What Are Electrolytes? Benefits, Imbalances & When to Use Supplements

Electrolytes are tiny electrically charged minerals that keep almost every system in your body working. They control hydration, regulate nerve signals, drive muscle contractions including the heartbeat, and balance your blood pressure and blood pH from minute to minute.

For most UK adults, food and drink cover daily needs. But heavy training, hot weather, low-carb diets, illness with vomiting or diarrhoea, and even simple over-hydration can quickly tip the balance. This guide explains what electrolytes are, what they actually do, the warning signs of an imbalance, and exactly when an electrolyte supplement is worth taking.

What Are Electrolytes?

Electrolytes are minerals that carry a positive or negative electrical charge when dissolved in body fluid. That charge is what lets them move water across cell membranes, fire nerve impulses, and trigger the muscle contractions that let you walk, lift, and pump blood.

The seven main electrolytes in human physiology are sodium, potassium, magnesium, calcium, chloride, bicarbonate, and phosphate. Sodium, chloride, and potassium do most of the visible work around hydration and energy; magnesium, calcium, and phosphate sit deeper inside cells, doing the structural and signalling work.

Your kidneys, hormones, and gut work together to keep these minerals in a narrow range. When that balance breaks, even by small amounts, you feel it within hours as cramps, fatigue, headache, or dizziness.

What Each Electrolyte Actually Does

The table below summarises the role of each of the seven main electrolytes and where most UK adults get them from food.

Why Electrolytes Matter Day to Day

Electrolytes do far more than fuel your gym session. They are involved in five core processes that run constantly in the background.

Hydration and fluid balance is the most familiar role. Sodium pulls water into the bloodstream, potassium moves it into cells, and the kidneys fine-tune the volume. Without enough sodium and potassium in the right ratio, drinking more water alone will not actually rehydrate you.

Nerve signalling and muscle contraction rely on rapid sodium-potassium exchange across cell membranes. This is why an imbalance can show up as twitches, cramps, weakness, or palpitations long before you notice thirst.

Blood pressure regulation is driven mainly by sodium and potassium working in opposition. UK guidance from NHS and SACN recommends adults stay below 6 grams of salt (about 2.4g sodium) per day, while pushing potassium intake up via fruit and vegetables for healthier blood pressure.

Energy production and cognition depend on phosphate (in ATP) and on stable hydration. Even mild dehydration of just 1 to 2% of body mass can impair short-term memory, attention, and mood (Armstrong et al., 2012, DOI: 10.3945/jn.111.142000).

Signs of Electrolyte Imbalance

Electrolyte imbalances rarely look dramatic. They more often show up as a vague, low-grade sense that something is off. The most common symptoms include:

The most common signs are fatigue that does not lift after rest, muscle cramps or twitches (particularly in the legs at night), and headaches with light-headedness on standing. Brain fog, nausea, palpitations, and unexplained mood changes can also point to an electrolyte issue.

If you notice several of these together, especially after illness, hot weather, heavy training, or a sudden diet change, electrolytes are a sensible first thing to check. Persistent symptoms always warrant a GP visit rather than a self-diagnosed top-up.

What Causes Electrolyte Imbalance?

Most cases come down to losing more than you take in, or shifting the ratio of one electrolyte against another. The common UK triggers are heavy sweating from sport or hot weather, vomiting or diarrhoea, prolonged fasting and very low-carb diets, frequent alcohol use, certain medications, and over-hydration.

Diuretics, laxatives, and proton-pump inhibitors are the medications most likely to nudge electrolytes off-balance, often without obvious symptoms. If you take any of these long-term, ask your GP about routine bloods rather than reaching for a sports drink.

Drinking large volumes of plain water without enough sodium can also cause hyponatraemia. This is well documented in marathon runners and is now also seen in fasting protocols and in people drinking 4+ litres of water per day on social-media advice.

Who Benefits Most From Electrolyte Supplements?

Most adults eating a varied UK diet do not need a daily electrolyte supplement. The groups most likely to benefit are clear-cut.

Athletes and Active People

Anyone training over 60 minutes in heat, sweating heavily in the gym, or doing back-to-back sessions can lose significant sodium and potassium that water alone will not replace. Endurance athletes consistently perform and recover better when sodium intake matches sweat losses rather than relying on water only.

Adults Over 65

Older adults feel thirst less reliably, often eat less varied diets, and are more likely to take medications that affect electrolyte balance. Electrolyte imbalance is a common, treatable cause of dizziness, falls, and confusion in this age group, which is why a daily oral rehydration product can be a sensible part of a routine for some, after a chat with a GP.

People on Low-Carb or Keto Diets

Cutting carbs lowers insulin, which signals the kidneys to excrete more sodium, water, and potassium in the first weeks. The "keto flu" of headaches, fatigue, brain fog, and cramps is largely an electrolyte problem and usually resolves quickly with added sodium, potassium, and magnesium.

People Recovering From Illness

Vomiting, diarrhoea, and fever all dump electrolytes fast. Adult oral rehydration with a balanced electrolyte powder is more effective than plain water and faster than waiting for solid food to do the job. NHS Dioralyte-style protocols are based on exactly this principle.

Hot-Climate Workers and Heat-Wave Days

UK heatwaves are no longer rare. Outdoor workers, runners, cyclists, and anyone exercising in temperatures over 25C should treat sodium replacement as part of the kit rather than an optional extra.

Electrolytes vs Sports Drinks vs Plain Water

The labels on the supermarket shelf get blurry. The table below clarifies which option fits which situation.

How to Choose an Electrolyte Supplement

Most products on the UK shelf are either too high in sugar, too low in potassium, or both. A good electrolyte supplement should follow three rules.

It should contain meaningful sodium AND potassium, not just one. A sensible serving for active adults targets roughly 300 to 600mg of sodium and 300 to 800mg of potassium, with magnesium added in the 50 to 100mg range. Anything that is mostly sodium with a sprinkle of "trace minerals" is not a balanced product.

It should be sugar-free or low-sugar unless you specifically need carbohydrate fuel during a long endurance session. Sugar is fine in racing context but unnecessary for daily hydration, keto, or fasting.

It should be made to GMP standards with clear UK-style labelling. The Supplements Wise Electrolyte Powder hits all three: 757mg potassium, 439mg sodium, and 12mg magnesium per 5g serving, sugar-free, naturally lemon-flavoured, and UK manufactured.

If your concern is occasional puffiness or water retention rather than rehydration, the Fluid Balance Support capsules use magnesium, vitamin B6, and eight botanicals for a different but related job. These two products solve different problems and should not be confused.

Electrolyte-Rich Foods (UK-Friendly Choices)

Before reaching for a supplement, audit the diet. The everyday UK foods below cover the main electrolytes without supplementation:

Potassium-heavy: jacket potatoes with skin, bananas, baked beans, white fish, leafy greens, dried apricots, mushrooms.

Sodium and chloride: sea salt, olives, cheddar, tinned anchovies, smoked fish, salted nuts.

Magnesium-heavy: pumpkin and sunflower seeds, dark chocolate (70% or higher), almonds, brown rice, oats, spinach.

Calcium and phosphate: dairy, tinned sardines with bones, fortified plant milks, eggs, lentils, tofu set with calcium sulphate.

If two or more of those food groups are missing from a typical week, a daily electrolyte product becomes a more sensible insurance policy.

Safety, Side Effects and When to See Your GP

Balanced electrolyte supplements are well tolerated by most healthy adults. The common side effects are mild stomach upset if taken on an empty stomach, and a salty aftertaste that some people find harder to enjoy than others.

People with kidney disease, heart failure, high blood pressure on potassium-sparing diuretics, or anyone on lithium should speak to a GP before adding electrolyte supplements, as the safe range is narrower for these groups. Pregnancy and breastfeeding usually allow standard doses but always benefit from a quick check.