Magnesium Citrate: What Is It, Benefits, Side Effects & How to Choose

How it works

Magnesium is an essential mineral present in every cell of the human body. About 50–60% of the body's magnesium is stored in the bones, with the remainder in muscles and soft tissues. Magnesium citrate is a combination of magnesium and citric acid, which increases its solubility in water compared to some other forms. This can make it easier for the body to absorb, though absorption rates can vary between individuals and products.

Magnesium citrate is valued for its solubility and is a common choice in dietary supplements.

Magnesium is involved in hundreds of biochemical reactions in the body, including those related to muscle contraction, nerve signalling, and energy production. However, only the specific authorised claims listed below may be made for magnesium supplements.

Magnesium’s role in the body

Magnesium acts as a cofactor for more than 300 enzyme systems that regulate diverse biochemical reactions, such as protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. It is critical for the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione. Magnesium also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important for nerve impulse conduction, muscle contraction, and normal heart rhythm.

In the context of energy production, magnesium is necessary for the conversion of food into energy, as it is involved in the activation of adenosine triphosphate (ATP), the primary energy carrier in cells. This underpins the authorised claim that magnesium contributes to normal energy-yielding metabolism, provided the supplement is at least a source of magnesium.

Why magnesium citrate?

Magnesium citrate is a salt of magnesium and citric acid. Its relatively high solubility in water makes it a popular choice for supplements, as it can be formulated into powders, liquids, capsules, and tablets. The higher solubility may enhance its absorption compared to less soluble forms, though individual absorption can still vary. Some consumers also prefer magnesium citrate for its mild taste and versatility in different supplement formats.

What the research and authorised claims say

According to European regulations, only certain health claims are permitted for magnesium, and only if the product is at least a source of magnesium:

• Magnesium contributes to the maintenance of normal bones.
• Magnesium contributes to normal energy-yielding metabolism.
• Magnesium contributes to a reduction of tiredness and fatigue.
• Magnesium contributes to normal muscle function.
• Magnesium contributes to the normal functioning of the nervous system.

These claims are based on well-established roles of magnesium in the body. No other health or disease-related claims are permitted for magnesium supplements.

Only the above authorised claims may be made for magnesium supplements in the EU.

Understanding the authorised claims

• Normal bones: Magnesium is a structural component of bone and helps maintain bone mineral density. It works alongside calcium and vitamin D in bone formation and maintenance.
• Energy-yielding metabolism: Magnesium is essential for the enzymatic reactions that convert carbohydrates, fats, and proteins into usable energy.
• Muscle function: Magnesium is required for muscle contraction and relaxation, and it helps prevent involuntary muscle cramps and spasms.
• Nervous system: Magnesium plays a role in neurotransmitter release and nerve impulse transmission, supporting normal nervous system function.

What is not permitted

Key limitations

• Individual absorption and response can vary depending on age, diet, health status, and other factors.
• Magnesium citrate may have a mild laxative effect at higher doses.
• Only products that are at least a source of magnesium can use the authorised claims.

Bioavailability and absorption factors

Bioavailability refers to the proportion of magnesium that is absorbed and available for use in the body. While magnesium citrate is generally considered to have better solubility and absorption than magnesium oxide, actual absorption can be influenced by several factors:

• Gastrointestinal health: Conditions affecting the gut, such as celiac disease or inflammatory bowel disease, can reduce magnesium absorption.
• Dietary composition: High intake of dietary fiber, phytates (found in whole grains and legumes), and certain medications can bind magnesium and reduce its absorption.
• Age: Older adults may have reduced absorption due to changes in digestive function.
• Dosage: Very high doses of magnesium, especially from supplements, can overwhelm the body’s absorption capacity, leading to increased excretion and potential gastrointestinal side effects.

Limitations in research

While there is strong evidence for the essential roles of magnesium, research on the comparative effectiveness of different magnesium salts (such as citrate, oxide, bisglycinate) is ongoing. Most studies focus on bioavailability and tolerability, but individual responses may differ.

How to choose

With 777 magnesium products in Tigoo's range, including 39 magnesium citrate options and other forms such as magnesium oxide (30) and magnesium bisglycinate, it can be difficult to know which to select. Here are some key considerations:

• Form: Magnesium citrate is often chosen for its solubility and ease of swallowing, available as tablets, capsules, powders, and liquids.
• Dosage: The median dose in Tigoo's magnesium citrate products is 120 mg elemental magnesium per serving. Check the label for the amount of elemental magnesium, not just the compound weight.
• Purpose: Choose a product that matches your preference for form (e. g. , powder vs. tablet) and any dietary restrictions (e. g. , vegan, allergen-free).
• Other ingredients: Some products combine magnesium with other nutrients (e. g. , vitamin B6, zinc, calcium). Only the authorised claims for magnesium apply unless the product also meets the conditions for other nutrients.
• Quality and certification: Look for products that are tested for purity and quality by reputable manufacturers.

Comparison of Common Magnesium Forms in Supplements

Form	Solubility	Elemental Mg (%)	Common Uses	Median Dose (Tigoo)
Magnesium citrate	High	~16%	General supplementation, powders, liquids	120 mg
Magnesium oxide	Low	~60%	Tablets, higher-dose products	250 mg
Magnesium bisglycinate	Moderate	~14%	Gentle on stomach, capsules	100 mg

When comparing magnesium supplements, consider the form, the amount of elemental magnesium, and any additional ingredients. If you are comparing products from different retailers, focus on these criteria rather than brand names.

Product formats and user preferences

Magnesium citrate is available in a variety of formats to suit different preferences and needs:

• Tablets and capsules: Convenient for daily use, easy to transport, and offer precise dosing.
• Powders: Can be mixed with water or juice, allowing flexible dosing and easier swallowing for those who dislike pills.
• Liquids: Suitable for people who have difficulty swallowing tablets or capsules, and may be absorbed more rapidly.

Some products are designed to be taken with or without food; always follow the manufacturer's instructions for optimal absorption and tolerability.

Reading supplement labels

When selecting a magnesium citrate supplement, carefully read the label to determine:

• The amount of elemental magnesium per serving (not just the total weight of magnesium citrate).
• Serving size and recommended daily intake.
• Any additional active ingredients or excipients (such as sweeteners, flavourings, or fillers).
• Certifications (e. g. , vegan, allergen-free, third-party tested).

Products that provide at least 15% of the nutrient reference value (NRV) for magnesium per serving can use the authorised health claims.

Cost and value considerations

The price of magnesium citrate supplements can vary widely depending on brand, format, and additional ingredients. Higher cost does not always equate to higher quality. Consider the cost per dose of elemental magnesium and whether the product meets your specific needs and preferences.

Safety, interactions and risk groups

Magnesium citrate is generally considered safe for most adults when used as directed. However, excessive intake can cause gastrointestinal symptoms such as diarrhoea, abdominal cramping, and nausea. People with kidney problems, those taking certain medications (such as diuretics, antibiotics, or heart medications), pregnant or breastfeeding women, and children should consult a healthcare professional before using magnesium supplements. Do not exceed the recommended dose on the product label unless advised by a healthcare provider. Supplements should not be used as a substitute for a varied and balanced diet.

Potential side effects

• Gastrointestinal effects: The most common side effect of magnesium citrate is diarrhoea, especially at higher doses. This is due to its osmotic effect in the intestines.
• Abdominal discomfort: Some individuals may experience cramping, bloating, or nausea.
• Electrolyte imbalance: Excessive use, particularly in people with compromised kidney function, can lead to imbalances in electrolytes, including hypermagnesemia (high blood magnesium).

Drug and nutrient interactions

Magnesium supplements can interact with certain medications and nutrients. Notable interactions include:

• Antibiotics: Magnesium can bind to some antibiotics (such as tetracyclines and quinolones), reducing their absorption and effectiveness. Take magnesium supplements at least 2 hours apart from these medications.
• Diuretics: Some diuretics can increase magnesium loss in urine, while others may decrease it. Consult a healthcare professional if you are taking diuretics.
• Bisphosphonates: Used for osteoporosis, these medications may have reduced absorption if taken with magnesium. Separate dosing is recommended.
• Other minerals: High doses of magnesium may interfere with the absorption of other minerals, such as calcium, iron, and zinc, if taken simultaneously.

Who should be cautious?

• People with kidney disease: Impaired kidney function can reduce the body’s ability to excrete excess magnesium, increasing the risk of toxicity.
• Pregnant and breastfeeding women: Safety has not been established for high-dose supplementation; consult a healthcare professional before use.
• Children: Magnesium supplements should only be given to children under medical supervision.
• Individuals on medication: Always check with a healthcare provider before starting magnesium supplements if you take prescription medications.

Signs of excessive intake

Symptoms of too much magnesium from supplements (not from food) can include diarrhoea, low blood pressure, muscle weakness, confusion, and in severe cases, cardiac arrhythmia. If you experience any of these symptoms, discontinue use and seek medical advice.

Dietary sources and magnesium in the diet

While supplements can help individuals meet their magnesium needs, a varied and balanced diet is the preferred source. Magnesium is naturally present in many foods, including:

• Green leafy vegetables (e. g. , spinach, kale)
• Nuts and seeds (e. g. , almonds, pumpkin seeds)
• Whole grains (e. g. , brown rice, oats)
• Legumes (e. g. , beans, lentils)
• Fish and seafood
• Dark chocolate

Magnesium from food sources is unlikely to cause adverse effects in healthy individuals, as the kidneys efficiently excrete excess amounts. Supplements should be considered when dietary intake is insufficient or when increased needs are identified by a healthcare professional.

Recommended intake

The recommended daily intake of magnesium varies by age, sex, and life stage. For adults, the nutrient reference value (NRV) in the EU is 375 mg per day. Most people can meet their needs through a balanced diet, but certain groups may require supplementation under professional guidance.

How magnesium citrate is used in supplements

Magnesium citrate is used in a wide range of dietary supplements. It is often chosen for its solubility and versatility in product formulation. Manufacturers may use magnesium citrate alone or combine it with other forms of magnesium or nutrients. The choice of form can affect the supplement’s taste, texture, and absorption characteristics.

Some products are marketed as “gentle on the stomach” or “fast-absorbing,” but only the authorised claims for magnesium can be used unless the product meets conditions for other nutrients.

Usage tips

• Follow the manufacturer’s instructions regarding dosage and timing.
• Take with water, and with or without food as directed.
• Store supplements in a cool, dry place away from direct sunlight.
• Keep out of reach of children.

Responsible supplementation

Supplements are intended to complement, not replace, a healthy diet. Magnesium citrate can help individuals meet their magnesium needs when dietary intake is insufficient, but it should be used responsibly. Always consult a healthcare professional before starting a new supplement, especially if you have underlying health conditions or take medication.

Monitor for any side effects, and discontinue use if you experience persistent gastrointestinal symptoms or signs of excessive intake. Report any adverse reactions to your healthcare provider and the relevant national food safety authority.