Magnesium; The Essential Mineral in our Diet

Magnesium is important. Two weeks ago, I wrote an article about salt intake, so it makes sense to also include something on magnesium! Why?……..you may well ask? Well, all sorts of reasons really. Next to salt, magnesium is the next most abundant mineral in seawater, and it is also an electrolyte and (like sodium in salt) one of the most important minerals in our bodies. In vertebrates, magnesium exists in abundance, and it is the second most common intracellular cation (potassium being the first). There is however a very different issue with magnesium as, even in developed countries, there is an increasing percentage of people that may be magnesium deficient (whereas salt intake in excessive).

Where does Magnesium Come From?

About 13 % of the Earth’s entire mass is Mg2+, so there is plenty of it inside and outside us! This means there’s enough Mg2+ is one of the most important minerals in our bodies, however there is an increasing percentage of people that may be  Mg2+ deficient  within the planet Earth to make a planet of the same mass as Mars and have enough  Mg2+  left over to make three more objects of the same mass as our moon! It probably wouldn’t surprise you to know therefore that Mg2+ is therefore one of the ten most abundant elements in the universe. It forms in large stars as a result of fusion of helium with neon. Clearly back on planet Earth, the resources from which Mg2+ can be recovered range from large to virtually unlimited (most  is deep inside the Earth’s crust). Meanwhile on the Earth’s surface, apart from seawater, Mg2+ reserves are highly concentrated in three countries: Russia, China and Korea. Magnesite is the major source from which these countries extract Mg2+t. In 2013, identified world resources of magnesite totalled 12 billion tones with 2.4 billion tones in China accounting for 21% (500 million tonnes), Russia accounting for 27% (650 million tonnes) and North Korea accounting for 18.8% (450 million tonnes). Since its discovery in 1808, people have utilised magnesium in many ways. It is one of the most important metals commercially. Its properties make it easy to weld, forge, cast or machine. It can be alloyed with other metals, making them more beneficial. But it is extremely important biologically as well!

Why is Important?

Mg2+ is essential for life. It is at the centre of every chlorophyll molecule in every plant because it is the key that enables photosynthesis.  Mg2+ gives leaves their green hue and activates most plant enzymes needed for growth while also contributing to protein synthesis. Just as it is important for plants, it is important for us too. It is required for hundreds of chemical reactions in the body. Magnesium is a co-factor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation.  Mg2+ is required for energy production, during the key phases of ‘oxidative phosphorylation’ and ‘glycolysis’. Ever wondered why you need to breath in oxygen? These processes use electrons to reduce molecular oxygen to water, during which time a large amount of free energy is liberated. Mg2+ contributes to the structural development of bone and is required for the synthesis of DNA and RNA. It also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm.

Where does it Come From?

Therefore, our Recommended Daily Allowance (RDA) in the UK is about 300mg for men and 270mg for women a day. In fact, an adult body contains about 25g of Mg2+, 99% of which is in our bones and soft tissue and about 1% in blood serum.  Mg2+ has been re-discovered as an overlooked key to overall wellness, with numerous medical researchers recommending increases to the RDA—some suggesting amounts as high as double the current recommendations. With its role in regulating the thousands of biochemical reactions that occur on an ongoing basis, enough Mg2+ is essential to achieving the delicate balance necessary to the body’s function. Protecting this delicate balance should be considered a fundamental goal in achieving optimal health and well being. Foods which are generally high in magnesium include dark green leafy vegetables, legumes, nuts, seeds and unrefined grains.

Even the act of drinking mineral water can potentially account for 10% of our daily magnesium intake and obviously chlorophyll (abundant in dark green leafy vegetables) is also often a key source from plant materials. Nuts, seeds and unprocessed cereals are also significant, while legumes, fruit, meat and fish have an intermediate Mg2+ concentration. Low Mg2+ concentrations are found in dairy products. Processed foods however are particularly low in magnesium and this might help explain why, even in the UK (and other countries) Mg2+  appears to be less abundant in our diets.

Why are We Increasingly Deficient?

When I studied at Reading University key authors in nutritional circles at the time were McCance and Widdowson (I remember their books very well as being valuable reference books). They released a book in 2007 called ‘Nutrition and Health. The mineral depletion of foods available to us as a nation (1940–2002)’. Some the information they divulged was startling. In the UK for example, there has been loss of Mg2+ in beef (−4 to −8%), bacon (−18%), chicken (−4%), cheddar cheese (−38%), parmesan cheese (−70%), whole milk (−21%) and vegetables (−24%).The loss of magnesium during food refining/processing is significant: white flour (−82%), polished rice (−83%), starch (−97%) and white sugar (−99%).

Much of this may down to modern day agricultural practices. Since 1968 the magnesium content in wheat has dropped almost 20%, this may be due to changing soil profiles, yield dilution and fertilisation strategies (high levels of nitrogen, phosphorus and potassium, the latter of which antagonises the absorption of  Mg2+in plants). One recent review paper (titled ‘Magnesium deficiency in plants: an urgent problem’ Nazim and Liang 2016) concluded: ‘Magnesium deficiency in plants is becoming an increasingly severe problem with the development of industry and agriculture and the increase in human population’.

Magnesium Deficiency

Our  Mg2+deficiency often goes undiagnosed. One of the issues with magnesium deficiency is that our blood serum magnesium status (if you remember this contains only 1% of our total magnesium) does not necessarily reflect our intracellular magnesium levels (99% of total body magnesium), so most cases of chronic Mg2+ deficiency are undiagnosed. A slightly alarming study was recently published in 2018 called “Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis”. This paper (also supported by previous studies) suggests that an RDA of 300 mg  must be supplemented to establish significantly increased serum Mg2+ concentration. So, while the recommended daily allowance (RDA) for magnesium may prevent overt Mg2+ deficiency, it is unlikely to provide optimal health and longevity, which should really be the goal. This study also suggested that magnesium status has a direct effect upon the relaxation capability of vascular smooth muscle cells in our arteries and veins. As a result, nutritional  status could have both direct and indirect impacts on the regulation of our blood pressure and therefore on the occurrence of hypertension.

A nutritional review on Mg2+ status in the U.S published in 2016 estimated that around half (48%) of the US population consumes less than the recommended amount of magnesium from food. The authors of the review suggested ‘These intake levels suggest that a substantial number of people may be at risk for Mg deficiency, especially if concomitant disorders and/or medications place the individual at further risk for Mg depletion’.  The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. NHANES surveys from 2003-2006 found that about 36% of children and adolescents and 61% of adults had intakes lower than the EAR for magnesium. I could not find any information on our status in the UK, but other data appears to support that magnesium intake may be inadequate in many countries. A French study on 2373 subjects (4–82 years of age) in 2006 noted that 71.7% of men and 82.5% of women had an inadequate magnesium intake.

Magnesium Supplements

It is a good idea to take magnesium as a supplement in combination with other vitamins and minerals.  But too high dosages could potentially lead to loose tummy because of osmotic retention of fluid within the colon. Some magnesium salts, such as magnesium sulphate and magnesium hydroxide, are commonly employed as laxatives for that reason. Other than the diarrhoea occurring with high doses, oral magnesium supplements are generally considered to be safe and relatively free of adverse effects.

Possible side effects include bloating, diarrhoea, upset stomach, nausea, vomiting. Very large doses of magnesium can cause serious side effects, including low blood pressure, irregular heartbeat, mental confusion, changes to breathing, coma, and death. There are conditions that are associated with higher risks for magnesium deficiency, including high alcoholism intake and diabetes. There are also conditions that may reduce the amount of magnesium the body absorbs, including:

• Inflammatory bowel disease
• Diabetes that is not well controlled
• Stomach infections
• Immune conditions

Magnesium supplements are available in a variety of forms. The absorption rate and bioavailability of magnesium supplements differs depending on the kind; usually types that dissolve in liquid are better absorbed in the gut than less soluble forms.

It’s believed that magnesium in citrate, chelate and chloride forms are absorbed better than magnesium supplements in oxide and magnesium sulphate forms.

• Here’s information about the different types of magnesium supplements:
• Magnesium Chelate —highly absorbable by the body and the kind found in foods naturally. This type is bound to multiple amino acids (proteins) and used to restore magnesium levels.
• Magnesium Citrate —magnesium combined with citric acid. This may have a laxative effect in some cases when taken in high doses but is otherwise safe to use for improving digestion and preventing constipation.
• Magnesium Chloride Oil —an oil form of magnesium that can be applied to skin. It’s also given to people who have digestive disorders that prevent normal absorption of magnesium from their food. Athletes sometimes use magnesium oil to increase energy and endurance, to dull muscle pain, and to heal wounds or skin irritation.
• Magnesium Glycinate —highly absorbable, this is recommended for anyone with a known magnesium deficiency and less likely to cause laxative effects than some other magnesium supplements.
• Magnesium Threonate —has a high level of absorbability/bioavailability since it can penetrate the mitochondrial membrane. This type is not as readily available, but as more research is conducted, it may become more widely used.
• Magnesium Orotate —these supplements have orotic acid, and magnesium

How much magnesium should you take per day? Keep in mind that magnesium needs vary on different individual factors, like your age and gender. According to the National Institute of Health in the U.S., below are the current RDAs for magnesium (these are a little higher than the UK):

Infants–6 months: 30 milligrams

7–12 months: 75 milligrams

1–3 years: 80 milligrams

4–8 years: 130 milligrams

9–13 years: 240 milligrams

14–18 years: 410 milligrams for men; 360 milligrams for women

19–30 years: 400 milligrams for men; 310 milligrams for women

Adults 31 years and older: 420 milligrams for men; 320 milligrams for women

Pregnant women: 350–360 milligrams

Women who are breastfeeding: 310–320 milligrams