Magnesium: How is it absorbed by the body?

Magnesium: An Introduction

Magnesium is an essential mineral that is indispensable for numerous functions in the body. It is a crucial component of over 300 enzymes and plays a vital role in energy production, muscle contraction, and nerve transmission. Magnesium is also important for bone health and the function of muscles and nerves. Without sufficient amounts of this mineral, many processes in the body cannot function optimally, potentially leading to various health problems. Therefore, it is essential to meet the body's magnesium needs and ensure adequate intake.

History and Occurrence

Magnesium was first discovered in the 18th century by the Scottish physicist and chemist Joseph Black. It is a widely distributed element found in many minerals and rocks. Magnesium is also an important component of seawater and is used in industry for the production of metal, paper, and other products. The discovery and utilization of magnesium have significantly increased over time due to its versatile properties being highly beneficial in various fields. From industrial applications to medical uses – magnesium plays a significant role in our daily lives.

Properties and Applications

Magnesium has a range of unique properties that make it suitable for various applications. It is a lightweight, silvery metal that is about one-third lighter than aluminum. Magnesium is also an important component of alloys used in aerospace, automotive manufacturing, and other industries. Additionally, magnesium is used as a dietary supplement to meet the body’s magnesium needs. The recommended daily total intake of magnesium is 400 mg (from food and supplements). A magnesium deficiency can lead to a variety of symptoms, including fatigue, muscle cramps, and bone issues. Trimagnesium dicitrate is a form of magnesium often used in dietary supplements. It is important that magnesium is taken in combination with other minerals to achieve optimal effectiveness. The diverse applications and essential role of magnesium in numerous bodily functions make it an indispensable part of our health and well-being.

How is magnesium absorbed by the body?

The Absorption Process

The absorption of magnesium primarily occurs through the digestive system, especially in the stomach and small intestine, and partially in the large intestine. The absorption process can be divided into several steps:

1. Dissolution and Ionization: Magnesium is dissolved and ionized in the acidic environment of the stomach.

2. Transport: The ionized magnesium ions are absorbed into the cells of the intestinal mucosa through specialized transport proteins.

3. Release into the Bloodstream: After being absorbed into the cells, magnesium is released into the bloodstream, where it is transported to various tissues and organs.

This process requires energy and is supported by Vitamin D. Magnesium plays a crucial role in the activation of ATP-dependent enzymes, which are essential for numerous biochemical reactions in the body.

1. Absorption in the Digestive Tract:

Where is magnesium absorbed?

Mainly in the Small intestine, particularly in the last section (ileum). A small portion is also absorbed in the large intestine.

How is it absorbed?

Magnesium exists in food or supplements as a chemical compound, e.g., Magnesium Citrate or -oxide. Many people prefer taking magnesium in capsule form, as they are easy to swallow and well-tolerated. These compounds dissolve in the digestive tract and release magnesium ions.

Magnesium ions are absorbed through two main mechanisms:

1. Passive transport: Magnesium enters along with water through the cell walls (without energy expenditure).

2. Active transport: Magnesium is transported into the intestinal cells via special transport proteins (e.g., TRPM6 and TRPM7). This process requires energy and is supported by Vitamin D .

2. Absorption in the stomach:

• In the stomach, magnesium is converted into an ionized form (Mg²⁺) by gastric acid. This step is important because only ionized magnesium can be absorbed by the intestinal cells.

• The high acid concentration in the stomach favors this process, especially in the case of organic magnesium compounds like magnesium malate or glycinate. In contrast, the solubility of inorganic compounds like magnesium oxide is lower, which hinders absorption.

3. Absorption into the blood:

• Some of the magnesium absorbed through the intestinal wall enters the bloodstream. There it exists in three forms:

  • Unbound (free): About 55% of magnesium is free and biologically active.

  • Bound to proteins (e.g., albumin): About 30%.

  • Bound to organic molecules (e.g., citric acid): About 15%.

4. Distribution in the body:

Magnesium is transported via the blood to various organs and tissues:

• Cells: Magnesium is taken up by cells, particularly those with high energy demands, such as muscle and nerve cells. Here, it supports many biochemical processes, e.g., energy production from food. It acts as a cofactor for over 300 enzymes that regulate a variety of biochemical reactions and cellular functions, including the activation of ATP-dependent enzymes, which are crucial for processes like glycolysis, the citric acid cycle, and lipid metabolism.

• Bones: Over 50% of the body's magnesium is stored in the bones.

5. Excretion:

• The body excretes excess magnesium via the Kidneys (urine).

• Rapid excretion prevents too much magnesium from remaining in the blood. However, this also means that continuous intake is necessary to meet the body’s needs.

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Better absorption of organic compounds and their benefits

The better absorption of organic magnesium compounds (e.g., Magnesium taurate or Magnesium glycinate) compared to inorganic ones like magnesium oxide is due to several factors related to their chemical structure and behavior in the digestive tract:

1. Solubility of the compound:

• Organic magnesium compounds (e.g., malate, glycinate) are much more water-soluble than inorganic compounds like magnesium oxide. High solubility means that more magnesium ions are present in dissolved form in the digestive tract, which is a prerequisite for absorption.

• Magnesium oxide on the other hand, is poorly water-soluble and remains undissolved for a longer time. This limits the amount of magnesium ions that can be absorbed.

2. pH-dependent solubility:

• Organic compounds dissolve well in the slightly acidic to neutral environment of the stomach and small intestine. This makes magnesium ions available early for absorption.

• Magnesium oxide requires a strongly alkaline environment (such as in the colon) to dissolve. Since the small intestine is the main site of magnesium absorption, a portion of magnesium oxide is lost unused.

3. Transport mechanisms in the gut:

• Organic compounds such as magnesium citrate can be absorbed better through additional mechanisms:

  • The citrate (or another organic anion) can be transported together with magnesium into the cells of the small intestine. This supports absorption.

• Inorganic compounds like magnesium oxide do not benefit from this advantage because they are not coupled with anion transport.

4. Chemical stability and availability:

• Organic compounds keep magnesium in a stable, dissolved form that can be directly utilized for absorption.

• Magnesium oxide may break down into individual ions less easily in the digestive tract, reducing its availability.

5. Byproducts in the digestive tract:

• When magnesium oxide eventually reacts, it can slowly and inefficiently convert into magnesium chloride and water in stomach acid.

• Organic magnesium compounds release magnesium ions without producing significant byproducts that could hinder the absorption process.

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What factors influence magnesium absorption?

Inhibitory factors

1. Phytic acid: This substance found in whole grains and legumes binds magnesium and reduces its availability.

2. Calcium and zinc: High amounts of these minerals can compete with magnesium for absorption.

3. Gastrointestinal health: Conditions such as Crohn's disease, celiac disease, or a disrupted microbiota can impair absorption.

4. High fat and sugar consumption: An unhealthy diet can reduce absorption efficiency.

Promoting factors

1. Vitamin D: It plays an important role in magnesium absorption by supporting active transport mechanisms. (Reddy et al., 2018).

2. Healthy gut flora: A healthy gut flora can improve absorption.

3. Dose splitting: Taking magnesium in smaller doses spread throughout the day can increase bioavailability.

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Optimizing magnesium absorption

Magnesium-rich diet

Natural foods are an excellent source of magnesium. Here are some examples:

• Nuts and seeds: Almonds, cashews, chia seeds, and pumpkin seeds.

• Leafy greens: Spinach, Swiss chard, and kale.

• Whole grain products: Quinoa, oats, and brown rice.

Supplements: Which ones are suitable?

If magnesium intake through food is insufficient, supplements can help.

• When to take it? Magnesium should ideally be taken with a meal to optimize absorption.

• Which form? Organic compounds like magnesium glycinate or citrate are often better tolerated and more efficiently absorbed.

Additional tips

• Hydration: Sufficient hydration promotes digestion and absorption.

• Stress reduction: Chronic stress can increase magnesium excretion.

  

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Potential issues with inadequate magnesium intake and magnesium deficiency

A magnesium deficiency can lead to a variety of health problems, including:

• Muscle cramps and weakness: These symptoms often occur in athletes or individuals with high stress levels.

• Bone health: A long-term magnesium deficiency can increase the risk of osteoporosis.

• Chronic diseases: Studies suggest that a magnesium deficiency is linked to diabetes, high blood pressure, and heart arrhythmias. (Guerrera et al., 2009).

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