Magnesium is an important essential mineral in the body. Being the fourth most abundant mineral in the body, magnesium is required for normal cellular function, muscle relaxation, protein synthesis, and energy release. It is an important cofactor for more than 300 enzyme systems. Magnesium helps regulate the body temperature and adapt to stress. This is why it is considered as the “anti – stress mineral”.
Food Sources and Absorption of Magnesium:
Foods rich in magnesium are dark green leafy vegetables, legumes, seeds, nuts especially almonds, pecans and Brazilian nuts, fish, dark chocolate, avocado, and whole grains.
The total body magnesium in an average person is 25 grams (1000 mmol), of which about 65% is in the bones and teeth. The remaining 35% is in the blood, brain, heart, and body fluids. The normal level of magnesium in the blood is 1.7 – 2.4 mg/dl (0.7 – 1 mmol/L), of which 30% is bound to proteins and 15% is complexed to phosphate and other anions.
Approximately 40% – 50% of dietary magnesium is absorbed, mainly in the middle and last parts of the small intestine. Vitamin D enhances absorption of magnesium, while oxalate, alcohol, caffeine, diets high in protein and fat, phosphorous, and high doses of calcium, and phytic acid decrease absorption of magnesium.
The ratio of calcium to magnesium is highly important in magnesium absorption. For optimal absorption, the best ratio of calcium to magnesium is 2 to 1. Vitamin B6 increases the transport of magnesium into the cells.
Athletic Benefits of Magnesium:
- Plays an important role in protein synthesis.
- May help relieve pre – competition anxiety.
- May prevent muscle spasms and cramps during intense training or competition.
- Supports the body against the stress of exercise.
- Reduces post – exercise exhaustion.
Non – Athletic Benefits of Magnesium:
Magnesium may be beneficial in the following conditions:
- Tension and cluster headaches.
- Cardiac arrhythmia.
- Congestive heart failure (CHF).
- Pregnancy – induced hypertension.
- Dysmenorrhea (painful menstruation).
- Dyspareunia (painful intercourse).
- Premenstrual syndrome (PMS).
- Kidney stones.
- Mitral valve prolapse (MVP).
- Chronic fatigue syndrome.
- Raynaud`s disease.
- ADHD (attention - deficit hyperactivity disorder).
- Sickle cell anemia.
- Alcohol withdrawal and preventing hangover (when combined with vitamin B1).
Dosage and Side Effects:
The RDAs for magnesium for men and women are 400 – 420 mg and 310 – 320 mg, respectively. Women would need 350 – 360 mg a day during pregnancy and breastfeeding periods. Athletes may consider taking 600 – 1000 mg per day for optimum protein synthesis and muscle contraction. Magnesium is added to many multivitamins – multiminerals. It is also available as tablets and powder.
The most common side effect of magnesium is diarrhea. Some people may experience diarrhea even in lower doses.
Magnesium supplementation should be avoid or should be under the supervision of a doctor in the following medical conditions, as they may be associated with hypermagnesemia (increased blood levels of magnesium):
- Renal failure.
- Severe burns.
- Sepsis (systemic infection).
- Low function thyroid.
- Adrenal insufficiency.
- Lithium therapy.
- Cardiac arrest.
There are interactions between magnesium and some medications and you need to be cautious when combing them:
- Aminoglycosides (such as gentamicin, kanamycin, and streptomycin): they may aggravate muscle – relaxing effect of magnesium, causing severe muscle weakness. Avoid taking magnesium at the same time with these antibiotics.
- Quinolones, Fluoroquinones, and Tetracylines: magnesium may reduce the absorption of these antibiotics. They should be taken 2 – 4 hours apart.
- Bisphosphonates (such as tiludronate and alendronate): magnesium may decrease the absorption of these medications. They should be taken minimum 2 hours apart.
- Diuretics (such as furosemide and hydrochlorothiazide): they may lower blood levels of magnesium.
- Potassium – sparing diuretics (such as spironolactone and triamterene): they may increase blood levels of magnesium.
- Calcium Channel Blockers (such as nifedipine, diltiazem, and verapamil): magnesium may increase their effectiveness, and your blood pressure may drop too low.
- Levothyroxine: magnesium – containing antacids have also calcium that can reduce the absorption of levothyroxine. They should be taken at least 4 hours apart.
- Labetalol: magnesium increases effectiveness of this medication, leading to abnormal drop of heart rate and blood pressure.
- Amphotericin B: it may lower magnesium levels.
- Corticosteroids: they may lower magnesium levels.
- Insulin: it may lower magnesium levels.