Updated July 2020
Magnesium is the fourth most common mineral in the body after calcium, potassium, and sodium.
You’d think to be in the top four, magnesium would get some attention when it comes to health and well-being as calcium does for example.
But despite its importance, not many people could say why getting enough magnesium is important nor name a good food source of this essential mineral that gets no respect.
Want to save this article? Click here to get a PDF copy delivered to your inbox
Magnesium is an essential mineral that does a body good
Magnesium plays a number of roles in the body, being involved in more than 325 different metabolic reactions which means it’s in high demand. It helps the body to metabolize fat, protein, and carbohydrate enabling it to get ‘energy’ from the food we eat.
People who eat more magnesium-containing foods tend to have less diabetes. It aids in the proper functioning of your genes, DNA synthesis, and cell replication (your body’s cells are constantly being renewed).
Magnesium helps to both relax and contract your muscles which are very important for those who exercise and especially so for athletes.
Magnesium helps different types of muscles including your heart and blood vessels and it’s very important in bone health by helping calcium and phosphorus to be used to make a strong skeleton.
People who get a lot of magnesium from their diet tend to have lower blood pressure, lower rates of heart disease, diabetes, and better bones.
10 evidence-based health benefits of magnesium
Heart Arrhythmia
Magnesium is central to a healthy heart rhythm because it’s involved in transporting other electrolytes, such as calcium and potassium, into cells. As these electrolytes move in and out of your heart cells, they allow for nerve signals/impulses to send signals enabling the muscle contractions of a normal heartbeat. Research shows that magnesium deficiency, or restricted magnesium intake, increases irregular heartbeats known as arrhythmias.
Not getting enough magnesium predisposes people to heart arrhythmia or irregular, and abnormally fast heartbeats or atrial fibrillation. This happens when there’s an imbalance between blood levels of calcium and magnesium. They normally compete with each other: calcium is all about muscle contraction and magnesium is all about muscle relaxation.
This is neither good nor bad, it just is. They work together in this sense. When calcium enters your heart muscle cells, it stimulates the muscle fibers to contract (this allows your heart to squeeze blood out into your blood vessels). Once calcium has done its job, magnesium counters this contraction effect, helping your heart cells to relax (1, 2) (this helps your heart to refill with blood for the next contraction).
An imbalance of potassium levels inside and outside of heart muscle cells may be to blame, a condition associated with magnesium deficiency (3, 4). Magnesium and potassium supplements may also reduce symptoms in some patients with arrhythmia (5).
Low serum magnesium has been shown to be associated with the development of atrial fibrillation in the general public and is therefore an important public health risk factor for consideration (6). When your magnesium levels are low, calcium may overstimulate your heart muscle cells. One common symptom of this is a rapid and/or irregular heartbeat, which may be life-threatening (7).
In a British study, taking magnesium daily for six weeks reduced arrhythmia between 25% and 50% (8). In another study of 68 patients with hypomagnesemia (low blood magnesium concentration) and ventricular arrhythmias, a single infusion of 8 g of magnesium sulphate, which provided 1600 mg directly into their circulation, showed stark improvement of cardiac function (9).
On a side note, In a review published in May 2019 in Cardiology Research and Practice, researchers found that a low level of blood magnesium may increase the risk of developing cardiovascular disease.
In addition, the review showed that a low magnesium level is associated with atrial fibrillation (afib), the most common heart rate disorder. Afib occurs when a malfunction in the heart’s electrical system causes the upper chambers of the heart to quiver.
High blood pressure
Higher intakes of magnesium are well understood to support healthy blood pressure. Animal studies have shown that magnesium deficiency is a risk factor for high blood pressure (10, 11).
The more magnesium you have in your cells, including the cells that make up your blood vessels, the less calcium that’s present. This makes your blood vessels more elastic, or flexible, resulting in lower blood pressure.
Think of magnesium as nature’s calcium channel blocker. This is how calcium channel blocking medication works; by reducing the amount of calcium that gets into cells, blood vessels can expand easier.
Several observational studies indicate that poor dietary intake (not getting enough magnesium from your food/diet), which leads to low magnesium blood levels, may increase blood pressure (12, 13, 14). Still, there’s some stronger evidence of magnesium lowering blood pressure from several controlled studies.
Reviews have concluded that magnesium supplements can play a supportive role in blood pressure-lowering, including those with high blood pressure (15, 16). An analysis of 34 studies found that a median dose of 368 mg of magnesium significantly reduced both systolic and diastolic blood pressure values in both healthy adults and those with both mild and high blood pressure (17, 18, 19, 20).
In another study, people who took 450 mg of magnesium daily experienced a fall in the systolic (upper) and diastolic (lower) blood pressure values by 20.4 mm Hg and 8.7 mm Hg, respectively (21). Another study found that magnesium lowered blood pressure in people with high blood pressure but had no effect on those with normal levels (22).
Depression
Low levels of magnesium have also been linked to symptoms of depression; this includes observational studies that have associated low magnesium blood levels with an increased risk of depression (23).
One study that involved over 8,800 people found that among adults aged 65 and under, those with the lowest intake of magnesium had a 22% greater risk of this condition (24). Within your brain cells (neurons), magnesium helps to regulate your brain function and mood by balancing the effects of calcium and glutamate which stimulate nerve activity. Magnesium makes sure your nerves don’t get overstimulated; because magnesium ‘inhibits’ this from happening, magnesium has been called the calming mineral.
Several studies have shown that supplementing with magnesium may reduce symptoms of depression. Some studies even found it to be as effective as antidepressant drugs (25, 26). Conservatively, many experts still believe that more research in this area is needed before giving recommendations (27).
Magnesium plays a critical role in brain function and mood, and low levels are linked to an increased risk of depression (28, 24). Some experts believe the low magnesium content of modern food may cause many cases of depression and mental illness (25).
Over the past century, magnesium levels in soils have been decreasing and therefore the amount of magnesium in the modern diet has decreased as well. Some cited reasons are over-farming, mono-crops, inadequate resting of plots between seasons, and more. As well, it’s estimated that between 60-70% of the calories in the modern food supply comes from highly-processed foods and most of those calories come from refined flour, added sugars, and vegetable oils.
Nevertheless, magnesium is an essential nutrient and most of us don’t get enough of it. It’s estimated that about 50% of the population is getting less than half of the recommended minimum amount so, supplementing with this mineral may help reduce symptoms of depression — and in some cases, the results can be dramatic (25, 26). In a randomized controlled trial in depressed older adults, 450 mg of magnesium daily improved mood as effectively as an antidepressant drug (26).
Anxiety
On a side note, researchers have also speculated that magnesium deficiency might promote anxiety, but direct evidence is lacking (29). One systematic review concluded that magnesium supplements might benefit a subset of people with anxiety disorders, but the strength of the evidence is poor and the authors suggest better studies are needed before any conclusions can be reached, or recommendations made with confidence (30).
On the other hand, some studies have shown that lower intakes of magnesium have been associated with an increased risk for anxiety (31, 32). However, when it comes to magnesium and anxiety, getting more magnesium by food and supplements may be beneficial (33, 34, 35). Given that most don’t get the recommended intake, supplements can help to fill the gap.
Type 2 diabetes
Magnesium is needed for the production and efficient use of insulin and insulin stimulates magnesium uptake in insulin-sensitive tissues (36). The irony, of course, is when this doesn’t happen the way it should when people consume high glycemic load diets but don’t get enough dietary magnesium.
The very tissues that need magnesium to properly use insulin to metabolize dietary glucose/carbs can’t. What ends up happening is that blood glucose stimulates insulin which causes your cells and tissues to take up the glucose but then isn’t handle the way the glucose should be. If magnesium levels are low, your cells can’t use insulin effectively, leaving blood sugar levels high (37, 38, 39).
This is likely a contributing factor to/supports what research has indicated; people with low magnesium intake have a higher risk of developing diabetes (40, 41). It’s estimated that lower intakes of magnesium will increase your risk for diabetes by 33%. One study which followed more than 4,000 people for 20 years found that those with the highest magnesium intake were 47% less likely to develop diabetes (42).
Magnesium also benefits people with type 2 diabetes.
Studies suggest that about 48% of people with type 2 diabetes have low levels of magnesium in their blood because more magnesium is lost in the urine, a.k.a. “urinary wasting”; This can impair insulin’s ability to keep blood sugar levels under control (43, 44). Magnesium supplementation is likely needed to top up whatever intake there is from the diet in those with both insulin resistance/pre-diabetes/metabolic syndrome and diabetes.
A study showed that people with type 2 diabetes taking high doses of magnesium each day experienced significant improvements in blood sugar and hemoglobin A1c levels, compared to a control group over a 16 week period (45). An analysis of eight studies showed that taking a magnesium supplement significantly reduced fasting blood sugar levels in participants with type 2 diabetes (46).
However, these effects may depend on how much magnesium you’re getting from food. In a different study, supplements did not improve blood sugar or insulin levels in people who weren’t deficient which makes sense (47).
Bones
Magnesium is as vital as calcium when it comes to strong bones and teeth, but calcium has gotten all the press – good job milk and dairy marketing boards.
When bones lose more bone tissue than can be replaced, bone disease progresses from osteomalacia (where there’s some degree of demineralized bone tissue) to osteopenia and then finally osteoporosis.
Osteoporosis is a disorder characterized by weak bones and an increased risk of bone fractures. The risk of getting osteoporosis is influenced by numerous factors. These include old age, lack of weight-bearing exercise, ethnicity, smoking, alcohol consumption, and a chronically poor intake of vitamins C, D3, and vitamin K2, protein, boron, zinc, and yes, calcium.
What many don’t realize is that magnesium is also important for bone health. So it should be no surprise that magnesium deficiency is also a risk factor for osteoporosis. Deficiency might weaken bones directly by not providing enough bone-building magnesium, but a deficiency also lowers blood levels of calcium, the main building block of bones (48, 49, 50, 51).
Studies have associated poor magnesium intake with lower bone mineral density (52, 53).
Migraines
Migraine headaches are painful and debilitating and those who are suffering from them know this first hand. Nausea, vomiting, and sensitivity to light and noise often occur.
What was news to me, was the role magnesium has in migraine occurrences. It’s estimated that up to half of migraine suffers have a low magnesium intake, that low magnesium levels may cause migraines (54). Studies have shown that increasing magnesium has been shown to reduce both the duration, intensity, and frequency of migraines (55, 56, 57)
Increasing magnesium intake could be a simple way to combat migraines (58, 59). Headache frequency dropped by 42% in a study where subjects took 600 mg of magnesium in divided doses (for better absorption) daily for 3 months (60).
In another study, supplementing with 1 gram (1000 mg) of magnesium provided relief from an acute migraine attack more quickly and effectively than a common medication (61). Additionally, magnesium-rich foods may help reduce migraine symptoms (62).
Better sleep quality
Poor sleep is a major health problem around the world. Sleep is now being recognized as an independent risk factor for health just as alcohol use, diet, smoking, and activity are.
Poor sleep/sleep deprivation increases the risk of daytime accidents, impaired thinking, learning and memory, increased risk of cardiovascular disease, diabetes, high blood pressure, weakened immunity, premature aging of the skin, and increased level of stress hormones such as cortisol.
When it comes to self-care, try to make sleep and getting better sleep a goal; there are many ways to improve sleep with lifestyle measures without needing to rely on medications.
Magnesium is critical for normal electrical activity in the brain and so lower intakes of magnesium can lead to less sound sleep. In sleep studies, participants have been shown to have increased episodes of agitated sleep and frequent awakenings when food records indicate they habitually consume low amounts of magnesium.
Taking magnesium may improve sleep quality by helping your mind and body relax. Magnesium has been touted as the “anti-stress mineral” because it has a calming effect on the nervous system. This relaxation helps you fall asleep faster and may improve your sleep quality (63). In an 8-week study in 46 older adults, those getting 500 mg of magnesium from a supplement daily fell asleep faster. They also noticed improved sleep quality and decreased insomnia symptoms (64).
What’s more, animal studies have found that magnesium can regulate melatonin production, which is a hormone that guides your body’s sleep-wake cycle (65, 66). Melatonin normally starts to increase about 2 hours before you fall asleep assuming you keep a regular sleep schedule and let your natural circadian rhythm regulate this. Magnesium has also been shown to bind to gamma-aminobutyric (GABA) receptors (not unlike L-theanine does). The hormone GABA helps calm down nerve activity, which may otherwise affect sleep (67, 68).
Pain relief
Magnesium also plays a role in regulating muscle contractions. In your muscles, calcium binds to proteins such as troponin C and myosin. This process changes the shape of these proteins, which generates a contraction (69). Because magnesium competes with calcium for these same binding spots to help relax your muscles.
So, muscle twitches, tremours, and muscle cramps can be a sign of magnesium deficiency and in worst-case scenarios, magnesium deficiency may even cause seizures or convulsions (70, 71). If your body doesn’t have enough magnesium to compete with calcium, your muscles may contract too much, causing cramps or spasms.
For these reasons, magnesium supplements are commonly recommended to treat muscle cramps (72). However, other studies show mixed results regarding magnesium’s ability to relieve cramps — some even finding no benefit at all (73). This may be due to differences with the amount of elemental magnesium used, the form of magnesium, the frequency of dosing (once a day versus two or more times for better absorption), and the duration of supplement use (1 week, 4 weeks, 16 weeks, etc.).
Intakes of at least 400 mg of elemental magnesium per day from supplements can help to bring relief. There’s also promising evidence that extra magnesium can help to improve symptoms of myalgia, fibromyalgia, chronic muscular lower back pain, restless leg syndrome, and chronic fatigue syndrome.
Asthma
Magnesium deficiency has been documented in patients with severe asthma (74). Also, when compared to those without asthma, magnesium levels tend to be lower in individuals with asthma (75, 76).
Researchers believe a lack of magnesium may cause the buildup of calcium in the muscles lining the airways of the lungs. Because calcium is responsible for muscle contractions, higher amounts of calcium in the bronchioles causes the airways to constrict, making breathing more difficult (77, 78). Interestingly, an inhaler with magnesium sulfate is sometimes given to people with severe asthma to help relax and expand the airways – magnesium acts as a calcium blocker, preventing constriction. For those with life-threatening symptoms, injections of magnesium sulfate are the preferred route of delivery (79, 80).
However, evidence for the effectiveness of dietary magnesium supplements in asthmatic individuals is inconsistent (81, 82, 83). As with all supplement studies, there’s so much variation between studies as far as dosing, frequency, the form of the supplement, and duration, that it’s also premature to categorically dismiss them all.
Exercise performance
Magnesium also plays a role in exercise performance. Amazingly, during exercise, you may need 10–20% more magnesium than when you’re resting, depending on the activity (84).
Magnesium helps to optimize the role of insulin whose job it is to move blood sugar into your muscles. Magnesium also disposes of lactate, which can build up during exercise and cause fatigue (85). Studies have shown that supplemental magnesium can improve exercise performance for athletes, weekend warriors, the elderly, and people with chronic disease (86, 87, 88). In one study, volleyball players who took 250 mg of elemental magnesium per day experienced improvements in jumping and arm movements (89).
In another study, athletes who supplemented with magnesium for four weeks had faster running, cycling, and swimming times during a triathlon. They also experienced reductions in insulin and stress hormone levels (90).
However, the evidence is mixed. Other studies have found no benefit of magnesium supplements in athletes with low or normal levels of the mineral (91, 92).
How to get more magnesium
Despite magnesium’s vital role in health, most people aren’t getting enough from the foods that they eat. Based on the analysis of dietary intakes, it’s estimated that people in Western societies are getting less than half of those recorded 100 years ago from about 500 mg/day to 175-225 mg/day, and magnesium intake is still falling.
This is due primarily because our modern diets are highly processed and refined. To make matters worse, research is suggesting that the amount of magnesium required for optimum health has been underestimated in the past.
While there isn’t an easy test to determine magnesium status (i.e. a blood test), there are some nutritional risk factors and eating habits that are associated with low magnesium intake:
- If you eat more white flour products instead of 100% whole wheat
- If you don’t eat a lot of green leafy vegetables
- If you don’t eat many nuts, seeds, and legumes
- If you regularly eat or drink sugar or sugary products/beverages
- If you drink alcohol regularly [big magnesium depletion here]
- If you take an H2 antagonist [Zantac] or proton pump inhibitor [Prevacid]
- If you follow a calorie-restricted or high-protein, low carbohydrate diet that doesn’t include a lot of nuts, seeds, pulses [chickpeas, lentils, dried peas & beans]
- If you have pre-diabetes or diabetes [lots of magnesium lost in urine]
- Use antibiotics like Gentamicin or Amphotericin
- Take diuretics like Lasix, Bumex, Edecrin or hydrochlorothiazide
How much magnesium do you need?
| Age | Women | Men |
| 14-18 | 360 mg/dau | 410 mg/day |
| 19-30 | 310 mg/day | 400 mg/day |
| 31+ | 320 mg/day | 420 mg/day |
Magnesium is abundant in:
There are a lot of great food sources of magnesium to be had. Getting more magnesium is about being consistent with your choices of magnesium-rich foods such as:
- Unrefined whole and intact grains and grain products
- 100% whole grain whole wheat bread and cereals, steel-cut oats, bran, quinoa, black and wild rice, teff
- Green vegetables:
- Broccoli, Swiss chard, collard greens, spinach, asparagus, Brussels sprouts, and kale
- Nuts and seeds
- Pulses:
- Chickpeas, lentils, dried peas & beans
- Dark chocolate
- The darker, the better
The following are a list of good food sources.
| Food | Magnesium content per 100g |
| Pumpkin seeds | 532 mg (177 mg per 1/3 cup) |
| Almonds | 300 mg (100 mg per 23 almonds) |
| Brazil nuts | 225 mg (75 mg per 8 nuts) |
| Peanuts (roasted) | 183 mg (124 mg per ½ cup) |
| Walnuts | 158 mg (53 mg per 7 walnuts) |
| Rice (whole grain brown) | 110 mg (55 mg per ½ cup cooked) |
| 100% Whole grain bread | 85 mg (about 3 slices) |
| Spinach | 80 mg (about ½ cup cooked) |
| Cooked legumes | 40 mg (about ½ cup cooked) |
| Broccoli | 30 mg (about 1 cup chopped) |
| Banana | 29 mg (1 medium) |
Want to save this article? Click here to get a PDF copy delivered to your inbox
Bottom line?
Magnesium is a mineral involved in hundreds of cellular reactions.
It competes with calcium, ensuring your heart and muscles contract and relax properly, and can even improve migraines, depression, blood pressure, blood sugar levels, and sleep quality.
Yes, despite this amazing mineral’s benefits, it hasn’t received the attention that other minerals have such as calcium, iron, zinc, or potassium have – in short, it doesn’t get any respect.
Given the potential for sub-optimal magnesium intake (up to 75% of North Americans), anyone not already doing so should make a conscious effort to eat more magnesium-rich foods every day. Even simple changes like eating more dark green and dark green leafy vegetables and boosting your intake of nuts and seeds can make a big impact.
In addition to eating more magnesium-rich foods, reach for a multivitamin/mineral – look for one with at least 100 mg of magnesium.
A word of caution: taking more than 400 mg of magnesium from supplements [but not food], in a single dose, it MAY cause looser stools – this is not something to be worried about if this happens, just reduce the amount you’re getting from supplements. Keep in mind this is very rare.
In order to meet the recommended DAILY minimum intake of 320 mg of magnesium for women and 420 mg for men, strive to eat more magnesium-rich foods, and consider a supplement. Supplements can be even more important for those of whom have higher intakes, such as:
Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on anti-aging, brain, and mental health. Follow me on Facebook, Instagram, and Twitter.