Magnesium is an important mineral, playing a role in over 300 enzyme reactions in the human body. Its many functions include helping with muscle and nerve function, regulating blood pressure, and supporting the immune system.
An adult body contains around 25 gram (g) of magnesium, 50–60% of which the skeletal system stores. The rest is present in muscle, soft tissues, and bodily fluids.
Many people in the United States do not get enough magnesium in their diet, though deficiency symptoms are uncommon in otherwise healthy people.
Doctors link magnesium deficiency with a range of health complications, so people should aim to meet their daily recommended levels of magnesium.
Almonds, spinach, and cashew nuts are some of the foods highest in magnesium. If a person cannot get enough magnesium through their diet, their doctor may recommend taking supplements.
In this article, we look at the function and benefits of magnesium, what it does in the body, dietary sources, and possible health risks doctors link to too much.
Magnesium is one of seven essential macrominerals. These macrominerals are minerals that people need to consume in relatively large amounts — at least 100 milligrams (mg) per day. Microminerals, such as iron and zinc, are just as important, though people need them in smaller amounts.
Magnesium is vital for many bodily functions. Getting enough of this mineral can help prevent or treat chronic diseases, including Alzheimer's disease, type 2 diabetes, cardiovascular disease, and migraine.
The following sections discuss the function of magnesium in the body and its effects on a person's health.
1. Bone health
While most research has focused on the role of calcium in bone health, magnesium is also essential for healthy bone formation.
Magnesium may improve bone health both directly and indirectly, as it helps to regulate calcium and vitamin D levels, which are two other nutrients vital for bone health.
A magnesium deficiency may worsen insulin resistance, which is a condition that often develops before type 2 diabetes. On the other hand, insulin resistance may cause low magnesium levels.
In many studies, researchers have linked high magnesium diets with diabetes. In addition, a systematic review from 2017 suggests that taking magnesium supplements can also improve insulin sensitivity in people with low magnesium levels.
However, researchers need to gather more evidence before doctors can routinely use magnesium for glycemic control in people with diabetes.
3. Cardiovascular health
The body needs magnesium to maintain the health of muscles, including the heart. Research has found that magnesium plays an important role in heart health.
A 2018 review reports that magnesium deficiency can increase a person's risk of cardiovascular problems. This is partly due to its roles on a cellular level. The authors observe that magnesium deficiency is common in people with congestive heart failure and can worsen their clinical outcomes.
People who receive magnesium soon after a heart attack have a lower risk of mortality. Doctors sometimes use magnesium during treatment for congestive heart failure (CHF) to reduce the risk of arrhythmia, or abnormal heart rhythm.
Some research also suggests that magnesium plays a role in hypertension. However, according to the Office of Dietary Supplements (ODS), based on current research, taking magnesium supplements lowers blood pressure "to only a small extent."
The ODS call for a "large, well-designed" investigation to understand the role of magnesium in heart health and the prevention of cardiovascular disease.
4. Migraine headaches
Magnesium therapy may help prevent or relieve headaches. This is because a magnesium deficiency can affect neurotransmitters and restrict blood vessel constriction, which are factors doctors link to migraine.
People who experience migraines may have lower levels of magnesium in their blood and body tissues compared with others. Magnesium levels in a person's brain may be low during a migraine.
A systematic review from 2017 states that magnesium therapy may be useful for preventing migraine. The authors suggest that taking 600 mg of magnesium citrate appears to be a safe and effective prevention strategy.
The American Migraine Foundation report that people frequently use doses of 400–500 mg per day for migraine prevention.
The amounts that may have an affect are likely to be high, and people should only use this therapy under the guidance of their doctor.
5. Premenstrual syndrome
Magnesium may also play a role in premenstrual syndrome (PMS).
Small-scale studies, including a 2012 article, suggest that taking magnesium supplements along with vitamin B-6 can improve PMS symptoms. However, a more recent 2019 review reports that the research is mixed, and further studies are needed.
The American College of Obstetricians and Gynecologists suggest that taking magnesium supplements could help to reduce bloating, mood symptoms, and breast tenderness in PMS.
According to a systematic review from 2017, low magnesium levels may have links with higher levels of anxiety. This is partly due to activity in the hypothalamic-pituitary-adrenal (HPA) axis, which is a set of three glands that control a person's reaction to stress.
However, the review points out that the quality of evidence is poor, and that researchers need to do high quality studies to find out how well magnesium supplements might work for reducing anxiety.
The following table shows the recommended daily allowance (RDA) for magnesium intake by age and sex, according to the ODS.
|1–3 years||80 mg||80 mg|
|4–8 years||130 mg||130 mg|
|9–13 years||240 mg||240 mg|
|14–18 years||410 mg||360 mg|
|19–30 years||400 mg||310 mg|
|31–50 years||420 mg||320 mg|
|51+ years||420 mg||320 mg|
People should increase their magnesium intake by around 40 mg per day during pregnancy.
Experts base the adequate intake for babies under 1 year old on the amounts found in breastmilk.
Many foods contain high levels of magnesium, including nuts and seeds, dark green vegetables, whole grains, and legumes. Manufacturers also add magnesium to some breakfast cereals and other fortified foods.
The best sources of magnesium include:
|Source||Per serving||Percentage of daily value|
|Almonds (1 ounces or oz)||80 mg||20%|
|Spinach (half a cup)||78 mg||20%|
|Roasted cashews (1 oz)||74 mg||19%|
|Oil roasted peanuts (one-quarter cup)||63 mg||16%|
|Soy milk (1 cup)||61 mg||15%|
|Cooked black beans (half a cup)||60 mg||15%|
|Cooked edamame beans (half a cup)||50 mg||13%|
|Peanut butter (2 tablespoons)||49 mg||12%|
|Whole wheat bread (2 slices)||46 mg||12%|
|Avocado (1 cup)||44 mg||11%|
|Potato with skin (3.5 oz)||43 mg||11%|
|Cooked brown rice (half a cup)||42 mg||11%|
|Low fat yogurt (8 oz)||42 mg||11%|
|Fortified breakfast cereals||40 mg||10%|
|Oatmeal, instant, 1 packet||36 mg||9%|
|Canned kidney beans (half a cup)||35 mg||9%|
|Banana (1 medium)||32 mg||8%|
Wheat products lose magnesium when the wheat is refined, so it is best to choose cereals and bread products made with whole grains. Most common fruits, meat, and fish contain low in magnesium.
While many people do not meet their recommended intake for magnesium, deficiency symptoms are rare in otherwise healthy people. Magnesium deficiency is known as hypomagnesemia.
Magnesium inadequacy or deficiency can result from excess consumption of alcohol, a side effect of certain medications, and some health conditions, including gastrointestinal disorder and diabetes. Deficiency is more common in older adults.
Symptoms of magnesium deficiency include:
- a loss of appetite
- nausea or vomiting
- fatigue or weakness
Symptoms of more advanced magnesium deficiency include:
- muscle cramps
- personality changes
- heart rhythm changes or spasms
Research has linked magnesium deficiency with a range of health conditions, including Alzheimer's disease, type 2 diabetes, cardiovascular disease, and migraine.
An overdose of magnesium through dietary sources is unlikely because the body will eliminate any excess magnesium from food through urine.
However, a high intake of magnesium from supplements can lead to gastrointestinal problems, such as diarrhea, nausea, or cramping.
Very large doses can cause kidney problems, low blood pressure, urine retention, nausea and vomiting, depression, lethargy, a loss of central nervous system (CNS) control, cardiac arrest, and possibly death.
People with a kidney disorder should not take magnesium supplements unless their doctor advises that they do so.
Magnesium supplementation may also give rise to some drug interactions. Medications that may interact with magnesium supplements or affect magnesium levels include:
- oral bisphosphonates that treat osteoporosis, such as alendronate (Fosamax)
- tetracycline antibiotics, including doxycycline (Vibramycin) and demeclocycline (Declomycin)
- quinolone antibiotics, including levofloxacin (Levaquin) and ciprofloxacin (Cipro)
- diuretics, such as furosemide (Lasix)
- prescription proton pump inhibitors, including esomeprazole magnesium (Nexium)
Magnesium supplements are available to purchase online, but it is best to obtain any vitamin or mineral through food because nutrients work better when people combine them with other nutrients.
Many vitamins, minerals, and phytonutrients work synergistically. This term means that taking them together brings more health benefits than taking them separately.
It is better to focus on a healthful, balanced diet to meet daily requirements for magnesium and to use supplements as a backup, but under medical supervision.
Magnesium is an essential macronutrient that plays a key role in many body processes, including muscle, nerve, and bone health, and mood.
Research has linked magnesium deficiencies with a range of health complications. If a person is unable to get their daily requirements from their diet, a doctor may recommend taking magnesium supplements.