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Can Magnesium Prevent High Blood Pressure?


Updated April 23, 2014

What is Magnesium?

Magnesium is a naturally occurring mineral, and is essential for proper functioning of the human body. In fact, more than 300 biochemical processes directly depend on magnesium. While magnesium is the fourth most abundant mineral in the human body, very little actually circulates in the blood or other tissues. Instead, most of the body’s store of magnesium is locked up in the hard outer layer of our bones. We obtain magnesium through the foods we eat – it is absorbed in the small intestine and excess amounts are excreted by the kidneys. In the past few years, there has been an increased interest in the possible role that magnesium may play in preventing and managing conditions like high blood pressure and cardiovascular disease.

Can Magnesium Prevent High Blood Pressure?

Maybe. The evidence up to this point is not entirely clear. One study found data which seems to show that magnesium plays an important role in regulating blood pressure. Additionally, a number of other studies have looked at various nutritional factors and how they contribute to the prevention of high blood pressure – these studies have shown that diets rich in magnesium do seem to have some protective effect, and that people who have diets rich in magnesium seem to develop high blood pressure at a lower rate.

There are, however, some problems with interpreting all this data. The main problem is that none of the studies so far have looked at the effects of magnesium alone. Rather, they have focused on "diets rich in magnesium." As it turns out, a magnesium-rich diet consists of lots of fruits and vegetables, and usually includes fairly high levels of fiber and whole grains, and only small amounts of red meats. In other words, magnesium-rich diets tend to be good for you regardless of the magnesium they contain. To make matters more complicated, foods that are rich in magnesium also tend to contain high levels of potassium. Unlike magnesium, potassium - by itself - has been shown to provide beneficial effects for preventing and managing high blood pressure.

In light of this complicated research picture, the real question is: Is it the magnesium in these "magnesium-rich diets" that is providing the apparent protection, or is the observed benefit related simply to the fact that diets rich in magnesium are just plain good for you? To date, this question has no conclusive answer. However, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, a well-known and respected medical body, feels that the data is strong enough for them to officially state that diets which provide plenty of magnesium are a "positive lifestyle modification for individuals with hypertension."

Should I Take Oral Magnesium Supplements?

No. There is no data to support the claim that oral magnesium supplements offer the same benefits as a magnesium rich diet. Even though magnesium may be beneficial, it may be the case – as it is with other minerals – that how you get magnesium is as important as the magnesium itself. In other words, the human body is very good at digesting real foods and absorbing the vitamins and minerals they contain. On the other hand, the human body does not seem to be very good at extracting much nutritional benefit from various types of dietary supplements. The ideal way to get the recommended daily allowance(RDA)of magnesium is from natural food sources. For healthy adults, the male RDA is about 420mg and the female RDA is about 320mg, or 360mg during pregnancy.

What are Good Dietary Sources of Magnesium?

Magnesium is found in a wide variety of healthy, inexpensive foods. Fish and nuts are especially rich in the mineral – one ounce of almonds (a small handful) contains about 80mg of magnesium. Potatoes, beans, and low-fat dairy products are also good sources of magnesium, as are certain vegetables such as spinach. As an example, consider the magnesium content of these foods:

  • Cooked white fish, 3oz: 90mg
  • Cashews, 1oz: 75mg
  • Medium baked potato: 50mg
  • Plain lowfat yogurt, 8oz: 45mg
  • Medium banana: 30mg
  • Ready-to-eat pudding, 4oz: 24mg
Each of these foods is also a good source of potassium and calcium, which are helpful in the prevention and management of high blood pressure. A simple rule of thumb for eating a healthy diet is to eat foods that are many different colors. Green peppers, red apples, yellow bananas, brown potatoes, etc.

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1. Svetkey LP, et al. Effects of dietary patterns on blood pressure: Subgroup analysis of the Dietary Approaches to Stop Hypertension (DASH) randomized clinical trial. Archives of Internal Medicine, 159:285-93.
2. Saris NE, et al. Magnesium: an update on physiological, clinical, and analytical aspects. Clinica Chimica Acta 2000;294:1-26.
3. Vormann J. Magnesium: nutrition and metabolism. Molecular Aspects of Medicine 2003:24:27-37.
4. Abbott L, Nadler J, Rude RK. Magnesium deficiency in alcoholism: Possible contribution to osteoporosis and cardiovascular disease in alcoholics. Alcohol Clinical Experience Research 1994;18:1076-82.
5. Kaplan NM. Treatment of hypertension: Insights from the JNC-VI report. American Family Physician 1998;58:1323-30.

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