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Dietary intake of magnesium in the West has declined to less than half of those recorded 100 years ago, and is still falling. Furthermore many scientists believe that the amount of magnesium required for optimum health has been underestimated in the past, and now new research suggests that even small shortfalls in magnesium intake can seriously impair day to day energy levels.
Magnesium plays a number of roles in the body, being required for more than 325 enzymatic reactions, including those involved in the synthesis of fat, protein and nucleic acids, neurological activity, muscular contraction and relaxation, cardiac activity and bone metabolism. Even more important is magnesium’s pivotal role in both anaerobic and aerobic energy production, particularly in the metabolism of adenosine triphosphate (ATP), the ‘energy currency’ of the body. The synthesis of ATP requires magnesium-dependent enzymes called ‘ATPases’. These enzymes have to work extremely hard: the average human can store no more than about 3oz of ATP, yet during strenuous exercise the rate of turnover of ATP is phenomenal, with as much as 15kgs of ATP per hour being broken down and reformed (from adenosine diphosphate and phosphate)!
In a recent very tightly controlled three-month US study the effects of magnesium depletion on exercise performance in 10 women were observed. In the first month, the women received a magnesium-deficient diet (112mgs per day), which was supplemented with 200mgs per day of magnesium to bring the total magnesium content up to the RDA of 310mgs per day. In the second month, the supplement was withdrawn to make the diet magnesium-deficient, but in the third month it was reintroduced to replenish magnesium levels.
At the end of each month, the women were asked to cycle at increasing intensities until they reached 80% of their maximum heart rate, at which time a large number of measurements were taken, including blood tests, ECG and respiratory gas analysis. The researchers found that, for a given workload, peak oxygen uptake, total and cumulative net oxygen utilisation and heart rate all increased significantly during the period of magnesium restriction, with the amount of the increase directly related to the extent of magnesium depletion.
In plain English, a magnesium deficiency reduced metabolic efficiency, increasing the oxygen consumption and heart rate required to perform work – exactly what any individual doesn’t want!