Wednesday, February 12, 2014

Magnesium: From Muscle Relaxation to Heart Disease Prevention

by Anne Guzman, PCG Nutritionist

Peaks Coaching Group Magnesium for Endurance Athletes

Magnesium has many important functions in the body, ranging from energy production and nerve function to muscle relaxation. This important mineral also plays a key role in cardiovascular disease prevention. Its effects are far reaching.

About two-thirds of our bodies’ magnesium is found in our bones. Magnesium in our bones helps give them their physical structure; this magnesium is part of the bone's crystal lattice and is found in the bone’s “scaffolding," together with the minerals phosphorus and calcium. Magnesium is also found on the surface of the bone. Rather than being part of the bone structure, this magnesium is in storage and available for use when the body has poor dietary supply. It also acts to alkalize the body when put in a state of acidity.

Magnesium and its fellow macronutrient, calcium, act together to help regulate the body's nerve and muscle tone. In many nerve cells, magnesium serves as a chemical gate blocker; as long as there’s enough magnesium around, calcium can't rush into the nerve cell and activate the nerve. This gate blocking helps keep the nerve relaxed. If our diet provides us with too little magnesium, this gate blocking can fail and the nerve cell can become over activated. When some nerve cells are over activated, they can send too many messages to the muscles and cause the muscles to over-contract. This chain of events helps explain how magnesium deficiency can trigger muscle tension, muscle soreness, muscle spasms, muscle cramps, and muscle fatigue. It is important for athletes to ensure they are consuming enough high magnesium foods to prevent muscle spasms.

Many chemical reactions in the body involve the presence of an enzyme. Enzymes are special proteins that help trigger chemical reactions. Over 300 different enzymes in the body require magnesium in order to function. For this reason, the functions of this mineral are especially diverse. Magnesium is involved in the metabolism of proteins, carbohydrates, and fats. Some fuels cannot be stored in our muscle cells unless adequate supplies of magnesium are available. Since magnesium is important for enzyme function, magnesium will also be important for proper digestion, which requires many enzymes.

Magnesium is also known for helping nerve function throughout the entire body, and it does the same thing for your heart muscle and the nerves that initiate the heartbeat. If your magnesium levels are low, you are more likely to be at risk for arrhythmias (irregular heartbeats) and heart palpitations. While doctors can temporarily stabilize irregular heartbeats with injections of a magnesium compound, this is generally not done except in an emergency situation. The fact that they do this in emergency scenarios tells us how impactful magnesium is.

For those with angina, magnesium can help with spasms of coronary arteries, which is what causes intense chest pain. High blood pressure can also be affected by magnesium. Magnesium can relax the muscles that control blood vessels so that blood can flow more freely, which can reduce the chances of having a stroke or heart attack and lower blood pressure.

An analysis published in February 2012 in the European Journal of Clinical Nutrition evaluated 141 studies involving magnesium’s effect on blood pressure. The researchers found that magnesium supplementation produced a “clinically significant reduction” in both systolic and diastolic blood pressure. People who have congestive heart failure especially need to be cautious of both arrhythmias and blood pressure, and for this reason it’s important that they have sufficient magnesium in their diets.

In February 2012, the American Journal of Clinical Nutrition published an analysis of seven studies involving more than 240,000 participants in Sweden. The researchers found that for every 100mg increase of magnesium intake, the risk of strokes caused by blood clots in the brain was reduced by 8 percent. According to Carolyn Dean, M.D., N.D. (Wellness Times editorial advisor), in the 1900s people received about 500 mg of magnesium per day, but because of soil depletion, food processing, and other factors, the average daily intake is now only about 175 mg.

“A burst or clot-blocked blood vessel in the brain is all it takes to cause a stroke that results in the destruction of critical brain functioning,” explains Dean, who is also the medical director of the Nutritional Magnesium Association. “Stroke is said to be caused by hypertension, atherosclerosis, and/or diabetic complications, all of which are associated with magnesium deficiency.”

Excess magnesium can cause diarrhea and feelings of weakness. In 1997 the National Academy of Sciences set a tolerable upper limit (UL) on intake of magnesium at 350 milligrams per day for individuals 9 years old and older. This limit was restricted, however, to magnesium obtained from dietary supplements, and no upper limit was set on intake of magnesium from food sources. Magnesium citrate powder is one of the best-absorbed forms of supplemental magnesium.

Finding the right balance is key. Magnesium pulls water into the small intestine which is useful for relieving constipation, but again, if overdone it can cause diarrhea. Slowly increasing doses is a good idea.

The RDA for magnesium differs for all age categories, ranging from 80 mg for kids 1-3 years old to as high as 350. The table below lists the ULs for supplemental magnesium for healthy infants, children, and adults in milligrams (mg). Physicians may prescribe magnesium in higher doses for specific medical problems. There is no UL for dietary intake of magnesium; only for magnesium supplements.

Office of Dietary Supplements, National Institutes of Health

Some foods high in magnesium include:
  • Swiss chard
  • Spinach
  • Mustard greens
  • Blackstrap molasses
  • Turnip greens
  • Pumpkin seeds
  • Green beans
  • Sea vegetables
  • Cantaloupe
  • Kale
  • Celery
  • Bell peppers
  • Sunflower seeds
  • Flax seeds
  • Quinoa
  • Fennel
  • Broccoli

This list could be much longer, but these are some top choices.

As you can see, magnesium plays a very important part in many aspects of our health. Be sure to pay attention to your dietary intake. Supplementation is also an option, as many foods are now lower in minerals due to poor soils.

1. Agatston, Arthur, M.D. “The Link Between Magnesium and Heart Disease.” Heart Health. 2012.
2. Dean, Carolyn, M.D., N.D. The Wellness Times. “Magnesium’s Many Heart Health Benefits.” 2012.
3. Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Magnesium. 

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