When muscle cramps are severe or occur frequently, they may be a sign of a mineral or vitamin deficiency. A muscle cramp — or spasm — occurs when one of your muscles contracts strongly and doesn't relax right away. It can last for a few seconds to 15 minutes or longer, producing extreme pain.
Any muscle of the body can cramp, including the toe muscles. Toe cramps may be caused by deficiencies of potassium, calcium, vitamin D or magnesium.
Potassium is a mineral necessary for normal function of all body cells. It is particularly important for the conduction of nerve impulses, contraction of muscles, and maintenance of a regular heartbeat.
Low potassium levels — called hypokalemia — can cause severe muscle cramping in the toes and elsewhere. Muscle weakness, fatigue, constipation and heartbeat irregularities are other possible symptoms of hypokalemia.
Potassium deficiency is often the result of excessive loss of potassium in the urine, digestive tract or sweat. Water pills are a common cause of potassium loss in the urine, while vomiting and diarrhea are frequent causes of digestive tract losses.
Potassium is present in a large number of foods, so inadequate intake alone does not usually cause low levels. But poor intake can worsen the hypokalemia resulting from excessive potassium loss. Good dietary sources of potassium include bananas, beans, lentils, orange juice and potatoes.
Calcium is another important mineral. Like potassium, calcium is needed for proper function of all body cells. It is necessary for strong bones, conduction of nerve impulses, muscle contraction, maintaining a regular heartbeat and clotting of blood.
Low levels of calcium — hypocalcemia — can cause severe muscle cramps. Other possible signs of low calcium include heartbeat irregularities, low blood pressure, muscle aches, tingling sensations, weak bones and seizures.
There are a number of causes of hypocalcemia, including vitamin D deficiency, magnesium deficiency, kidney disease, parathyroid gland disease and certain medications.
Inadequate calcium intake may cause low levels, especially in people who avoid dairy products. Good dietary sources of calcium include all dairy products, canned sardines, canned salmon, kale and broccoli. Some foods, such as orange juice, can be purchased with added calcium.
Vitamin D Deficiency
The human body cannot make vitamin D on its own. Regular exposure to direct ultraviolet rays from sunlight is needed to produce vitamin D in the skin. When sun exposure is inadequate, vitamin D must be obtained from food or supplements.
Vitamin D has a variety of functions and is necessary for adequate absorption of calcium from the digestive tract. So vitamin D deficiency usually produces hypocalcemia, which in turn can lead to severe cramping in the toes.
Regular sun exposure without sunscreen is the best way to avoid vitamin D deficiency. Most foods naturally contain only minimal amounts of vitamin D, but a number of foods, including milk and breakfast cereals, are fortified with extra vitamin D.
Magnesium is yet another mineral needed by all body cells. It plays important roles in the conduction of nerve impulses, contraction of muscles, maintenance of normal heartbeat and blood pressure, and production of body proteins.
Low magnesium levels — hypomagnesemia — can lead to low levels of both calcium and potassium, resulting in severe muscle cramping. Other possible symptoms of hypomagnesemia include nausea, vomiting, weakness, numbness, tingling sensations, heartbeat irregularities and seizures.
Magnesium deficiency may be caused by reduced absorption through the digestive tract — as may occur with diarrhea — or increased magnesium loss in the urine — as may occur with water pills. Many foods contain magnesium, so hypomagnesemia is usually not caused by inadequate intake.
However, a very poor diet may lead to inadequate magnesium intake. Good dietary sources of magnesium include whole grains, nuts, spinach, avocados, beans, dark chocolate, some fatty fish and bananas.
See your doctor if you have frequent or severe cramping episodes. The information discussed above can provide clues about whether you may have a mineral or vitamin deficiency but do not try to make the diagnosis yourself. Your doctor can determine whether you have a mineral or vitamin deficiency by simple blood tests.
Reviewed by Mary D. Daley, M.D.
- American Academy of Orthopaedic Surgeons: Muscle Cramps
- Merck Manual Professional Version: Hypocalcemia
- Merck Manual Professional Version: Vitamin D
- Oregon State University: Magnesium
- Merck Manual Professional Version: Hypomagnesemia
- Merck Manual Professional Version: Hypokalemia
- National Institutes of Health: Magnesium
- National Institutes of Health: Calcium
- National Institutes of Health: Potassium
- National Institutes of Health: Vitamin D