There is perhaps no more contentious subject in medicine than the role of vitamin pills and supplements. It is a huge subject area, and one to which we shall return.

There is perhaps no more contentious subject in medicine than the role of vitamin pills and supplements. It is a huge subject area, and one to which we shall return. Rather than address the entire field, I want to stick with just two questions: Who needs to take magnesium supplements? What should they take? The answer to the first question is, "A lot of us." Studies indicate that 12% to 25% of the population is deficient in magnesium. The Recommended Daily Intake (RDI) of magnesium is 320 to 380 mg/day for adults. Most of us do not get that from the food that we eat. Some people get some in their water, 13 to 20 mg/liter in tap water from ground sources, but many people drink only bottled water. Ozarka water in Texas has 1 mg of magnesium per liter. Cooking with water low in magnesium (Mg) can also reduce the Mg content of foods. Foods that are high in magnesium include dark leafy greens, nuts and seeds, fish, soybeans, avocados, bananas, dark chocolate, and yogurt.

Many health conditions are made worse by magnesium deficiency. Leg cramps, in particular, can be debilitating in some people with magnesium deficiency, and I have never seen a case of leg cramps that did not improve with Mg supplementation. Diabetes also can be greatly affected by magnesium levels. A study published in the journal Diabetes Care in 2003 showed that the addition of magnesium chloride supplementation resulted in reducing average blood sugar from 240 to 183. Another study from Harvard University revealed that a high daily magnesium intake reduces the risk of diabetes by up to 33 percent. Low magnesium can cause potassium to be low, and it increases blood pressure in hypertensive patients. It will also make asthma and migraine headaches worse and it is associated with obesity.

In addition to low dietary intake, certain medications cause loss of Mg, especially the combination of diuretics ("water pills") and medications like Nexium or Prilosec, known as proton pump inhibitors. Anything that causes large losses of fluids in the urine or the stool, such as uncontrolled diabetes or chronic diarrhea, will cause Mg deficiency. Blood tests are notoriously inaccurate for diagnosis of magnesium deficiency, because less than 1% of the body stores of Mg are in the blood. Therefore, blood levels are mostly determined by physiologic factors that determine the movement of magnesium within the body. However, if a blood test does pick up a low level it is a good indication that total body stores are low. Another problem with blood tests is that magnesium is not on any of the routine laboratory panels, even more frustrating is the fact that insurance usually won't pay for a blood test without the documentation of one of a handful of specific diagnoses… like "low magnesium." Of course!

As far as which supplement to take, the usual factors should be considered: availability, cost, side effects and efficacy or effectiveness. Magnesium oxide (e.g. MagOx) and magnesium chloride (e.g. Slow K) are the two most readily available supplements, and neither is very expensive. Any type of magnesium can cause diarrhea as well as stomach upset and cramping. I find that magnesium oxide has less in the way of side effects than some others, but that is probably because so much of it passes through the gut without being absorbed. I find that some people don't absorb anything at all from it. Slow K is better absorbed, but causes more side effects. It takes at least 3 months to replenish a body that has a significant magnesium deficiency. One tablet of a non-prescription magnesium supplement is safe for almost anyone who does not have kidney disease, but if you do have kidney disease you should probably not take any supplement -- and especially not magnesium -- without your doctor's specific recommendation. The kidney is the only organ that can compensate for excessively high magnesium levels in the body.

This article is intended to provide general information only, and is not to be taken as medical advice. For advice about a particular case or situation, consult your own physician or other trusted health professional.

This column is a service of The Health and Wellness Coalition of Runnels County which now meets every second Thursday at 7 pm. The next meeting will be May 10 at 7 pm in Winters, and will be devoted to Emergency Planning and Preparation for Healthcare Services and Facilities.