Magnesium & The Heart
With heart disease still the major cause of death in the UK, magnesium is one nutrient that it is most important to have enough of in the diet. Not only is it vital to the health of the cardiovascular system, but it is involved in 70% of the body’s known enzyme systems.
70% of the magnesium in the body is found in the bones and teeth. The remainder is found in soft tissue cells and in the extracellular fluid. It is needed for the formation of protein and glycogen, the metabolism of carbohydrate, the storage and release of energy in ATP, and for DNA replication. It acts as a co-enzyme in the sodium pump, is required by the pituitary gland and works in balance with calcium in the nerve cells.
Signs of magnesium deficiency mainly involve the muscles and nerves and include the following:
Muscle tremors and pains
While calcium is responsible for heart contraction, magnesium is responsible for heart relaxation. It can also prevent spasms of the arteries and can prevent elevated blood pressure. Studies have shown that in the coronary arteries of heart disease victims, concentrations of magnesium are lower.
Many studies show the importance of this mineral in atherosclerosis. One of these concludes that “chronic low grade magnesium deficiency may be much more common than is conventionally considered”.
I. Szeleny writing in World Review of Nutrition and Dietetics said that magnesium opposes the progress of atherosclerosis in 6 ways:
It impedes the deposition of calcium in the aortic wall.
It lowers elevated serum cholesterol levels.
It decreases total lipid concentration in the serum.
It obstructs the “ageing” of collagen.
It elicits an increase in fibrinolytic activity.
It stabilises blood platelets.
Magnesium deficiency is associated with increased risk of coronary artery disease, sudden cardiac death, and myocardial infarction.
Although high levels of blood cholesterol are cited as a risk factor in atherosclerosis, it has never been clear how these fatty deposits and ionic calcium gain access to arterial walls that are normally impermeable. Both animal and human research suggest that magnesium may hold the key. The lower the magnesium intake, the higher the serum lipid levels and the higher the atherogenesis and fatty deposition in arterial muscle. Studies suggest that the extent of atherogenic lesions is poorly related to the level of serum cholesterol, but highly dependent on the level of dietary magnesium and also on the calcium/magnesium ratio.
Research in the last 5 years suggests that magnesium deficiency states can lead to the formation of a protein radical called ferrymyoglobin and other products of lipid peroxidation. Antioxidants offered protection in these cases, supporting the idea that free radicals are an important factor in vascular injury.
A recent French study has clearly demonstrated that the peroxidation of lipoproteins is affected by the levels of magnesium.
Many investigators have shown that magnesium lowers elevated blood pressure.
1000 patients deficient in magnesium were found to need more drugs to maintain pressure than those with normal levels.
A study using rats found that those on magnesium deficient diets for 3 months had significant elevation of blood pressure compared to controls.
There seems to be an inverse correlation between arterial blood pressure and total magnesium concentration in serum and tissue.
Of 45 consecutive patients with symptomatic atrial fibrillation, 20% had deficient serum magnesium levels.
9 patients with symptomatic atrial fibrillation and deficient serum magnesium levels needed twice as much digoxin as those with normal magnesium levels.
A study of the hardness of water in Ontario, Canada, led the investigator to suggest that the protection that was given against sudden death due to ischemic heart disease was because of the magnesium levels in it.
Many other studies lead to the same conclusion.
A 1985 study found that those living in areas where the concentration of magnesium in the water was low had a greater incidence of high blood pressure.
Researchers J. Durlach et al. stated that “studies carried out on the water magnesium level alone, as opposed to those on water hardness (magnesium and calcium) have all shown a reverse correlation between cardiovascular mortality and the magnesium level.”
The intake of magnesium can vary enormously depending on the water supply. In the USA, with a typical daily fluid intake, it has been found to be as low as 2mg or as high as 300mg.
The western half of the USA has drinking water that is twice as hard on average as the eastern half. Its death rate is around 14% less.
A recent report from the University of Mississippi, states that the frequency of myocardial calcification at autopsy after cardiac death correlated inversely to the magnesium levels in drinking water.
Magnesium researchers Altura and Altura conclude that “it is now clear from several studies in which magnesium levels were carefully ascertained that there is an inverse relationship between magnesium intake and ischemic heart disease, sudden cardiac death, and hypertensive vascular disease.”
There has been a steady decline in the intake of magnesium during this century. A typical daily intake is 185 to 260mg for men and 172 to 235mg for women. This is below the Recommended Daily Allowance of 350mg for men and 300mg for women.
A 1979 study of the diets of young women showed a magnesium intake of only 60% of the RDA.
Dr. Maurice E. Shils, Adjunct Professor (Nutrition) of Public Health Sciences at Bowman Gray School of Medicine stated that “with increasing ease and frequency of measurement of magnesium in body fluids, it has become obvious that human depletion occurs much more commonly than had been assumed previously.” Mildred Seelig of New York Medical College suggests that the RDA is too low and should be 450 to 500mg.
Many people are clearly lacking in dietary magnesium. Diets high in dairy products pose a particular problem because of their high calcium to magnesium ratios. For instance 1 ounce of Edam cheese provides 207mg of calcium and only 8mg of magnesium. Milk, cream and yoghurt have ratios of 10:1, Eggs, 5:1. Butter, 13:1.
Rich food sources are wheat bran and wheat germ, nuts, millet, tofu, spinach, and dried fruits.
The need for magnesium increases as intake of protein, calcium, fibre and alcohol increases. It also increases in lactation and possibly pregnancy. Those living in soft water areas also have increased needs. Men are given a higher RDA than women because they excrete more. Additional amounts are lost in semen, of which the prostatic component is especially rich.
Supplements usually combine magnesium with calcium. Experts differ on what ratios should be. This is probably highly individual. A better policy might be to take “green” food supplements rich in magnesium such as spirulina, green barley, chlorella, chlorophyll, or a mix of green foods.
This article was first published in Enzyme Digest No. 27, December 1995Any health and medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.