Nutrition · Nervous System · Energy · Recovery
Magnesium: why you need it, why you don't have enough, and what happens when you fix it
Magnesium is not a trendy supplement. It is an essential mineral involved in over 300 reactions in the human body. The problem is that most people don't get the dose they need — and they don't know it.
When we ask a person with chronic fatigue, unrefreshing sleep, or frequent cramps in our consultation if they take magnesium, the usual answer is one of these three: "no, I've never taken it," "I tried and didn't feel anything," or "yes, but I'm not really sure what it's for."
All three cases have something in common: there is a lack of understanding about what magnesium does in the body, why it is so often deficient, and what needs to be done to truly correct it. This article aims to answer these three questions.
What exactly does magnesium do?
Magnesium is the fourth most abundant mineral in the human body and the second most important intracellular cation, after potassium. What that means in practice is that virtually every cell in the body needs magnesium to function. That's not hyperbole: it's biochemistry.
These are the functions where its role is most relevant and well-documented:
Magnesium is necessary for ATP — the energy currency of every cell — to function. Without magnesium, ATP is not activated. This explains the direct link between magnesium deficiency and persistent fatigue.
Magnesium regulates NMDA receptors for glutamate, the brain's main excitatory neurotransmitter. Without sufficient magnesium, the nervous system becomes more reactive: more irritable, more anxious, more difficult to calm.
Magnesium is essential for muscle relaxation. Calcium causes contraction; magnesium, relaxation. Without the proper balance, cramps, muscle spasms, and chronic muscle tension appear.
Magnesium activates the parasympathetic nervous system (the calming one) and is a cofactor for the synthesis of melatonin and GABA, the neurotransmitters of rest. Magnesium deficiency is a frequent and overlooked cause of insomnia.
Magnesium regulates heart rhythm, relaxes vascular smooth muscle, and helps maintain blood pressure within the normal range. It is one of the minerals with the most evidence in heart health.
Magnesium activates the enzyme that converts vitamin D into its active form. Without sufficient magnesium, supplementing vitamin D has less effect than expected — even if blood levels rise.
Magnesium improves insulin sensitivity and glucose transport to cells. Deficiency is associated with an increased risk of insulin resistance and type 2 diabetes.
Magnesium is a cofactor for over 300 enzymes, including those involved in protein synthesis and DNA replication. It is a foundational mineral, not an optional supplement.
Why 75% of people are deficient
Magnesium deficiency is so common that some researchers have called it "the silent epidemic." The causes are multiple and cumulative:
Industrial agriculture has reduced the magnesium content in soils by up to 80% compared to 50 years ago. The foods we eat have less magnesium than those of previous generations.
Cortisol increases renal excretion of magnesium. The more sustained stress, the more magnesium is eliminated in the urine. Modern stress is, in itself, a factor in magnesium depletion.
Industrial processing removes a large part of the magnesium from foods. Brown rice has 5 times more magnesium than white rice. Whole-wheat bread has much more than white bread.
Proton pump inhibitors (omeprazole, pantoprazole), diuretics, and certain antibiotics reduce magnesium absorption or increase its elimination.
Both substances increase renal excretion of magnesium. Regular, even moderate, coffee consumption can contribute to low levels in individuals on the borderline.
From the age of 50, intestinal absorption of magnesium progressively decreases, and renal excretion increases. Older individuals are particularly vulnerable to deficiency.
Why normal lab tests don't detect it
Only 1% of total body magnesium is found in blood plasma. The remaining 99% is inside cells and in bone. When the standard lab test measures magnesium in the blood, it measures that 1%. The body maintains this value within the normal range at the cost of emptying intracellular stores. The result: you can have "normal" serum magnesium and have had a functional deficiency for months. The real diagnosis of magnesium deficiency is clinical, not laboratory-based.
How magnesium deficiency manifests
Magnesium deficiency does not have a single, characteristic symptom. It manifests diffusely, in several systems at once, which means many people do not associate it with a specific cause:
The diagnostic key is accumulation. An isolated symptom can have many causes. When several of these symptoms appear together, magnesium deficiency should always be considered.
Who benefits most from correcting magnesium deficiency
Magnesium is essential for everyone, but there are profiles where deficiency is particularly common and the benefit of correcting it is more noticeable:
Chronic stress increases magnesium elimination through urine. People with sustained high work pressure have double the reason to look after their levels. Magnesium doesn't eliminate stress, but it helps the nervous system manage it better.
Magnesium is one of the nutrients with the most evidence in improving sleep. It activates the parasympathetic nervous system and is a cofactor for melatonin synthesis. If insomnia does not have a clear medical cause, magnesium deficiency is one of the first factors to rule out.
Exercise increases magnesium losses through sweat and urine. Athletes have higher-than-average requirements. Magnesium reduces cramps, improves muscle recovery, and supports the mitochondrial function necessary for performance.
Magnesium is one of the nutrients with the most evidence in reducing the symptoms of premenstrual syndrome: pain, irritability, fluid retention. It is also essential during pregnancy for the muscular and nervous development of the fetus.
Proton pump inhibitors reduce intestinal absorption of magnesium. Prolonged use of omeprazole is one of the most frequent and overlooked causes of magnesium deficiency. If you take it regularly, reviewing your magnesium intake is not optional.
With age, intestinal absorption of magnesium decreases, and renal excretion increases. This means that effective requirements are higher and more difficult to meet through diet alone.
What changes when you correct the deficiency
Correcting magnesium deficiency is not an immediate experience. It is a progressive process that follows a fairly predictable sequence. Knowing this helps to set realistic expectations:
The first effects usually appear in sleep: less time to fall asleep, less frequent awakenings, deeper sleep. Night cramps also tend to reduce during this phase. The nervous system begins to calm down.
Chronic muscle tension (especially in the shoulders and neck) begins to decrease. Irritability and reactivity to stress diminish. Many people describe an increased ability to "unwind" at the end of the day.
The impact on energy and fatigue becomes more evident. Intracellular magnesium stores take longer to replenish; that's why the effects on energy metabolism are the slowest to appear but also the most solid once consolidated.
The benefits on cognitive performance, cardiovascular health, and metabolic balance manifest sustainably. Magnesium is not an immediate-effect supplement: it is a foundational mineral whose real effect is consolidated over time and with consistency.
How much magnesium do you need per day?
The official recommended daily allowance (RDA) for magnesium is 375 mg for adults (EFSA, European Union). However, some researchers point out that this figure may underestimate the real needs of people with chronic stress, sports practice, or certain health conditions, where requirements can reach 400-500 mg daily.
The foods richest in magnesium are seeds (pumpkin, flax), nuts (almonds, cashews), pure cocoa, legumes, and whole grains. The problem is that to reach 375 mg through diet alone, one would have to consume quantities that most people do not achieve in their daily lives.
The magnesium you eat is not all the magnesium you absorb
The absorption of dietary magnesium is variable: it depends on the form of the mineral, the condition of the intestine, gastric acidity, and the presence of other nutrients. Phytic acid in cereals and legumes, for example, reduces magnesium absorption. This means that even with a theoretically adequate diet, actual absorption can be significantly lower than expected.
Why not all magnesium supplements work the same way
The chemical form of magnesium determines its bioavailability. Magnesium oxide — the most widely sold in pharmacies — has a bioavailability of only 4%. Bisglycinate, malate, and taurate, the three forms we use in TriMagnesio, exceed 80% absorption with excellent digestive tolerance. The difference is not cosmetic: it is the difference between noticing the effect or not noticing it.
TriMagnesio — tres60
Triple source of highly bioavailable magnesium: bisglycinate + malate + taurate. With active vitamin B6. No oxide, no laxative effect. Formulated by doctors. Suitable for vegans and coeliacs.
View TriMagnesio →Synergies: magnesium doesn't work alone
LOGOUT combines melatonin, adaptogenic plants, and magnesium bisglycinate in a specific nighttime formula. If your main goal is sleep, this is the most direct combination.
Magnesium activates vitamin D. Without enough magnesium, vitamin D does not convert to its active form even if blood levels are correct. The three together have a synergistic effect on bones, immunity and muscles.
Frequently Asked Questions
Can I tell if I have a magnesium deficiency with a blood test?
Standard blood tests measure serum magnesium, which represents only 1% of total body magnesium. The body keeps this value stable at the cost of emptying intracellular stores. This means you can have normal blood magnesium levels and have had a functional deficiency for months. The most reliable diagnosis of magnesium deficiency is clinical: the combination of characteristic symptoms and the patient's context.
Why does pharmacy magnesium give me diarrhea?
Because almost all magnesium sold in conventional pharmacies is magnesium oxide. This form has very low absorption (approximately 4%): the 96% that is not absorbed reaches the large intestine and acts as an osmotic laxative, drawing water into the intestine. Highly bioavailable forms—bisglycinate, malate, taurate—are absorbed before reaching the colon and do not have this effect.
Does magnesium make you sleepy during the day?
Not directly. Magnesium promotes nervous system relaxation, not drowsiness. The feeling of calm it produces is confused with sleep by some people, but the mechanism is different. You can take magnesium in the morning or at midday without any problem. If you want to enhance the effect on nighttime sleep, taking it with dinner is the most effective.
How long do I have to take it to notice anything?
Effects on sleep and cramps are usually noticed within the first 1-2 weeks. Effects on energy, stress, and muscle recovery require 4 to 8 weeks of continuous use to be accurately assessed. Intracellular magnesium stores take time to fully replenish. Magnesium is not an immediate-result supplement: it is a foundational mineral whose effect consolidates with consistency.
Can I take too much magnesium?
Dietary magnesium has no risk of toxicity in healthy people: the kidneys efficiently eliminate excess. In supplements, tolerance is high with forms of good bioavailability. The most common sign of excess is the laxative effect, which usually appears with low-absorption forms (oxide, high-dose citrate) before premium forms. In people with kidney failure, medical supervision is necessary before supplementing with magnesium.
Is magnesium good for stress?
Yes, and there's a bidirectional relationship that's important to understand: stress depletes magnesium (cortisol increases its renal elimination), and magnesium deficiency makes the nervous system more reactive to stress. Correcting the deficiency doesn't eliminate the causes of stress, but it does improve the nervous system's ability to manage it. Magnesium regulates glutamate receptors (the main excitatory neurotransmitter) and promotes GABA activity (the main inhibitor), which translates into less reactivity and a greater capacity for calm.
This article is for informational purposes and has been written by the tres60 medical team. It does not replace the advice, diagnosis, or treatment of a health professional. If you take regular medication or have a diagnosed medical condition, consult your doctor before starting any supplementation.
