Salt, potassium and electrolytes from everyday food

Calf cramp after a session, and the first thought is always the same: I must be low on magnesium. Before you buy a tub of powder, the more useful question is how much sodium, potassium and magnesium you already get from ordinary food, and where the real gap sits.

Electrolytes are minerals that carry an electrical charge in the body: sodium, potassium, magnesium, calcium and chloride. All of them come from food. For most people training three to five times a week, the issue isn't a shortage but a ratio problem — plenty of sodium, not much potassium.

How much salt you already eat

Salt is roughly 40 per cent sodium. One gram of salt gives about 400 mg of sodium, and a level teaspoon holds around 5 to 6 grams of salt. General guidance is to stay under about 5 g of salt a day, or roughly 2000 mg of sodium. Actual average intake tends to sit somewhere between 9 and 12 grams.

Where it comes from matters more than the total. The salt cellar on the table is a small share; most of it is already in the food.

• a slice of bread (40 g): about 0.5 g salt — which bread you pick shifts this more than people expect
• 30 g hard cheese: about 0.5 g salt, more in the saltier types, covered in the piece on salt and fat in cheese
• 50 g salami or cured meat: 1.5 to 2 g salt
• a tablespoon of soy sauce: around 2 g salt
• a handful of olives (40 g): 1 to 1.5 g salt

These are rounded averages and they move with the brand and the preparation. The direction is clear enough: a cheese and salami sandwich carries 3 to 4 g of salt before you season anything.

Potassium per realistic portion

The reference point for adults is around 3500 mg of potassium a day. Most people stall at 2000 to 2500, because potassium lives in vegetables, pulses, potatoes and dairy — exactly the foods that disappear first on a rushed day.

• boiled potato, 200 g: about 800 mg
• cooked beans or chickpeas, 150 g: about 600 mg
• cooked spinach, 100 g: about 500 mg
• broccoli, 150 g: about 450 mg, plus the fibre discussed in the piece on green vegetables and fullness
• a medium banana (120 g): about 450 mg
• a glass of milk or yoghurt (250 ml): 350 to 400 mg
• half an avocado (80 g): about 400 mg, as covered in the piece on avocado and its calories
• 30 g dried apricots: about 350 mg

Bananas are decent, but they aren't the champion. A plate of potatoes with a portion of beans delivers nearly three times what one banana does.

Magnesium and calcium, briefly

Adults need roughly 300 to 400 mg of magnesium a day. Thirty grams of pumpkin seeds gives about 150 mg, the same weight of almonds about 80 mg, 60 g of oats about 80 mg, 150 g of cooked beans about 90 mg, and 20 g of dark chocolate about 45 mg. Two or three of those and the day is covered.

Calcium sits near 1000 mg. A 250 ml glass of milk gives about 300 mg, 200 g of yoghurt about 250 mg, and 30 g of hard cheese 200 to 250 mg. If you don't drink cow's milk, check whether your plant drink is fortified — the gap is large, and it's set out in the piece on milk versus plant drinks.

What you actually lose in training

Sweat losses run roughly 0.5 to 1.5 litres an hour depending on heat, intensity and build. A litre of sweat contains somewhere between 0.5 and 1.5 g of sodium, which is 1.5 to 4 g of salt. Potassium losses are far smaller, around 0.2 g per litre.

For a 60 to 90 minute gym session in a cool room, that's under a gram of sodium. A normal meal afterwards replaces it without any planning. Added salt starts to make sense when work runs past 90 minutes, when it's genuinely hot, when you train twice a day, or when your shirt dries white with salt marks.

Fitting it into the day

1. Swap one sodium source: less cured meat in the sandwich, more egg, chicken or tuna in spring water.
2. Add one potassium source to every meal: potatoes with the meat, beans in the salad, yoghurt with breakfast.
3. Don't strip salt out of your own cooking to leave room for ready meals. The reverse works better — cook it yourself and season to taste.

Who this suits, and who it doesn't

If your blood pressure is high, cutting salt and raising potassium are among the few dietary changes where the evidence is fairly consistent. The size of the effect varies between people, but the direction doesn't.

If you have kidney disease, or you take potassium-sparing diuretics, ACE inhibitors or sartans, more potassium is not automatically better. The same applies to potassium-chloride salt substitutes: useful for some people, not harmless for others. That call belongs to a doctor, not an article.

The opposite case exists too. If you're lean, train in the heat and eat mostly unprocessed food you cook yourself, you may be running short on sodium rather than swimming in it.

Simple combinations

• Roast chicken, boiled potatoes and a spoon of yoghurt: roughly 1200 mg of potassium on one plate with very little added salt.
• Bulgur, chickpeas, tomato and lemon — a lunch box that holds until the break, with solid potassium and magnesium.
• Oats, milk, banana and a spoon of peanut butter: potassium, calcium and magnesium in the same bowl.
• Beans with 30 g of smoked meat instead of 150 g: the flavour survives, the salt drops by nearly two grams.

Common misconceptions

Cramp means low magnesium. The evidence for that is weak. Cramps turn up more often when the load is unfamiliar or the muscle is fatigued than when blood minerals are low. This one isn't settled, so it's honest to say magnesium may well do nothing for your cramp.

Sea or pink salt is healthier. The sodium is the same. Trace minerals appear in amounts too small to change anything about your diet.

A 45 minute session needs a sports drink. It doesn't. Water and a proper meal afterwards do the same job without 30 g of sugar.

Potassium comes from bananas. It does, but potatoes, pulses and dairy give more per realistic portion.

I don't add salt, so my intake is low. If bread, cheese, cured meat and jarred sauces are in the mix, the salt cellar is the smallest part of the story.

When to see a doctor

Get checked if your blood pressure stays high despite dietary changes, if you notice swelling in the legs or face, marked muscle weakness, palpitations, or fainting during training. The same applies if you take blood pressure medication or diuretics and are thinking about salt substitutes or potassium supplements. One situation needs urgent attention rather than another bottle of water: nausea, headache and confusion after a long run during which you drank heavily.

In short

• 1 g of salt is about 400 mg of sodium; aim for around 5 g of salt a day, while most people sit at 9 to 12 g.
• Most salt arrives via bread, cheese, cured meat and ready-made sauces, not the salt cellar.
• Potassium target is roughly 3500 mg; potatoes, pulses, yoghurt and green vegetables carry the most per portion.
• Sessions under 90 minutes don't need electrolyte powder — water and a meal cover it.
• With kidney disease or certain blood pressure drugs, extra potassium is not a harmless addition.