Magnesium — Health Benefits, Food Sources, and Supplements

by Victoria Mazmanyan | Last updated on March 25, 2024

Medically reviewed by Arpi Gasparyan

Introduction

Magnesium is an essential mineral that plays a crucial role in various bodily functions. It is classified as a microelement or micronutrient because the body requires it in relatively small amounts compared to macronutrients like carbohydrates, proteins, and fats. However, despite its small requirement, magnesium is involved in over 300 enzymatic reactions in the body, highlighting its significance for overall health and well-being.

Table of contents

Recommended Intake

Food Sources Of Magnesium

Magnesium Supplements

Absorption, Metabolism, and Regulation

Functions in the Human Body

Magnesium Deficiency or Hypomagnesemia

Muscle Symptoms

Cardiovascular Symptoms

Neurological Symptoms

Glucose and Diabetes

Other Symptoms

Hypomagnesemia Causes

Hypermagnesemia

Hypermagnesemia Causes

Interactions with Medication

Summary

References

Recommended Intake

According to the USDA Dietary Guidelines for Americans 2020-2025, the recommended daily allowance (RDA) for magnesium for females and males aged 19 to 30 is 310mg and 400mg, respectively. After age 30, this value increases by 20mg for both men and women (1).

For boys and girls aged 14 to 18, the RDA for magnesium is 410mg and 360mg, respectively. However, for kids aged 9 to 13, this value is significantly lower - 240mg.

The recommended intake of magnesium increases for pregnant women and during certain diseases.

The magnesium RDA for pregnant women aged 19 to 30 is 350mg. For lactating women of the same age group, this value is 310mg.

Food Sources Of Magnesium

Food groups rich in magnesium include green leafy vegetables, nuts and seeds, whole grains, legumes, dark chocolate, fruits, seafood, soybean products, and fortified foods.

Chlorophyll, the pigment that gives plants their green color, contains magnesium, which is why green leafy vegetables are abundant in this microelement. Some examples of green leafy vegetables high in magnesium are spinach, kale, Swiss chard, and collard greens.

Nuts, such as almonds, cashews, pumpkin seeds, peanuts, and sunflower seeds, are rich in not only magnesium but also healthy fats, dietary fiber, and other micronutrients.

Below, we present a list of foods as good sources of magnesium based on their average serving sizes per person.

Food name	Serving size	Magnesium content
Sunflower seed	1 cup or 46g	150mg
Brazil nut	1oz (6 kernels) or 28.35g	107mg
Caviar	1tbsp or 16g	48mg
Tofu	0.25 block or 81g	47mg
Banana	1 cup, sliced or 150g	41mg
Brown rice	0.5 cup or 101g	39mg
Sesame seeds	1tbsp or 9g	32mg
Cocoa powder	1tbps or 5.4g	27mg
Salmon	3oz or 85mg	26mg
Spinach	1 cup or 25g	22mg

On our website, you can also find a list of foods rich in magnesium based on 100g serving sizes.

Other foods high in this mineral include avocados, peanut butter, quinoa, beans, yogurt, etc.

Magnesium Supplements

Magnesium supplements are dietary supplements that contain various forms of magnesium, such as magnesium oxide, magnesium citrate, magnesium chloride, magnesium sulfate, and magnesium glycinate. These supplements are commonly used to address magnesium deficiency, which can occur due to inadequate dietary intake, certain medical conditions, or intake of medications that interfere with magnesium absorption.

Here are some common forms of magnesium supplements:

Magnesium citrate - This form is more bioavailable than magnesium oxide and is commonly used to promote bowel regularity and alleviate constipation. It is also absorbed relatively well by the body.
Magnesium glycinate - This form is magnesium bound to glycine, an amino acid. It is highly bioavailable and well-tolerated, making it a popular choice for individuals with magnesium deficiency or those who experience gastrointestinal upset with other forms of magnesium.
Magnesium oxide - This form has a high magnesium content but is not as well absorbed by the body compared to other forms. It is often used as a laxative to relieve constipation.
Magnesium chloride - This form is absorbed well by the body and is often used in topical magnesium products, such as magnesium oil or sprays, for transdermal absorption.
Magnesium sulfate - Commonly known as Epsom salt, magnesium sulfate is often used in baths to promote relaxation and soothe sore muscles. It can also be taken orally as a laxative in certain medical situations. Similar to magnesium oxide, this form is not as absorbable as the others.

When taking magnesium supplements, following the recommended dosage provided by healthcare professionals or the product label is important.

The Supplement Facts panel on a dietary supplement label specifies the quantity of elemental magnesium present in the product rather than the total weight of the compound containing magnesium (2). Excessive intake of magnesium supplements can lead to adverse effects such as diarrhea, abdominal cramping, and nausea. The tolerable upper Intake level - the maximum daily intake unlikely to cause harmful effects on health - for magnesium is 350mg from supplements only (3).

Individuals with kidney disease or other medical conditions should consult their healthcare provider before taking magnesium supplements, as they may need to monitor their magnesium levels closely.

Absorption, Metabolism, and Regulation

An average healthy adult body contains about 22 to 26g of magnesium. About 60% of this magnesium is stored in the bones, 20% in skeletal muscles, 19% in other soft tissues, and only 1% in the blood and tissues outside the cells (3). About half of the magnesium found in the bones can be used to restore depleting magnesium levels in the body.

The normal total magnesium range in the serum for healthy adults is 0.7 to 1.1mmol/L.

The intestines, the bones, and the kidneys control magnesium levels in the body.

The percentage of magnesium absorption from the intestines depends on the intake level. The higher the magnesium intake, the lower the absorption. Its absorption primarily takes place in the small intestine, particularly in the ileum and jejunum. Magnesium absorption can also change depending on the body’s needs.

Other than dietary intake, various factors influence magnesium absorption, including the presence of other nutrients like calcium and vitamin D, intestinal pH levels, and certain medications. Studies find that vitamin D stimulates magnesium absorption. Conversely, magnesium plays a role in forming the active form of vitamin D in the body (5). The magnesium that is not absorbed in the intestines is excreted through the feces.

The kidneys strictly control the regulation of magnesium levels. Excess magnesium is excreted through urine, with reabsorption occurring in the renal tubules based on the body's magnesium needs. On average, around 100mg of magnesium is excreted through urine each day (6).

Additionally, a small amount of magnesium is lost through sweat during physical activity or in hot environments.

A mutation in the proteins controlling magnesium reabsorption can cause a genetic disease known as familial hypomagnesemia with hypercalciuria and nephrocalcinosis (7). In other words, the mutated protein loses its function in reabsorbing magnesium in the kidneys, leading to low levels of magnesium in the blood, high levels of calcium in the urine, and an abnormal accumulation of calcium in the kidneys, leading to chronic renal failure.

Hormones such as parathyroid hormone (PTH) and calcitonin also play roles in magnesium homeostasis by influencing its reabsorption in the kidneys. PTH, secreted by the parathyroid glands, increases renal magnesium reabsorption to maintain adequate blood levels.

Estrogen also increases magnesium levels in the body by stimulating absorption in the gut and reabsorption into the blood from the kidneys (6).

Functions in the Human Body

Magnesium is a cofactor for over 300 enzymes in the human body, meaning it helps speed up and regulate reactions responsible for basic functions, such as muscle contraction, blood pressure and glucose control, energy production, bone development, neuromuscular conduction, and much more.

Magnesium is involved in blood pressure control and maintaining normal heart rhythm by impacting the electrical activity of cardiac cells and the intracellular calcium concentration of muscle cells.

Magnesium plays an essential part in the structure of bones, proteins, and intracellular components, such as mitochondria, DNA, and RNA.

This mineral is also important for the immune system, being involved in the multiplication of lymphocytes, endotoxins binding to monocytes, granulocyte oxidative burst, and bacteria-killing activity of macrophages (6).

Magnesium Deficiency or Hypomagnesemia

The signs and symptoms of magnesium deficiency are often nonspecific and may overlap with those of other electrolyte imbalances. The severity of these symptoms depends on the extent of magnesium depletion and how rapidly magnesium levels decline. Typically, symptoms become apparent when serum magnesium levels drop below 0.5 mmol/L (1.2 mg/dL) (6).

Hypomagnesemia can also be asymptomatic in people and go unnoticed at times. The presentation of symptoms could be influenced more by how rapidly magnesium deficiency develops or the overall deficit in the body rather than solely relying on the serum magnesium concentration itself.

In patients in intensive care, hypomagnesemia is linked to a higher death rate. Thus, it’s recommended to routinely assess magnesium levels in all critically ill patients, particularly those with conditions, illnesses, or undergoing treatments that could increase the risk of magnesium deficiency.

Muscle Symptoms

Magnesium deficiency can cause involuntary muscle contractions, leading to cramps and spasms, particularly in the calves, feet, and hands. These cramps may occur frequently and be quite painful. Manifestations of neuromuscular symptoms include tremors and fasciculations due to hyperexcitability of the muscles.

Magnesium plays a crucial role in preserving the structural integrity of skeletal muscles. Inadequate magnesium levels may result in muscle weakness and reduced strength, affecting physical performance and endurance (8).

Cardiovascular Symptoms

Magnesium deficiency can disrupt the electrical signals that regulate heart rhythm, leading to arrhythmias - palpitations, rapid heartbeat, or irregular heartbeats. Low magnesium intake has also been associated with an increased risk of heart attack (5).

There is an inverse relationship between magnesium intake and blood pressure. Magnesium supplementation has been associated with a significant decrease in blood pressure in various studies (5). Magnesium helps relax blood vessels and regulate blood pressure. Deficiency may contribute to elevated blood pressure levels. Magnesium deficiency-induced insulin resistance can also elevate the vascular tone.

Magnesium deficiency has been linked with the development of atherosclerosis due to its effects on.

Neurological Symptoms

Low magnesium levels can cause sensations of numbness, tingling, or "pins and needles" in the extremities, indicating nerve dysfunction. The medical name for these symptoms is paresthesia.

Magnesium deficiency may be associated with declining mental health and symptoms of anxiety, depression, irritability, and mood swings due to its role in neurotransmitter regulation. Hypomagnesemia can also cause agitation and sudden changes in behavior. Magnesium supplementation has been studied to improve mental health disorders, such as depressive disorder and ADHD (9).

Severe magnesium deficiency can lead to neurological complications, including seizures and encephalopathy, due to disruptions in nerve function.

Magnesium has been researched as a sleep quality modulator. Magnesium deficiency may disrupt sleep patterns and contribute to insomnia, difficulty falling asleep, or restless sleep. Magnesium supplementation can also improve sleep quality in some instances (10).

Some studies suggest that magnesium deficiency may be linked to an increased risk of headaches and migraines. There is some evidence in support of using magnesium supplements as part of the treatment for headaches and migraines (11).

Glucose and Diabetes

Magnesium plays a crucial role in numerous enzyme systems that regulate glucose homeostasis. Consequently, magnesium deficiency can lead to changes in glucose metabolism. Magnesium influences glucose homeostasis by affecting insulin secretion and the uptake of glucose by cells. Studies have demonstrated that magnesium supplementation can decrease insulin needs and enhance glucose disposal in individuals with diabetes (5).

Other Symptoms

Magnesium is essential for energy production at the cellular level. Inadequate magnesium levels can lead to feelings of fatigue, weakness, and lethargy. Magnesium deficiency has been correlated with chronic fatigue syndrome (12).

Long-term magnesium deficiency can affect bone density and increase the risk of osteoporosis, although bone symptoms may not be immediately apparent. Hypomagnesemia can directly lead to the formation of excessively large crystals in the bone tissue, which results in weakened bones. Additionally, it indirectly influences the secretion and function of parathyroid hormone and contributes to low-grade inflammation (13).

Some individuals with magnesium deficiency may experience gastrointestinal symptoms such as nausea, vomiting, and loss of appetite (5).

Hypomagnesemia Causes

Magnesium deficiency can occur due to various factors, including:

Inadequate dietary intake: not consuming enough magnesium-rich foods, such as leafy green vegetables, nuts, seeds, whole grains, and legumes, can lead to magnesium deficiency.
Poor absorption: certain medical conditions, predominantly gastrointestinal disorders like Crohn's disease, celiac disease, and chronic diarrhea, chronic alcoholism, can impair magnesium absorption from the intestines, leading to deficiency.
Increased losses: conditions or factors that result in increased magnesium excretion through urine or sweat, such as excessive sweating due to intense physical activity and chronic alcoholism, can contribute to magnesium deficiency.
Medical conditions: some health conditions, including diabetes, kidney disease, hyperthyroidism, and pancreatitis, can disrupt magnesium balance in the body and lead to deficiency.
Old age: elderly people may be at increased risk of magnesium deficiency due to factors such as reduced dietary intake, impaired absorption, and increased magnesium losses associated with aging.
Low magnesium in soil and water: in regions where the soil and water have low magnesium content, people may not obtain sufficient magnesium from their diets, potentially leading to deficiency.
Medications: certain medications, including proton pump inhibitors (PPIs), antibiotics, and certain drugs used to manage conditions like hypertension and heart disease, such as diuretics, can interfere with magnesium absorption or increase urinary excretion, contributing to deficiency over time.
Chronic stress: prolonged periods of stress can deplete magnesium levels in the body due to increased magnesium utilization, potentially leading to deficiency.

People with gastrointestinal issues, type 2 diabetes, chronic alcoholism, and elderly individuals are at risk for magnesium deficiency (14).

Hypermagnesemia

Hypermagnesemia, or an excess of magnesium, occurs much less frequently than hypomagnesemia. This condition can arise due to various factors, including excessive intake of magnesium-containing medications or supplements, impaired kidney function, or certain medical treatments.

Symptoms of hypermagnesemia can vary depending on the severity of the condition. These symptoms usually begin to show when the magnesium level in the blood is above 2mmol/L and include nausea and vomiting, weakness and lethargy, flushing, hypotension or low blood pressure, respiratory depression, bradycardia or slow heart rate, cardiac arrhythmias.

Research finds that in the absence of mineral deficiency, dietary magnesium supplementation may also lead to the onset of intestinal dysbiosis (15).

Severe hypermagnesemia can be life-threatening and may result in paralysis, cardiac arrest, and coma.

Hypermagnesemia Causes

Here are some common causes and risk factors for hypermagnesemia:

Kidney dysfunction: the kidneys play a crucial role in filtering and excreting excess magnesium from the body. Impaired kidney function, such as acute or chronic kidney disease, can lead to decreased magnesium excretion, resulting in hypermagnesemia.
Excessive magnesium intake: overconsumption of magnesium-containing medications or supplements, especially in individuals with normal or decreased kidney function, can lead to elevated blood magnesium levels. This may occur due to the indiscriminate use of magnesium-based laxatives, antacids, or magnesium supplements without medical supervision.
Intravenous magnesium administration: administration of magnesium sulfate or other magnesium-containing intravenous fluids, particularly in high doses or in individuals with impaired kidney function, can cause hypermagnesemia.
Endocrine disorders: certain endocrine disorders, such as hypothyroidism or adrenal insufficiency, may lead to impaired magnesium metabolism and contribute to the development of hypermagnesemia.
Tissue injury or necrosis: extensive tissue injury, such as rhabdomyolysis (muscle breakdown) or extensive burns, can release large amounts of magnesium into the bloodstream, potentially leading to hypermagnesemia.

Interactions with Medication

Drugs and micronutrients utilize similar pathways for absorption, metabolism, and elimination within the body. Therefore, the efficacy of a drug might be compromised by a micronutrient, while at the same time, the functionality of a mineral like magnesium could be impaired by a drug (16).

Below are some examples of interactions between magnesium and certain medications:

Bisphosphonates (Pamidronate), prescribed for osteoporosis treatment, experience reduced absorption if taken closely before or after consuming supplements or medications containing high magnesium levels.
The absorption of antibiotics, such as tetracycline antibiotics (Doxycycline), may be diminished if taken close to magnesium-containing dietary supplements.
Diuretics can either enhance or diminish magnesium loss through urine, depending on their type. Thiazide and loop diuretics (Chlorothiazide, Furosemide) tend to increase magnesium loss through the kidneys.
Long-term use of prescription drugs for acid reflux or peptic ulcers (Omeprazole) can lead to low blood magnesium levels due to decreased absorption.
Excessive intake of zinc supplements may disrupt the body's magnesium absorption and regulation.

Summary

Magnesium is a vital mineral involved in numerous bodily functions and enzymatic reactions. The recommended daily intake varies by age and gender - 310mg per day for females and 400mg per day for males aged 19 to 30. Food sources rich in magnesium include green leafy vegetables, nuts and seeds, whole grains, and seafood.

Magnesium absorption depends on factors like intake level and the presence of other nutrients. Deficiency can lead to various symptoms such as muscle weakness and contractions, low blood pressure and arrhythmias, paraesthesia, declining mental health, nausea, and vomiting.

Causes of magnesium deficiency include inadequate dietary intake, poor absorption, certain medical conditions, increased losses through sweat and urine, and some medications. People with gastrointestinal issues, type 2 diabetes, chronic alcoholism, and elderly individuals are at risk for magnesium deficiency.

Hypermagnesemia, characterized by excessive magnesium levels, is rare and can result from kidney dysfunction or excessive intake. It may lead to serious symptoms such as nausea, weakness, hypotension, and cardiac arrhythmias.

Understanding magnesium's role in the human body and sustaining its levels is crucial for maintaining optimal health.

References

Author name: Victoria Mazmanyan

Education: General Medicine at YSMU

Last updated: March 25, 2024

Medically reviewed by Arpi Gasparyan