Are you at risk for a magnesium deficiency? You could be if you are active, especially if you engage in intense exercise. Magnesium is lost through your sweat as you exercise. An increase in urinary output from vigorous physical activity also results in magnesium loss. According to the results of the 1999-2000 National Health and Nutrition Examination Survey, a large number of the general population fail to meet the Dietary Reference Intake (310-420 mg/day based on age and gender). This insufficient intake, in combination with intense exercise, increases your risk for developing a deficiency.

Magnesium has many roles in your body. It is involved in more than 300 biochemical reactions according to The National Institutes of Health, Office of Dietary Supplements. Some of these include:

• Nerve conduction
• Muscle function
• Regulation of heart rhythm and blood pressure
• Energy metabolism
• Protein synthesis
• Regulation of insulin and blood sugar levels
• Maintenance of a healthy immune system

Data from several studies have shown that athletes, particularly those involved in weight-class and body-conscious sports such as skating, gymnastics, ballet, wrestling, and tennis, have suboptimal levels of magnesium. Although more research needs to be conducted, there is some evidence to indicate that exercise endurance is affected by low levels of magnesium, with a deficiency increasing the body's need for oxygen at submaximal workloads.

Insufficient intake of magnesium is associated with an increased risk for chronic health conditions such as metabolic syndrome and type 2 diabetes. Researchers are investigating the role of magnesium in the prevention and management of high blood pressure and cardiovascular disease.

Factors that can lead to magnesium deficiency:

• Insufficient intake
• Older age - older adults tend to have a lower intake of magnesium compared to younger individuals, regardless of race and gender
• Intense exercise
• Exercising in hot and humid environments which promote greater sweating rates
• Poor health of the digestive and kidney systems (magnesium is absorbed via the small intestines and excreted by the kidneys)
• Certain medications can increase urinary excretion of magnesium, such as diuretics
• Poorly-managed diabetes
• Alcoholism
• Stress

Signs and symptoms of magnesium deficiency:

• Loss of appetite
• Nausea/vomiting
• Feelings of stress are worsened
• Sleep disturbance
• Muscle spasms/cramps
• High blood pressure
• Irregular heart rhythm
• Depression/change in personality

The signs and symptoms associated with magnesium deficiency are general and can be the result of other medical conditions. Contact your physician if you are experiencing any of the above conditions. He or she will give you a thorough examination and may perform blood tests. You may also receive a referral to a nutritionist or registered dietitian who may give suggestions on how you can increase your intake of magnesium.

Some of the literature suggests that active individuals, especially those involved in intense exercise regimens, may benefit from an increase in magnesium intake by 10-20% above values recommended for the general population. Good food sources of magnesium include dark-green, leafy vegetables (spinach), legumes, nuts (almonds and cashews), and whole grains (oatmeal and wheat bran/germ).

Resources:

The Coaches' Guide to Sports Nutrition, 2007, Benardot, D. and Thompson, W.R.

ACSM's Health & Fitness Journal, January/February 2008, Volume 12, Number 1, pp. 33-35, "Magnesium and Athletic Performance," Volpe, S.L.

National Institutes of Health, Office of Dietary Supplements: "Magnesium"

ACSM, ADA, DC Joint Position Stand "Nutrition and Athletic Performance," 2009 Medicine & Science in Sports & Exercise