There is widespread potassium deficiency, and it is common knowledge that an increased potassium intake lowers the risk of hypertension, which is the leading cause of stroke, cardiovascular disease, and early death. However, not many people know that potassium has a vital impact on blood sugar levels and the prevention of diabetes, just as it counteracts side effects of diuretics. The question is how much potassium do we need – and how does the balance between potassium and sodium (salt) affect our health?
Of all minerals, potassium is the one that we need in the largest quantities. 98 percent of our potassium is inside our cells. Potassium and sodium, which is mainly found outside of the cells, work in close collaboration. The potassium-sodium ratio is vital for the electrolyte balance of cells. Put differently, the balance between potassium and sodium ions creates an electric potential difference across the cell membrane (membrane potential) that is determining for cells and their ability to absorb nutrients, get rid of waste products, and maintain essential fluid balances. Potassium is essential to all cells, especially those responsible for nerve transmissions that control muscles, the heart, intestinal peristalsis, insulin sensitivity, and blood sugar levels.
Our kidneys control the body’s potassium levels that must always be in proper balance with sodium. Too much potassium compared with sodium causes potassium depletion and disturbs the electrolyte balance and many other functions that depend on potassium.
Potassium deficiencies are widespread
Seaweed, beans, potatoes, almonds, apples, bananas, and other types of fruit and vegetables are rich in potassium. However, our modern, refined diets that consists mainly of grain, meat and dairy products and far fewer vegetables, contain substantially less potassium. The problem is only made worse by the fact that our intake of sodium in the form of table salt has increased substantially, and that makes us need potassium even more. There is also quite a lot of sodium in bread, cheese, chips, peanuts, sausages, cold cuts, ready meals, and numerous other kinds of industrially refined foods.
Too much sugar, coffee, and alcohol, or loss of fluid caused by diarrhea, excessive sweating, and the use of diuretics, may also cause potassium deficiency. In addition, there is stress that causes the adrenal hormone, adolsterone, to retain sodium and excrete potassium.
Different recommendations in the Nordic countries and the United States
The average potassium intake in the United States is around 2.6 grams per day. An estimated 3 percent of the adult population is thought to be able to reach the recommended potassium intake, which is 4.7 grams in the United States. The Nordic Nutrient Recommendations are somewhat lower (3.1 grams for women and 3.5 grams for men).
This shows that there is disagreement about the actual need for potassium, which depends on several factors. Nonetheless, there is widespread potassium deficiency in the United States as well as in Europe, and this has serious implications for public health and for the explosive growth rate for lifestyle-associated diseases.
Our modern lifestyle is what causes widespread potassium deficiency
The combination of refined food, too much salt, overconsumption of coffee and alcohol, and stress lowers our potassium status and causes the body to excrete too much potassium. The use of diuretics is also a problem.
Potassium and its role in blood pressure management
Potassium controls and lowers our blood pressure by means of various mechanisms that include enzyme processes and nerve impulses to the muscles and heart. It is even possible that increased potassium intake may lower blood pressure by increasing the excretion of sodium. Potassium is even able to increase insulin sensitivity and reduce inflammation. In fact, both type-2 diabetes and the early stage of diabetes (metabolic syndrome) are characterized by elevated blood pressure, insulin resistance, and inflammation.
A new British study shows that elevated blood sugar levels lead to blood vessel constriction, which can cause the blood pressure to go up. In other words, sugar, not saturated fat, causes cardiovascular disease. It is also important to pay attention to potassium and chromium, both of which help control blood sugar levels.
A diet that controls blood sugar levels combined with supplements of potassium may therefore have a positive effect on blood pressure. The same is the case with magnesium, physical activity, and weight management (it is particularly important to have a normal waistline)
Potassium, insulin resistance, and diabetes
Potassium influences the pancreas and its release of insulin, the hormone that helps convey sugar into the cells. Lack of potassium may lead to reduced insulin secretion and impaired glucose tolerance that reduces cellular glucose uptake.
According to The Nurses’ Health Study, high potassium intake is associated with a reduced risk of developing type-2 diabetes among women with a BMI count of 29 or less. Another study that monitored 4,754 people for 20 years showed that 373 of the participants developed diabetes. Their potassium intake was generally lower than the potassium intake of those participants who did not get diabetes.
Fruit and vegetables are good sources of potassium, fiber, magnesium, and other nutrients that are beneficial for the cardiovascular system and blood sugar levels.
Anti-hypertensive medication disturbs blood sugar levels
As described, elevated blood pressure may be a result of getting too little potassium. It is therefore problematic that so many people manage elevated blood pressure levels with diuretics (thiazide preparations) that are associated with potassium deficiency. There is an established link between thiazide usage and low potassium levels in blood serum and impaired glucose tolerance, elevated blood sugar levels, increased risk of diabetes, and aggravation of existing diabetes.
However, patients, who lack potassium because of thiazide therapy, can restore their insulin secretion and keep their blood sugar under control by taking supplements of potassium. This indicates that low potassium in blood serum is linked to blood sugar disturbances.
Did you know that headaches, fluid retention, constipation, heart rhythm disturbances, muscle cramps, and a tingling sensation in the arms and legs may also be caused by too little potassium?
We used to get more potassium than sodium from our diet
Now, it is typically the other way around, and this imbalance may actually be bad for our health. The Nordic Nutrient Recommendations recommend that the salt intake of women and men stay below 6 and 7 grams daily respectively (this corresponds with 2.4 and 2.8 grams of sodium). Also, the daily potassium intake, as mentioned earlier, should be above 3 grams.
A minor potassium deficiency can be controlled with dietary measures – especially by eating more potassium-rich foods and less salt.
Potassium supplements should mainly be taken together with diuretics to avoid side effects. As the loss of potassium differs from one person to another, it is important to measure blood levels of potassium before and after treatment.
Potassium supplements may also be considered in the case of elevated blood pressure and blood sugar disturbances. It is often a good idea to combine potassium supplements with supplements of magnesium and vitamin B6, which are also important for the fluid balance, blood pressure, and blood sugar levels.
Michael S. Stone. Potassium Intake, Bioavailability, Hypertension, and glucose Control. Nutrients. 2016
Houston M.C. The importance of potassium in managing hypertension. Curr. Hypertens. Rep. 2011. PubMed
Zillich A.J. et al. Thiazide diuretics, potassium, and the development of diabetes. A quantitative review. Hypertension 2006
Goldner M.G. Zarowitz H., Akgun S. Hyperglycemia and glycosuria due to thiazide derivatives administered in diabetes mellitus. N. Engl. J Med 1960