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Magnesium: foods, benefits & RDA

Siski Green / 29 July 2021

Magnesium is vital for releasing energy from food. It can be found in a range of foods including nuts, seeds and green vegetables

Walnuts on a table, as a source of magnesium
Walnuts are a good source of magnesium

What is magnesium used for?

Your body can’t create magnesium so, like other essential minerals, you need to ingest it. Along with calcium, zinc and iron, magnesium is one of the most used minerals in your body. Without it, your body won’t function properly. It’s used for around 300 mechanisms within your body, including producing energy, a strong immune system, and regulating your metabolism.

If you have high blood pressure magnesium supplements may help. An overview of 22 studies found that taking around 400mg of magnesium every day could lower systolic and diastolic blood pressure significantly.

Those who have been diagnosed with depression may also experience benefits from taking magnesium. Several studies have shown a reduction in symptoms, compared to placebo, when taking magnesium supplements of between 250 and 400mg.

What’s the best way to take magnesium?

Ideally as a woman you’ll get 400-420mg per day and 320-360mg if you’re a man. You can get this from your diet by eating plenty of legumes (beans, chickpeas etc), nuts, wholegrains, and seeds, among other foods. While serious deficiency is rare you may not be getting as much as is optimum.

Magnesium ‘inadequacy’ is actually fairly common. Certain lifestyle behaviours and illnesses make you more prone to low levels of magnesium – alcoholism for example, and digestive disorders that disrupt how much the body absorbs may also have an impact. Low levels are related to type 2 diabetes and heart disease, as well as Alzheimer’s. Initial symptoms of an inadequate intake of magnesium include nausea, fatigue, loss of appetite, then muscle cramps, irregular heart rhythm, and insomnia.

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Does magnesium really work?

If you are not getting adequate amounts via your diet and you are experience symptoms of magnesium deficiency then taking a supplement should help. In studies looking at depression, and blood pressure, study participants took around 400mg daily.

Where can I get magnesium?

Magnesium is available via a wide range of healthy foods – an avocado will give you around 15% of your RDA (around 60mg), a small serving (fits into a circle within your palm) of almonds, cashews and Brazil nuts provide around a fifth of your daily needs. Other good sources include pumpkin seeds, lentils, beans, chickpeas, tofu, wholegrains, and bananas (with one providing around 10% of your daily needs).

You can also get a reasonable amount of your RDA from a few squares of dark chocolate – a 28g serving (around 2 squares) contains around 15% of your RDA.

Magnesium is also available in supplement form, in supermarkets, healthfood shops and online.

What are the side effects of taking magnesium?

Taking too much magnesium may trigger digestive symptoms – most commonly diarrhoea as magnesium has a laxative effect. You may also experience stomach upset or nausea.

Are there any contraindications when taking magnesium?

If you have experience kidney disorders see your GP before taking magnesium. Magnesium may also interact with blood thinners, statins and anti-diabetics, so see your GP if you are in doubt.

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The opinions expressed are those of the author and are not held by Saga unless specifically stated. The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.