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    Magnesium deficiency: what to look out for

    Serena Chisty

    By Serena Chisty


    Previously we talked about the importance of magnesium, but what happens if we don't get enough and what are the symptoms to look out for? 

    Magnesium intake in the UK

    Given the importance of magnesium and its involvement in almost every process in our body's functioning, it may be surprising to know that as a population we aren't getting enough magnesium through our diet. The graph below shows that across all age ranges, the UK population is consuming less than the recommended intake of magnesium and other important minerals1

    But why is this? 

    Much like selenium, food sources with adequate magnesium are limited, mainly because of poor soil quality and farming practices. This means that foods known as rich sources of magnesium such as spinach, almonds, and dark chocolate, aren't always as high in magnesium as we may think2.

    Figure 1: Dietary mineral intakes across UK adults across mid-life 20191

    What happens if we don't get enough?

    Since magnesium is mainly stored within the bones, with only a small percentage free within the blood, it is difficult to determine magnesium deficiency through a blood test and so it can go undiagnosed until it becomes severe3

    Symptoms that may indicate low magnesium include3,4

    • muscle twitches/cramps 
    • brain fog/memory loss
    • fatigue and weakness
    • weak or brittle bones
    • headaches/migraines
    • anxiety/depression

    Who may be at risk of magnesium deficiency?

    True magnesium deficiency is mostly seen among ICU/hospitalised patients. However, there are certain groups which may be more at risk of deficiency, and therefore also have higher magnesium requirements3,4.

    • Older Adults (60+)

    Older adults tend to consume a lower number of magnesium-rich foods, absorb less in the gut, and increase excretion through urine; all leading to signs of deficiency.

    • Those with digestive disorders

    As magnesium is absorbed within the intestinal tract, digestive problems such as Crohn’s disease could lead to malabsorption decreasing the amount of magnesium absorbed into the body.

    • Alcohol dependant individuals 

    Magnesium deficiency is common among alcohol dependant individuals. Alcohol acts as a diuretic, causing a loss of magnesium through excess alcohol consumption and increased urination.

    • Excess caffeine consumption

    Although caffeine does not decrease the levels of magnesium stored in the body, research has shown that caffeine interferes with the body’s absorption of magnesium. (reference)

    • Those who do high-intensity exercise

    High-intensity exercise may lead to excessive sweating and urination, in which magnesium is expelled from the body. 

    If you are aware your magnesium consumption may be lacking and want to optimise your psychological function, muscle function, and bone health, then a magnesium supplement may be of benefit. 


    Read more about Magnesium here > 

    If you are worried about your symptoms, be sure to check with your GP or health professional for more tailored guidance.

    1. Derbyshire E. Micronutrient intakes of British adults across mid-life: A secondary analysis of the UK national diet and nutrition survey. Frontiers in Nutrition. 2018;5. doi:10.3389/fnut.2018.00055 
        2. Broadley MR, White PJ, Bryson RJ, et al. Biofortification of UK food crops with selenium. Proceedings of the Nutrition Society. 2006;65(2):169-181. doi:10.1079/pns2006490 
        3. Office of dietary supplements - magnesium. NIH Office of Dietary Supplements. Published June 2022.
        4. Magnesium deficiency. Healthdirect.