Muscle cramps and mineral deficiency

Can muscle cramps and pains be linked to mineral deficiencies and can taking mineral supplements cure the problem?

Why some people get muscle cramps
Many people experience cramps when they sleep, which can be associated with excruciating pain. Athletes, on the other hand, tend to develop muscle cramps when they are exercising.

A wide variety of factors can cause muscles to contract painfully. The following are common causes:

  • A mineral deficiency involving potassium, calcium, magnesium and/or sodium.
  • Dehydration, which can occur in athletes when they exercise hard in hot conditions and do not drink sufficient liquid.
  • Excessive intake of fluid (drinking 2-3 litres or more of water in addition to your daily fluid intake) - this can ‘wash’ the above-mentioned minerals out of your body and lead to cramps.
  • Lack of fitness - well-trained muscles are less likely to cramp. Although this mainly applies to athletes, people who are not fit and get too little exercise often develop cramps because their muscles are so poorly used.
  • Wearing tight constrictive clothing, especially in bed. Try to wear comfortable, loosely fitting clothes at all times (be comfortable, rather than stylish if you are plagued by cramps), as constriction of the blood supply to muscles can cause them to contract painfully.

Minerals that play a role
There are four minerals that can influence how a muscle contracts, namely calcium, potassium, magnesium and sodium.

a) Calcium
Most people are not aware of the fact that calcium is essential for the normal contraction of muscle tissues, including those of the heart. Patients with extremely low blood calcium levels can develop a condition called tetani where the muscles fibres contract continuously. When this occurs, heart failure can ensue.

Fortunately, such severe calcium deficiencies are rare, but on the other hand, sub-optimal calcium intakes are relatively common, especially in teenagers and young women who cut out calcium-rich foods like milk and dairy products because they are afraid of gaining weight. If you hardly drink any milk and never eat yoghurt, or cheeses, you may well be inclined to a subclinical calcium deficiency and will need to top up on these foods or take a calcium supplement (Calcium Sandoz or Caltrate or Berroca Calcium, for example).

b) Magnesium
Once again, outright magnesium deficiencies are relatively rare, but people eating a western diet that lacks fresh fruit, vegetables, legumes and unprocessed grains and cereals, may well have inadequate intakes. If you suffer from muscle cramps, you can try increasing your intakes of the foods listed above (especially green, leafy vegetables such as spinach, cabbage, lettuce, broccoli) or take a calcium and magnesium supplement (taking these two minerals together improves their mutual absorption).

Note: Magnesium, if taken in excess, can cause diarrhoea. You may have to take your Slow-Mag or Magnesite supplements only every second day.

c) Potassium
Potassium is one of the most abundant minerals available in common foods and most people should not develop a deficiency. However, eating minimalistic or monotonous diets to lose weight or cutting out all fruits and vegetables and grains and cereals, can cause a potassium deficiency. Drinking too much water can also deplete your potassium reserves.

The easiest way of ensuring that you have abundant potassium is to eat five or more servings of fruit and/or vegetables a day. If you think you lack potassium, buy a variety of fresh or frozen vegetables and boil them lightly in chicken stock to make a delicious, fat-free soup that is loaded with potassium. If you have a juicer, make an apple or grape and carrot drink to boost your potassium intake.

Potassium supplements should preferably only be taken if your potassium levels have been checked by a medical doctor and have been found to be low.

Potassium supplements should also only be taken under the supervision of your doctor, because a number of medications can influence the potassium levels in the body - for example, the so-called ‘potassium-sparing diuretics’ prevent loss of potassium from the body. If you take a potassium supplement, you could develop hyperkalaemia (excess potassium in the blood), which is also harmful. So rather eat fruit and vegetables and whole grains to top up on potassium, unless your doctor has prescribed supplements like ‘Slow-K’ for you.

d) Sodium
Most people on a western diet, which is based on processed foods, won’t develop a sodium deficiency. However, drinking too much water, sweating a lot, and certain imbalances in kidney function can lead to sodium depletion, which in turn can cause cramps.

If you do a lot of exercise in hot weather or if you are an athlete training hard, you need to make sure that you are getting some sodium in your diet. Luckily, most sports drinks like Energade and Powerade contain sodium to assist with hydration, so drink some while you exercise and during the recovery phase.

People who develop cramps and do not eat any salt or use salt substitutes (which are rich in potassium) should consider that they might have a sodium deficiency. Try adding a pinch of table salt to your food for a week or two to see if this alleviates the problem.

Other tips on preventing cramps

  • Get as fit as possible - the fitter you are, the fewer cramps you will develop.
  • Drink sufficient liquid to prevent dehydration, but don’t overdo your fluid intake.
  • Follow a low-fat diet to prevent clogged arteries as poor blood circulation to the limbs can cause cramps.
  • Do stretching exercises every day, especially with the muscles that tend to cramp.
  • Wear loose, comfortable clothes, especially at night.

Any questions? Ask DietDoc

Health24, August 2004

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