Why you should eat your beans! Magnesium deficiency risks, food sources and supplements explained.
Magnesium is an important mineral that has many roles in the body including helping with muscle and nerve function, blood pressure regulation, and supporting the immune system. But according to the World Health Organisation, up to two thirds of the world’s population may not be getting adequate amounts of magnesium in their daily diets.
Magnesium deficiency has been linked to serious medical conditions including osteoporosis, heart disease and type 2 diabetes. The goods news is provided you eat the right foods the majority of people can get enough magnesium from their diet without the need for supplements.
Award-winning author and running health expert Dr Juliet McGrattan explains more about magnesium, the important role it plays in the body, symptoms of magnesium deficiency and how to ensure you hit your daily quota:
What is magnesium?
Magnesium is a metallic element found in every cell in the body. Only one per cent of our magnesium is circulating in our blood stream, the other 99 per cent is tucked away in our bones, muscle and soft tissues.
What does magnesium do in the body?
Magnesium has lots of functions in the body including roles in:
- Energy production
- Ensuring strong bones
- Muscle contraction
- DNA synthesis
- Making protein
- Nerve function and transmission
- Insulin metabolism and controlling blood sugar levels
- Blood pressure regulation
Magnesium doesn’t work alone and is a cofactor to around 350 enzyme systems which means it’s essential for lots of the body’s chemical reactions, including those which turn the food we eat into energy.
Where do you get magnesium?
The amount of magnesium in the body is controlled by how much is being absorbed in your intestines from the food you eat and how much magnesium is being removed by the kidneys. Dietary levels, problems with gut absorption and conditions of the kidneys can therefore all lead to either high or low magnesium levels.
Magnesium is present in a wide variety of foods so it’s easy to get an adequate amount from your diet.
Magnesium is present in a wide variety of foods so it’s easy to get an adequate amount from your diet. Having said that, it’s thought that the changes in our diet over the last 100 years, with an increased reliance on processed food, might be responsible for the reports that two thirds of people in the Western world aren’t eating enough magnesium every day.
Foods that contain magnesium
A balanced, healthy diet full of fresh fruit, vegetables and wholegrains should give you all the magnesium your body needs to function normally.
Here are some of the top magnesium-rich foods to include in your diet:
- Leafy green vegetables including spinach and Swiss chard
- Nuts – almonds, cashews, Brazil nuts
- Seeds – pumpkin, sunflower and flaxseeds
- Beans – black beans, edamame, kidney beans
- Grains – wholegrains, quinoa and wheat bran
- Fish – mackerel, salmon and halibut
- Dark chocolate
How much magnesium do I need?
The recommended daily intake of magnesium for adults varies between countries. In the UK it is 300mg per day for men and 270mg per day for women. In the US, the recommended daily amount is higher, 400-420mg for men and 300-310mg for women.
17 magnesium deficiency signs
Magnesium deficiency where levels are low enough to cause symptoms and medical problems is rare. Not achieving the recommended daily intake and having a below optimal level of magnesium as a result, is common and goes undetected in most people.
Remember that only 1 per cent of magnesium is in the blood. The rest is tied up in bones and other tissues, there’s currently no test that will tell you how much magnesium in total is in your body.
Symptoms from low magnesium are rare but a doctor may decide to test your levels if you are affected by any of the following conditions:
- Osteoporosis– low bone strength.
- Muscle weakness, twitching or cramping.
- Restless leg syndrome.
- Abnormal heart rhythms – also known as cardiac arrhythmias.
- Long term diarrhoea for example as part of Crohn’s diseaseor coeliac disease.
- Uncontrolled diabetes.
- Hypo or hyperparathyroidism – an under or overactive parathyroid gland. This gland regulates the amount of magnesium, calcium and phosphorus in the body.
- Severe burns.
- Pre-eclampsia– a condition with high blood pressure during pregnancy.
- Kidney disease.
- Liver disease.
- Long term use of certain medications including diuretics (‘water tablets’).
- Abnormal calcium or potassium levels which are often associated with abnormal magnesium levels.
The full role of magnesium in the body isn’t yet understood. Many of the research comes from studies done on animals and may not translate to humans. It seems that magnesium may have an anti-inflammatory effect in the body. Long-term inflammation is partly responsible for many major medical conditions and a deficiency of magnesium has been linked to type 2 diabetes, heart disease, high blood pressure, Alzheimer’s disease and migraines.
There are also medical studies which link magnesium to mental health conditions including anxiety and depression, mood swings, sleep and behavioural problems but more research needs to be done to confirm this.
Should I take a magnesium supplement?
It is very easy to get enough magnesium from your diet – choose some of the foods from the list above and include them in your daily meals and snacks. If you are doing this then you don’t need to be concerned about being deficient in magnesium.
If you have specific medical conditions that affect how much magnesium you can absorb or how much your kidneys excrete (see the list above), then your doctor may check your magnesium levels and discuss supplementation with you if your levels are low.
It is easy to get enough magnesium from your diet – choose some of the foods and include them in your daily meals.
Magnesium supplements are usually given as a tablet. Magnesium may be given intravenously (directly into the bloodstream) in hospital for treatment of certain conditions such as pre-eclampsia in pregnancy. There is still conflicting evidence as to whether magnesium can be effectively absorbed in adequate quantities through the skin.
Can I take too much magnesium?
You don’t need to worry about having too much magnesium from your diet. Your kidneys will clear any excess.
However, it is possible to take too much magnesium in supplement form. Magnesium supplements at a normal dose can cause some side-effects including diarrhoea, stomach cramps and nausea. In toxic doses they can lower blood pressure, affect the heart rhythm and cause cardiac arrest and death. Don’t take supplements containing more than 400mg of magnesium as the long term consequences are not known.
Be aware that magnesium can interact with or stop the absorption of other medications you are taking including:
- Antibiotics eg tetracycline
- Antacid or indigestion remedies
- Bisphosphonates – used to treat osteoporosis
- Diuretics – ‘water tablets’ often used to treat high blood pressure
Speak to your pharmacist or doctor if you are interested in taking magnesium supplements and you have an ongoing medical condition or you are currently taking other medications.