Magnesium is an essential mineral that is important for numerous physiological functions and critical for maintaining health. Although magnesium is found in a wide variety of foods, there may be times when a supplement is warranted. With countless supplements on the market, knowing which one is best for your needs can be difficult. 

Chelated magnesium is a magnesium supplement that is bound to a carrier, making it more readily absorbed by the body so you can reap the benefits of this essential mineral. 

In this article, we’ll learn about magnesium, its absorption in the body, and its importance for health. Then we’ll discuss chelated magnesium, the different types of supplements, and what you should be aware of before introducing a magnesium supplement into your routine.

Magnesium in the Body

Magnesium is a mineral abundant in the body. It participates in numerous physiological processes and plays a key role in energy production, protein synthesis, muscle and nerve function, blood sugar control, and blood pressure regulation. 

The body holds roughly 25 grams of magnesium, with about 50% to 60% stored in the bones and the remainder in soft tissue. Less than 1% of total magnesium is circulating in body fluids at any one time. Normal magnesium blood levels range from 0.75 to 0.96 millimoles (mmol) per liter (L). Magnesium concentrations below 0.75 mmol/L constitute hypomagnesemia (low magnesium). 

It is difficult to truly assess your magnesium status, as most magnesium in the body is inside cells or bone. A serum magnesium test is used to evaluate magnesium levels in the blood, but it doesn’t tell us much about how much magnesium is stored in the body. (Source) 

What Is Chelated Magnesium?

Chelated magnesium is a form of magnesium found in supplements. The term chelated refers to the binding of molecules. In the case of chelated magnesium, magnesium is attached to another molecule (or two). Chelation increases bioavailability, or the amount of a substance the body can absorb. 

The various molecules used for chelation contribute to the plethora of chelated magnesium supplements available, and influence the bioavailability of each. For example, magnesium oxide supplements may provide large amounts of magnesium, but relatively little of that magnesium is actually available for the body to use. Magnesium citrate supplements, on the other hand, may contain smaller amounts of magnesium, but more of it is absorbed by the body. (Source)  

How Is Magnesium Absorbed in the Body?

Your body absorbs roughly 30% to 40% of the magnesium you consume. Magnesium is primarily absorbed in the small intestine, with a small amount taken up by the large intestine. Intestinal absorption is affected by the level of magnesium your body has on hand. If your magnesium is low because you’re not taking in enough of the mineral, more of what you do take in will be absorbed. Furthermore, multiple factors — endogenous (within the body) and exogenous (external to the body) — influence magnesium absorption. (Source, Source) 

What Factors Influence Magnesium Absorption?

Endogenous factors include magnesium status and age. The kidneys are actively involved in regulating magnesium levels, holding on to the mineral when levels in the body are low, and excreting more of it in the urine when levels are high. Additionally, magnesium absorption becomes less efficient with age. (Source) 

Certain foods and nutrients can positively or negatively influence magnesium absorption. Some foods — such as those containing lactose, protein, medium-chain triglycerides (coconut-based products), or indigestible carbohydrates (for example, resistant starch, short-chain fructo-oligosaccharides, and lactulose) — may improve absorption. On the other hand, compounds in certain foods — such as oxalic acid (found in spinach and cruciferous vegetables) and phytic acid (present in bran and whole-grain bread) — may decrease magnesium absorption. (Source)

Magnesium and Health

Besides its role in more than 300 enzymatic reactions in the body, magnesium may also confer numerous health benefits. In particular, an adequate magnesium status may improve sleep, while reducing inflammation, migraines, and symptoms of anxiety and depression.

• Magnesium may reduce inflammation. Supplementing with magnesium may play an important role in reducing inflammatory markers, particularly C-reactive protein (CRP), a protein made by the liver that increases with inflammation. Some studies have suggested that magnesium supplementation may decrease CRP. (Source) 
• Magnesium levels may be correlated with migraines. Some research suggests that magnesium supplementation may reduce the number of migraine attacks and the severity of symptoms. Low magnesium levels can affect blood flow and the release of neurotransmitters, factors that can lead to headaches and migraines. Though research is limited, the American Academy of Neurology and the American Headache Society include magnesium in their guidelines, believing there is sufficient evidence to conclude that magnesium therapy is “probably effective” at migraine prevention. (Source, Source, Source)   
• Magnesium intake is inversely associated with anxiety and depression. Magnesium is essential for converting tryptophan (an amino acid) to serotonin, a neurotransmitter vital for mental health and mood. Supplementing with magnesium may prevent depression and benefit symptoms. (Source)
• ‍Supplementing with magnesium may improve insomnia. Magnesium may improve sleep time and efficiency in at least two ways. First, it blocks the actions of the neurotransmitter N-methyl-D-aspartate (NMDA) and binds to (GABA) receptors to exert a relaxing and sleep-inducing effect. And second, supplementing with chelated magnesium may decrease nighttime restless leg syndrome, improving sleep quality. (Source)

Magnesium and Autoimmune Diseases

Research is ongoing on the relationship between magnesium and autoimmune disease. But maintaining adequate magnesium levels may be important for managing symptoms associated with and reducing the risk of developing an autoimmune disease.

There May Be a Link Between Magnesium and Hashimoto’s Disease

The exact relationship between magnesium and Hashimoto’s thyroiditis is unclear. But research indicates that low serum magnesium levels may be associated with an increased risk of Hashimoto’s disease. And magnesium deficiency may worsen symptoms of Hashimoto’s. (Source, Source) 

Magnesium and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) — a term that includes ulcerative colitis and Crohn’s disease — causes intestinal inflammation that can affect the absorption of nutrients, including magnesium. Furthermore, diarrhea, which can accompany IBD, causes loss of nutrients and can exacerbate already low magnesium. (Source)

Intestinal inflammation from IBD can limit the usefulness of serum magnesium levels, and research has suggested hair can be tested for a more accurate picture of magnesium status. A 2022 study found lower hair magnesium concentrations in people with IBD than in healthy controls. Study participants with Crohn’s disease had even lower magnesium levels than participants with ulcerative colitis. The study also discovered an association between hair magnesium concentration and IBD activity. (Source)

What Are the Different Forms of Magnesium?

Many forms of chelated magnesium are available. Though similar, there are slight differences in the effect of each form on the body. Common magnesium supplements include magnesium oxide, magnesium glycinate, and magnesium citrate.

Magnesium Oxide

Magnesium oxide has an array of applications — for example, it is used as a laxative or to relieve heartburn or indigestion. It is commonly sold as a dietary supplement to increase magnesium levels in the body, but this form of the mineral has limited bioavailability. (Source)

Magnesium Glycinate

Magnesium glycinate is formed by combining magnesium with the amino acid glycine. This version of chelated magnesium is often recommended to help with sleep. Taking glycine before bedtime is associated with greater ease and speed of falling asleep and enhanced sleep quality and, as discussed earlier, magnesium inhibits certain neurotransmitters to encourage sleep. Therefore, a combined supplement of magnesium and glycine may promote sleep — however, whether the combined supplement magnesium glycinate provides this benefit has yet to be explicitly addressed. (Source)

Regardless, magnesium glycinate is one of the most bioavailable types of magnesium. Additionally, magnesium glycinate may be better tolerated than other forms, reducing diarrhea and other gastrointestinal side effects sometimes associated with magnesium supplementation.

Magnesium Citrate

Magnesium citrate is one of the most frequently used forms of chelated magnesium, as the body absorbs it more easily than others. 

Magnesium citrate supplements are available as tablets or powders. Tablets can help increase magnesium levels in the body, whereas powders are often used to treat occasional constipation. As a laxative, magnesium citrate causes the intestines to hold onto water, resulting in softened stool that is easier to pass. (Source) 

What Is the Best Form of Chelated Magnesium? 

There is no one best form of chelated magnesium. Which chelated form you select will depend on the intended use. And while some types of magnesium may have better bioavailability than others, research is inconclusive on which form is best for optimal absorption.

One small study in men observed better bioavailability with magnesium citrate than with magnesium oxide supplements. This study assessed magnesium status by measuring urine and serum concentrations. Both metrics showed higher concentrations with magnesium citrate supplements compared to magnesium oxide. (Source) 

Generally, organic salts (such as magnesium citrate and magnesium glycinate) appear to have greater bioavailability than their inorganic counterparts (magnesium oxide and magnesium chloride), as the organic salts break down more effectively in the body. But other factors — such as the supplement formulation — can affect how chelated magnesium supplements are absorbed in the body. (Source, Source) 

Who Can Benefit From Chelated Magnesium?

Despite its important role in the body, many people may not be getting enough magnesium from their diet. According to data from the Centers for Disease Control and Prevention’s National Health and Nutrition Exam Survey (NHANES), 48% of Americans do not meet the requirements for magnesium through food and beverages alone. The recommended dietary allowance (RDA) for men ages 31 and older is 420 mg per day; for women ages 31 and older, the RDA is 320 mg per day. In some cases, prioritizing magnesium-rich foods — such as nuts, pumpkin seeds, enriched breakfast cereals, potatoes, and spinach, among others — may not be adequate to increase magnesium levels. In these instances, a chelated magnesium supplement may be beneficial. (Source) 

Side Effects of Magnesium Supplements

Common side effects are usually related to the influence of magnesium supplements on the gastrointestinal tract. Magnesium supplements are often used to promote gastric motility, the intestinal contractions that move food and waste through the intestines. But too much magnesium can adversely affect the intestines and cause symptoms such as diarrhea, nausea, and abdominal cramping. 

Additionally, very large doses (more than 5,000 mg per day) of magnesium supplements — found in products such as laxatives and antacids — may contribute to magnesium toxicity. Symptoms of magnesium toxicity include nausea, vomiting, facial flushing, hypotension (low blood pressure), intestinal blockages, depression, and fatigue. Left untreated, magnesium toxicity can progress to muscle weakness, trouble breathing, irregular heartbeat, and cardiac arrest. (Source)

Medication Interactions

Chelated magnesium may interact with certain medications. In particular, chelated magnesium may affect the absorption of bisphosphonates (used to treat osteoporosis), antibiotics, diuretics, and proton pump inhibitors (used to reduce gastric acid). Always consult your health care provider before starting any supplement to ensure it is safe and effective for you to use. (Source)

Dosage Guidelines and Tips

Chelated magnesium should be taken as directed on the supplement label or as prescribed by your health care provider. To minimize any gastrointestinal-related side effects of chelated magnesium, stay within the recommended upper tolerable limit of 350 mg daily. Magnesium may be more effectively absorbed in smaller doses spread throughout the day rather than ingested as one larger dose. Be sure to consult your medical provider before making any changes to your supplement regimen. (Source, Source, Source)

The Bottom Line on Chelated Magnesium

Magnesium is an essential mineral involved in countless physiological functions. Maintaining adequate magnesium status is one way to help your body run smoothly. However, adding more magnesium-rich foods to your diet may not provide you with all the magnesium you need. If you frequently get migraines, have trouble sleeping, experience anxiety, or have inflammatory bowel disease, it may be beneficial to speak with a health care professional about chelated magnesium. The Nutrition Therapy Practitioners at WellTheory can work with you and your primary care provider to assess your magnesium levels and help you find the right supplement for your health.