Getting enough of this mineral is a must
Potassium is one of the 16 minerals your body requires to maintain optimum health. It’s hard to downplay the importance of potassium: Your body needs it for almost everything it does, including proper kidney and heart function, muscle contraction, and nerve transmission.
Potassium in the Diet
Since your body can’t manufacture minerals, you have to get them from your diet. Like calcium, phosphorus, magnesium, sodium, chloride, and sulfur, potassium is a “macromineral,” so-called because it’s needed in large quantities—adults are encouraged to consume at least 4,700 mg a day. Potassium is widely available in food (fruits and vegetables are particularly good sources), yet most people consume less than half the recommended daily amount. Even when food and dietary supplements are combined, total potassium intakes for most people are below recommended amounts, according to the National Institutes of Health.
Because of the key role potassium plays in the body, it’s important that your blood potassium levels remain within a narrow range. Although getting potassium from your diet is preferable, if you’re very active or don’t consume enough potassium-rich food on a regular basis, it may make sense to take supplemental potassium on an as-needed basis.
However, it’s not recommended that you take potassium supplements without first speaking with your healthcare provider. Blood levels of potassium are tightly regulated by the body, mostly by the kidneys. But when the kidneys aren’t working properly, whether as a result of age, diabetes, heart failure, or certain other conditions, potassium levels can rise to high levels, leading to dangerous heart rhythm problems and even cardiac arrest.
Because of this potential danger, the Food and Drug Administration limits over-the-counter potassium supplements to less than 100 mg, a mere 2 percent of the recommended daily amount. For similar reasons, talk to your physician before starting a high-potassium diet.
Like most other macrominerals, potassium is an electrolyte, which means it dissolves to create electrically charged ions that your body needs to regulate metabolism. Potassium helps regulate every cell, tissue, and organ of the human body.
Because of potassium’s wide-ranging roles in the body, low intakes can increase the risk of illness. Potassium seems to play a role in these four areas:
An extensive body of literature shows that low potassium intakes increase the risk of hypertension (high blood pressure), especially when combined with high intakes of sodium. 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 cardiovascular disease (CVD).
For instance, a meta-analysis of 11 prospective cohort studies in 247,510 adults found that a 1,640 mg per day higher potassium intake was associated with a significant 21 percent lower risk of stroke, as well as nonsignificant lower risks of coronary heart disease and total CVD.
Similarly, the authors of a meta-analysis of nine cohort studies reported a significant 24 percent lower risk of stroke with higher potassium intakes and a nonsignificant reduction in coronary heart disease and CVD risk.
However, one review found inconsistent relationships between potassium intakes and risk of stroke based on 15 observational studies, which is why more research on both dietary and supplemental potassium is needed before firm conclusions can be made. While it’s been suspected that the benefit of potassium on CVD is due to its effect on high blood pressure, other mechanisms may be involved, as research finds that higher potassium intakes still produced a significantly lower risk of stroke (as high as 15 percent) even when blood pressure was accounted for. One possibility is that potassium may prevent atherosclerosis, also known as hardening of the arteries, a finding that scientists reported on in 2017.
While more research is needed to fully understand the link between potassium and kidney stones, observational studies show that higher potassium intakes are associated with a lower risk of kidney stones—in part because potassium attaches to calcium in the urine, preventing the formation of mineral crystals that can develop into kidney stones.
In a study of 45,619 men aged 40 to 75 years with no history of kidney stones, those with the highest potassium intakes (more than 4,042 mg a day on average) had a 51 percent lower risk of kidney stones over four years of follow-up than those with the lowest intakes (less than 2,900 mg a day).
Similarly, in a study of over 90,000 women who had no history of kidney stones, those who consumed an average of over 4,099 mg of potassium a day had a 35 percent lower risk of kidney stones over a 12-year follow-up period than those who averaged less than 2,407 mg of potassium per day.
Studies suggest that dietary potassium is associated with an increased bone mineral density that may improve bone health. For instance, one 2015 review of 14 studies found that potassium significantly reduces bone resorption, the process by which bone is broken down, thereby increasing their strength. Though the underlying mechanism behind the bone boost is unclear, the study seems to confirm the hypothesis that potassium helps protect bone by neutralizing the adverse effect of a diet high in acid-forming foods, such as meats and cereal grains.
Type 2 Diabetes
Numerous observational studies of adults have found associations between lower potassium intakes or lower serum or urinary potassium levels and increased rates of fasting glucose, insulin resistance, and type 2 diabetes. The possible mechanism: Because potassium is needed for insulin secretion from pancreatic cells, too little potassium may impair insulin secretion and could lead to glucose intolerance.
However, this association hasn’t been adequately evaluated in clinical trials. In one small clinical trial in 29 African American adults with prediabetes and low to normal serum potassium levels, supplementation with 1,564 mg potassium for three months significantly lowered fasting glucose levels but didn’t affect glucose or insulin measures during an oral glucose tolerance test. While the findings are promising, more research is needed to confirm potassium’s link with blood glucose control and type 2 diabetes.
Possible Side Effects
Potassium from food has not been shown to cause harm in healthy people who have normal kidney function. Potassium is water-soluble, meaning that any excess is flushed out in the urine. Because there’s no evidence that high intakes of dietary potassium are dangerous in adults with normal kidney function, an upper limit for dietary potassium hasn’t been set.
Potassium supplements can cause minor gastrointestinal side effects. Chronic ingestion of very high doses of potassium supplements (up to 15,600 mg for five days) in healthy people can increase plasma levels of potassium, but not beyond the normal range. However, very high amounts of potassium supplements or salt substitutes that contain potassium could exceed the kidney’s capacity to excrete potassium, causing acute hyperkalemia even in healthy individuals.
Effects of High Potassium Levels
People who have chronic kidney disease and those who use certain medications—including ACE inhibitors and potassium-sparing diuretics—can develop abnormally high levels of potassium in their blood, a condition called hyperkalemia. Hyperkalemia can occur in these people even when they consume typical amounts of potassium from food.
Hyperkalemia can also develop in people with type 1 diabetes, congestive heart failure, liver disease, or adrenal insufficiency, a condition where the adrenal glands don’t produce enough of certain hormones.
Getting too much potassium from supplements or salt substitutes can even cause hyperkalemia in healthy people if they consume so much potassium that their bodies can’t eliminate the excess.
People at risk of hyperkalemia should talk to their healthcare providers about how much potassium they can safely get from food and supplements. The National Kidney Disease Education Program has information about food choices that can help lower potassium levels.
Effects of Low Potassium Levels
Certain people may have trouble getting enough potassium:
- People with inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis
- People who use certain medications, such as laxatives or some diuretics
Those on low-carbohydrate diets may also be at risk for potassium loss in the short term. This is because excessive amounts of potassium will be needed to convert glycogen, the stored form of glucose, back into glucose for energy. Without the customary intake of carbohydrate (which the body traditionally uses to create glucose), the body will have no choice but to use up its glycogen reserves and, with it, whatever potassium there is in the body. And because the body only retains as much potassium as is needed for that moment, you need to keep consuming potassium-rich foods to keep your levels up.
While your body’s potassium stores may plummet in the first week or two on a low-carb diet, as your body begins to adapt to the diet and starts converting fat into glucose, your glycogen stores will eventually be restored.
Even a moderate potassium deficiency can raise your blood pressure, increase your risk of cardiovascular disease and kidney stones, deplete calcium in your bones, and interfere with the normal rhythm of your heart (arrhythmia). Excessively low potassium levels, known as hypokalemia, can lead to fatigue, muscle cramps, glucose intolerance, abnormal nerve sensations (neuropathy), and digestion problems. More severe hypokalemia can cause increased urination, decreased brain function, high blood sugar levels, muscle paralysis, difficulty breathing, and irregular heartbeat. Severe hypokalemia can be life-threatening.
Tell your doctor, pharmacist, and other healthcare providers about any dietary supplements and prescription or OTC medications you take. They can tell you if the dietary supplements might interact with your medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down potassium.
Dosage and Preparation
The amount of potassium people need depends on their age and sex. The recommended daily intake for adolescents and adults is 4,700 mg. Breastfeeding women require 5,100 mg a day. Recommended intakes for children ages 1 to 3 is 3,000 mg a day; 4 to 8 years is 3,800 mg a day, and 9 to 13 years is 4,500 mg a day.
What to Look For
Potassium is found in many multivitamin/multimineral supplements, as well as in supplements that contain only potassium. Because supplements are only regulated to a certain degree by the FDA, it’s up to the supplement manufacturers to supply safe products. A 2017 ConsumerLab.com analysis of potassium supplements found most to be of high-quality, though one was contaminated with arsenic.
When shopping for supplements, consider seeking out products that have been certified by ConsumerLabs, the U.S. Pharmacopeial Convention, or NSF International. These organizations don’t guarantee a product is safe or effective, but they indicate that it’s undergone testing for quality.
Forms of Potassium
Potassium in supplements comes in many different forms—potassium chloride is a common one, but other forms include potassium citrate, potassium phosphate, potassium aspartate, potassium bicarbonate, and potassium gluconate. Research hasn’t shown that any form of potassium is better than the others. Whatever the form, most dietary supplements provide only small amounts of potassium, no more than 99 mg per serving.
Good Food Sources of Potassium
Your nutritional needs should be met primarily through your diet, according to the Dietary Guidelines for Americans. Supplements can help fill in dietary gaps, but they can’t replicate all of the nutrients and benefits of whole foods. While you may think of bananas as the king of high-potassium foods (a medium banana contains more than 400 mg), there are plenty of other foods that have just as much, if not more, potassium per ounce.
Rich Sources of Potassium
- Dried apricots (1,511 mg in a half cup)
- Beet greens (1,300 mg in a cup of cooked greens)
- Baked potato with skin (926 mg in a medium spud)
- Spinach (840 mg in one cup cooked)
- Prunes and prune juice (700 mg in a half cup)
- Plain nonfat yogurt (500 mg in a cup)
- Halibut (500 mg in a 5-ounce baked fillet)
- White beans (477 mg in a half cup of lima beans)
- Broccoli (460 mg in one cup cooked)
- Tomatoes and tomato products (450 mg in a half cup)
- Cantaloupe (430 mg in one cup)
- Coffee (116 mg in one cup)
Relationship Between Sodium and Potassium
It’s not uncommon to hear about potassium in relation to sodium, another electrolyte that helps maintain fluid and blood volume in the body. That’s because each of these two minerals can offset the effect of each other, with too much of one decreasing the amount of the other. This can lead to many potential negative health effects. Research shows:
- There’s a strong relationship between consuming too much sodium and having higher blood pressure. Americans consume on average about 3,400 mg of sodium per day, mostly from eating packaged and restaurant food. However, the Dietary Guidelines for Americans recommends limiting sodium intake to less than 2,300 mg per day—an amount equal to about one teaspoon of salt.
- The combination of consuming more sodium and having too little potassium in your diet (as most Americans do) is associated with higher blood pressure.
- Reducing sodium and increasing potassium in your diet can help control hypertension and lower your risk of heart disease and stroke.
So connected is the relationship between sodium and potassium that the FDA determined that foods that contain at least 350 mg of potassium are permitted to say on their label: “Diets containing foods that are good sources of potassium and low in sodium may reduce the risk of high blood pressure and stroke.”
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