Potassium and Blood Pressure
What is Potassium?
Potassium is a chemical compound, or mineral, which is found naturally occurring in certain foods, and is an important tool in the fight against high blood pressure. It is an important nutrient for maintaining good heart health, as it is necessary for smooth muscle contraction, of which the heart is possibly the most important example. It also assists with other essential body health functions such as kidney and digestive function.
The role of Potassium in the body
Potassium is critical for the normal functioning of the muscles, heart, and nerves. It plays an important role in controlling the activity of the muscles of the heart. Normal blood levels of potassium are critical for maintaining normal heart electrical rhythm. Both low blood potassium levels (hypokalemia) and high blood potassium levels (hyperkalemia) can lead to abnormal heart rhythms (arrythmias).
Natural sources of Potassium
Potassium can be found in many natural foods ranging from fruits, vegetables and legumes, and a diet which contains sufficient potassium can usually be achieved by eating a variety of foods containing potassium. Consequently, potassium deficiency is usually rare in healthy individuals who are eating a balanced diet.
Foods with high sources of potassium
The best dietary sources of potassium are fresh unprocessed foods – meats, fish, fruit and vegetables.
These include whole grains, orange juice, potatoes, bananas, avocados, tomatoes, broccoli, soybeans, brown rice, garlic and apricots, although it is also common in most fruits, vegetables and meats. The most well known potassium food from the above list however, is bananas.
High Potassium Diet Benefits
Diets high in potassium can reduce the risk of hypertension. Dietary intake is the preferred method of maintaining the correct level of potassium in the blood. The recommended daily amount according to the US Institute of Medicine is 4g or 4,000mg, although most Americans consume only half that amount on average, per person, per day.
However Supplements of potassium are not generally recommended for boosting the body’s Potassium levels. Whilst some earlier animal and human research did suggest that potassium supplements could help to lower blood pressure, more recent improved studies suggest that potassium supplements do not improve blood pressure significantly.
Excessive Potassium in the diet
Having too much potassium in the blood is called hyperkalemia, and in its mild form is a common condition, causing stomach pain, nausea and diarrhea. Extremely high levels of potassium in the blood (severe hyperkalemia) can lead to cardiac arrest and death. Incorrect diagnosis and treatment of severe hyperkalemia results in a mortality rate of about 67%.
The most important clinical effect of hyperkalemia is related to the electrical rhythm of the heart. While mild hyperkalemia usually has a limited effect on the heart, moderate hyperkalemia can produce EKG changes (EKG is an electrical reading of the heart muscles), and severe hyperkalemia can cause suppression of electrical activity of the heart and can cause the heart to stop beating.
Low Potassium or having too little Potassium in the blood is known as hypokalemia. Studies in rats have shown that a potassium deficiency combined with an inadequate level of the vitamin thyamine has produced heart disease in rats. One of the most important uses of potassium is to treat the symptoms of hypokalemia, which include weakness, lack of energy, muscle cramps, stomach disturbances, an irregular heartbeat, and an abnormal EKG (electrocardiogram, a test that measures heart function). Treatment of this condition takes place under the guidance and direction of a physician.
Potassium and High Blood Pressure
Some studies have linked low dietary potassium intake with high blood pressure. The US Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends adequate amounts of potassium in the diet, along with other measures such as dietary calcium and weight loss, to prevent the development of high blood pressure. Similarly, the Dietary Approaches to Stop Hypertension (DASH) diet emphasizes eating foods rich in fruits, vegetables, and low- or non-fat dairy products to provide high intake of potassium, as well as magnesium and calcium.
Potassium and Stroke
In several population based studies evaluating very large groups of men and women over time, a diet rich in potassium was associated with a reduced risk of stroke. For men, this seems to be particularly relevant for those suffering from high blood pressure and/or those taking diuretics (blood pressure medications that help the kidneys eliminate sodium and water from the body). Potassium supplements, however, do not seem reduce the risk of stroke.
The crucial link between Potassium and Sodium (Salt)
The correct level of potassium in the body unfortunately depends on the body’s sodium intake. This means that excessive salt consumption may deplete the body’s stores of potassium.
Other conditions that can cause potassium deficiency include diarrhea, vomiting, excessive sweating, malnutrition, and use of diuretics. In addition, coffee and alcohol can increase the amount of potassium excreted in the urine. Adequate amounts of magnesium are also needed to maintain normal levels of potassium.
Because of the potential for side effects and interactions with medications, dietary potassium supplements should only be taken under the supervision of a physician or healthcare provider. This is especially important in the elderly, as they are at high risk for developing hyperkalemia due to decreased kidney function that often occurs in later years. Older people should be careful when taking medication that may further affect potassium levels in the body, such as nonsteroidal anti-inflammatories (NSAIDs) and ACE inhibitors.
Individuals suffering from kidney diseases may suffer adverse health effects from consuming large quantities of dietary potassium. End stage renal failure patients undergoing therapy by renal dialysis must observe strict dietary limits on potassium intake, since the kidneys control potassium excretion, and buildup of blood concentrations of potassium may trigger fatal cardiac arrhythmia. Acute hyperkalemia can be reduced through eating baking soda, or glucose.