Potassium Series: Part 2

By: Dr. Ameya Tripathi, Associate Editor-ICN

What does Potassium do in human body?

LUCKNOW: What are functions of Potassium? In its various forms it regulates and controls a wide varieties of functions in our body and ensure its optimum working.

Potassium is the third most abundant mineral in the body. It helps the body regulate fluid, send nerve signals and regulate muscle contractions. Roughly 98% of the potassium in your body is found in your cells. Of this, 80% is found in your muscle cells, while the other 20% can be found in your bones, liver and red blood cells. Once inside your body, it functions as an electrolyte. When in water, an electrolyte dissolves into positive or negative ions that have the ability to conduct electricity. Potassium ions carry a positive charge. Your body uses this electricity to manage a variety of processes, including fluid balance, nerve signals and muscle contractions. Therefore, a low or high amount of electrolytes in the body can affect many crucial functions.

Biochemical function

Potassium levels influence multiple physiological processes in human body, their importance cannot be stressed enough. Many of their functions are

  • resting cellular-membrane potential and the propagation of action potentials in neuronal, muscular, and cardiac tissue. Due to the electrostatic and chemical properties, K+
  • ions are larger than Na+
  • ions, and ion channels and pumps in cell membranes can differentiate between the two ions, actively pumping or passively passing one of the two ions while blocking the other.
  • hormone secretion and action
  • vascular tone
  • systemic blood pressure control
  • gastrointestinal motility
  • acid–base homeostasis
  • glucose and insulin metabolism
  • mineralocorticoid action
  • renal concentrating ability
  • fluid and electrolyte balance

Now let’s discuss few of these functions in detail. How does this ion matters so much and helps performing such functions?

Regulating fluid balance

Our human body is composed of 65 percent roughly of water and a significant portion (around 40 percent) is located inside cells known as intracellular fluid and rest in divided into blood, spinal fluid and between cells as extracellular fluid. Potassium is the main electrolyte in the ICF, and it determines the amount of water inside the cells. Conversely, sodium is the main electrolyte in the ECF, and it determines the amount of water outside the cells. The number of electrolytes relative to the amount of fluid is called osmolality. Under normal conditions, the osmolality is the same inside and outside your cells. Simply put, there’s an equal balance of electrolytes outside and inside your cells. However, when osmolality is unequal, water from the side with fewer electrolytes will move into the side with more electrolytes to equalize electrolyte concentrations. This may cause cells to shrink as water moves out of them, or swell up and burst as water moves into them. That’s why it’s important to make sure you consume the right electrolytes, including potassium. Maintaining good fluid balance is important for optimal health. Poor fluid balance can lead to dehydration, which in turn affects the heart and kidneys.

Potassium is an electrolyte and mineral that helps keep your bodily fluids at the proper level. Your body can do the following if your fluids are in check:

-contract your muscles without pain

-keep your heart beating correctly

-keep your brain functioning at its highest capability

If you don’t maintain the right level of potassium, you can experience a variety of symptom that include simple muscle cramps to more serious conditions, such as seizures.

Nervous system and potassium

As we all know our nervous system is the most important system of our body. Our body functions because of this nervous system. Everything is controlled by our nervous system. But how is this controlled? The nervous system relays messages between your brain and body. These messages are delivered in the form of nerve impulses and help regulate your muscle contractions, heartbeat, reflexes and many other body functions. Interestingly, nerve impulses are generated by sodium ions moving into cells and potassium ions moving out of cells.

The movement of ions changes the voltage of the cell, which activates a nerve impulse. These nerve impulses are messages which are transferred. these are like work orders.so if there is potassium deficiency than these nerve impulses will not be generated and it will lead to disturbances in nervous system and its associated functions. Nerve impulses help regulate muscle contractions, the heartbeat, reflexes and many other processes. The nervous system helps regulate muscle contractions. However, altered blood potassium levels can affect nerve signals in the nervous system, weakening muscle contractions. Both low and high blood levels can affect nerve impulses by altering the voltage of nerve cells The mineral is also important for a healthy heart, as its movement in and out of cells helps maintain a regular heartbeat. When blood levels of the mineral are too high, the heart may become dilated and flaccid. This can weaken its contractions and produce an abnormal heartbeat. Likewise, low levels in the blood can also alter the heartbeat. When the heart does not beat properly, it cannot effectively pump blood to the brain, organs and muscles. In some cases, heart arrhythmia, or an irregular heartbeat, can be fatal and lead to sudden death.

Hypertension and stroke

Hypertension, a major risk factor for heart disease and stroke. A stroke occurs when there is a lack of blood flow to the brain. According to an extensive body of literature, low potassium intakes increase the risk of hypertension, especially when combined with high sodium intakes. Higher potassium intakes, in contrast, may help decrease blood pressure, in part by increasing vasodilation and urinary sodium excretion, which in turn reduces plasma volume; this effect may be most pronounced in salt-sensitive individuals. he Dietary Approaches to Stop Hypertension (DASH) eating pattern, which emphasizes potassium from fruits, vegetables, and low-fat dairy products, lowers systolic blood pressure by an average of 5.5 mmHg and diastolic blood pressure by 3.0 mmHg. The DASH eating pattern provides three times more potassium than the average diet. Higher potassium intakes have been associated with a decreased risk of stroke and possibly other cardiovascular diseases. In an analysis of 33 studies including 128,644 participants, scientists found that people who ate the most potassium had a 24% lower risk of stroke than people who ate the least.

Higher potassium intakes have been associated with a decreased risk of stroke and possibly other cardiovascular diseases (CVDs). Any beneficial effect of potassium on CVD is likely due to its antihypertensive effects. However, some research shows a benefit even when blood pressure is accounted for. The FDA has approved the following health claim: “Diets containing foods that are a good source of potassium and that are low in sodium may reduce the risk of high blood pressure and stroke”. Overall, the evidence suggests that consuming more potassium might have a favorable effect on blood pressure and stroke, and it might also help prevent other forms of CVD. However, more research on both dietary and supplemental potassium is needed before firm conclusions can be drawn.

Bone health

Observational studies suggest that increased consumption of potassium from fruits and vegetables is associated with increased bone mineral density. This evidence, combined with evidence from metabolic studies and a few clinical trials, suggests that dietary potassium may improve bone health.

The underlying mechanisms are unclear, but one hypothesis is that potassium helps protect bone through its effect on acid-base balance. Diets that are high in acid-forming foods, such as meats and cereal grains, contribute to metabolic acidosis and might have an adverse effect on bone. Alkaline components in the form of potassium salts (potassium bicarbonate or citrate, but not potassium chloride) from food or potassium supplements might counter this effect and help preserve bone tissue. One trial found that supplementation with potassium citrate at either 60 mmol/day (2,346 mg potassium) or 90 mmol/day (3,519 mg potassium) for 6 months significantly reduced urinary calcium excretion compared with placebo in 52 healthy men and women older than 55 years. In another clinical trial, 201 healthy adults aged 65 years or older received daily supplementation with 60 mEq potassium citrate (providing 2,346 mg potassium) or placebo as well as 500 mg/day calcium (as calcium carbonate) and 400 IU/day vitamin D3 for 2 years. Potassium supplementation significantly increased bone mineral density at the lumbar spine and bone microarchitecture compared with placebo.

In a similar clinical trial among older adults, supplemental potassium bicarbonate (mean doses of 2,893 or 4,340 mg/day potassium) for 84 days significantly reduced biochemical markers of bone turnover and urinary calcium excretion. Conversely, a clinical trial in 276 postmenopausal women aged 55–65 years found that supplementation with potassium citrate at either 18.5 mEq/day (providing 723 mg potassium) or 55.5 mEq/day (2,170 mg potassium) for 2 years did not significantly reduce bone turnover or increase bone mineral density at the hip or lumbar spine compared with placebo.

Kidney stones

Kidney stones are most common in people aged 40 to 60 .in India a wide range of population is affected by this. Stones containing calcium—in the form of calcium oxalate or calcium phosphate—are the most common type of kidney stone. Low potassium intakes impair calcium reabsorption within the kidney, increasing urinary calcium excretion and potentially causing hypercalciuria and kidney stones. Low urinary levels of citrate also contribute to kidney stone development. Some research suggests that supplementation with potassium in a clinical trial of 57 patients with at least two kidney stones (either calcium oxalate or calcium oxalate plus calcium phosphate) over the previous 2 years and hypocitraturia (low urinary citrate levels), supplementation with 30–60 mEq potassium citrate (providing 1,173 to 2,346 mg potassium) for 3 years significantly reduced kidney stone formation compared with placebo. This study was included in a 2015 Cochrane review of seven studies that examined the effects of potassium citrate, potassium-sodium citrate, and potassium-magnesium citrate supplementation on the prevention and treatment of calcium-containing kidney stones in a total of 477 participants, most of whom had calcium oxalate stones. The potassium citrate salts significantly reduced the risk of new stones and reduced stone size’s citrate reduces hypercalciuria as well as the risk of kidney stone formation and growth.

Diabetes and potassium

Although obesity is the primary risk factor for type 2 diabetes, other metabolic factors also play a role. Because potassium is needed for insulin secretion from pancreatic cells, hypokalemia impairs insulin secretion and could lead to glucose intolerance. This effect has been observed mainly with long-term use of diuretics (particularly those containing thiazides) or hyperaldosteronism (excessive aldosterone production), which both increase urinary potassium losses, but it can occur in healthy individuals as well. Usually, your body processes the food you eat and turns it into a sugar called glucose. Your body uses glucose for energy. Insulin is a hormone your pancreas produces. Your body uses the insulin to help move glucose into cells throughout your body. If you have diabetes, your body is unable to produce or use insulin efficiently. Researchers in one study at Johns Hopkins University School of Medicine linked low levels of potassium with high levels of insulin and glucose in people who were otherwise healthy. Low levels of potassium with high levels of insulin and glucose are both traits doctors associate with diabetes. One 2011 study found that people taking thiazides to treat high blood pressure experienced a loss of electrolytes, such as potassium. Researchers noted that this loss might increase a person’s risk of developing diabetes.

So here we discussed in brief how potassium participates and regulates our daily functions and overall well being.in our next part we will discuss certain diseases which results from high or low potassium intake and what is the exact science behind them. Until then keep taking optimum amount of potassium in your diet. (refer to our part 1 of potassium series) and stay healthy.