Magnesium: What It Is, How Much You Need, Best Food Sources
Magnesium is a veritable workhorse among the minerals your body needs. You need it for muscle function, normal heart rhythm, blood glucose control, nerve function, to transport other minerals throughout the body, and for basic energy needs. (1)
Here’s what you should know about how much magnesium you need every day, where to get it, and when you should think about taking magnesium supplements.
Magnesium is a mineral that is naturally found in plant and animal foods. For humans, it’s an essential nutrient, helping with more than 300 different biochemical reactions that take place in our bodies all the time. (1)
As an ionic or “charged” particle, magnesium is an important electrolyte that supports optimal nerve and muscle function, including involuntary muscles like the heart. It may help lower blood pressure. In fact, one study found that participants who received additional magnesium through a supplement of about 300 milligrams (mg) per day for three months increased their blood levels of the mineral and reduced their systolic blood pressure (the top reading of a blood pressure reading) by two points and diastolic blood pressure (the bottom number on that reading) by 1.78 points. (2)
Magnesium — along with other nutrients like chromium — also helps regulate blood sugar. Magnesium intake has been shown to improve insulin sensitivity and may be useful for the prevention and management of type 2 diabetes. (3) The human body needs adequate magnesium to support immunity and turn food into energy.
What’s more, magnesium helps the body absorb other essential minerals, including calcium and potassium — meaning it plays a role in all the functions that those minerals support, such as maintaining bone health.
You may also be surprised to learn that magnesium is the third most prevalent mineral in human bones, after calcium and phosphorus — and 60 percent of the magnesium in the body is stored in the skeleton. (1)
Recommended dietary allowances (RDAs) are the average daily intake levels of any given vitamin or mineral that sufficiently meet the nutrient requirement for most healthy individuals. RDAs for magnesium vary by age and gender: (1)
Generally speaking, some of the best food sources of magnesium are those that are high in fiber. They include: (1)
The above list includes good sources not only of magnesium, but also phytonutrients, which are plant chemicals that promote health and immunity. Refining and processing foods depletes naturally occurring magnesium, so as usual, it is best to opt for minimally processed sources.
Other foods with magnesium include:
Some of the early symptoms of a deficiency are muscle weakness, fatigue, low appetite, nausea, and vomiting. Because these symptoms may be due to a multitude of other issues, it is advisable to see your physician if you are experiencing them.
Blood tests, however, are not a valid measure of overall magnesium stores, since we store most of the mineral in our bones. Some researchers believe many cases of chronic magnesium deficiency go undiagnosed. (1) This type of unrecognized deficiency is problematic because it may contribute to many common medical conditions, including cardiovascular disease, diabetes, and osteoporosis. (4)
Although Americans generally don’t get optimal amounts of magnesium every day, deficiencies that result in health harms are relatively rare. (5) The following would put you at risk for magnesium deficiency: (6)
Not getting enough magnesium can disrupt a lot of bodily processes that happen each day. And new evidence suggests that over time the consequences can add up and may play a role in these chronic problems.
“Your heart is essentially a large muscle,” says Olivia Wagner, RDN an integrative registered dietitian nutritionist in Chicago. Magnesium works in tandem with calcium to support blood pressure, and it also may balance lipid levels, all of which helps promote healthy heart function, she says.
A 2016 study found a link between low serum magnesium levels and both coronary heart disease (CHD) and sudden cardiac death. But it remains unclear exactly why the relationship exists or if supplementing with magnesium would lower the risk of either. ( 7)
Several studies have associated healthy levels of magnesium in the diet with a lower incidence of stroke, but because much of the research on both CHD and stroke is from observational studies, this is just an association; more data are needed from randomized clinical trials to determine if higher magnesium levels directly reduce the risk of these conditions. (8)
RELATED: The 6 Best Nutrient Pairings for Your Heart
A 2015 review of observational research on magnesium and type 2 diabetes suggests that adequate magnesium intake may lower the risk of the disease, because people who get enough magnesium in their diets seem to have a lower incidence of this chronic health problem. (9)
“If you’ve been diagnosed with insulin resistance or prediabetes, then taking extra magnesium may really help you,” says Robin Foroutan, RDN, who specializes in integrative and functional medicine at the Morrison Center in New York City.
Furthermore, if you have diabetes, magnesium supplementation may also help keep you healthy. Having type 2 diabetes raises your risk for heart disease, but people with a higher blood level of magnesium are less likely to develop coronary heart disease. ( 10)
Magnesium is essential for bone formation, says Foroutan. It also indirectly affects bone density because it is part of the system that regulates the important bone nutrients calcium and vitamin D. Thus, it is important to get enough magnesium to support your skeleton.
As a study on middle-aged and older adults suggests, consuming magnesium-rich foods may play an important role in preventing diseases like osteoporosis and bone fracture. (11)
In the few clinical trials conducted, magnesium helped lower the frequency, duration, and severity of migraine. (12) The therapeutic dose for migraine treatment is well above the recommended maximum from supplements, so it is safest to seek the help of a healthcare professional for advice and monitoring. Still, Foroutan says that for some people with migraine who aren’t actually low in magnesium, megadoses (excess magnesium) may be helpful in inhibiting attacks.
You may not need a supplement, and you can optimize your intake through dietary changes, says Wagner.
Still, some healthcare professionals believe that much of the public has what’s called “subclinical magnesium deficiency,” which means that a person runs chronically low in the mineral but not low enough to be defined as deficient. There may be several factors at work in this widespread deficiency, including lack of nutrients in soil and an excess intake of processed foods, which are stripped of minerals. (2)
If you’re dealing with certain symptoms that might suggest you’re running low in magnesium — frequent headaches, muscle cramping at night or with exercise, fatigue, or constipation — you may benefit from a magnesium supplement, says Wagner. Talk to a healthcare professional to see what’s right for you.
Overall, magnesium supplements are safe, as long as you’re following the label or a doctor’s recommendations and not consuming excessive amounts, says Foroutan. Taking too much will act as a laxative — one clue that you’re going overboard.
While your kidneys do flush out excess magnesium (it is a water-soluble mineral), getting too much of the mineral from supplements can cause diarrhea (often accompanied by nausea and abdominal cramping) — and in very large doses can cause more serious problems like retention of urine, difficulty breathing, irregular heartbeat, and cardiac arrest. Those more serious consequences have resulted from magnesium doses exceeding 5,000 mg per day. (1)
People with acid reflux who take proton pump inhibitor medications for more than one year are at risk for low magnesium levels. The U.S. Food and Drug Administration warns that even magnesium supplements didn’t raise levels enough in these people. (13)
Because extra magnesium is eliminated by your kidneys, anyone who has renal impairment should not take supplements without discussing it with a healthcare provider. Likewise, anyone taking certain medications, including bisphosphonates, antibiotics, diuretics, or proton pump inhibitors should be aware of possible adverse drug-nutrient interactions. Be sure to speak with your healthcare team before starting this or any other supplement.
If you do decide to take a magnesium supplement, you’ll need to decide what type to take. Different types of magnesium vary in price, how well your body can absorb them, and potential side effects. Research suggests that magnesium aspartate, lactate, chloride, and citrate are best absorbed by our bodies. Whereas magnesium oxide and magnesium sulfate (also known as Epsom salt), which can also be taken orally, are less easily absorbed.
The types of magnesium most likely to cause diarrhea are magnesium carbonate, chloride, gluconate, and oxide, according to past research. (14) Keep in mind that supplements can be a natural way to relieve constipation due to their laxative effect.
Magnesium threonate is a form of magnesium that may pass into the brain more efficiently, thus both Wagner and Foroutan use it when addressing mood, sleep, and cognition issues.
Magnesium clearly plays a large role in the healthy function of your body. It’s possible that you are running low on magnesium, especially if you’ve been struggling with insulin levels, muscle cramps, or migraine. Magnesium-rich foods and supplements can safely help get your levels back up so you can feel great.
Additional reporting by Jessica Migala.
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