What Actually Is Magnesium?
Magnesium is the fourth most abundant mineral stored in the human body and plays a role in over 300 biochemical reactions that occur daily. The body cannot produce magnesium on its own, which means it must come from food sources or supplements.
Leafy greens, whole grains, beans, legumes, nuts, seeds, and even cocoa-based products are all natural sources of magnesium. Different forms of magnesium are also absorbed differently by the body. Magnesium citrate is relatively well absorbed but can have a laxative effect, whilst magnesium glycinate tends to be gentler on the digestive system and better tolerated overall.
Where Does Magnesium Occur, and Why Do We Need It?
Magnesium acts as a cofactor, meaning it helps enable many of the body’s most important processes to function correctly. These include protein synthesis, cellular energy production, DNA and RNA synthesis, and muscle and nerve function.
It also plays a central role in maintaining heart rhythm, supporting the nervous system, and keeping muscles and bones structurally strong. Because magnesium influences so many systems throughout the body, even a mild deficiency can affect how the body feels and functions.
The recommended daily intake for adults is generally between 310 and 420 milligrams depending on age and sex, although many people do not consistently reach these levels through diet alone.
What Do Studies Say About Magnesium’s Benefits?
Research on magnesium is generally positive, particularly in areas such as cardiovascular health, blood sugar regulation, migraines, and muscle recovery.
Large meta-analyses have shown that magnesium supplementation may help modestly reduce blood pressure, with even small reductions linked to meaningful long-term cardiovascular benefits.
Studies also suggest that people with adequate magnesium intake tend to have better insulin sensitivity and a lower risk of developing type 2 diabetes. For individuals concerned about blood sugar regulation or metabolic health, magnesium intake may therefore be worth paying closer attention to.
Magnesium has also been studied extensively in relation to migraines. Research suggests it may help reduce migraine frequency and severity in some individuals, particularly those with lower magnesium levels. For those with chronic or more severe migraine, it can also sit alongside established medical treatments such as prescription preventatives or Botox injections, which are licensed for chronic migraine management.
For muscle health, magnesium helps regulate muscle contraction and relaxation through its interaction with calcium and cellular energy systems. Low magnesium levels may contribute to cramps, spasms, and muscle tightness, although evidence for magnesium preventing chronic muscle cramps remains mixed overall.
Can You Take Too Much Magnesium?
Magnesium toxicity from food sources is extremely rare because healthy kidneys are generally very effective at regulating magnesium levels and removing excess amounts through urine.
However, supplementation should still be approached carefully, particularly for individuals with kidney disease or renal impairment, as excess magnesium may not be cleared properly from the body.
The most common side effects of taking too much magnesium are gastrointestinal, including diarrhoea, nausea, and abdominal cramping. This is why magnesium is frequently used in some laxative products.
Taking magnesium with food and gradually increasing the dosage can help minimise digestive discomfort.
Should You Take Magnesium Before Bed?
Many people choose to take magnesium in the evening because it may promote muscle relaxation and support better sleep quality. Magnesium also has a calming effect on the nervous system, which may help reduce feelings of restlessness or insomnia.
For people who exercise regularly, evening magnesium may also help support muscle recovery and reduce muscle tension after intense training sessions.
On the other hand, some people prefer taking magnesium earlier in the day, particularly if fatigue is a concern, as magnesium also plays an important role in energy production.
Does Exercise Affect How Much Magnesium You Need?
Research suggests that athletes and physically active individuals may require 10–20% more magnesium than sedentary individuals, although exact requirements depend on exercise type, intensity, and duration.
Endurance athletes, such as runners, may lose more magnesium through sweat and increased metabolic demand, whilst people focused on strength training may benefit more from consistent intake that supports muscle recovery and protein synthesis.
A practical approach is to first ensure baseline intake requirements are being met consistently through both diet and supplementation where appropriate.
Final Thoughts on Magnesium
Magnesium is one of the most widely discussed supplements for a reason. Its role in sleep, muscle function, cardiovascular health, energy production, and metabolic regulation is well supported by research.
However, supplements should never completely replace a balanced diet, and magnesium intake should always be tailored to individual health needs, lifestyle factors, and existing medical conditions.
For anyone considering supplementation, a GP can check serum magnesium levels via a blood test, although this only reflects a small proportion of the body’s total magnesium stores. In practice, assessment often involves looking at dietary intake, lifestyle factors and symptoms alongside blood results with your doctor.
Remember, too much of anything can be bad for you, so be sure to consult a GP or specialist prior to supplementing magnesium or making radical changes to your diet.
Want to learn more? Read Dr. Kaywaan Khan’s full feature on British GQ here: https://www.gq-magazine.co.uk/article/best-time-to-take-magnesium-for-fitness-goal
