In 2011, researchers in Italy and the Karolinska Institute in Sweden (the same institution that hosts the Nobel Prize every year) revealed findings from two meta-studies that pooled results from several previous clinical studies that had investigated the relationship between dietary intake of potassium and its association with stroke, blood pressure and heart attacks.
The conclusions from the two research centres were very similar. Both studies indicated that higher intakes of potassium were associated with reduced risks of stroke as well as significant reductions in blood pressure and in turn, reduced rates of heart attack.
In 2012, as a result of these studies, the World Health Organisation’s (WHO) updated its daily recommended dietary intake of potassium to 3510 mg. As a comparison, the US recommended daily intake is 4700 mg.
The Swedish study suggested that 1000 mg of potassium a day appears to reduce the risk of stroke by 11%, whereas the Italian paper suggested that 1600 mg of potassium reduced the incidence rate by double that (22%.)
Both pooled meta-studies mentioned the significant blood pressure lowering effects of potassium.
The 2012 WHO report had this to say about potassium:
“Low potassium intake has been associated with a number of disorders, including hypertension, cardiovascular disease, chronic kidney stone formation and low bone-mineral density. An increased potassium intake may reduce blood pressure, decrease risk of cardiovascular disease, have beneficial effects on bone-mineral density, and mitigate the negative consequences of high sodium consumption.”
What is Potassium, where did it come from?
Up until the 18th century, potassium and sodium were considered the same element. It wasn't until the British chemist Sir Humphrey Davy performed electrolysis on a sample of potash (potassium hydroxide from burned plants) in 1807 that he discovered and named the element. Interestingly, potassium was the first element to be discovered through the process of electrolysis (where an electrical current is run through an otherwise unreactive chemical reaction to separate elements.)
Until then, chemists were unknowingly making soap by mixing animal fat with potassium carbonate. Davy was a bit of a hero as he went on to discover sodium, barium, calcium and magnesium by the same process. All in one year, 1807! No wonder they knighted him.
Why do we need it?
In our bodies, potassium is vital for our nervous and immune systems as well as for promoting proper muscular functioning. It aids the electrical conductivity of neurons by pushing currents along from synapse to synapse via an intricate pump system (the sodium potassium pump.)
Potassium inhibits muscle action potentials (via a complex concentration gradient) and is thus important for maintaining muscular integrity by preventing erroneous muscle contractions.
It is the third most prevalent mineral in our body and often acts as a pH buffer, helping to alkalise water in interstitial fluids (water between cells) when these becomes too acidic.
At any given time, 0.2% of our body is made up of potassium which means that 60 kg human would have around 120 g of potassium coursing through their system.
How do we obtain Potassium from the Food we eat?
As our image suggests, bananas are a great source of potassium. But did you know that a 100 g serving of black beans contains three times more potassium than one banana? In fact, raw milk, tomatoes, almonds, potatoes, avocados, fresh orange juice and fresh water salmon all contain more potassium per serving than one banana.
In order to ensure that we get at least 1000 mg of potassium into our bodies every day, it may make sense to supplement* with it (especially if you get bored eating 2-3 bananas a day or have difficulty maintaining a balanced diet.)
So, whilst an apple a day may keep the doctor away, it appears a banana (or two, or three) may just keep the neurosurgeon at bay.
*Make sure you check with a health professional that your kidneys are healthy, otherwise supplementing with potassium can be dangerous as the kidneys control potassium excretion and if potassium builds up excessively in the body, it results in a condition called hyperkalemia, which in turn can result in arrhythmia of the heart.
NB Fun fact trivia tip of the day: If you want to find out the specific nutritional content of any specific food, then type said food name (say ‘potato’) and the ingredient (say ‘potassium’) directly into Google (“potassium potato”,) hit enter and then see what happens! Hint: it’s a very cool application – have a play around with it. For instance, I didn’t know that an avocado grown in Florida has lower potassium content than an avocado from California! Would be a great, collaborative school project for NZ kids to analyse nutritional variations of different vegetables growing around New Zealand and then load the results on to Google..
by Christopher von Roy BSc, MSc, DCP Immunology
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Do you supplement with potassium? What have your experiences been?