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What is Potassium

Potassium is a mineral that your body needs to work properly. It is a type of electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance 1). Electrolytes are minerals in your body that have an electric charge. They are in your blood, urine and body fluids. Maintaining the right balance of electrolytes helps your body’s blood chemistry, muscle action and other processes. Sodium, calcium, potassium, chlorine, phosphate and magnesium are all electrolytes 2). You get them from the foods you eat and the fluids you drink. Levels of electrolytes in your body can become too low or too high. That can happen when the amount of water in your body changes, causing dehydration or overhydration.

Levels of electrolytes in your body can become too low or too high. That can happen when the amount of water in your body changes, causing dehydration or overhydration. Causes include some medicines, vomiting, diarrhea, sweating or kidney problems. Problems most often occur with levels of sodium, potassium or calcium. Before processed foods became widely available, humans consumed much more potassium than sodium. Today, we get almost twice as much sodium as potassium 3).

Potassium balance is crucial for regulating the excitability of nerves and muscles and so critical for regulating contractility of cardiac (heart) muscle. Although the most important changes seen in the presence of deranged potassium are cardiac, smooth muscle is also affected with increasing muscle weakness, a feature of both hyperkalaemia (high blood potassium) and hypokalaemia (low blood potassium) 4).

The kidneys are primarily responsible for maintaining your body’s total potassium content by balancing potassium intake with potassium excretion. If your intake of potassium far outweighs your kidneys’ ability to remove it, or if your kidney function decreases, there can be too much potassium and hyperkalemia may occur 5).

Potassium and sodium concentrations play a crucial role in electric signal functioning of the heart’s middle thick muscle layer, known as the myocardium. An above normal level of potassium can interfere with proper electric signals in that muscle layer and lead to different types of heart arrhythmias.

Potassium is a very important mineral for the human body. Most individuals can replace needed potassium through food consumption without the need for supplements or specially formulated products 6), 7), 8).

Your body needs potassium to:

Build proteins
Break down and use carbohydrates
Build muscle
Maintain normal body growth
Control the electrical activity of the heart
Control the acid-base balance
Reduced potassium consumption has been associated with hypertension and cardiovascular diseases, and appropriate consumption levels could be protective
against these conditions 9). A recent meta-analysis including 11 cohort studies reported an inverse association between potassium intake and risk of stroke 10). Additionally, two meta-analyses of trials comparing increased potassium to lower potassium intake found that increased potassium intake lowers blood pressure
11), 12). These results were further supported by a systematic review without a meta-analysis, which concluded
that increased potassium intake results in decreased blood pressure in adults 13). Thus, a public health intervention aimed at increasing potassium intake from food could be a cost-effective strategy to reduce the burden of cardiovascular morbidity and mortality. Moreover, increasing potassium consumption from food in the population is safe; in individuals without renal impairment caused by medical conditions or drug therapy, the body is able to efficiently adapt and excrete excess potassium via the urine when consumption 14).

The American Heart Association recommended potassium intake for an average adult is 4,700 milligrams (mg) per day. Most of us aren’t getting nearly that much. On average, adult males eat almost 3,200 mg/day, and adult females eat about 2,400 mg/day 15). Remember that potassium is only part of an overall heart-healthy eating pattern. Other dietary factors that may affect blood pressure include amount and type of dietary fat; cholesterol; protein, sugar and fiber; calcium and magnesium, and of course, sodium.

For example, the DASH (Dietary Approaches to Stop Hypertension) diet study found that a diet rich in fruits, vegetables, fat-free or low-fat (1 percent) milk and milk products, whole-grain foods, fish, poultry, beans, seeds and unsalted nuts reduced blood pressure compared to a typical American diet. The DASH eating plan also had less sodium; sweets, added sugars and sugar-containing beverages; saturated and trans fats; and red meats than the typical American diet.

People with kidney problems, especially those on dialysis, should not eat too many potassium-rich foods. The health care provider will recommend a special diet.

Mechanism of Action of Potassium
Potassium is the major cation (positive ion) inside animal cells, while sodium is the major cation outside animal cells. The concentration differences of these charged particles causes a difference in electric potential between the inside and outside of cells, known as the membrane potential. The balance between potassium and sodium is maintained by ion pumps in the cell membrane. The cell membrane potential created by potassium and sodium ions allows the cell generate an action potential–a “spike” of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function. Potassium is also an essential mineral needed to regulate water balance, blood pressure and levels of acidity 16). The more potassium you eat, the more sodium you pass out of the body through urine. Increased potassium intake has no adverse effect on blood lipid concentration, catecholamine concentrations, or renal function in apparently healthy adults without impaired renal handling of potassium 17). The largest benefit was detected when sodium intake was more than 4 g/day, which is the intake of most populations globally 18), so increased potassium intake should benefit most people in most countries. However, the authors also found a statistically significant decrease in blood pressure with increased potassium when sodium intake was 2-4 g/day. Therefore, increased potassium can continue to be beneficial in terms of blood pressure even as individuals and populations decrease their sodium intake. Studies examining both nutrients simultaneously support this concept, showing an increased benefit with simultaneous reduction in sodium and increase in potassium compared with changes in one nutrient individually 19), 20).

Potassium also helps relax blood vessel walls, which helps lower blood pressure 21).

World Health Organization recommends an increase in potassium intake from food to reduce blood pressure and risk of cardiovascular disease, stroke and coronary heart disease in adults. World Health Organization suggests a potassium intake of at least 90 mmol/day (3510 mg/day) for adults (conditional recommendation) 22).

Physiologically, potassium exists as an ion in the body. Potassium (K+) is a positively charged electrolyte, cation, which is present throughout the body in both intracellular and extracellular fluids. The majority of body potassium, > 90%, are intracellular. It moves freely from intracellular fluid (ICF) to extracellular fluid (ECF) and vice versa when adenosine triphosphate (ATP) increases the permeability of the cell membrane. It is mainly replaced inside or outside the cells by another cation, sodium (Na+). The movement of potassium into or out of the cells is linked to certain body hormones and also to certain physiological states. Standard laboratory tests measure ECF potassium. Potassium enters the body rapidly during food ingestion. Insulin is produced when a meal is eaten; this causes the temporary movement of potassium from ECF to ICF. Over the ensuing hours, the kidneys excrete the ingested potassium and homeostasis is returned. In the critically ill patient, suffering from hyperkalaemia, this mechanism can be manipulated beneficially by administering high concentration (50%) intravenous glucose. Insulin can be added to the glucose, but glucose alone will stimulate insulin production and cause movement of potassium from ECF to ICF. The stimulation of alpha receptors causes increased movement of potassium from ICF to ECF. A noradrenaline infusion can elevate serum potassium levels. An adrenaline infusion, or elevated adrenaline levels, can lower serum potassium levels. Metabolic acidosis causes a rise in extracellular potassium levels. In this situation, excess of hydrogen ions (H+) are exchanged for intracellular potassium ions, probably as a result of the cellular response to a falling blood pH. Metabolic alkalosis causes the opposite effect, with potassium moving into the cells 23).

Foods high in Potassium
Potassium is an essential nutrient that is needed for maintenance of total body fluid volume, acid and electrolyte balance, and normal cell function 24). Many people get all the potassium they need from what they eat and drink. Many foods contain potassium. All meats (red meat and chicken) and fish such as salmon, cod, flounder, and sardines are good sources of potassium. Soy products and veggie burgers are also good sources of potassium.

Vegetables including broccoli, peas, lima beans, tomatoes, potatoes (especially their skins), sweet potatoes, and winter squash are all good sources of potassium.

Fruits that contain significant amounts of potassium include bananas, citrus fruits, cantaloupe, kiwi, prunes, and apricots. Dried apricots contain more potassium than fresh apricots.

Since people with high blood pressure may also be trying to lose weight, consider potassium rich foods that are low in calories and carbohydrates. Good examples include broccoli, water chestnuts, spinach, and other leafy greens. Also good—although slightly higher in carbs and calories—are butternut squash and sweet potatoes, and fruits such as cantaloupe, kiwi, and nectarines 25).

Milk, yogurt, and nuts are also excellent sources of potassium.

Other potassium-rich foods include:

Lima beans
Tomatoes, tomato juice and tomato sauce
Oranges and orange juice
Cantaloupe and honeydew melon
Grapefruit and grapefruit juice (talk to your healthcare provider if you’re taking a cholesterol-lowering drug)
Prunes and prune juice
Apricots and apricot juice
Raisins and dates
Fat-free or low-fat (1 percent) milk
Fat-free yogurt
People with kidney problems, especially those on dialysis, should not eat too many potassium-rich foods. The health care provider will recommend a special diet.

A low blood level of potassium is called hypokalemia. It can cause weak muscles, abnormal heart rhythms, and a slight rise in blood pressure. You may have hypokalemia if you: