Foods high in magnesium: a UK list

What foods are high in magnesium?

Seeds, nuts, wholegrains, beans and pulses, and some leafy greens are the richest everyday sources. Fish, meat, milk and most fruit contain smaller amounts. The figures below come from the UK's official food composition data, McCance and Widdowson's Composition of Foods Integrated Dataset (CoFID), published by Public Health England in 2021. Portion sizes are from the British Dietetic Association (BDA), apart from seeds, where we've used the same 30 g handful as for nuts. Figures are rounded to the nearest milligram.

Wholegrain versions carry far more magnesium than white ones: a portion of brown rice has about nine times as much as white, and a slice of wholemeal bread about three times as much as white bread.

Spinach figures vary with the type. CoFID's value for boiled baby spinach, from a 2013 analysis, is more than three times its value for boiled mature spinach, which comes from analyses in the 1980s. Spinach is a useful source, but the amount in your portion could sit anywhere in that range.

What food is highest in magnesium?

Gram for gram, the highest foods in CoFID are ones you eat in pinches: dried herbs, dried seaweed and cocoa powder (520 mg per 100 g). Among foods people eat by the handful or spoonful, Brazil nuts (410 mg per 100 g), sunflower seeds (390 mg), wheat bran (389 mg), tahini (380 mg) and sesame seeds (370 mg) lead. Per portion, a 30 g handful of Brazil nuts or sunflower seeds gives the most.

Brazil nuts are also very high in selenium. CoFID gives 254 µg per 100 g, so a 30 g handful has about 76 µg, roughly a whole day's selenium for an adult (the NHS says men need 75 µg a day and women 60 µg). If you eat nuts daily, it's worth mixing Brazils with other kinds.

What is magnesium good for?

In Great Britain, the health claims allowed for magnesium are set by law, and there are 10 of them. Magnesium contributes to:

• a reduction of tiredness and fatigue
• electrolyte balance
• normal energy-yielding metabolism
• normal functioning of the nervous system
• normal muscle function
• normal protein synthesis
• normal psychological function
• the maintenance of normal bones
• the maintenance of normal teeth

It also has a role in the process of cell division. Claims that magnesium regulates blood pressure or blood sugar, maintains the immune system or acts as an antioxidant were assessed and not authorised, and there's no authorised claim for sleep (our guide to magnesium and sleep covers what the trials found). A magnesium product sold in Great Britain shouldn't make any of those claims.

What does magnesium do in the body?

The NHS describes magnesium as a mineral that helps turn the food we eat into energy. An adult body holds about 24 g of it, according to a review in Clinical Kidney Journal. Around half to 60% is in bone, and almost all the rest is in muscle and other soft tissue, so only a small share is circulating in your blood at any time.

How much magnesium do you need?

The NHS says adults aged 19 to 64 need 300 mg of magnesium a day (men) or 270 mg (women), and that you should be able to get it all from a varied, balanced diet. The lower reference nutrient intake, an amount that is enough only for the small number of people with the lowest needs, is 190 mg for men and 150 mg for women.

As an example from the table, 40 g of porridge oats, two slices of wholemeal bread, a 30 g handful of almonds, a portion of chickpeas and 150 g of brown rice add up to about 310 mg, before you count milk, vegetables or anything else you eat that day.

How much magnesium do children need?

UK reference nutrient intakes for magnesium are 85 mg a day at ages 1 to 3, 120 mg at 4 to 6, 200 mg at 7 to 10, 280 mg at 11 to 14 and 300 mg at 15 to 18, the same for boys and girls. The foods in the table above count towards a child's intake too, in smaller portions than an adult's, and the NHS says a varied, balanced diet should provide the magnesium you need. The NHS recommends vitamin supplements containing A, C and D for children aged 6 months to 5 years, says to talk to a pharmacist about which supplement suits your child, and doesn't mention magnesium. Ask a pharmacist or GP before giving a child a magnesium supplement, particularly if they have a medical condition or take regular medicines.

Do most people in the UK get enough magnesium?

Most do, but a sizeable minority don't. The main UK source on this is the National Diet and Nutrition Survey (NDNS). A 2018 analysis of NDNS data from 2008 to 2014, covering 3,238 adults aged 20 to 59 and counting food only, found average intakes of about 91% of the reference intake for men and 80% for women. About 14% of men and 12% of women got less than the lower reference amount, rising to about one in five of those in their twenties. The author declared funding from the Health and Food Supplements Information Service (HSIS).

The reference nutrient intake is set to be enough for 97.5% of people, so an average a little below it doesn't mean most people are short. The lower reference amount is enough for only 2.5% of people, and the NDNS says an intake below it is only a problem if it carries on over time. An official NDNS report for Wales also cautions that the UK reference values for magnesium rest on very limited data.

Who is more likely to run low?

Diet is only one reason. NHS hospital information also lists:

• not absorbing magnesium properly, including after part of the small intestine has been removed, or with coeliac disease or Crohn's disease
• losing it through diarrhoea or in urine
• some medicines, including proton pump inhibitors that protect the stomach lining, diuretics, some antibiotics, cancer drugs and immunosuppressants
• long-term heavy drinking and poorly controlled diabetes

What are the symptoms of low magnesium?

Low magnesium often causes no symptoms at all, and when it does, the signs of magnesium deficiency are usually vague. NHS hospital patient information lists tremors, muscle spasms, trouble sleeping, an irregular heartbeat, mood changes, feeling sick, reduced appetite, loss of vision, and fits or seizures. The MHRA's list for low magnesium caused by long-term use of stomach medicines adds tiredness, dizziness and delirium (sudden confusion). Low magnesium can come with low calcium and potassium, which also need correcting.

Each of these symptoms has many other possible causes, so they can't tell you on their own whether your magnesium is low.

When should you see a GP about low magnesium?

See your GP if you have symptoms like these with no other explanation, particularly if you also have one of the risk factors listed above, such as a bowel condition, long-term heavy drinking or a medicine that can lower magnesium. They can arrange a blood test and interpret it alongside your symptoms, medicines and other results, bearing in mind that a blood level shows only part of the picture. Severe symptoms need urgent help: the NHS says to call 999 or go to A&E if you have palpitations that don't go away, or palpitations with chest pain, shortness of breath or fainting.

How to get more magnesium from food

Simple swaps add up, because many of the best sources are everyday staples.

• Swap white rice, pasta and bread for brown or wholemeal versions.
• Start the day with porridge oats or a wholegrain cereal.
• Add a tin of chickpeas, kidney beans or other pulses to stews, curries and salads.
• Keep a mix of unsalted nuts and seeds for a daily handful, or stir a spoonful of seeds into yoghurt or porridge.
• Add leafy greens such as spinach or chard to meals.

You don't need to worry about getting too much magnesium from food if your kidneys work normally. Safe upper levels apply to supplements, and our guide to magnesium side effects explains why.

Food or a supplement?

For most people, food is enough. If you do take a supplement, keep to the NHS guide of 400 mg or less a day from supplements, and count magnesium from every product you use, including multivitamins and electrolyte drinks. Avoid magnesium supplements if you have kidney disease unless your doctor advises them. Our guide to magnesium glycinate vs citrate explains the forms and how to read a label. If a blood test shows low magnesium, your doctor will decide the treatment, which may be a prescribed product rather than a shop-bought supplement.

Where Natura fits

Natura's Daily Magnesium (coming soon) is one capsule giving 200 mg of magnesium as glycinate, within the NHS guide for supplements. Magnesium contributes to normal muscle function and to normal psychological function. You'll find it among the single bottles.