Magnesium: what it does, foods that provide it and when levels may be low

What is magnesium for?

Magnesium is involved in processes that allow the body to use energy from food. It also plays a part in muscle and nerve function and is part of the structure of bone [1]. Taking more than you need does not, by itself, improve performance or bone health.

A practical way to get enough is to eat a variety of food groups throughout the week. A chickpea and seed salad or porridge made with oats and almonds can contribute magnesium without treating any one food as a remedy.

If your question is about bone health during menopause or symptoms related to the menstrual cycle, each topic has its own guide.

Which foods provide the most magnesium per serving?

Typical servings put the figures in context. This table estimates the magnesium in each portion using BEDCA values per 100 g [2]. These are approximate amounts; products and preparation methods can vary.

Food	Suggested serving	Approximate magnesium
Pumpkin seeds	30 g	178 mg
Sesame seeds	15 g	53 mg
Raw almonds	30 g	77 mg
Boiled chickpeas	180 g	95 mg
Raw oats	40 g	71 mg
Boiled spinach	150 g	70 mg
Dark chocolate with sugar	20 g	21 mg

Chocolate provides magnesium, but the serving is small. Pulses and whole grains, which are eaten in larger amounts, contribute more over the course of the day [2].

How much magnesium is needed each day?

The European Food Safety Authority sets an indicative daily reference intake for the population [1]. For adults, it is 350 mg a day for men and 300 mg for women. The reference remains 300 mg during pregnancy and breastfeeding [1].

Life stage	Daily magnesium reference
7–11 months	80 mg
1 to under 3 years	170 mg
3 to under 10 years	230 mg
10 to under 18 years: girls / boys	250 / 300 mg
Adults: women / men	300 / 350 mg
Pregnancy and breastfeeding	300 mg

These are indicative references for daily food intake. They are not a reason to give magnesium supplements to children or pregnant people without professional assessment.

Who may be at risk of magnesium deficiency?

Clinical deficiency is uncommon in healthy people who eat enough. According to the US National Institutes of Health, the risk is higher with malabsorption, type 2 diabetes, high alcohol consumption, persistently low magnesium intake or older age [3]. Some diuretics increase magnesium losses; long-term use of proton pump inhibitors may also lower magnesium levels [3].

Early symptoms, such as loss of appetite, nausea or weakness, are not specific [3]. That is why we consider diet, medication and clinical context before drawing conclusions. If you take one of these medicines, talk to the prescriber; do not stop it based on this information.

What is the relationship between magnesium, sport and cramps?

Training requires adequate energy and nutrients from your diet. According to the Australian Institute of Sport, magnesium supplements have not been shown to improve performance in trained athletes who already eat enough [4]. If you train a lot and eat too little, we first assess whether your eating plan provides what you need.

Cramps during exercise do not prove that you have a magnesium deficiency: the Cochrane review found no trials testing magnesium for exercise-associated cramps [5]. You can find what is known about cramps in our guide to foods high in potassium.

For help planning meals before and after training, see our sports nutrition guide.

How much magnesium from supplements is safe?

A magnesium supplement should be recommended by your doctor or dietitian-nutritionist after considering your diet, symptoms, medication and kidney function. If there is a cause of deficiency, identifying it is part of the decision. If you have fibromyalgia, our guide reviews what is known about magnesium and other supplements. See “Magnesium after 60”.

The European table of upper limits sets a limit for added magnesium for people aged 4 and over, including pregnant and breastfeeding people [6]. No such limit has been established for children under 4 [6]. It applies to salts and compounds in supplements, water or fortified foods, not to magnesium naturally present in food [6].

At high doses, magnesium from supplements, laxatives or antacids can cause diarrhoea and other digestive symptoms [3]. If you have kidney disease, any product containing magnesium needs medical assessment before use [3]. Do not add up the amounts in several products or medicines on your own.

Can it help with sleep, anxiety or migraine?

For better sleep, a recent review of trials found inconsistent results and low-certainty evidence. It does not support routine use of magnesium as a treatment for insomnia [7]. In mild anxiety, another review found promising results, especially in people with low levels, but called for larger, more consistent trials before a recommendation can be established [8].

For migraine, a meta-analysis of trials found fewer migraine attacks and migraine days per month with magnesium supplements [9]. If you are already receiving treatment, consult your doctor. A supplement should be recommended by your doctor or dietitian-nutritionist. Eating foods that contain magnesium is not the same as the intervention studied.

Questions we are asked about magnesium in consultations

The most common question is whether one isolated cramp is enough to diagnose magnesium deficiency. It is not. We review what you eat over the week, what medication you take and whether there is a cause that needs medical attention.

We also see labels that advertise magnesium without making clear how much a serving provides. Compare the stated daily amount with the upper limit for added magnesium [6], and bring the packaging to your appointment if you need help interpreting it.