pressure usually involved.  Life Ahead now uses a healthful value target of 3800 mg per day as that now adequately verified by research.  Inadequate potassium in the blood also can cause PVC's or irregular heart beats that can produce sudden death.  Low potassium can be produced by diuretic medicines, and anyone taking such medication should monitor potassium carefully.  Potassium levels should be obtained from diet, as the amounts in supplements usually are too low to be helpful.

Deficiencies in dietary or blood Potassium long have been related to higher blood pressures and increased risk of stroke.   Life Ahead identifies this effect as quite significant, and provides a caution to users if Potassium levels in diet are not adequate.

The Old Theory:  A theory long held was that added Potassium intake produced lower blood pressures, and the benefit obtained was due to these lower blood pressures.  Yet an overkill of research on this never succeeded in verifying this blood pressure theory.  A review from a Meta analysis of the average result from 33 studies found that a substantial difference in Potassium intake produced a lowering of blood pressures by only  3.3 mm systolic, and 1.97 mm diastolic.  This difference could explain a benefit of only a few percent in the risk of heart disease or stroke.

Today’s Actual Results:  Table P summarizes the direct research relating Potassium to stroke.  All studies show a significant benefit that is far in excess of what could be attributable only to blood pressure.  Studies #1 and #2 that are today’s largest of their kind found the effect on both men and women.   A fifth study not listed confirmed this further, but is not included here because too few cases were involved for adequate significance.   A summary of these results suggests a probable average risk ratio benefit on stroke for an increased of 2,000 mg per day of Potassium at 0.71.

It further was clear from both studies #1 and #3 that the key effect of Potassium was obtained on men and women with high blood pressures.   Risk ratios were about 0.5 for hypertensives, and only about 0.8 for non-hypertensives.  The formula used for Life Ahead recognizes this.  For example the current formula values that are consistent with the research results in Table P for different blood pressure levels are:

Blood Pressure, mm sys/dias                     120/70           135/85         145/90           160/100

Risk ratios for a 2,000 mg/day

  Difference in Potassium                            0.84              0.73             0.67               0.54

Life Ahead assumes an average population value of 2,300 mg/day dietary intake of Potassium, credits benefits for up to 4,500 mg/day, and suggests a usual healthful target of 3,500 mg/day. 

Adequate research on Potassium vs. Heart Disease and for Potassium vs. Cancer was not found.

The Mechanisms Involved:  A most interesting study of rats having high blood pressures of Tobian (J Hypertens 4:S67) shows that high potassium in their diets eliminated 97% of the strokes obtained in a low potassium diet.  Potassium decreased vascular smooth muscle cell proliferation in the small arteries of the brain.  The benefits for achieving target levels of Potassium for those having normal blood pressures and who have usual intakes of dietary Potassium are small.  But anyone that has elevated blood pressure should be sure that Potassium levels in diet are at least at the 3500 mg/day target.  Low Potassium levels for a hypertensive person can near double the risk of a disabling stroke.

Inadequate dietary potassium – and particularly inadequate levels in the blood – can produce irregular heart beats called PVC’s.  These sometimes can lead to a sudden heart death. Two of three astronauts that returned from the moon had these PVC’s on return from Potassium depletion during their trip   Those taking diuretic medications for blood pressure control will tend to loose Potassium, incur low Potassium levels in blood and be subject to these PVC’s.  Thus Potassium supplements are often prescribed for those taking these medications.  Anyone on such medications should check their Potassium levels obtained in blood tests.

All health interested persons should review their blood Potassium levels regularly, and aim for at least 3,000 to 3,500 mg of dietary Potassium.   Such levels can be maintained by prudent diets. Foods high in Potassium included potatoes, bananas, and cereals.  Sort the food library values in the Life Ahead Diet option to view foods that produce best Potassium levels.  Usual non-prescription Potassium supplements include only 100 mg of Potassium, and thus are not very helpful.  A single banana, potato or cereal portion can provide more Potassium than such a supplement.  Those having elevated blood pressures should have their Potassium monitored medically.  Prescription Potassium tablets can include far more than the above 100 mg.