The French place great value in taking magnesium to help reduce the risk of heart disease. Is this nutrient truly useful for this? If "yes", where can I get it in food and how should I use supplements, if necessary?

Your question is very timely, given that June is Heart Disease Awareness Month (editor’s note: this article appeared initially in the June issue of Vitalité Quebec). Furthermore, would venture to add that magnesium is most likely the key nutrient needed for heart health.

Let's start with some clarifications. First, while this article focuses on magnesium and its cardioprotective effects, magnesium is not the only nutrient that plays a role in cardiovascular health. Indeed, several nutrients, including vitamin E, are almost as important as magnesium when it comes to cardiovascular health. Moreover, optimal cardiovascular health is not only due to an adequate intake of vitamins and minerals - healthy eating, exercise, getting enough rest and proper stress management are all crucial elements.

But back to magnesium. It is so important to the cardiovascular system that the authors of the American Pharmaceutical Association’s official text wrote "Magnesium is a nutritional superstar when it comes to cardiovascular disease." (Drugs Induce Nutrient Depletion Handbook). Few nutrients have shown such a broad spectrum of effects in terms of heart health.

What is magnesium?

Magnesium is one of the most abundant minerals in the body and is involved in over 300 enzyme reactions. It plays a crucial role in energy production and hormone balance as well as in vitamin D absorption and maintaining bone mass. Often overlooked because of the popularity of its antagonist (and sometimes agonist) calcium, magnesium is nonetheless important. Its role in the health of the central nervous system is such that the University of Adelaide in Australia has devoted a 355-page volume to it!

Cardiovascular effects

Magnesium plays an essential role in cardiovascular health. This cardiovascular system being made up of the heart and blood vessels, arteries and veins.

1. Endothelium: The endothelium, or endothelial cells, line the inside of blood and lymphatic vessels. Thus, these cells are in direct contact with blood (and lymph) and ensure the integrity of these vessels. Magnesium is essential to the health of these cells. Researchers have also suggested that taking magnesium helps prevent and treat blood vessel dysfunctions thereby preventing atherosclerosis. Moreover, researchers found that magnesium deficiency is responsible for increasing inflammation in this tissue group. Magnesium thus exerts an anti-inflammatory effect at the vascular level.

2. Vascular Toning: Smooth muscle contractions cause blood vessels to constrict or dilate. Magnesium plays a vital role in relaxing these muscles. Therefore, a lack of magnesium can cause stronger contractions in muscles that control the blood vessels thereby causing a rise in blood pressure. Many studies have shown that magnesium is essential to maintain normal blood pressure levels.

3. Cardiac Excitability: Magnesium is an important muscle relaxant. And let’s remember that the heart is a muscle, the most active muscle in the body. Magnesium plays a vital role in controlling the excitability of the heart muscle. Calcium channel blockers are the class of drug most often used to treat cardiac arrhythmias, angina and high blood pressure. These drugs prevent the activity of calcium (a muscle stimulant) in the cardiac muscle. However, certain calcium channel blockers act by facilitating the transport of magnesium to the heart muscle cells and promoting its absorption. A significant number of studies have shown that the effects of magnesium resemble those of calcium channel blockers - minus the side effects. Thus, magnesium improves arrhythmias, tachycardia and fibrillation.

4. Cholesterol: Researchers at the State University of New York published a comparative study which indicates that magnesium is as effective as statin drugs - the most commonly prescribed medication to treat and reduce high cholesterol. Among other findings, they noted that the effects of magnesium are more comprehensive than those of statins - not only does magnesium lower LDL cholesterol, it also increases the "good" cholesterol, HDL, and lowers triglycerides.

5. Heart Attack and Stroke: Magnesium reduces the risk of stroke and increases the chance of surviving a heart attack. Researchers have also shown that a magnesium deficiency is implicated in heart attacks that occur in people with healthy hearts.

But there is more! 

"Magnesium deficiency, even when it is of short duration, has consequences on the physiological, biochemical and molecular ‘machinery’ of cardiovascular cells and tissues." This is the conclusion of a study published in 2016 in the prestigious Journal of Cardiovascular Diseases & Diagnosis. Researchers suggest that a magnesium deficiency has genotoxic effects. In other words, this deficiency can adversely affect cardiovascular genetic information. This is of paramount importance in our understanding of the role of magnesium nutrition in the development of cardiovascular disease. It also suggests that one way to reduce the risk of cardiovascular disease in the population to ensure adequate intake in children as well as in adults.

Calcium and magnesium 

If magnesium is a cardiovascular relaxant, calcium is an excitotoxin – which explains why some cardiovascular drugs are intended to block the absorption of calcium into the cells of the heart muscle. Some researchers, including Dr. Rosanoff, stress that the increased incidence of certain cardiovascular problems appears to correspond with increased calcium in our diet. Since calcium and magnesium must be balanced, the increase in dietary calcium and decrease in magnesium observed since the 50’s may be having negative effects on the cardiovascular system. Non-organic fertilizers do not usually contain magnesium, but they abound in calcium. The overall effect is to reduce the concentration of magnesium in our food. What’s more, the increased calcium in food and calcium supplementation have increased the imbalance between these two minerals even more. 

This excess calcium combined with low levels of magnesium is most likely why a meta-analysis published in 2010 in the prestigious British Medical Journal suggests that people taking calcium supplements have a 27 to 31% greater risk of heart attack. High levels of calcium require high levels of magnesium.

And blood tests?

The blood tests generally prescribed by doctors do not analyze magnesium levels. Moreover, even if they were analyzed, blood magnesium levels do not adequately mirror the levels of magnesium in the cells. In other words, the fact that there is enough magnesium in the blood does not ensure that there are enough in the tissues that need it most, such as those of the cardiovascular system.

What are dietary sources of magnesium?

Magnesium is present in a variety of plant foods. Since it is the central mineral in chlorophyll, it is present in all green vegetables. It is also found in nuts, seeds and legumes. The table below lists the most important food sources of magnesium based on normal-sized portions. Note that foods grown organically usually contain more magnesium because magnesium is rarely present in "standard" fertilizers. In addition, magnesium levels may be lower when a food is cooked in water because some of the magnesium leaches into the cooking water.

Interestingly, pure cocoa is an excellent source of magnesium.

It must be emphasized that the amount of dietary magnesium is much lower than it was a hundred years ago. For example, when analyzing foods from the years 1919 to 1992, the Council for Responsible Nutrition has shown a decline of 50-80% in the magnesium found in some fruits and vegetables. This decrease is due to the fact that conventional agriculture generally does not use magnesium as a fertilizer. Furthermore, acid rain causes the soil to lose magnesium and the magnesium that is naturally found in foods declines during storage and transportation.

What are the antagonists?

Several medications can either reduce magnesium absorption or increase its elimination. It goes without saying that, wherever possible, it is better to reduce, even eliminate these drugs. However, when they cannot be eliminated, as with some medications, it is advised to increase the intake of magnesium or take supplements.

Source: Drug Influences on Nutrient Levels and Depletion, http://naturaldatabase.therapeuticresearch.com/ce/ceCourse.aspx ceid=CE4141894&cs=&s=ND&pv=1&pc=08-40&quiz=  

Some factors increase our magnesium requirements. They are either lifestyle habits, such as alcohol, or health problems such as diabetes. In these cases, it is often necessary to supplement the diet with magnesium to ensure adequate intake. 

Should we supplement?

If you consume a lot of dietary magnesium, especially from organic sources, and you have few factors that increase your needs, you may not need to take supplements. However, in all other situations, magnesium supplementation is required. Also, if you have a "genetic predisposition" for certain cardiovascular diseases or you have certain cardiovascular symptoms, it is probably necessary to take a magnesium supplement. It goes without saying that if you take a calcium supplement you should also take a magnesium supplement to ensure a healthy balance between these two nutrients. Generally, do not exceed 300mg of magnesium per day, unless directed by a healthcare professional. One important note, magnesium supplements should be taken at least 1 hour before or 2 hours after taking antibiotics. People with significant kidney disease, except for kidney stones, should not take a magnesium supplement unless it is prescribed by a health professional.

Conclusion

Cardiovascular disease remains, along with cancer, one of the major causes of non-accidental death. When we discover all that magnesium can do for the cardiovascular system, it is justified to wonder why its consumption is not encouraged and why its supplementation is not recommended more diligently. Yes, magnesium is indeed a nutritional superstar when it comes to heart health, and yes, our French cousins ​​are right.