You have probably heard the advice to drink more water. It is everywhere — eight glasses a day, stay hydrated, water is essential for everything from skin health to energy levels. All of this is true, but it is incomplete in an important way. Water without the right electrolytes can actually make hydration worse, not better. This is one of the most common and least recognised hydration mistakes that active people make.
Why Electrolytes Matter
Electrolytes are minerals that carry an electrical charge when dissolved in water — sodium, potassium, magnesium, chloride, and bicarbonate. They are what allow your cells to maintain their water balance, allow nerves to send signals, and allow muscles to contract. When you sweat, you lose sodium and potassium in amounts that matter. When you drink plain water after heavy sweating, you dilute the sodium in your bloodstream without replacing it, which can cause a condition called hyponatraemia — low blood sodium — that produces confusion, nausea, and in severe cases, seizures.
This is not theoretical. Studies in marathon runners have found that approximately 13 percent of finishers develop hyponatraemia, and it is not caused by dehydration — it is caused by overdrinking plain water while losing sodium in sweat. The solution is not to drink less water. It is to make sure the water you drink during exercise contains electrolytes, particularly sodium.
The Sodium-Potassium Balance
The ratio of sodium to potassium in your diet has a measurable effect on blood pressure and fluid balance. Most people eating a standard diet get far more sodium than potassium — typically a 3-to-1 ratio when it should be closer to 1-to-1 or even lower in sodium. This matters because sodium draws water out of cells and into the bloodstream, while potassium does the opposite. When sodium is chronically elevated relative to potassium, blood pressure tends to rise because the body is holding onto more water than it should.
The blood pressure effect of increasing potassium intake is clinically significant. A meta-analysis in the British Medical Journal found that potassium supplementation at 1 to 2 grams daily reduced systolic blood pressure by 4 to 5 points and diastolic by 2 to 3 points — effects comparable to some blood pressure medications. The mechanism involves the kidney increasing sodium excretion in response to higher potassium levels, which reduces fluid retention and blood pressure simultaneously.
What You Can Do Today
For exercise lasting more than 60 minutes, use an electrolyte drink providing 300 to 500mg of sodium per hour and 100 to 200mg of potassium per hour. For everyday hydration, adding a pinch of sea salt to your water makes the hydration more effective than plain water. Coconut water is a natural source of potassium. For general health, aim for 3 to 5 grams of potassium daily from food — bananas, potatoes, beans, and coconut water are all good sources. Most people exceed the recommended sodium limit without trying, so added salt is rarely needed unless you are an endurance athlete or have been advised to salt-load by your doctor.
You have probably heard the advice to drink more water. Eight glasses a day, keep a bottle with you, stay hydrated. All of this is correct as far as it goes, but there is a problem with the advice that nobody mentions: water without the right minerals can actually make hydration worse. This sounds counterintuitive, but the physiology is straightforward, and the consequences of getting it wrong are surprisingly common — fatigue, muscle cramps, brain fog, headaches, and in endurance athletes, something called hyponatraemia, which is low blood sodium that can be genuinely dangerous. Most people have never heard of it because the sports drink companies would rather you did not.
Why Electrolytes Are Not Optional
Electrolytes are minerals that carry an electrical charge when they are dissolved in water — sodium, potassium, magnesium, chloride, and bicarbonate. They are what allow your cells to maintain their water balance, your nerves to send signals, and your muscles to contract properly. When you sweat, you lose sodium and potassium in amounts that can be significant — a heavy sweat session can lose 500mg or more of sodium in an hour. When you then drink plain water, you dilute the sodium concentration in your bloodstream without replacing what you lost. The result is that your cells end up with relatively more water and relatively less sodium than they should, which disrupts the electrical signalling that depends on proper electrolyte gradients.
The practical consequence is muscle cramping, fatigue, and in severe cases the confusion and disorientation of hyponatraemia. The reason this is not more widely understood is that the sports drink industry has framed hydration as a simple problem — water plus sugar plus sodium — but the sodium component is not optional, and the sugar is actively counterproductive for most people exercising at moderate intensity. You do not need the sugar. You need the electrolytes.
The Sodium-Potassium Ratio Nobody Talks About
The balance between sodium and potassium in your diet has an outsized effect on blood pressure and fluid balance. Sodium draws water out of cells and into the bloodstream. Potassium does the opposite — it pulls water into cells and helps the kidneys excrete sodium. The typical Western diet has a sodium-to-potassium ratio of about 3-to-1 when it should be closer to 1-to-1 or even lower in sodium. This imbalance is one of the dietary drivers of hypertension, and correcting it is one of the most effective dietary interventions for blood pressure management.
The blood pressure effect of potassium is not subtle. A meta-analysis in the British Medical Journal found that potassium supplementation at 1 to 2 grams daily reduced systolic blood pressure by 4 to 5 points and diastolic by 2 to 3 points. For context, that is comparable to some blood pressure medications. The mechanism is straightforward: higher potassium intake tells the kidneys to excrete more sodium, which reduces fluid retention and blood pressure simultaneously. The solution is not to avoid sodium entirely — your body needs it — but to shift the balance by eating more potassium-rich whole foods.
The Magnesium Factor
Magnesium is the electrolyte that gets least attention and causes the most problems when it is deficient. It is required for the sodium-potassium ATPase pump — the mechanism that maintains the electrolyte gradients across cell membranes. Without magnesium, the pump does not work properly, and cells lose their ability to maintain their internal environment. This produces muscle cramps, twitches, elevated resting heart rate, and in severe cases, cardiac arrhythmias. Athletes who get regular muscle cramps despite adequate sodium and potassium are frequently magnesium deficient.
Magnesium deficiency is underdiagnosed because serum magnesium levels do not reflect whole-body magnesium status — the body maintains blood magnesium levels at the expense of tissue magnesium when intake is inadequate. A more informative test is the magnesium loading test, but this is rarely available outside of specialised settings. Empirically supplementing magnesium when symptoms suggest deficiency is a reasonable approach, particularly for people with muscle cramps, anxiety, or sleep disturbance.
What You Can Do Today
For everyday hydration, adding a quarter teaspoon of sea salt to a litre of water makes it far more hydrating than plain water — the electrolytes allow the water to actually enter cells rather than just floating in the bloodstream. For exercise over an hour, use an electrolyte drink with 300 to 500mg sodium and 100 to 200mg potassium per hour, not a sugary sports drink. Coconut water is a natural source of potassium. For general health, aim for 3 to 5 grams of potassium daily from food — bananas, potatoes, beans, spinach, and coconut water are all good sources. If you get muscle cramps, try magnesium glycinate at 200 to 400mg before bed. Most people are significantly under-hydrated in the mornings — starting the day with water and electrolytes before caffeine is a simple change with meaningful effects on energy and mental clarity.
A quality supplement routine can make a real difference to your results.
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