Potassium: What Is It & Why Is It Important?
Article by Namrata Ashok
Potassium is an essential mineral. Minerals are different from vitamins as minerals are inorganic substances that plants and animals absorb from soil and water, whereas vitamins are organic substances produced by plants or animals (1). Furthermore, potassium is an electrolyte because it carries a small electrical charge, participating in nerve functions, muscular contraction, blood pressure, and co-regulation of fluid levels in cells with sodium (2). The NHS guidelines recommend consuming 3500mg of potassium a day for adults between the ages of 19-64 years, marking normal blood potassium levels at 3.5 - 5.5 mmol/ litre. Ultimately, potassium metabolism is dictated by the kidney’s ability to excrete excess potassium through urine, sweat, or stool (3).
Sources of potassium
Forms of dietary potassium found in the following potassium-rich foods include potassium phosphate, sulfate, and citrate (4,7):
Dark green vegetables
Dried fruit
Beans and legumes
Potatoes and starchy vegetables
Avocados
Bananas
Cantaloupe
Oranges
Tomatoes
Dairy products
Cashews
Almonds
Coconut water
Moreover, the most common form of potassium in supplements is potassium chloride. Whilst approximately 85-95% of dietary potassium is absorbed by the small intestine in healthy individuals, there exists only a small body of research that examines the absorptive capacity of different supplemental potassium forms, all of which suggest promising, yet inconclusive results regarding bioavailability (7). On one hand, the form of potassium appears to be less significant when regulating blood pressure, however, supplement forms of potassium tend to be unfavourable due to their bitter and unpalatable nature. Also, dietary forms of potassium tend to favour bone health with more efficient absorptive properties (5).
Hypokalemia vs Hyperkalemia
Potassium deficiency (Hypokalemia) occurs with inflammatory bowel diseases (Crohn’s disease, ulcerative colitis), as well as low food intake combined with heavy sweating, vomiting, magnesium deficiency, or excessive diuretic and laxative use. This combination leads to less than optimal blood potassium levels (<3.5 mmol/L). On the other hand, elevated blood potassium levels (Hyperkalemia) are typically associated with non-steroidal anti-inflammatory medication, which promotes the accumulation of potassium in the body, or with the consumption of over 4700mg of potassium a day. In both circumstances, fatigue, muscle weakness, constipation, and heart palpitations are common symptoms (4).
Circadian rhythm
The circadian rhythm conceptualizes our 24-hour biological clock that dictates several physiological functions throughout the day, including kidney function. Excretion of potassium is typically lower at night and in the early morning, increasing gradually throughout the day and peaking in the afternoon. This pattern coincides with the timing of potassium-rich food consumption and the genetic coding “for kidney proteins related to potassium secretion” (6).
Blood pressure
Dietary potassium modulates blood pressure by stimulating sodium-potassium pumps in the walls of blood vessels, creating a more negatively charged fluid environment in cells. This negative environment inhibits the ability of calcium channels to function and affect muscle contraction. Therefore, potassium influx within cells promotes the relaxation of blood vessels, subsequently decreasing blood pressure as blood vessels widen in a relaxed state (7). Research suggests high blood pressure (hypertension) is one of the strongest risk factors for all cardiovascular diseases, to which sodium and potassium intake contribute highly to. A review suggests that higher sodium to potassium ratio is associated with increases in cardiovascular disease risk (4). While an increase of 1000mg of urinary sodium leads to an 18% increase in cardiovascular disease risk, an 1000mg increase in potassium, from diet or a supplement, leads to an 18% decrease in cardiovascular disease risk and a blood-pressure lowering effect (6). Studies depict an average reduction in blood pressure of 2-3 mmHg when potassium intake increases by 30-40mmol (7). It is important to note that the detrimental effects of sodium have been predominantly correlated with diets high in sodium, present in highly processed diets (4).
Stroke
A stroke occurs when blood flow to the brain is impaired. A 12-year study found a 40% reduction in deaths from strokes when daily potassium intake increased by 10mmol (6). The lowest risk of stroke has been attributed to intakes of 3500 mg of potassium daily (4). These advantageous effects are closely related to the effects of blood pressure reduction.
Hypercalciuria
Hypercalciuria occurs when excess calcium is present in urine, which is highly correlated with the development of kidney stones (6). A study investigating eleven children with hypercalciuria found a significant reduction in urinary calcium after two weeks of increased potassium intake through dietary and supplement forms (4).
Bone health
Potassium has been shown to have beneficial effects on bone health. Although the body of evidence remains low, it is interesting to consider the effects of increased potassium intake on pre-menopausal women. Fundamentally, oestrogen has protective effects on bone health and declining oestrogen production is characteristic of pre-menopause. Therefore, decreases in oestrogen production correlate with declining bone competency and increased fracture risk, which is particularly accelerated during the premenopausal period (9). One study of 994 premenopausal women found an increase in low back and upper thigh bone mineral density with increased potassium intake. Another study on women aged 45-55 years found a higher bone mass and lower excretion of bone collagen with increased potassium consumption (6). Unfortunately, bone collagen protein destabilises with age and has been linked to more stiffness and brittleness, however, these aspects of ageing may be delayed with increased potassium intake (8). Mechanisms that explain the effects of potassium on bone health suggest that the increased production of bicarbonate may contribute partially to improved bone mineral density (4).
Insulin
The insulin hormone regulates glucose concentration and plays an important role in shifting dietary potassium into cells before excretion. Insulin upregulates specialised glucose transporters and stimulates potassium uptake by increasing the activity of specialized sodium/potassium pumps in insulin-responsive tissues (6). In fact, a 6-year study examining 84, 360 US women found a decreased risk of type-2 diabetes with increased potassium intake (4).
Should you eat an “alkaline diet”?
The acid-alkaline diet proposes that eating “alkaline” foods, such as potassium-rich foods, counterbalance high “acidic” foods that might lead to various chronic diseases. With tightly regulated physiological mechanisms to maintain a blood pH balance of 7.3 - 7.4, changes in pH, through diet, is difficult and life-threatening. While potassium-rich foods has its benefits, as outlined in this article, eliminating foods based on the acid-alkaline ideology may present other vitamin and mineral deficiencies (4). Thus, consuming a diverse and whole-foods diet remains most optimal.
Summary
Potassium is a mineral that contributes to fluid regulation, muscular contraction, bone health, and blood pressure regulation.
Potassium levels should be monitored when consuming certain medications, such as non-steroidal anti-inflammatories.
Increasing potassium levels have been linked to improved glucose uptake, blood pressure, and markers that are linked to reducing cardiovascular disease and stroke.
With tightly regulated mechanisms to balance pH, focusing less on counteracting the effects of food on pH and more on increasing the diversity of fruits and vegetables consumed is highly beneficial.
This blog post was written by Namrata Ashok, a Sports Science and Nutrition BSc student at the University of Glasgow. Currently involved in two internships, work experience, podcasts, and further reading, alongside her studies, Namrata is enthusiastic about helping individuals heal and restore from the inside out, honing in on approaching the root cause. She is determined to explore the world of health, nutrition, and movement by combining research, theory, and practical experience.
References:
(1) https://www.hsph.harvard.edu/nutritionsource/vitamins/
(2) https://pubmed.ncbi.nlm.nih.gov/31082167/
(4) https://www.hsph.harvard.edu/nutritionsource/potassium/
(5) https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/
(6) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1121081/