Sodium, potassium, calcium and magnesium. These four electrolytes play a vital role in the functioning of our heart and indeed every part of our body. The heart ticks along peacefully when their blood level is within the normal range. But, when their levels are abnormal, the effect on the heart can be very deleterious, even leading to death.
What are the normal values of sodium, potassium, calcium and magnesium?
How these minerals affect our health?
What are hyponatraemia, hypernatraemia, hypocalcaemia?
Natural calcium in food Vs calcium tablets
Normal blood level: 136 to 147 mEq/l
Daily recommended salt intake: 5 g or less
This ubiquitous mineral plays a vital role in our well-being, right down to the normal functioning of every cell of our body. Salt (sodium chloride) is the principal source of sodium in our diet, and is a common ingredient which is added to our food and beverages. It enhances flavor, improves the taste, helps retain the freshness of food for longer periods, and prevents the growth of harmful microorganisms.
Salt is also naturally present in almost everything that we eat such as fruits and vegetables, dairy produce, meat, fish.
Doctors are unanimous in believing that excess intake of salt can lead to hypertension (high blood pressure) and make it difficult to control existing hypertension.
Salt activates the gene that produces hypertension. It is not clear whether there is critical safe level below which salt does not have any effect on the gene. It is highly likely that there are other items in our food that empower this gene as well.
The fact that distills out from numerous scientific studies is that excessive consumption of salt is harmful. It would be prudent to moderate the use of salt whilst cooking, minimize the intake of excessively salty food and avoid the practice of sprinkling salt on food and beverages. It definitely would not be right to cut out salt altogether in a country like ours where a significant amount of salt is lost in sweat.
The basic message is: use salt but in moderation
Severe hyponatraemia or low blood sodium level is a very serious medical issue, especially a level below 110 mEq/l. It is usually caused by excessive sweating, persistent vomiting and diarrhoea, and by certain medicines such as diuretics like frusemide – particularly in individuals who have severely restricted the intake of salt in their diet. It is characterised by extreme physical weakness, lethargy and mental confusion. Unless urgently treated a sodium level below 100 mEq/l often leads to death. Treatment is pretty effective in restoring the normal sodium level and in promptly reversing all the symptoms.
Hypernatraemia or high level of sodium in the blood is a rare and critical condition. Unless promptly and effectively treated, it leads to irreversible brain damage.
Some people reckon it is safe to consume any amount of salt as long as it has been added to food whilst it is being cooked. They believe that the culprit is uncooked salt which is sprinkled on food. This is absolutely incorrect. Salt has the same effect, whether it is cooked or uncooked.
Normal blood level: 3.8 to 5.2 mEql/l
Daily recommended intake: 4700 mg
Potassium plays a vital role in the normal functioning of our heart and nerves. A diet naturally rich in potassium maintains the tone of blood vessels, reduces the risk of hypertension and stroke, helps control blood pressure, plays an important role in the production of several hormones, and promotes the normal functioning of the kidneys and the gastrointestinal system.
A healthy potassium intake is achieved by eating a diet which includes vegetables, fruits, nuts, meat, eggs and fish. Food rich in potassium include bananas, tomato paste and puree, sweet potato, yoghurt, milk, dal, fish, soya, coconut water, dried apricots, and prunes.
Low blood potassium, called hypokalaemia, can be fatal if severe. Mild deficiency can cause fatigue, muscle weakness, cramps, respiratory distress, constipation; and severe deficiency can produce potentially life-threatening irregular and abnormal heat beats. Potassium deficiency can be caused by eating disorders, certain drugs (such as Lasix), excessive use of laxatives, excessive sweating, persistent vomiting and diarrhoea and consuming a diet poor in potassium. Hypokalaemia may require potassium supplement in the form of a pill or liquid and, if severe, may even require urgent administration of potassium intravenously.
High levels of blood potassium, called hyperkalaemia, can lead to death specially if the blood level crosses 7 mEq/l. This can be caused by certain drugs (such as aldactone, and ACE-inhibitors like ramipril) specially when the kidney function is impaired. Treatment should be initiated promptly to bring the potassium level to within the normal range.
Normal blood level: 8.5 to 11 mg/dl
Recommended intake: 1000-1200 mg/day
Calcium plays a very important role in heart contractility, muscle function, cellular function, production of several hormones and in maintenance of the arteries in a healthy state.
Sources of calcium include milk, yogurt, cheese; vegetables like spinach, kale, lady’s finger and broccoli; and nuts and seeds such as almonds, pistachio, and sesame seeds.
Dietary calcium and supplemental calcium appear to have different effects.
Dietary calcium helps reduce blood pressure and reduces the risk of heart disease by improving the blood levels of cholesterol. High intake of dietary calcium does not appear to cause kidney stones and may actually protect against developing them.
On the other hand, studies have shown that calcium supplements increase the risk of heart disease, heart attacks and kidney stones. This has been attributed to the fact that supplemental calcium causes a sharp spike in the calcium level in the blood whereas dietary calcium causes a smaller and smoother increase in calcium level.
Vitamin D is required to absorb calcium from the intestine. Vitamin D deficiency causes hypocalcaemia (low levels of calcium in the blood). Hypocalcaemia also results from longterm inadequate intake of calcium. High intake of salt can deplete calcium by increasing urinary calcium excretion. Hypocalcaemia is often seen in patients suffering from certain medical diseases such as renal failure, and in patients taking certain medicines (a diuretic like frusemide). Vegetarians absorb less calcium than non-vegetarians because the plant products contain oxalic acid (as in spinach) and phytic acid (as in whole grains) which bind calcium and hinder its absorption.
Hypocalcaemia leads to lethargy, muscle cramps, numbness of fingers tips, poor blood clotting, and abnormal heart rhythm. Our body responds to hypocalcaemia by breaking down our bones to release calcium into the blood. This unfortunately leads to osteoporosis which increases the risk of fractures. Left untreated, severe calcium deficiency can lead to death.High level of calcium in the blood is called hypercalcaemia, is usually caused by malignancy but can also result from excessive calcium supplements (calcium tablets) taken over a long period of time. Hypercalcaemia is associated with increased blood coagulation, arterial calcification and stiffness, increased risk of heart disease, renal failure and kidney stones.
Normal blood level: 0.7 to 1.4 mmol/l
Recommended daily intake: 400 mg
Magnesium plays a very solid and positive role in the maintenance of good health, enhances the energy level of the body, prevents hypertension, maintains normal heart rhythm, elevates the blood level of the ‘good’ HDL-cholesterol and lowers the ‘bad’ LDL-cholesterol and helps in regulating bowel movement.
Magnesium can easily be obtained from the food we eat. Food that are high in fibre are also rich in magnesium, and these include: banana, beetroot, spinach, oats, seeds (such as sunflower, pumpkin, watermelon), nuts (such as almonds, cashew nuts, peanuts), and legumes like black beans, mung dal.
When deficiency strikes, magnesium level can be boosted by magnesium supplements. Most salts of magnesium are poorly absorbed from the intestine but tablets of magnesium chelate or magnesium glycerinate produce a reasonable response. Diarrhoea is often a troublesome side effect of magnesium pills. A concentrated solution of magnesium chloride in water (called ‘magnesium oil’ because of its oily texture) rubbed on hands and forearms results in rapid absorption of magnesium through the skin. Another easy way of replenishing our body’s magnesium is by relaxing in a tub of warm water to which a handful of epsom salt has been added. Magnesium is sometimes administered intravenously to rapidly restore the depleted level of the electrolyte.
The common thread running through these four minerals is that they are all important for the health of the heart and it is vital that their blood levels are maintained within the normal range. This can best be achieved by eating a nutritious diet which includes whole grains, dairy produce, fruits, leafy green vegetables, nuts and seeds, legumes (dal), soybeans, eggs, fish, and meat.