By Erica Whisson, In-house Naturopath
Recommended Daily Allowance: 2-5g
Supplemental Range: 3-8g
Great food sources: all vegetables, apricots, avocado, citrus, bananas, nuts, seeds, sardines
The list of things the body needs potassium for is rather long, but the major things you need it for include blood pressure control, pH control of blood and other body fluids, intracellular acid-base balance, muscle contraction, nerve and heart function, adrenal function and maintenance of normal water balance.
Kind of important? VERY important!
About 98% of our potassium is found mainly in skeletal muscle cells. When a nerve wants to send a message, it releases potassium out of the cell, and sodium gets dragged into the cell. (The sodium/potassium pump – see the sodium page for an explanation.) This movement of electrolytes creates an action potential – much like a little electricity switch – and the message gets sent along the nerve – lots of little switches in a row – until the muscle gets the message: it has to contract. It does this by releasing calcium in the muscle fibres, but that’s another story.
We all need Potassium to turn glucose into glycogen. Glucose is what the cells use for energy, but it gets stored, mostly in the liver and muscle cells, as glycogen. The glycogen in the liver can get turned back into glucose and be used anywhere, (60% of it in the brain). But the glycogen in muscle cells is only for the muscles. It can’t be removed. So when the muscle needs to do something, it doesn’t have to wait for the glucose to get there. It ‘s waiting inside the cells.
You need potassium (and sodium) for fluid balance. That is a balance of where the fluid is in your body. Is it inside your cells, or outside?
If there is too much fluid inside a cell then potassium ‘leaves the building’ and sodium comes in. The fluid follows the potassium. If the cell is a bit dehydrated then potassium enters and fluid goes with it. Providing there is enough fluid in total and you have sufficient sodium and potassium then the fluid will be where it needs to be. Any excess fluid is then excreted via urine.
And yes, we all lose a lot of potassium this way as well.
Potassium is an alkali metal. Elemental potassium vaporises in the air, so you always find it attached to something else. This means that its pH depends on what it is bound t – but is usually around 10-11.
If the body is slightly acidic, potassium is released from cells into the extracellular fluid. When this happens, hydrogen ions enter the cell. If the body is too alkaline, potassium enters the cells and hydrogen leaves. Due to potassium being an alkali, this increases the pH of the extracellular fluid when too acidic and decreases it when too alkaline. This exchange of potassium for hydrogen is enough to maintain the pH of body fluids within their very narrow constraints.
The main reasons people take potassium include:
- for maintaining or lowering blood pressure,
- decreasing the chance of kidney stones,
- to help in carbohydrate loading before endurance events
- for adrenal exhaustion.
The kidneys can only handle so much calcium and anything left can form into kidney stones in those predisposed to developing them. By increasing potassium, therefore decreasing the acid load on the kidneys you can decrease the amount of calcium in urine, thus reducing how much calcium the kidneys have to cope with. Less calcium means the kidneys can keep up and there is less calcium to make stones with.
‘Carbohydrate loading’ is the process in which endurance athletes eat a load of carbohydrates in days before a major event, thereby stimulating the body to make and store more muscle glycogen. Remembering that muscle glycogen is how the muscles store glucose in anticipation of energy being needed, to turn glucose into glycogen you need potassium. By increasing potassium levels when eating carbs, you can enhance how much glycogen is stored.
One of the hormones secreted by the adrenals is aldosterone. Like all adrenal hormones, it’s released at times of stress. One of the things that happen in response to aldosterone is that the body tends to retain more sodium and excrete more potassium. Net result? You end up deficient in potassium and as you need potassium for aldosterone to be secreted, the body’s ability to secrete aldosterone reduces.
The sufferer will be exhausted. But by maintaining potassium levels you can prolong the release of aldosterone while you work on your stress coping skills.
Potassium’s ability to lower blood pressure is especially the case in people whose blood pressure is highly sensitive to sodium. Sodium drives blood pressure up as it causes more water in the blood and increases overall blood volume. With enough potassium to counteract the sodium, you can prevent this increase. For instance, in one study of people with normal blood pressure, when they increased potassium, their BP lowered by about 2.8/1.1 So from about 120/80 to 118/79. In people with hypertension, it lowered by about 7.2/2.8. The higher a person’s salt intake, the greater the response to potassium.
One of the aldosterone’s jobs is to look after mineral balance in the body. This includes retaining sodium and excreting potassium. If it goes on for too long you end up high in sodium, low in potassium and blood pressure goes up.
What if I decide I need more potassium and don’t think I’m getting it from my diet?
Many potassium supplements are in the form of potassium bicarbonate. This makes sense, especially for helping maintain pH levels in the body and excreting excess acids. Not only is potassium nicely alkaline, but one of the main ways we get rid of excess hydrogen ions, (H, not H2) and thus reducing acidity is by breathing out. The carbon dioxide takes the hydrogen with it.
The bicarbonate is a really good source of carbon for the CO2. Your potassium can then go and do everything it needs to.
Like all minerals in the body, you need the right amount. The right amount, in balance with other minerals, helps you get all the positive benefits of potassium. But, in really excessive amounts your heart and brain won’t function as well as normal. Think arrhythmias and confusion, weakness, heart attacks and kidney failure.
So, puh-leeze! Stick to the recommended dose on the label.