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A Closer Look at Electrolytes

Essential to the regulation of water balance within the body, Chloride, Potassium and Sodium are required in adequate amounts but conversely care should be taken to limit excessive intakes.

Chloride

Chloride is an electrolyte which is found in the fluids surrounding body cells, where it works with sodium and potassium to control the flow of body fluids, regulate electrolyte imbalance and help reduce acidity. It is also present in the stomach in hydrochloric acid which helps digestion, and in the liver where it is involved in the detoxification of waste.

Chloride intake is most abundant in the form of salt (sodium chloride), and its metabolism and requirements are linked to that of sodium. There is no official set figure for daily requirements, but 2.3g per day is accepted as an adequate amount. High sodium chloride intakes have been linked to high blood pressure, which is common in Western diets and campaigns are focused on getting people to consume less salt.

Deficiency of chloride has been observed in severe cases of diarrhoea and vomiting where there is dehydration or from over use of diuretics. Symptoms are low blood pressure and general weakness.

Chloride is abundant in our diets, due to the use of salt which is added to various food products as it helps flavour and is a food preservative. Foods like crisps, chips, salted nuts, savoury snacks, tomato sauces, processed meats, canned meats and fish (especially in canned in brine), olives, canned vegetables and soups contain the most. Chloride sources are especially abundant in processed foods because of the high levels of preservatives needed to keep these foods fresh. Marmite, Bovril and pickles are also high in salt. Potassium chloride is also found in some foods and is the main ingredient of salt substitutes.

It is also found in many vegetables and some other sources include:

  • Seaweed
  • Rye
  • Tomatoes
  • Lettuce
  • Celery
  • Olives
  • Milk
  • Cheese
  • Red meat
  • Liver
  • Seafood

Potassium

Potassium is an electrolyte which assists in muscle contraction and in maintaining fluid and electrolyte balance in body cells. Potassium is also important in sending nerve impulses as well as releasing energy from protein, fat, and carbohydrates during metabolism.

Adults should aim to have at least 3,500mg of potassium per day, which with a balanced varied diet is quite easy. Deficiency of potassium causes muscle weakness, impaired heart function (in extreme cases will lead to death), mental depression and confusion.

Although abundant in the Western diet, potassium is a very labile micronutrient and is lost in cooking foods even under the best conditions. To retain as much potassium as possible cook foods in a minimal amount of water and for the shortest possible time with a cover or lid.

Potassium is generally plentiful in the diet, but good sources include:

  • Sweet potato, cooked, (150g) 450mg
  • Potato, baked (140g) – 882mg
  • Tomato puree (50g) – 575mg
  • Yogurt, plain, low-fat (150g) – 375mg
  • Prunes, in juice (150g) – 510mg
  • Avocado (130g) – 585mg
  • Apricots (110mg – 297mg
  • Bananas (135g) – 540mg
  • Raisins (35g) – 360mg
  • Mixed dried fruit (100g) – 880mg
  • Melon, cantaloupe (½ melon) – 755mg
  • Melon, galia (½ melon) – 540mg
  • Melon, honeydew (¼ melon) – 400mg
  • Watermelon (300g) – 300mg
  • Spinach, boiled (130g) – 650mg
  • Lentils, cooked (100g) – 310mg
  • Red kidney beans, cooked (100g) – 420mg
  • Soya beans, cooked (100g) – 510mg
  • Cod, baked (130g) – 455mg
  • Haddock, steamed (130g) – 420mg
  • Halibut, steamed (130mg) – 440mg
  • Plaice, steamed (130mg) – 364mg
  • Mackerel, smoked (130mg) – 400mg
  • Salmon, cooked (130g) – 430mg
  • Gammon (120g) – 300mg
  • Chicken (85g) – 245mg
  • Turkey (85g) – 264mg
  • Tomato juice (250ml) – 575mg
  • Orange juice (250ml) – 375mg
  • Milk, all types (250ml) – 375mg

Sodium

Sodium is an electrolyte which is essential for regulating the body's water balance and acid-base balance, nerve stimulation, muscle contraction and the uptake of nutrients by cells in the intestines and kidneys.

Dietary reference values for sodium are 1.6g per day for adults. In the West there is over-consumption of sodium through people having too much sodium chloride (salt) in their diet. It is rare for there to be sodium deficiency without an underlying medical condition, except in severe heat dehydration from perfuse sweating causing loss of fluid and sodium. Symptoms include weakness, apathy, nausea and muscle cramps. Taking additional salt in tablet form is a preventive measure, and increased use of table salt is also recommended to replace sodium lost during dehydration and sweating. In rare cases, sodium deficiency can lead to systemic shock due to decreased blood pressure.

High sodium diets, common in modern society, may lead to water retention and high blood pressure. However, sodium is generally nontoxic for healthy adult individuals because it is excreted readily in the urine. Government campaigns are focused on getting people to consume less salt (sodium).

Sodium occurs naturally in a wide range of foods and it is also present in drinking water, although the amount varies deepening on the source. Salt is added to various food products as it helps flavour and is a food preservative.

Sodium is also found added to food as part of food additives including monosodium glutamate, sodium nitrite, sodium saccharin, baking soda (sodium bicarbonate) and sodium benzoate. These additives are ingredients in condiments and seasonings such as Worcestershire sauce, tomato ketchup, soya sauce, garlic salt and gravy granules, and processed and fast food take aways (which are typically very high in sodium).

Processed meats, such as bacon, sausage and ham, and canned soups and vegetables are all examples of foods that contain added sodium. Many prescription and OTC drugs are also significantly high in sodium (check labels).

Marmite, Bovril and pickles are also high in salt. Snack foods like crisps and salted nuts are very high in sodium due to salt content.

Natural food sources which contribute to sodium intake include:

  • Milk
  • Cheese
  • Red meat
  • Chicken
  • Turkey
  • Fish, especially sea fish
  • Butter
  • Dark green leafy vegetables
  • Carrots
  • Celery
  • Asparagus
  • Beets
  • Pumpkin
  • Runner beans
  • Olives
  • Kelp (seaweed)