When the subject turns to minerals (granted, this is not a common occurrence) we can usually name a few of the big hitters – calcium, iron, maybe zinc – but how many of us would leap up and shout ‘Magnesium!’ And even if you did, would you know what it does in the body? In short, a lot.
WHAT IS IT?
Magnesium is the fourth-most abundant mineral in the body, with approximately 60 per cent of it found in bone and 30 per cent in skeletal and cardiac muscle. Magnesium is also found in the blood and body fluids. It is involved in over 300 biochemical reactions in the body and is crucial for energy production, muscle function, protein synthesis and insulin metabolism. This makes it of critical importance for good physical performance. Yet magnesium is one of the most common nutritional deficiencies seen in athletes, resulting in reduced performance, lactic acid build-up, muscle cramping and poor recovery.
WHAT DOES IT DO?
PERFORMANCE: Magnesium is vital for the conversion of glycogen to glucose – the body’s main fuel during exercise. Without sufficient levels the body switches to anaerobic metabolism, resulting in a build-up of lactic acid and associated muscle soreness and spasms. This also means if you are low in magnesium you are likely to feel tired and listless. Magnesium also influences protein metabolism, making it important for strength and power as well as recovery. Research published in the Journal of Nutrition suggests that even small shortfalls in magnesium intake can seriously impair your athletic performance.
BONE HEALTH: If you’re concerned about bone health it’s worth remembering that while calcium is important it does nothing without adequate levels of magnesium and vitamin D. Magnesium activates cellular enzyme activity, allowing the body to convert vitamin D into its active form to help with calcium absorption and bone building.
RECOVERY: Magnesium, together with calcium, is essential for optimal muscle function. A deficiency in magnesium can result in muscle and nerve twitches, spasms and cramping. Heavy exercisers often experience a build up of lactic acid, shin splints and painful muscles during and after exercise. Having sufficient magnesium helps speed up recovery, limit fatigue and reduce the risk of getting an injury.
BODY COMPOSITION: Low levels of magnesium will decrease your insulin sensitivity, making it harder for you to lose fat. So if you are looking to change your body composition make sure you are getting enough of the stuff.
DEFICIENCY – WHY RUNNERS ARE AT RISK
Magnesium deficiency is common in runners, and people who exercise regularly are at a greater risk because of its role in energy production and metabolism. It is also lost through sweat during exercise, and in urine. Several studies, including one published in the American Society for Clinical Nutrition, have revealed that many athletes, particularly women, are failing to consume sufficient magnesium in their diet.
WHAT FOODS CONTAIN MAGNESIUM?
Top food sources of magnesium include unrefined wholegrains, such as wholemeal bread and wholegrain cereals, green leafy vegetables, nuts and seeds (especially pumpkin seeds), peas, beans and lentils. Some fish, such as halibut and mackerel, are also good sources. Drinking water can be an important source of magnesium, especially “hard water”. But even if you have a healthy diet you may not be getting enough – you would need to eat about ten bananas to get the recommended daily amount of magnesium.
HOW MUCH DO I NEED?
The UK recommended intake for magnesium is 300mg for men and 270mg for women. The recommended intake can also be expressed in mg/kg and is roughly 6mg per kilogram of body weight. So if you weighed ten stone (63kg) this would be 378mg magnesium per day. Your daily needs may be higher if you exercise. And if you’re reading this, you do.
WHAT IS THE BEST WAY TO SUPPLEMENT?
Not all forms of magnesium are created equal in terms of absorption and bioavailability (the amounts that enter the circulation and therefore have an affect on the body). You can supplement internally and externally. Some of the best forms of supplemental magnesium are magnesium gluconate, citrate or malate, as these are readily absorbed and available to the body.
You can also increase your levels using a transdermal magnesium spray in the form of magnesium chloride. This can be applied to the skin before, during and after exercise. Because it is rapidly absorbed it makes an ideal supplement for quick results. Magnesium chloride oil or flakes can also be used as a liquid soak, either in a bath or footbath. This is ideal following exercise if you want to avoid muscle soreness and fatigue. It may also encourage a better night’s sleep.
SIGNS AND SYMPTOMS OF MAGNESIUM DEFICIENCY
If you experience any of the following symptoms you may benefit from increasing your magnesium levels:
- Irregular or abnormal heartbeat
- Asthma, wheezing
- Food cravings, eg carbohydrate, chocolate, salt
- Headaches and migraines
- Muscle cramps and spasms
- Muscle twitches or tics
- Muscle weakness
- Numbness in hands and feet
- Aches and pains after exercise
- Poor recovery following exercise
- Low bone density, osteoporosis
- Feelings of irritability and/or lethargy
- Frequent mood swings, including depression
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