Electrolyte supplements are everywhere right now, from FitTok and celebrity-endorsed podcast ads to gym vending machines and supermarket shelves. If you’ve recently spotted a Lululemon-clad brunch-goer squirting a dash of liquid from a little plastic bottle into a glass of water at your local upmarket cafe, chances are they were topping up their electrolyte supply after a gym class.

The electrolyte market was valued at £6.5 billion in 2023 and is predicted to rise to around £11 billion by 2030 thanks to an astonishing variety of fruit-flavoured fizzing tablets, powders and ready-made drinks promising to hydrate you ‘better than water alone’.

But are they really necessary? Or could drinking milk be just as effective (not to mention cheaper) for post-exercise hydration? And should these electrolytes really be classed as UPFs? We asked health experts to explain all…

“Electrolytes are salts and minerals that are essential for the body to function properly,” says Dr Claire Merrifield, GP and medical director at Selph. “They’re found in blood, sweat and urine. Having enough electrolytes is important for enabling the body to function at its optimum.”

The five key electrolytes used in the body (sodium, potassium, magnesium, calcium and chloride) are lost via sweat, which is why electrolyte drinks are recommended for replenishing your stores after a sweaty spin class or hot yoga session.

“To avoid the compromising effects of dehydration, which can include headaches, dizziness, dry mouth and tiredness, you need to replace those depleted levels of electrolyte salts,” says nutrition expert and former elite triathlete Beau Smith from VOOM Nutrition.

However, that doesn’t necessarily mean you need an electrolyte supplement, says sports nutritionist Jess Hillard from supplement brand Warrior: “Only if you’ve done an especially hard session and know you’ve sweated a lot will you need additional electrolytes alongside increased water.”

It’s important to note that certain medical conditions, such as kidney disease, can cause an electrolyte imbalance, so you should always seek medical advice regarding water consumption and supplements.

To determine which is a better post-workout option, we need to look at the nutritional breakdown of milk versus a typical electrolyte drink.

“Whole cow’s milk is high in calcium, potassium and magnesium,” says Hillard. “A glass (240ml) contains 8g of protein, 8g of fat and about 12g of carbohydrates, while electrolyte drinks and powders will be lower in calories, protein and fat.”

That extra dose of protein can be helpful, Merrifield says: “Protein is important to consume after exercise to optimise health outcomes and muscle mass, and milk has been specifically shown to have muscle benefits after exercise.”

However, most sports drinks and supplements are formulated with hydration as the top priority. “Most electrolyte drinks are higher in sodium than cow’s milk, and they aim to drive rapid hydration,” Smith explains. “Sodium is the most rapidly depleted electrolyte and arguably the most important to replace post-workout.”

If you’ve been on a mission to cut down on ultra-processed foods (UPFs) following the explosion in research showing how unhealthy these products can be, you might be doubtful about taking a supplement that doesn’t seem to relate to any food stuffs. 

Merrifield believes that some electrolyte supplements and drinks could fall under the UPF umbrella, and says that it’s a good idea to be wary of these kinds of ultra-processed items “because they’re being linked to a whole host of physical and mental health issues”. However, Hillard says that just because something’s a UPF, that doesn’t mean we necessarily have to completely avoid them. “Just be mindful of how much you’re consuming.

“Little red flags to look out for [on ingredients lists] are stabilisers (sometimes hidden as polysorbates), artificial preservatives and artificial sweeteners such as aspartame or sucralose.”

As is so often the case with health questions, the answer to that question is: it depends.

“The best option is the one most suited to the needs of the individual’s diet and the nature of their workout,” says Smith. He recommends taking an electrolyte supplement if you want to prevent dehydration after a strenuous cardio session and milk if muscle-building is of utmost importance. Marathon training? It’s probably a good idea to have a sachet ready.

Merrifield, on the other hand, is sceptical about companies who claim that electrolytes are a post-gym essential. “There’s an enormous industry selling electrolyte drinks to enhance recovery after workouts, yet most sports scientists don’t recommend electrolytes unless exercise lasts over 90 minutes or is done in a hot climate,” she says.

“Most non-competitive athletes can make up their electrolytes by normal eating and drinking, but if rapid recovery is needed or exercise has made you very dehydrated then they can be beneficial.”

She agrees that cow’s milk is the clear winner when it comes to protein power: “There have been several studies showing the beneficial effects of milk on muscle health.”

As for price comparison, you might be surprised to learn that the lowest price electrolyte tablets (25p each) work out cheaper than milk, at around 46p per pint. It is worth pointing out, however, that very few people are going to drink an entire pint of milk in one go, so once you’ve had two or three cups of milk, you’re making a saving. Some electrolyte-infused sparkling waters are far more expensive, at up to £2 per 330ml can.

What if you’re vegan, lactose intolerant or don’t like the taste of milk? Could plant-based alternatives provide adequate post-workout replenishment?

“Non-dairy milks like soy, almond milk and rice milk have similar nutrient composition to dairy milk but may not be as effective in promoting muscle turnover,” Merrifield says.

Smith highlights almond milk as a good alternative: “While lower in protein, it is often enriched with calcium and vitamin D. It can be paired with a protein source to create a balanced recovery option.”

He also recommends a subtly sweet plant-based drink that ticks a lot of boxes: “Coconut water, often deemed a natural electrolyte drink, is rich in potassium, sodium and magnesium, making it useful for rehydration. However, it lacks protein, so combining it with a protein-rich snack or shake is recommended for optimal muscle recovery.”

Hillard agrees: “Coconut water is also low in calories and sugar, especially compared to targeted electrolyte drinks on the market.”

So now you know the pros and cons of electrolyte supplements, cow’s milk and plant-based drinks, and can choose your post-workout beverage accordingly.

Images: Getty