Combining Magnesium & Potassium: Using the Electrolyte Duo the Right Way

If you sweat a lot – during exercise, in the sauna, or on hot days – you quickly run into the topic of electrolytes. Two names almost always come up together: magnesium and potassium. These two minerals are considered the classic electrolyte duo because both are involved in the work of muscles and nerves. Athletes who train intensely and sweat heavily in the process often wonder whether they should specifically supplement both. In this guide, we take an objective look at why the two are mentioned together so often, how you can sensibly combine them through diet or supplementation – and what you should definitely watch out for, particularly with potassium.

Magnesium and Potassium Explained Briefly

Magnesium and potassium are what's known as electrolytes – minerals that exist in the body as charged particles and are involved in countless processes. Both belong to the group of nutrients for which the EU has officially authorised health claims.

Magnesium contributes to electrolyte balance and is involved in the transmission of impulses and in muscle activity: magnesium contributes to normal muscle function. The mineral is involved in a large number of metabolic processes and is found above all in whole-grain products, nuts, legumes, and green vegetables. A large portion of the magnesium in the body is stored in the bones.

Potassium is the most important mineral inside our cells. Potassium contributes to normal muscle function, and potassium also contributes to normal functioning of the nervous system and to the maintenance of normal blood pressure. Foods rich in potassium include bananas, potatoes, legumes, dried fruit, and vegetables. The body keeps blood potassium levels within a narrow range – it's mainly the kidneys that ensure any excess is reliably excreted.

Where exactly the differences between the two lie is something we've put together in a dedicated article: Magnesium or Potassium: What's the Difference?

Why Magnesium and Potassium Work So Well Together

There's a simple reason the two minerals are so often mentioned in the same breath: they work within the same systems. Muscles and nerves only function properly when charged particles – electrolytes – are distributed in the right ratio across cell membranes. Potassium plays a leading role mainly inside the cell, while magnesium, among other things, helps maintain that balance.

According to the authorised EU claims, both contribute to normal muscle function, and both are involved in impulse transmission within the nervous system. To put it visually, electrolytes make sure that "signals" between nerves and muscles are passed on cleanly – tension and relaxation, stimulus and response. That's why magnesium and potassium complement each other thematically: anyone thinking about an adequate electrolyte supply sensibly keeps an eye not just on one of the two, but on how they work together.

A sober assessment matters here: this isn't about the combination achieving "more" than the sum of its parts, and it isn't a remedy for specific complaints. It's simply that a good supply of both electrolytes is part of a balanced nutrient intake – especially during periods when the body loses minerals through sweat. If you're interested in other sensible combinations involving magnesium, we've covered those too, for example in Magnesium and Vitamin D.

How to Combine Magnesium and Potassium

There's a clear order of priority when combining them: diet first, then – only if actually necessary – targeted supplementation.

Through Diet

The simplest way to cover both electrolytes is through your plate. Many foods even deliver magnesium and potassium at the same time:

• Legumes such as lentils, chickpeas, and beans – rich in both
• Nuts and seeds, such as almonds, cashews, and pumpkin seeds
• Whole-grain products and oats
• Green vegetables such as spinach and chard
• Potatoes, bananas, and dried fruit as classic potassium powerhouses

If you regularly eat foods like these, you'll generally cover your needs for both minerals without additional supplements. A varied, colourful plate with plenty of plant-based foods essentially takes care of the combination by itself. A practical side note: if you use too much water when preparing potatoes and vegetables and then pour it away, you lose some of the water-soluble potassium – gentle steaming or baking preserves more of it.

Through Supplementation

When it comes to supplementation, there's an important difference between the two substances. Magnesium supplements are widely available and come in various compounds. Which form makes sense for you depends on your goals – we've put together a detailed magnesium buying guide as well as an extensive comparison of magnesium forms.

Potassium supplements, by contrast, are strictly regulated in Germany: dietary supplements are only allowed to contain comparatively small amounts. The reason is safety – more on that shortly. For most people, diet therefore remains the far more important source of potassium.

Timing Around Exercise

During intense exertion, the body loses minerals through sweat. If you sweat a lot and for a long time, it makes sense to focus on replenishing lost fluid and electrolytes – usually a balanced meal or a suitable drink after training is enough. A good rule of thumb: drink enough, eat something wholesome with vegetables, legumes, or potatoes after exercise, and you'll generally have the key electrolytes covered already. A fixed intake schedule for supplements isn't necessary for most recreational athletes. If you supplement magnesium, it's best to spread it across the day – many people like taking it in the evening. You can read how to approach electrolytes around exercise in practice in our guide Sport & Electrolytes: Keeping Magnesium, Potassium & Co. in Balance. If you supplement magnesium and are wondering when you can expect an effect, you'll find guidance here: How Long Does It Take for Magnesium to Work?

What You Should Watch Out For

As harmless as the topic of electrolytes may sound, particular caution is warranted with potassium.

Potassium and the kidneys: The body regulates blood potassium levels very precisely, and the kidneys play the central role in this. With impaired kidney function, potassium can no longer be excreted adequately – additional intake through supplements can then lead to a dangerously high potassium level. Certain medications, such as some blood pressure or diuretic drugs, also affect potassium balance. If you have kidney disease, take medication regularly, or are unsure, be sure to check with your doctor before taking potassium supplements. Getting potassium through a normal diet with fruit and vegetables, by contrast, is unproblematic for healthy people.

Magnesium and the upper limit: Moderation matters with magnesium too. Germany's Federal Institute for Risk Assessment recommends an upper limit of 250 milligrams per day for additional intake through dietary supplements, ideally spread across the day. Higher amounts can lead to soft stools or diarrhoea. You can read more in our article Too Much Magnesium? Side Effects & Upper Limit. How long it makes sense to take it is covered in the guide How Long Should You Take Magnesium?

Different magnesium forms: If you decide on a magnesium supplement, you'll come across different compounds – such as citrate, bisglycinate, or threonate. They differ in properties and tolerability, but not in what magnesium fundamentally contributes. You'll find an honest comparison in our articles Magnesium Bisglycinate or Magnesium Citrate and Magnesium Threonate or Citrate.

As a general rule: dietary supplements don't replace a balanced diet or a healthy lifestyle. If you have an existing condition, are pregnant or breastfeeding, or take medication long-term, getting medical advice before taking them is always the right call. If you're unsure whether you even have a deficiency, talking to a doctor and, if needed, having a blood test can provide clarity – that's far more sensible than combining several supplements on a hunch.

An Honest Assessment

Magnesium and potassium are a sensible electrolyte duo – but not a miracle cure, and in most cases not a reason to reach for two separate supplements. The honest takeaway is this: if you eat a varied diet with plenty of vegetables, fruit, legumes, nuts, and whole grains, you'll generally already cover your needs for both minerals through food.

Targeted supplementation can become relevant in certain situations – such as a deficiency diagnosed by a doctor or very high physical exertion with heavy sweating. With potassium in particular, though, diet is the more important and safer route anyway, while magnesium can be supplemented without much fuss as long as you keep the upper limit in mind. Combining the two substances is therefore less a question of two doses from a pack and more a question of your overall balance of eating, drinking, and movement.

Bottom line: don't think of magnesium and potassium in isolation as "supplements," but as part of an eating pattern rich in unprocessed, plant-based foods. If you want to bring both of these together sensibly in your own life, the best first step isn't a supplement, but a look at your own diet – and, if in doubt, a conversation with your doctor.