There’s much talk about electrolytes and how we should balance them in the body. When it comes to sports performance, it’s a hotly debated topic.
But do you know exactly what they are and why they’re so important?
Electrolytes are chemical elements or minerals such as sodium, potassium, magnesium, calcium, chloride, bicarbonate and the phosphates. They can either be simple salts, for example sodium chloride, or complex organic molecules.
These electrolytes have the capacity to undergo a process called “disassociation”, which turns them into substances called “ions”. These carry positive or negative charges. In chemical reactions, 1 quantity (a milliequivalent or mEq) of an ion with a positive charge (also called an anion) will combine with 1 mEq of an ion with a negative charge (also called a cation).
The reason why cations and anions should balance each other out in the human body is because they’re found both inside and outside the cells. For example, a balance must be maintained between the fluid surrounding a body cell and the fluid inside the cell. If this balance is disturbed, the cell may lose some of its fluid and become dehydrated. In extreme cases, this can lead to damage or cell death.
The important electrolytes on the outside of the cells are sodium, calcium chloride and bicarbonate, while the most important electrolytes inside the cells are potassium, magnesium and phosphate.
Electrolytes perform so many vital functions in the human body that if we lose too much of one or all of them, we’re in serious trouble. If there’s a build-up of any one electrolyte, it will seriously disturb the normal functioning of the body.
This delicate balance that controls and maintains practically all of our body functions can easily be disrupted by the following:
- Excessive intake of liquids, including water. Electrolytes (usually minerals and salts) need to dissolve in liquid so that they can disassociate and form ions, but if we drink more liquid than necessary, our kidneys excrete this fluid in the form of urine. Along with the fluid, we lose vital electrolytes. For this reason, it’s recommended that we drink adequate quantities of water and other fluids (especially when it’s warm), but that we don’t overdo our water intake to such an extent that we lose vital electrolytes and become ill.
- Excessive losses of electrolytes due to the abuse of diuretics and laxatives. Diuretics cause the kidneys to excrete more urine, which can lead to increased loss of electrolytes, particularly potassium. You may have noticed that some diuretics are labelled as “potassium sparing”, which means that they don’t deplete your potassium stores, thus creating a potassium imbalance.
Laxatives also tend to lead to increased fluid and electrolyte losses if they induce constant diarrhoea. Abuse of these products is common for various reasons, including chronic constipation (particularly in women) and overuse in slimming. Bulimic people also often use laxatives to purge themselves after they’ve eaten vast quantities of food.
Repeated use of harsh laxatives can cause extreme loss of body fluids, leading to dehydration and severe loss of vital electrolytes. This could lead to dizziness, tiredness, exhaustion, fainting, heart arrhythmias, heart failure, confusion, and even death in extreme cases.
Take note of these electrolytes
The most important electrolytes are calcium, sodium, potassium and magnesium. Take a look at their functions in the body and their recommended daily quantities:
You probably know that most of the calcium in your body is found in the skeleton and teeth (99%). But you might not know that the remainder occurs in your body as ionised calcium, an electrolyte. As a cation, ionised calcium is called the “second messenger”, which means that it reacts to changes in calcium levels inside the cells. It regulates cell function, the heartbeat and blood clotting.
The Recommended Daily Allowance (RDA) for calcium is between 1000mg and 1300mg per day, which can be supplied by milk and dairy products (our richest sources of readily available calcium), green vegetables such as broccoli and spinach, unsalted nuts, tinned fish (if you eat the bones), and calcium-extracted tofu, which is made from soy beans.
Sodium is the most important ion in the fluid outside the cells, and therefore regulates the volume of liquid inside the cells and also the volume of plasma in blood. Sodium is vital to both nerve and muscle function, and it helps to control and maintain the acid-base balance of the body. When people develop severe hyponatraemia (low sodium levels), they may suffer from seizures and coma, and they may even die due to a lack of sodium.
At the moment there’s no RDA for sodium, but the Institute of Medicine in the USA has published so-called Dietary Reference Intakes (DRIs) of 1.2g to 1.5g per day. Most people obtain much higher quantities of sodium from their diets by way of table salt, salt-containing foods and also medicines that contain sodium.
As excessive sodium intake is linked to high blood pressure, or hypertension, and other diseases of lifestyle, Australia’s National Health and Medical Research Council recommends that adults eat no more than 6g of salt a day. This drops to 4g a day to ward off chronic diseases. Always try to choose foods and meals with the Heart Foundation Tick, and don’t add salt to food at the table.
Most of the magnesium in the body is also located in bone, but about 1% of magnesium is found in the fluids outside the cells. Magnesium is regarded as one of the most important co-factors in enzyme reactions, so if your magnesium levels are dangerously low, it can have life-threatening consequences.
The RDA for magnesium varies between 310mg and 420mg per day, depending on age and gender.
The most important dietary sources are green leafy vegetables, legumes (cooked or canned dry beans, lentils, peas or soybeans) and unprocessed or whole grains and cereals, and products made from these grains such as wholewheat breads and crackers, wholegrain breakfast cereals, unsifted flour and brown rice.
Potassium is the most important cation in the fluid inside the cells. Together with sodium, this electrolyte is responsible for maintaining both the acid-base balance and the water balance of the body.
Potassium, together with calcium, also helps to regulate nerve and muscle activity in the body, and insufficient potassium intake can interfere with the storage of glycogen, the primary source of energy for muscle activity.
A deficiency and an excess of potassium can have severe and even fatal effects on the function of the heart. No RDA has been specified for potassium, but an intake of at least 4700mg per day has been suggested for adults.
Potassium is found in most foods, with fruits, vegetables, fresh meat and dairy products acting as primary sources of the mineral.
References: (Mahan LK et al (2012). Krause’s Food and the Nutrition Care Process, 13th Edition. Elsevier, USA; WHO (2012). WHO. Guideline: Sodium intake for adults and children. Geneva, WHO, 2012.)
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