While many of us know potassium as simply an ingredient in bananas, it is one of the most commonly measured minerals in a medical blood draw, and for good reason. As the third most abundant mineral in the body, potassium is important for the proper functioning of nerves and muscle contractions. It also helps us to metabolize carbohydrates, regulate fluid balance, and support protein synthesis. Potassium even functions to protect us against stroke risk and help prevent osteoporosis. This electrolyte is particularly important for the one in three Americans with hypertension, as it aids in the management of proper blood pressure by helping to reduce high sodium levels. While potassium works incredibly hard to keep us healthy, 98% of Americans fall short of consuming the daily recommended intake of potassium.
This ultimate guide to potassium will help to explain what potassium is, how it works within the body, why it is important for multiple populations (diabetics, athletes, elderly, and those with hypertension or poor kidney function), and ways in which we can easily add potassium to our diets. We know this is a ton of information but potassium plays a large role in many functions, we don’t want to short-change its effectiveness.
What is potassium?
Potassium is the third most abundant mineral in the body. With such a large amount of potassium you may be curious about where it is stored. The majority (78%) is found in our muscle cells. The cells of our liver, bones, and red blood cells contain 19%. The remaining 3% of potassium is found outside of our cells.
The location of this mineral is important due to its role as an electrolyte. An electrolyte is a mineral that has a charge when dissolved in water. This allows it to conduct electricity. The body uses this electrical charge to send signals and keep our systems in balance.
What does potassium do?
Regulates Fluid Balance
Potassium plays a key role in regulating the balance of fluid within our body. Given that approximately 60% of our body is water, shifting this fluid to its necessary locations is an important job. About 40% of our water is positioned inside the cells, where potassium is the primary electrolyte. On the other hand, sodium is the main electrolyte outside of the cells (where the other 60% of our water is found).
As a general rule, our bodies prefer balance. In the case of fluids, we want the same ratio of electrolytes to fluid both inside and outside of the cell. If this ratio is not equal, electrolytes (like potassium and sodium) shift in order to pull fluid in the proper directions. Potassium is particularly good at helping to get rid of excess fluid build up within the body. This happens by way of increasing urine production and decreasing sodium levels.
Reduces Blood Pressure
Hypertension (high blood pressure) is a hot topic within the healthcare community. Not only does one in three Americans have high blood pressure, but this hypertension is also a risk factor for heart disease (the leading cause of death throughout the world). Multiple studies have shown that diets rich in potassium reduce both systolic and diastolic blood pressure when compared to low-potassium diets. One study found that increasing potassium intake by 2.5 grams per day lowered systolic and diastolic blood pressure by an average of 12 mm Hg and 16 mm Hg, respectively.
In order to understand the mechanism behind this reduction we have to scroll up. Earlier in this article we mentioned how sodium and potassium work together to regulate the balance of fluid within the body. These two electrolytes also work together to regulate blood pressure. High levels of sodium can increase blood pressure; this is why individuals who have hypertension are often told to adhere to a low salt diet. Consuming potassium helps to remove excess sodium and, thus, reduce blood pressure.
Supports Protein Synthesis
Our previous blog, “A Quick Guide to Amino Acids”, explained how amino acids are the building blocks of proteins. The way in which these amino acids come together determine the shape and function of the protein molecule. The resulting proteins are then used to form the basis of skin, hair, antibodies, muscles, cytokines (cells that effect the immune system), and much more. Thus, making sure that amino acids are assembled in the correct way is integral to producing the protein molecule that our body needs at any given time. Potassium has been shown to help with the process of synthesizing protein molecules from amino acids in the cell.
Assists in Carbohydrate Metabolism
We previously mentioned that our body is happiest when it is in a balanced state. That balance also applies to the organization of fluid, electrolytes, and blood sugar. Typically, potassium is stored inside of our cells. However, when our blood sugar is too high, potassium attempts to restore balance by moving outside of the cell. This movement prompts insulin to help move sugar out of circulation and into the cell. Our potassium levels then return to normal and our system resets back to its balanced state. Under normal circumstances, this potassium signaling system is an effective way for us to regulate our blood sugar levels.
However, when the body is insulin resistant, does not use insulin properly, does not produce insulin (type 1 diabetes), or does not make enough insulin, our potassium signaling system is not able to function properly. When insulin is not able to be utilized, glucose has no way to be taken into the cell and out of circulation. This results in a buildup of glucose in the bloodstream.
Adequate potassium levels are also crucial to the proper functioning of this system. When individuals have low potassium levels, less insulin is released. Since glucose can only enter the cell with the help of insulin, the lower insulin release results in less glucose being taken into the cell. This means that blood sugar levels stay elevated. When blood sugar levels are chronically elevated, the risk of metabolic conditions and type 2 diabetes is increased. This link between potassium, insulin, and diabetes is why physicians closely monitor potassium levels when patients require insulin injections.
Protect Against Stroke
Every 40 seconds someone in the United States has a stroke. A stroke occurs when there is a lack of blood flow to the brain. Unfortunately, this occurrence is fatal for over 130,000 Americans each year. A diet rich in potassium may help to prevent strokes (particularly ischemic stroke) as well as heart disease. While the exact mechanism as to how potassium reduces stroke risk is still to be determined, research has shown that it is not only due to a reduction in blood pressure. Potassium also protects against the formation of free radials and may protect against endothelial damage. Individuals who ate a potassium rich diet have been shown to have a 24% lower risk of stroke than those who eat very little potassium.
Osteoporosis is a disease in which bones become brittle and are more likely to fracture. This weakening of the bones means that a fall or moderate stress can cause bones to break, which is particularly concerning in the elderly population. While this condition is commonly associated with low levels of calcium, potassium also plays a role. When we consume high levels of potassium, the body reduces the amount of calcium that we excrete through the urine. Multiple studies have shown that individuals who have diets rich in potassium have increased bone mass when compared to their counterparts with a low potassium diet.
Power the Nervous System and Muscle Contractions
Nerve impulses are a series of messages that your brain uses to communicate with the rest of the body. These messages can tell your heart to beat, your muscles to contract, or many other functions. These nerve impulses are created by the movement of potassium ions out of cells and sodium ions into cells. This movement changes the electrical charge (voltage) of the cell and signals the nerve’s message to be sent. When we are low on potassium, our body is not able to send these nerve impulses properly.
What foods are high in potassium?
Whether you are a vegetarian, vegan, gluten intolerant, lactose intolerant, or keto, there are plenty of ways to add potassium to your diet. Bananas is not the only potassium-rich option. If fact, bananas do not even have half the mg of potassium as baked potatoes or lima beans. Avocados, carrots, yams, clams, and beef are also great sources of potassium. Of course, GOOD IDEA also contains potassium. Check out our graphic on the right for ideas of food sources and volumes of potassium that can be added to any diet..
How much do you need per day?
While it is rare for potassium levels to become so low to be diagnosed with a true potassium deficiency, less than 2% of Americans consume the recommended amount of potassium per day. The recommended daily intake of potassium for healthy adults is between 3,500 and 4,700 mg. There are multiple combinations of vegetables, fruits, starches, and meats that can get us to this daily intake. For example, one medium baked potato (with skin), three ounces of beef, ¼ cup of spinach, and a GOOD IDEA (to help lower your post-meal glucose spike), summates to 1,473 mg of potassium. That is 42% of your daily value of potassium from one meal.
For individuals curious about a supplemental form of potassium, they are certainly an option for times when we may be unable to achieve our daily goals. However, most potassium supplements are typically limited to 99 mg. This maximum value is due to research that has shown high doses of potassium in the form of supplements can cause damage to the gut and possibly heart arrhythmia. Thus, when possible, it is best to get our potassium from real food sources.
What causes our potassium levels to be abnormal?
Given the many responsibilities of potassium, it should come as no surprise that it is a mineral frequently checked in blood draws. When you get a blood draw at a physician’s office, they measure your potassium levels in millimoles per liter (mmol/L). A normal blood potassium level is between 3.6 and 5.2 mmol/L. There are multiple reasons why someone may be low in potassium, chief among them, not consuming enough of this mineral. We already know that only 2% of Americans meet the daily recommended intake. Other reasons for a low potassium level include: diarrhea, vomiting, and gastrointestinal issues; these can quickly reduce potassium levels. Long-term use of laxatives, aspirin, digitalis, or cortisone have also been shown to deplete potassium over time.
What about the other end of the spectrum, too much potassium? Profuse sweating from a hot and humid environment and/or intense exercise can also cause dehydration. This dehydration means that potassium is unable to function properly and results in a buildup of potassium levels in the blood (hyperkalemia). However, when we stay hydrated, iIt is very uncommon for adults to consume too much potassium. This is especially true for those who are using whole foods are their potassium source. However, certain populations may want to keep an eye on their intake: individuals with uncontrolled diabetes, people with poor kidney function, those who take blood pressure medications, and the elderly (since kidney function typically decreases as we age). Individuals who consume their potassium in supplement form should be cautious about their dietary needs, as it is possible to ingest too much potassium in the form of supplements. As always, we encourage your to consult your healthcare provider before making any diagnoses or decisions.
Putting it all together
We hope this article gives potassium the credit it deserves as its utility goes well beyond the banana peel. Next time we are looking for a snack that can help to reduce blood pressure, power protein synthesis, support the nervous system, and assist in carbohydrate metabolism, reach for some spinach or a baked potato. Better yet, pair a GOOD IDEA with your meal in order to add some potassium to your diet while simultaneously reducing post-meal blood sugar.
Author: Dr. Colleen Gulick