Magnesium is an important mineral found predominately in our bones (50-60%), and the remainder distributed equally between muscle and non-muscular soft tissue. These magnesium levels are maintained and balanced via dietary intake, renal and intestinal function. This abundant mineral is utilised in a wide range of biological reactions in the body including over 300 essential enzymatic reactions, these enzymes play a vital role in the cell function, particularly energy metabolism – which is where magnesium becomes important for the cyclist/athlete. Other useful functions for the athlete are:
– muscle activity
– nerve conduction
– amino acid and protein synthesis
– optimise immune function
– regulate vascular tone
Magnesium maintains strong bones, calms the nervous system, regulates heartbeat, strengthens digestion, prevents swelling, regulates thyroid, assists hydration levels, prevents kidney stones, maintains a healthy prostate in men… the list goes on. There are many aspects of this mineral that would greatly assist your athletic performance and recovery to optimise the benefit of your hard work in training.
There are many forms of magnesium on the market and it can become very confusing with all the advertising claims, so it is best to be educated on the variations of this important mineral. Magnesium is not easily absorbed in the body unless attached to another substance to assist in the transporting into the cells, for this reason many products have ‘chelated’ magnesium to amino acids to increase their bioavailability. Consideration must also be made to what function you want your magnesium for e.g. heart or muscle support. The main types of magnesium are discussed below:
Magnesium oxide: Ever wondered why some magnesium supplements give you diarrhoea? Don’t be fooled by a product containing high amounts of magnesium oxide. This form can barely be absorbed and is usually added to increase the ‘total magnesium’ for labelling purposes. Magnesium oxide is chemically bound and is mostly used as a laxative. While the quantity may be high its absorption is only 4%.
Magnesium Amino Acid Chelate:This form of magnesium has smaller elemental magnesium amount therefore needs higher doses to achieve therapeutic dose. Mag Chelate is given to assist in nervous system and musculo-skeletal conditions.
Magnesium Citrate: This form has good absorption and derived from citric acid, absorption is at 85%. Mag Citrate is predominately used for musculo-skeletal and nervous system functions.
Magnesium Orotate: Derived from orotic acid and has a high absorption rate of 85%. Commonly used for cardiovascular therapies. However is beneficial for muscle cramps also, this due to the orotic acid that is used in the citric acid cycle.
Magnesium Chloride: This form has both positive and negative cations to enhance equilibrium (ionically stable). Chloride separates quickly and is absorbed in stomach before reaching the small intestine, this assisting gastric acid production. Mag Chloride is effective in detoxification and tissue purification.
Magnesium Aspartate: This form is not to be used. The magnesium is bound to the amino acid aspartate or aspartic acid. Aspartate is known as an excitatory neurotransmitter, which at high doses can over stimulate neurons and result in cell death.
Magnesium Sulfate: Also known as Epsom salts. This form stays bound when taken internally, therefore can only absorbed through the skin.
Magnesium can be depleted in the body by alcohol, caffeine, sugar, vitamin B6 deficiency, and increased calcium (>2600mg/day) or vitamin D consumption. Predominant deficiency signs:
– muscular weakness and spasm
– vertigo, anorexia and weight loss
– numbness, tingling, cramps
– difficulty remembering things
– mental confusion, lowered concentration
– Sleep and mood disordersSources of Magnesium
Maintaining adequate consumption of magnesium-rich foods can assist magnesium levels especially when at high demand in athletes. These foods include: legumes, nuts, dark green leafy vegetables (be cautious not to over cook as the mineral will be lost, if exposed to excessive prolonged heat), seeds, cacao, wheat germ, coconut water and spirulina.Recommended Daily Intake
Men: 400mg/day Woman: 310mg/day Children: 250mg/day If these dose results in loose stools, reduce dose to half or a quarter and spread throughout the day. Dosing can be increased from these amounts to 800mg/day when required and advised by your healthcare practitioner. Interactions Magnesium can potentially increase the excretion of Aminoglycosides, Digoxin, Cisplatin, Loop Diuretics and Thiazide diuretics. The following substances can decrease magnesium levels in the blood and body: Corticosteroids, Oral Contraceptives, Hormone replacement therapy, Beta Adrenergic, Riboflavin, Thyroxine, Laxatives, Caffeine, Aldosterone, Pentamidine. If in doubt, always check with your health practitioner of potential interactions.