Guest blog by Vicky Ware
Do you ever have difficulty sleeping, even though you feel exhausted? Feel anxious, but you’re not sure why? Have cravings for sugar and salt no matter how much you eat 1? These could be signs of a deficiency in a specific nutrient: magnesium. It is one of the most abundant minerals on Earth and responsible for over 300 enzymatic reactions in the human body but our diets are increasingly deficient in it.
With a number of friends having found magnesium supplementation made a big difference to how they felt (helping with health issues as diverse as insomnia, anxiety, hyperactivity, heart palpitations, asthma and sluggish thinking) I decided to dive into the scientific research to see if there’s an evidence base for the benefits they’ve seen.
What is Magnesium?
Magnesium is a mineral which is essential for human health.
It is found in numerous food sources but modern lifestyles and diets have reduced our intake meaning the majority of people in both North America and Europe do not get the recommended daily allowance (RDA) 2;3. The RDA does not take into account increased needs for magnesium caused by stress, high carbohydrate diets or regular exercise 4;5.
Magnesium is used by cells in the body for a number of processes, from signalling to other cells, allowing nerves to fire and maintaining strong cellular walls. It is also required to build proteins (and therefore muscle) and maintain the structure of DNA. Magnesium is also required for cells to use energy from food 6;7.
Around 60% of the 25 grams of magnesium in your body are stored in the bones, with less than 1% in the blood 8. Magnesium levels are controlled by the kidney, with around 120 mg lost through urine each day 9.
Because magnesium is stored in bones and inside cells, blood tests are not very useful in determining whether you’re magnesium deficient. Blood levels are low but tightly controlled because they’re essential for life – your body will leach magnesium from your bones to maintain blood levels if it has to. Therefore blood tests don’t give an accurate picture of the magnesium levels in your body 10.
What Happens if You’re Deficient?
In simple terms magnesium is used to relax the body, where calcium is used to contract or excite the body. Therefore too little magnesium results in muscle cramps, tics and spasms 11.
Early magnesium deficiency can cause 8:-
- Loss of appetite;
- Unclear thinking;
- Insomnia 12;
- Weakness; and
- High blood pressure 13.
More serious deficiency results in 8:-
- Decreased attention span;
- Mental confusion;
- Muscle contractions and cramps;
- Personality changes;
- Abnormal heart rhythms; and
- Coronary spasms.
What Are Low Levels Linked With?
In one study magnesium deficiency was found in 95% of children who had ADHD 14. It’s not known whether this is a cause of ADHD or a side-effect of the disease. Treating children who have ADHD with magnesium decreased their hyperactivity 15.
Magnesium is also needed to make the enzyme, DAO, which mops up histamine when it’s been released, if you can’t make DAO, histamine levels in the blood increase 16. Histamine release from immune cells causes many of the symptoms of allergic responses to, for example, pollen and insect bites. Lowering blood histamine levels may improve these symptoms 17.
Magnesium deficiency is also associated with anxiety because of its role in exciting the nervous system 18;19. It’s possible that this could also be linked to the fact that magnesium deficiency results in inflammation with inflammation a potential factor in anxiety 20.
Research suggests that some drugs used to treat psychiatric disorders affect (increase) blood levels of magnesium thereby making diagnosis of magnesium deficiency in these patients even more difficult 18.
How much magnesium your diet contains is linked directly to your chances of developing, or experiencing, asthmatic symptoms 8.
Magnesium supplementation was found to help 40% of patients with autism in one study 18.
Magnesium is also crucial for bone health. While we tend to think of calcium as the crucial mineral for bones, this is partly due to mass marketing of dairy products as a source of calcium. Dairy is a source of magnesium, but nowhere near the levels of magnesium – one cup of milk provides 30% of your RDA of calcium but only 6% of your RDA for magnesium 21.
Several population based studies have shown that magnesium deficiency significantly increases the risk of developing cancer 22. This could be due to the fact it is required to dampen inflammation in the body 23.
Low magnesium is also associated with depression 24;25.
Low magnesium makes insulin resistance worse, and is associated with development of Type II diabetes. Supplementing diet with magnesium has been shown to help with symptoms of diabetes 8.
Too much calcium without magnesium causes bones to become brittle and not getting adequate magnesium is linked with development of osteoporosis 6;3. When it comes to bone health long term studies have shown that more calcium is not better, especially when not combined with magnesium 26.
Low intake of magnesium is associated with increased risk of heart disease – again, potentially due to increase inflammation in the body 27. There is also a possibility that low magnesium is linked with sudden cardiac death although more research is needed to confirm this 8.
Magnesium deficiency is related to increased levels of total body inflammation 23. This could be the underlying reason it is linked with so many other conditions.
Magnesium supplementation and injection has also been found to be a good treatment for migraine in a number of studies 28;29.
Premenstrual tension (PMT) is also associated with magnesium deficiency – anything from period pain to bloating to feeling anxious before your period 30.
Magnesium deficiency leads to you feeling more stressed, but in a catch-22 situation less magnesium in your body also leads to you feeling stressed. Similarly, lack of sleep (in itself a cause of stress) means you use more magnesium but having too little magnesium may mean you find it difficult to sleep resulting in an increased need for magnesium 4. Magnesium supplementation has been found to help with insomnia 31.
Magnesium deficiency is associated with increased risk of stroke 13.
How Much do We Need?
The UK RDA is 300mg a day for men and 270mg a day for women. This should be do-able if you eat a diet high in vegetables, nuts and seeds 32. However, modern lifestyles are not only low in these foods but stress, lack of sleep and high carbohydrate intake mean the body needs more magnesium to thrive 18. Research suggests that magnesium intake has declined significantly since the beginning of the century when it was around 500mg per day 8.
Exercise also causes increased magnesium excretion in the urine and sweat meaning people who exercise regularly are more likely to be magnesium deficient 33. Low levels of magnesium will then impair an athlete’s ability to build and repair muscle, get energy from food and efficiently transport oxygen around the body – all essential to athletic performance 34.
Endurance athletes have been found to have deficiencies in magnesium 35. Magnesium deficiency doesn’t just stop you performing at your best, but also increases the oxidative stress caused by exercise 36.
Strenuous exercise seems to increase magnesium requirements by up to 20% per day 36. If you’re exercising for prolonged periods of time in hot conditions, this will be increased even further.
Why Are People Deficient?
Due to modern farming methods soil is magnesium depleted. Plants growing on that soil (both vegetables and grass) are therefore unable to uptake magnesium from the soil meaning when we eat them (or meat that was raised on magnesium deficient grass) we’re not getting the magnesium we need 37.
Alcohol, phytate, fibre, excessive calcium and excessive phosphate all reduce magnesium absorption in the intestine 8.
Fish, meat, milk and fruits are poor sources of magnesium where un-milled grains, green leafy vegetables, nuts, legumes and whole seeds are good sources. The latter are low in modern diets 8.
Magnesium is in drinking water in differing amounts depending where you live but in general will only contribute a small amount to your daily intake 8.
Processed foods are also low in magnesium compared to whole foods – processing removes the nutrient containing portion as when wheat is turned into white flour 38. In fact, some studies suggest that food processing removes almost all magnesium from foods 8.
If you take a calcium supplement and your magnesium intake is low calcium reduces magnesium absorption and retention further. However, taking a magnesium supplement helps the body use calcium 4.
Other conditions such as leaky gut can also make it more difficult to absorb magnesium 39.
How Can We Get it?
Magnesium is found in various foods and in supplement form. Because magnesium can be absorbed through the skin*, you can also use magnesium oil or Epsom salts to get your daily magnesium boost. Spraying oil on the skin or soaking in a salt filled bath has been shown to increase cellular magnesium levels 40.
Top foods that contain magnesium are:-
- Pumpkin seeds (Quarter of a cup contains 190mg of magnesium so 63% of the male and 66% of the female RDA);
- Spinach (One cup full has 156mg of magnesium, 52% of male and 58% of female RDA);
- Swiss chard;
- Sesame seeds;
- Quinoa (Three quarters of a cup has 188mg of magnesium, 62% of male and 70% of the female RDA);
- Cashew nuts;
- Sunflower seeds 21.
Is a Supplement Needed?
Magnesium supplements come in the form of magnesium oxide, chloride and citrate. It’s thought that citrate is one of the more bioavailable and better absorbed forms 41.
Zinc is absorbed from the gut via the same receptors as magnesium, therefore high levels of zinc in a supplement may decrease the amount of magnesium you absorb 42.
Some people find a magnesium supplement doesn’t agree with their digestion – too much magnesium in your intestines can result in diarrhoea which isn’t just unpleasant but stops the magnesium being absorbed and can flushes out other nutrients too 43. Epsom salt baths are a great way to absorb magnesium through your skin – research suggests they may up your magnesium absorption more than an oral supplement. I’ve written more on this topic over in my skin absorption blog* and a blog on different types of salt**
If you are going to take a supplement, some tips to improve absorption include:-
- Taking magnesium separately to zinc;
- Get the right ratio of magnesium and calcium in your diet 4;
- Eat magnesium and calcium with medium chain triglycerides 44; and/or
- Take with fructo-oligosaccharides 45.
Magnesium is really quite important, and research suggests many of us are not getting the amount we need for optimal health. Some people find supplements don’t agree with their digestion, and there’s research that suggests oral supplements are not well absorbed. A relaxing Epsom salt bath can up your magnesium levels and improve skin condition. Have you taken a supplement or used Epsom salts to increase your magnesium levels? Did you notice an improvement in your health? Let us know in the comments below!
Vicky has a degree in Biological Sciences with a focus on biochemistry and immunology and is currently studying for a MSc in Drug Discovery and Protein Biotechnology. She is also an endurance athlete.
- Morris (2008) Salt craving: The psychobiology of pathogenic sodium intake.
- Schimatschek (2001) Prevalence of hypomagnesemia in an unselected German population of 16,000 individuals.
- Rude (2004) Dietary magnesium reduction to 25% of nutrient requirement disrupts bone and mineral metabolism in the rat.
- Seelig (1994) Consequences of magnesium deficiency on the enhancement of stress reactions; preventive and therapeutic implications (a review).
- Durlap (1989) Recommended dietary amounts of magnesium: Mg RDA.
- Belluci (2013) Magnesium deficiency results in an increased formation of osteoclasts.
- Woolf (2008) Cell (patho)physiology of magnesium.
- Saris (2000) Magnesium: an update on physiological, clinical and analytical aspects.
- National Institute of Health (2015) Magnesium: Fact Sheet for Health Professionals.
- Ismail (2010) The underestimated problem of using serum magnesium measurements to exclude magnesium deficiency in adults; a health warning is needed for “normal” results.
- Bilbey (1996) Muscle cramps and magnesium deficiency: case reports.
- Abbasi (2012) The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial.
- Caojocaru (2007) Serum magnesium in patients with acute ischemic stroke.
- Kozielec (1997) Assessment of magnesium levels in children with attention deficit hyperactivity disorder (ADHD).
- Starobrat-Hermelin (1997) The effects of magnesium physiological supplementation on hyperactivity in children with attention deficit hyperactivity disorder (ADHD). Positive response to magnesium oral loading test.
- Nishio (1987) Specific change of histamine metabolism in acute magnesium-deficient young rats.
- White (1990) The role of histamine in allergic disease.
- Galland (1991) Magnesium, stress and neuropsychiatric disorders.
- Sartori (2012) Magnesium deficiency induces anxiety and HPA axis dysregulation: Modulation by therapeutic drug treatment.
- Salim (2012) Inflammation and anxiety.
- WHF (2015) Magnesium.
- Castiglioni (2011) Magnesium and cancer: a dangerous liason.
- Weglicki (2010) The role of magnesium deficiency in cardiovascular and intestinal inflammation.
- Serefko (2013) Magnesium in depression.
- Winther (2015) Dietary magnesium deficiency alters gut microbiota and leads to depressive-like behaviour.
- Warensjo (2011) Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study.
- Joosten (2013) Urinary and plasma magnesium and risk of ischemic heart disease.
- Demirkaya (2001) Efficacy of intravenous magnesium sulphate in the treatment of acute migraine attacks.
- Mauskop (1998) Role of magnesium in the pathogenesis and treatment of migraines.
- Abraham (1983) Nutritional factors in the etiology of the premenstrual tension syndromes.
- Rondanelli (2011) The effect of melatonin, magnesium, and zinc on the primary insomnia in long-term care facility residents in Italy: a double-blind, placebo-controlled clinical trial.
- NHS (2011) Vitamins and Minerals (Magnesium).
- Stendig-Lindberg (1992) Sudden death of athletes: is it due to long-term changes in serum magnesium, lipids and blood sugar?
- Laires (2008) Exercise, magnesium and immune function.
- Casoni (1990) Changes of magnesium concentrations in endurance athletes.
- Nielsen (2006) Update on the relationship between magnesium and exercise.
- Scientific American (2011) Dirt Poor: Have Fruits and Vegetables Become Less Nutritious?
- Winiarska (2011) Evaluation of the mineral composition of breadstuff and frequency of its consumption.
- Schweigel (2000) Magnesium transport in the gastrointestinal tract.
- Waring (2004) Report on absorption of magnesium sulphate (Epsom salts) across the skin.
- Lindberg (1990) Magnesium bioavailability from magnesium citrate and magnesium oxide.
- Spencer (1994) Inhibitory effects of zinc on magnesium balance and magnesium absorption in man.
- Liu (2014) Rhubarb tannins extract inhibits the expression of aquaporins 2 and 3 in magnesium sulphate-induced diarrhoea model.
- Tantibhedhyangkul (1978) Medium-chain triglyceride feeding in premature infants: effects on calcium and magnesium absorption.
- Van den Heuvel (2009) Short-chain fructo-oligosacchardies improve magnesium absorption in adolescent girls with low calcium uptake.
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