Magnesium is the fourth most common mineral in the human body and one of the most abundant minerals on earth. Magnesium participates in over 300 cellular reactions in the human body. However, we rarely talk about it during forums and discussions.
Awareness about magnesium and its role in maintaining various cellular processes that the human body depends upon, is relatively low. Packaging of food in our “to-go” fast paced life, depletion of magnesium in soil and a limited supply of foods that provide magnesium in our diets has augmented our dietary deficiencies. And we are paying the price.
A systematic deficiency
In the National Health and Nutrition Examination Survey (NHANES) conducted in 1999-2000, only 40% of Americans were meeting the recommended daily intake of magnesium through their dietary source(1). The average daily requirement of magnesium for an adult male is between 400-450 mg and for women about 350 mg.
These requirements substantially increase with athletic activities particularly those that cause significant strain on the muscles- e.g. endurance workouts, marathon runs/training and extended workouts in the gym. Precise data on requirements of magnesium for athletes is still missing, although there is a general consensus that a 20-30% of increased intake of magnesium above average is the minimum amount recommended for athletes every day (500-600 mg/day).
This requirement also increases in certain individuals with enhanced magnesium losses—these in particular are those who take diuretics (also called water pills) for heart failure or in diarrheal states.
Magnesium deficiency can also happen from a poor absorption of this mineral from the GI tract as a result of some medications. Common culprits are antacids such as proton pump inhibitors that are commonly prescribed for heart burn.
Lastly, alcohol intake leads to a magnesium deficiency over a period of time—the mechanism for this is thought to be due to loss of magnesium in urine with prolonged and consistent alcohol use.
A deficiency that can go unnoticed
Magnesium deficiency at times can be subclinical(2). Which means that the laboratory measurement of blood magnesium may be normal but the body tissue stores may still run low. And this is critically important for electrolytes, since these minerals constantly circulate between the blood (or the vascular compartment) and the cells.
If a person eats a magnesium rich diet, the blood magnesium levels increase first and then the electrolyte deposits in the bone and other tissues. These serve as a warehouse and enables the body to utilize the mineral in the future when the stores run low. Similarly, if the person becomes magnesium deficient, the body digs into these reserves to ensure that the blood levels of free magnesium remain normal for the tissues to function properly.
As the deficiency persists, eventually, the blood magnesium levels fall and these can be detected by a laboratory test. However, by the time that the blood magnesium levels drop, the deficiency is moderate or even severe and can continue to get worse.
The bottom line- blood magnesium levels do not tell the whole story. One could have a normal magnesium level and can still be deficient- and more importantly, have symptoms of magnesium deficiency with a normal blood test for magnesium(3).
We still do not have ways to accurately measure the total body magnesium in individuals. Total bone magnesium or red blood cell magnesium can be measured at some institutions but these tests are neither available everywhere nor are they cost effective.
What is evident however, at least through some clinical and observational studies, is that despite a fairly normal blood magnesium level, supplementation with magnesium can help with some symptoms of muscle fatigue, cramps and soreness in selected individuals. In some studies, elderly women who were supplemented with magnesium were able to improve their muscle performance over a three-month period(4).
Supplements that can help
There are a variety of supplements currently marketed for magnesium. Common ones being magnesium oxide, citrate or gluconate salts. The latter two are easily absorbed from the stomach as opposed to the oxide salt although magnesium oxide can “pack” a lot more elemental magnesium per dosing.
Magnesium supplements are often used to treat muscle cramps, particularly in individuals who have magnesium deficiency or those who take diuretics. Magnesium supplements are generally safe and restriction is only required in individuals with kidney disease.
The easier way to get magnesium is through dietary inclusion of eggs, leafy vegetables, bran cereal and nuts. In athletes who need more magnesium than average adults, an electrolyte mix such as MAGNAK® can help provide the extra requirement.
It is time to realize that magnesium deficiency is prevalent in the general population, far more than was previously thought. Athletes need to be educated on this so that they can make appropriate changes in their diet and hydration practices to ensure they get an adequate amount of this missing mineral. It is high time that sports drinks routinely start supplementing magnesium in their formulas and move away from their archaic mixture of salt and sugar.
References:
Dr. Kharait is an MD and a practicing Nephrologist in Northern California. He completed his Residency in Internal Medicine and Fellowship in Nephrology from the University of California, San Francisco. He has a PhD in Molecular Physiology from the University of Pittsburgh and specializes in treating patients with electrolyte disorders and kidney diseases.
