An exploration of cardiovascular disease and its related health conditions such as hypertension and kidney disease would be incomplete without a discussion on dietary potassium’s role in heart health. Potassium is far more than a major mineral; it is a direct influencer of cardiovascular function and health. The dietary changes that accompanied the industrial revolution were marked by an increase in convenient, processed foods which replaced potassium-rich fruits and vegetables. In the wake of this change, we saw a rise in cardiovascular disease. Most of the attention has been given to the abundance of sodium from processed foods, but perhaps the more relevant factor is actually the decline in dietary potassium, as a result of consuming fewer fresh fruits and vegetables. Without doubt, optimizing the potassium:sodium ratio is important when considering most risk factors for cardiovascular disease, but perhaps we have focused too strongly on the wrong side of this ratio, or at the very least, neglected to give equal attention to potassium.
Nearly 50 percent of all sudden cardiac deaths are due to ventricular tachyarrhythmias, and hypokalemia is a well-recognized risk factor for ventricular tachyarrhythmia. It reduces the activity of the Na+/K+-ATPase, which reduces cardiac repolarization reserve and increases intracellular Ca2+ in cardiomyocytes which causes arrhythmia. Further, hypokalemia is also associated with a worsening of heart failure, and its prevalence is between 19 and 54 percent. In a prospective population study published in 2018 in the American Journal of Medicine, mild hypokalemia was associated with increased systolic blood pressure, increased stroke risk and, to a lesser degree, increased mortality risk.
Besides dietary insufficiency, other common causes for hypokalemia include the use of diuretics (including nonpharmaceutical diuretics such as caffeine), activation of the renin-angiotensin-aldosterone system that causes an increased renal clearance of potassium, and higher catecholamine levels from chronic stress, which shifts potassium to intracellular compartments. Chronic stress is rarely considered in states of hypokalemia, but seeing the increased degree of stress experienced by the majority of the population, it follows that this should be a larger consideration in the cause of low potassium. Elevations in circulating epinephrine and norepinephrine cause a sudden translocation of cations, K+ and Mg2 into skeletal muscle for the Mg2+-dependent Na+-K+-ATPase pumps. The resultant decrease in potassium (and magnesium) causes a delay in myocardial repolarization and electrocardiographic QTc prolongation, raising the propensity for supraventricular and ventricular arrhythmias.
It is well-known that supplementary potassium can carry the risks of fatal heart arrhythmias if too much is taken; however, dietary potassium is safe for both preventing and improving risks for hypokalemia-driven cardiovascular risks. The best way to maintain a healthy level of potassium is through the consumption of more fresh fruits and vegetables. (Canned and frozen alternatives do not supply the same degree of potassium.)
Nearly everyone is aware that potatoes and bananas are noteworthy sources of potassium, but their high glycemic index does not always make them the best choice for increasing dietary potassium, especially for those seeking to better manage blood sugar, or on a Keto or Paleo diet. Other significant dietary sources of potassium include dark green leafy vegetables and spices such as fresh parsley and cilantro. Red and green sweet peppers, beet greens, cabbage, spinach, and Swiss chard have significant quantities of potassium at more than 500mg/100-gram serving. Additional sources of potassium include bamboo shoots, mushrooms, purslane, kale, mustard greens, tomatoes, Jerusalem artichokes, chicory greens, winter squash, sweet potatoes, fennel bulb, Brussels sprouts, arugula, and parsnips.
For individuals on-the-go, a greens-based powder blended with banana (if blood sugar is not a concern) is an excellent way to increase dietary potassium.
Dietary potassium must become a chief concern in the fight against cardiovascular disease and associated risk factors such as high blood pressure, vascular health, and chronic stress. As a primary electrolyte, its impact on electroconductivity of both skeletal and cardiac muscle cannot be underestimated. The direct association between low potassium and cardiovascular disease is just another reason the diet must be addressed as the foundation for some of our most prevalent chronic health conditions.