Magnesium plays an important role in developing and maintaining healthy, strong bones and is equally key for muscle function and tone. Unfortunately, the U.S. Department of Agriculture estimates that about 68 percent of Americans are deficient in magnesium, due partly to poor dietary choices, but also due to the mineral-depleted soil that most commercial vegetables and fruits now grow in. Magnesium deficiency leads to various musculoskeletal symptoms.
Function of Magnesium
Magnesium is an alkaline earth metal that is an essential component of the mineral matrix of bones. In fact, approximately 60 percent of the body's magnesium is held within the skeleton, according to "Biochemical, Physiological and Molecular Aspects of Human Nutrition." Magnesium is also required for normal muscle tone and function, especially relaxation, which explains why about 20 percent of it is found within skeletal muscle. Magnesium is sometimes used to reduce nerve excitation and blood vessel spasms, which occur in involuntary smooth muscle. Further, numerous enzymes need magnesium for their actions, including the production of ATP molecules, which are the main source of energy for the body.
Recommended Daily Amounts
The National Institutes of Health recommended daily amounts of magnesium for adults younger than 30 years is 400 mg for males and 310 mg for females. For adults older than 30 years, the levels increase to 420 mg and 320 mg, respectively, although 360 mg is recommended for pregnant females. Healthy adults should have serum levels of magnesium measured between 0.7 and 1.0 mmol/L and approximately 24 g of total magnesium within their bodies, as cited in "Textbook of Medical Physiology." Deficiency in some populations is related to food refining and modern fertilizers that contain no magnesium. High protein consumption often leads to reduced magnesium absorption.
Deficiency Effects
Non-muscular symptoms of magnesium deficiency frequently include nausea and fatigue. Chronic magnesium deficiency contributes to asthma, type-2 diabetes, osteoporosis, and may eventually lead to seizures, personality changes and ischemic stroke. According to "Human Biochemistry and Disease," muscular effects of magnesium deficiency include increased muscle tension and muscle cramps, although long-term effects can include abnormal heart rhythms and coronary artery spasms. Some researchers suggest that lack of magnesium is a contributing factor in developing "restless leg" syndrome, which can severely disrupt sleep and lead to insomnia and further complications. Eating magnesium-rich foods or taking a supplement prior to bedtime can help muscles relax, which is essential to progress beyond stage one of non-REM sleep and to achieve deep, restorative, delta-wave sleep.
Rich Sources of Magnesium
According to the "American Dietetic Association Complete Food and Nutrition Guide," rich sources of magnesium include green leafy vegetables, such as spinach and broccoli, fish with the bones, most legumes such as lentils and peas, some nuts such as almonds and cashews, yogurt, brown rice, bananas, chocolate, coffee and black teas. In terms of supplements, magnesium citrate is considered the most bio-available type.
References
- "Medical Nutrition and Disease: A Case-based Approach"; Lisa Hark; 2008
- "Biochemical, Physiological and Molecular Aspects of Human Nutrition"; Martha Stipanuk; 2006
- National Institutes of Health: Office of Dietary Supplements: Magnesium Fact Sheet
- "Textbook of Medical Physiology -- Tenth Edition"; Arthur C. Guyton et al; 2000
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
- "American Dietetic Association Complete Food and Nutrition Guide"; American Dietetic Association; 2006
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