Several months ago, I offered a “Tip of the Week” on HeartConnect that pointed out the importance of heart disease sufferers to maintain healthy magnesium levels. The tip included a link to an article that touted magnesium as an overlooked yet vitally important nutrient that helps regulate heart rhythm, blood sugar, and cholesterol — all of which are crucial to fighting heart disease.

More recently, a community member started a discussion about how low magnesium was affecting their health.

During the subsequent public and private discussions, I promised I would expand on my own research and use of magnesium in a more formal article — this one.

Our bodies need magnesium

Put bluntly, you cannot survive without magnesium. Magnesium is a vital nutrient required for a diverse collection of bodily functions such heart rhythm, blood pressure regulation, muscle contraction, and nervous system communication. When blood levels of magnesium are low, abnormal heart rhythms can suddenly develop. People suffering from atrial fibrillation and congestive heart failure (which describes a significant number of HeartConnect community members) are especially susceptible to these heart rhythm disturbances when magnesium levels are low. In addition to improved heart rhythm control, magnesium improves:

  • Insulin sensitivity: Pre-diabetes and metabolic syndrome are often due to poor insulin sensitivity and magnesium is required for insulin to function properly. Several studies using oral magnesium supplementation showed improved insulin sensitivity and reduced blood sugar by up to 37 percent.
  • Cholesterol: Improved sensitivity to insulin reduces triglycerides, which in turn results in a reduction of small LDL (bad) cholesterol particles. It is thought by many researchers that small LDL cholesterol particles (as opposed to large LDL particles) are the real culprit in coronary artery disease.
  • Blood pressure: Magnesium has been shown to modestly reduce blood pressure. The effect is small (about 2 to 4 mmHg), but every little bit helps.
  • C-Reactive Protein (CRP): CRP is a measure of inflammation and a known risk factor for heart disease. A study reviewing the massive NHANES health database showed that 50 percent of U.S. adults do not get the recommended daily allowance (RDA) of magnesium and this group had significantly higher CRP levels.

Unfortunately, determining if you have sufficient magnesium is frustratingly difficult. Even magnesium blood tests can be very misleading. If your magnesium blood level is low, that is indeed an indicator of low magnesium at the cellular level, where it is most important. One study found that only 7.7 percent of a test group of heart disease patients were low in blood level measures of magnesium. However, when the magnesium tissue levels of this same group were tested, more than 50 percent of the participants tested low in magnesium.

The message is clear. A normal blood level may hide the fact that your body tissues are still magnesium deficient. This is particularly true of magnesium levels in heart muscle.

Do I have low magnesium?

As stated above, a low magnesium blood level is proof-positive of low magnesium levels throughout the body tissues. However, a normal test misses low magnesium levels about half of the time. Perhaps the best way to determine if your magnesium levels are truly low (assuming your blood test is within the normal range) is to note your symptoms. If you have one or more of the following symptoms, low magnesium could be the cause.

  • Cardiac arrhythmias: Having any sort of heart rhythm disorder should alert your doctor to investigate whether your magnesium levels are low.
  • Low potassium: It is common for heart patients using diuretics to lower blood pressure to become potassium-depleted. The same is true of magnesium. If your potassium is low, it is a good bet your magnesium is low as well.
  • Muscle cramps: Cramping, especially leg cramps at night (as opposed to cramps that occur with physical activity, which is indicative of poor blood flow) is often a signal your body tissues are magnesium depleted.
  • Anxiety and fatigue: Common, non-specific symptoms like anxiety and fatigue can sometimes be a sign of magnesium deficiency.

How can I get the magnesium I need?

There are three easy ways to get the magnesium you need — including one that I found surprising and a little worrisome.

1. Supplements

A commonly recommended supplement dose is 500 mg per day of magnesium (the US RDA for magnesium is 320 mg for women and 420 mg for men). Look for the amount of magnesium listed on the supplement label.

There are many different forms of supplemental magnesium available at your neighborhood pharmacy, supermarket, or supplement store. These include magnesium oxide, magnesium gluconate, magnesium chloride, magnesium lactate, magnesium citrate and magnesium malate. I take the malate form.

A note of caution is in order — all magnesium supplements can have a laxative effect, causing loose stools and diarrhea. I have found magnesium oxide to be the worst offender. While it has a high concentration of magnesium, this high concentration seems to increase the laxative effect (taking in a high concentration doesn’t help if you just “lose” it at the other end).

2. Foods rich in magnesium

You can significantly increase magnesium intake by consuming foods rich in magnesium. In addition to the fact these sources are natural, they are also far less concentrated and not prone to exhibiting the laxative effect experienced with supplements. Here are a few foods found to be high in magnesium.

Magnesium content (mg)

Oat bran (1 cup, raw) — 221
Halibut (1/2 filet) — 170
Spinach (1 cup cooked) — 163
Barley (1 cup, raw) — 158
Pumpkin seeds (1 oz) — 151
Soybeans (1 cup, cooked) — 148
Beans, black (1 cup, cooked) — 120
Brazil nuts (1 oz) — 107
Artichokes (1 cup) — 101
Beans, lima (1 cup, cooked) — 101
Rice, brown (1 cup, cooked) — 84
Almonds (1 oz) — 78
Oatmeal (1 cup, cooked) — 56
Filberts, Hazelnuts (1 oz) — 46
Walnuts (1 oz) — 45

(Source: USDA National Nutrient database for Standard Reference)

  1. Water

Water, yes, water — at least unprocessed water — can be high in magnesium and it used to be one of the principal ways humans got the magnesium they need. But, studies suggest that magnesium intake is dropping because we are drinking more bottled water, soft drinks, and processed water that is depleted of magnesium by filtration, deionization, and water-softening (this includes softened water in our homes or municipal water systems). Moreover, many carbonated soft drinks contain phosphates that prevent magnesium from being absorbed. Even well-water can become magnesium depleted is it is softened to remove hard minerals.

A large number of Americans ingest less than the Recommended Daily Allowance (RDA) of magnesium per day. As a result, magnesium deficiency is becoming more and more common. Indeed, epidemiology studies confirm that magnesium deficiency is growing worldwide. The World Health Organization (WHO) reported a relationship between cardiovascular death and water hardness (as measured by magnesium and calcium content). The WHO concluded that:

“…results from the early epidemiologic studies suggest that sudden (cardiac) death rates in soft water areas are at least 10% greater than sudden death rates in hard water areas. If magnesium supplementation causes even a modest decrease in sudden death rates a substantial number of lives might be saved.”

You can certainly buy specialty mineral waters that contain magnesium but this would require you to drink substantial volumes which can be prohibitively expensive. A better idea may be to simply make your own “magnesium water.” It’s really quite easy. Just add about 2 tablespoons of unflavored Milk of Magnesia (MOM) to a liter of seltzer water (flavored or unflavored) and shake. Note that you should add the MOM slowly to avoid foaming. I’ve also found it also foams less when the seltzer water is cold. The water will appear cloudy at first but become clear over time and a small amount of MOM may also collect at the bottom of the bottle. Finally, like any carbonated beverage that is shaken, you should open the cap slowly the first time!

One 8-ounce glass per day will provide about 330 mg of the highly-absorbable magnesium bicarbonate form of magnesium. I find magnesium water to be a pleasant change of pace to taking yet another large supplement pill. In fact, when I make magnesium water I use it to wash down all the other vitamins and pills I take. You really need to play with the amount of MOM, as everyone has a different sensitivity to the laxative effect of MOM, but I have no problems at the stated concentration if I limit intake to one 8-ounce glass per day.

In conclusion

The takeaway lessons about magnesium are clear.

n A majority of Americans — and perhaps people worldwide — are deficient in magnesium.

n Magnesium is an essential heart-health nutrient for all heart disease sufferers and perhaps especially for those suffering heart arrhythmias.

n Healthy levels of magnesium are readily available from foods, supplements, and, with a little work these days, from our water.

Finally, as always, consult your health professionals before making any change to your health regimen. Remember, we are all different. What might be a healthy practice for most does not necessarily mean it will be healthy for you!

Looking out for your heart health,