Home HealthTopics Health Centers Reference Library Research
Join us on Facebook Join us on Facebook Share on Facebook

Pharmacy and Medications

Magnesium oxide

12/10/2007

Question:

hyperexol has as ingredients magnesium oxide, studies have proven that only 4% of magnesium gets dissolved, should i take an additional magesium spplement to get the full potential magesium will provide for my b/p

Answer:

To answer your question in a word. No.

This is the second response in recent weeks that addresses the use of Hyperexol. We recommend against using this product as treatment for high blood pressure.

Hyperexol is a dietary supplement containing a proprietary blend of vitamins, minerals and herbs including about 200mg of magnesium oxide per tablet. If taken as directed by the manufacturer, Hyperexol will deliver a daily dose of 800mg of magnesium oxide. This dose is equivalent to 20 millimoles/day of magnesium. This dose is similar to amount given in clinical trials of magnesium as a treatment for high blood pressure.

Its marketers claim Hyperexol reduces blood pressure. In other words, they claim that it can be used to treat high blood pressure. However, there are no studies published in the medical literature that substantiate the marketer's claim. Claiming that a dietary supplement treats a disease is illegal. This is because the claim that a supplement actually treats a disease, in this case high blood pressure, makes it a drug as defined by law. In the United States, drugs must be must be approved by the Food and Drug Administration (FDA) prior to being marketed. Part of the FDA approval process requires that the manufacturer provide information sufficient to show that the drug is both safe and effective for its claimed use. Clearly, the makers of Hyperexol have not done this.

Magnesium is used primarily as an antacid and a laxative depending on the salt form. Magnesium sulfate is used as an injection to treat eclampsia, a pathologic condition that occurs during pregnancy, and to treat certain types of aberrant heart rhythms. Some medicines, mainly diuretics, can deplete body stores of magnesium, and patients taking these medicines may need to magnesium supplements to counteract the losses.

Magnesium is poorly absorbed from the digestive tract. Your statement that only 4% of magnesium oxide is dissolved is incorrect, but may be based on a 2001 study by Firoz et al. This study compared the bioavailability of magnesium from a number of magnesium salts. Normal volunteers were given 21 milliequivalents/day (roughly 10millimoles) of magnesium as various magnesium salts. Based on urinary excretion data, the researchers found that only about 4% of the magnesium from magnesium oxide was absorbed. Other magnesium salts provided somewhat better bioavailability.

Even though the bioavailability of magnesium salts is typically low, toxicity may occur with over zealous supplementation. The risk of developing magnesium toxicity increases as kidney function decreases because the kidneys lose the ability to remove excess magnesium. Signs of excess magnesium can be similar to magnesium deficiency and include:

A 2002 meta-analysis evaluated the effect of magnesium supplementation on blood pressure. 20 English language studies conducted between 1983 and 1999 with various designs and using 7 different magnesium salts were included. The median dose of magnesium regardless of salt form was 15.4 mmol/day with a range of 10-40 mmol. The daily dose range of magnesium for the 4 studies in which magnesium oxide was used was between 12.4 and 24.7. Small reductions of blood pressure were noted in the pooled data.

Large epidemiologic studies attempting to determine the effect of magnesium on blood pressure have produced inconsistent results. In these studies no effect was noted, or initially positive results were refuted in follow up studies. Current treatment guidelines from Canada recommend against using magnesium supplements for either prevention or treatment of high blood pressure because the evidence of efficacy is lacking.

The United States National Institute of Health (NIH) provides the following input:

"Epidemiologic evidence suggests that magnesium may play an important role in regulating blood pressure." Diets that provide plenty of fruits and vegetables, which are good sources of potassium and magnesium, are consistently associated with lower blood pressure. The DASH study (Dietary Approaches to Stop Hypertension), a human clinical trial, suggested that high blood pressure could be significantly lowered by a diet that emphasizes fruits, vegetables, and low fat dairy foods. Such a diet will be high in magnesium, potassium, and calcium, and low in sodium and fat.

An observational study examined the effect of various nutritional factors on incidence of high blood pressure in over 30,000 US male health professionals. After four years of follow-up, it was found that a lower risk of hypertension was associated with dietary patterns that provided more magnesium, potassium, and dietary fiber. For 6 years, the Atherosclerosis Risk in Communities (ARIC) Study followed approximately 8,000 men and women who were initially free of hypertension. In this study, the risk of developing hypertension decreased as dietary magnesium intake increased in women, but not in men.

Foods high in magnesium are frequently high in potassium and dietary fiber. This makes it difficult to evaluate the independent effect of magnesium on blood pressure. However, newer scientific evidence from DASH clinical trials is strong enough that the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure states that diets that provide plenty of magnesium are positive lifestyle modifications for individuals with hypertension. This group recommends the DASH diet as a beneficial eating plan for people with hypertension and for those with "prehypertension" who desire to prevent high blood pressure"

http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/

http://www.ods.od.nih.gov/factsheets/magnesium.asp

The notion that reasonable exercise and eating a healthy diet rich in fruits and vegetables, high in fiber, and low in fat and sodium can reduce blood pressure makes sense. There is clear evidence that lowering blood pressure yields health benefits by reducing the risk of heart attacks, stroke and other cardiovascular accidents. The evidence that supplemental magnesium is particularly beneficial for blood pressure reduction is much less compelling. Further it does not make sense to attempt to self treat high blood pressure with expensive unproven therapies. At a minimum, patients with high blood pressure should work with their personal physician to develop a holistic treatment plan that works.

For more information:

Go to the Pharmacy and Medications health topic, where you can:

Response by:

Robert James Goetz, PharmD, DABAT
Assistant Professor of Pharmacy Practice
College of Medicine
University of Cincinnati