Magnesium is a mineral that you need to stay healthy.
It’s crucial for many functions in your body, including energy metabolism and protein synthesis. It also contributes to proper brain function, bone health and heart and muscle activity (1).
Magnesium is found naturally in foods like nuts, leafy green vegetables and milk products (2).
Supplementing with this vital nutrient has been linked to many benefits, including better blood sugar regulation, improved sleep and relief from constipation.
This article reviews different types of magnesium supplements and how to determine the best daily dosages for your needs.
Magnesium is essential for maintaining proper health.
However, low magnesium intake is relatively common.
It’s primarily found in people who follow a typical Western diet, which contains processed foods and refined grains and can lack foods like leafy green vegetables and legumes that provide magnesium and other important nutrients (3, 4).
The table below identifies the recommended daily allowance (RDA) or adequate intake (AI) of magnesium for adults, infants and children (2).
|Birth to 6 months (AI)||30 mg||30 mg|
|7–12 months (AI)||75 mg||75 mg|
|1–3 years (RDA)||80 mg||80 mg|
|4–8 years (RDA)||130 mg||130 mg|
|9–13 years (RDA)||240 mg||240 mg|
|14–18 years (RDA)||410 mg||360 mg|
|19–30 years (RDA)||400 mg||310 mg|
|31–50 years (RDA)||420 mg||320 mg|
|51+ years (RDA)||420 mg||320 mg|
For pregnant women 18 or older, the requirements are increased to 350–360 mg per day (2).
Taking a magnesium supplement may help increase magnesium levels in those who have a higher risk of deficiency or in those who don’t consume enough through their diet.
Summary The recommended daily allowance (RDA) for magnesium for adults is 310–420 mg depending on age and gender.
There are many forms of magnesium supplement available.
The most important thing to consider before deciding on a supplement is its absorption rate, or how well the supplement is absorbed by your body.
Here is a brief description of each of the most common magnesium supplements.
Magnesium gluconate comes from the magnesium salt of gluconic acid. In rats, it has been shown to have the highest absorption rate compared to other types of magnesium supplements (8).
Magnesium oxide has the highest amount of elemental, or actual, magnesium per weight. However, it’s poorly absorbed. Studies have found that magnesium oxide is essentially insoluble in water, making absorption rates low (9, 10).
In magnesium citrate, magnesium in salt form is combined with citric acid. Magnesium citrate has been shown to be absorbed relatively well by the body and has high solubility in water, meaning it mixes well with liquid (10).
Magnesium citrate is found in pill form but also commonly used as a saline laxative before a major surgery or colonoscopy.
Like magnesium gluconate and citrate, magnesium chloride has been found to be well absorbed by the body (2).
It’s also available as an oil that can be applied topically, but further studies are needed to fully understand how well magnesium in this form is absorbed through the skin (11).
Magnesium glycinate has been shown to have a relatively good absorption rate with less of a laxative effect.
This is likely because it’s absorbed in a different area of your intestine, compared to many other forms of magnesium supplements (15).
Summary There are many types of magnesium supplement. It’s important to consider the absorption rate of supplements before making a purchase.
Whether you struggle with acute or chronic constipation, it can be uncomfortable.
Magnesium hydroxide, or milk of magnesia, works as a laxative by pulling water into your intestines, which helps soften your stool and ease its passage.
It’s generally recommended to start with two tablespoons (30 ml) of milk of magnesia and increase the dosage to four tablespoons (60 ml) as needed.
However, exceeding four tablespoons (60 ml) daily could cause watery diarrhea or electrolyte imbalances.
Due to its laxative effect, milk of magnesia is generally used to treat acute constipation and is not usually recommended for chronic cases.
Magnesium citrate is another magnesium supplement used to treat constipation.
It’s better absorbed and has a gentler laxative effect than magnesium hydroxide (17).
The standard dose for magnesium citrate is 240 ml per day, which can be mixed with water and taken orally.
Summary Magnesium citrate and magnesium hydroxide are common magnesium compounds used to treat constipation. For best results, always follow standard dosage recommendations on the label.
Adequate magnesium levels are important for a good night’s sleep. Magnesium can help your mind relax and your body achieve deep, restorative sleep.
In fact, studies in rats have shown that magnesium levels below optimal led to poor sleep quality (18).
Currently, a limited number of studies have observed the effect of magnesium supplements on sleep quality, which makes it difficult to recommend a specific daily dose.
However, in one study, older adults who received 414 mg of magnesium oxide twice daily (500 mg of actual magnesium total per day) had better sleep quality, compared to adults who received a placebo (19).
Summary Based on limited research, taking 500 mg of magnesium daily may improve sleep quality.
High blood sugar can increase magnesium loss through your urine, causing low magnesium levels in your blood.
Studies have shown that magnesium supplements may help regulate blood sugar by managing insulin action (22).
Insulin is a hormone that helps control blood sugar levels by signaling your cells to take in sugar from your blood.
One study found that supplementing with 2,500 mg of magnesium in a magnesium chloride solution daily improved insulin sensitivity and fasting blood sugar levels in people with type 2 diabetes and low magnesium levels at baseline (23).
However, another study found that people who received a daily total of 20.7 mmol of magnesium oxide daily had no improvement in blood glucose regulation.
That being said, those who received a higher dosage of magnesium oxide (41.4 mmol daily) showed a decrease in fructosamine, an average measurement of a person’s blood sugar over about two to three weeks (24).
The researchers concluded that prolonged magnesium supplementation at higher than usual doses could be beneficial in blood glucose control, but further studies are needed (24).
Summary Very high doses of 2,500 mg of magnesium supplement daily have been shown to improve blood glucose levels in patients with diabetes, but more research is needed.
Many conditions can cause muscle cramps.
Since magnesium is key to muscle function, a deficiency may cause painful muscle contractions.
Magnesium supplements are often marketed to prevent or improve muscle cramping.
Though research on magnesium supplements for muscle cramping is mixed, one study found that participants who received 300 mg of magnesium daily for six weeks reported fewer muscle cramps, compared to those who received a placebo (25).
Another study observed the effectiveness of magnesium supplements on leg cramps experienced during pregnancy. Women who took 300 mg of magnesium daily experienced less frequent and less intense leg cramps, compared to women who took a placebo (26).
Summary Although further research is needed on magnesium and muscle cramps, taking 300 mg of magnesium daily has been shown to decrease symptoms.
Therefore, taking a magnesium supplement may improve symptoms in some people.
One study found that 248 mg of magnesium chloride improved depressive symptoms in those with mild-to-moderate depression (28).
Moreover, another study found that taking 450 mg of magnesium chloride was as effective in improving depressive symptoms as an antidepressant (29).
While magnesium supplements may improve depression in those with magnesium deficiency, further research is needed to conclude if supplements improve depression when magnesium is within normal limits.
Summary Supplementing with 248–450 mg of magnesium per day has been shown to improve mood in patients with depression and low magnesium levels.
Various studies involving the effect of magnesium supplements on exercise performance have shown that improvement is largely based on dosage.
For example, two studies that used doses of 126–250 mg of magnesium daily showed no significant change in exercise performance or muscle gain.
However, another study found that volleyball players who took 350 mg of magnesium per day showed improved athletic performance, compared to the control group (32).
Summary Supplementing with magnesium at doses of 350 mg or higher per day may boost exercise performance.
Premenstrual syndrome (PMS) is a group of symptoms, including water retention, agitation and headaches, that many women experience about one to two weeks before their period.
Supplementing with magnesium has been shown to improve PMS symptoms.
Another study determined that taking 360 mg of magnesium daily improved PMS symptoms associated with mood and mood changes (34).
Summary Magnesium doses of 200–360 mg daily have been shown to improve PMS symptoms in women, including mood and water retention.
People who experience migraines may be at risk of magnesium deficiency due to several factors, including a genetic inability to absorb magnesium efficiently or increased excretion of magnesium due to stress (35).
Another study showed that the same dose daily tended to decrease the frequency of migraine attacks (37).
Summary Supplementing with 600 mg of magnesium daily has been shown to prevent and possibly decrease the intensity and duration of migraines.
The US-based National Academy of Medicine recommends not to exceed 350 mg of supplemental magnesium per day (2).
However, several studies involve higher daily dosages.
If you’re taking a daily magnesium supplement that provides more than 350 mg, it’s recommended you do so only under medical supervision.
Though magnesium toxicity is rare, taking certain magnesium supplements at high doses may cause diarrhea, accompanied by nausea and abdominal cramping.
Magnesium supplements may also interact with some medications, including antibiotics and diuretics (2).
Summary Magnesium toxicity is rare, but be sure to speak with your healthcare provider before beginning supplementing with more than 350 mg daily.
Magnesium is involved in more than 300 biochemical reactions in the human body and crucial for maintaining good health.
The RDA for magnesium is 310–420 mg for adults depending on age and gender.
If you require a supplement, dosage recommendations can vary depending on your needs, such as to improve constipation, sleep, muscle cramps or depression.
Most studies found positive effects with daily doses of 125–2,500 mg.
However, it’s best to consult with your healthcare provider before taking a supplement, especially at higher doses.