Reviewed by Sarah Law, Naturopathic Nutritionist
What Are the Signs of Lacking Magnesium? Symptoms, Causes and What to Do
Magnesium deficiency — clinically known as hypomagnesaemia — causes a wide range of symptoms including muscle cramps, fatigue, poor sleep, anxiety, irregular heartbeat, and persistent headaches. It is one of the most common nutritional shortfalls in the UK, with research suggesting that up to 60% of adults fail to meet the recommended daily intake [1]. Symptoms are often subtle at first but worsen progressively as levels decline.
- Up to 60% of adults in the UK may not consume enough magnesium, leading to widespread underdiagnosis of deficiency [1].
- Common signs of low magnesium include muscle cramps, fatigue, anxiety, and poor sleep, with 7 key symptoms frequently cited in research [2].
- Factors like chronic stress, high-sugar diets, alcohol, and certain medications (e.g., PPIs) can significantly deplete magnesium levels [9].
- Magnesium glycinate is a highly bioavailable form, with typical supplemental doses ranging from 200–400 mg of elemental magnesium daily [6].
What Are the 7 Signs Your Body Needs Magnesium?
Seven symptoms appear most consistently in the clinical and research literature on magnesium deficiency [2]. These are muscle cramps and spasms, chronic fatigue, anxiety or low mood, disrupted sleep, frequent headaches or migraines, tingling or numbness in the extremities, and heart palpitations or irregular heartbeat.
Muscle cramps are among the earliest and most recognisable signs. Magnesium plays a direct role in muscle relaxation — without adequate levels, calcium-driven muscle contractions go unchecked, leading to involuntary cramping [4]. This is particularly common in the calves during the night.
Fatigue is another hallmark symptom. Magnesium is required for the production of ATP, the body's primary energy currency. When magnesium status is low, cellular energy production becomes inefficient [6]. Anxiety and poor sleep are closely linked — magnesium regulates the hypothalamic-pituitary-adrenal (HPA) axis and GABA receptors, both central to stress response and sleep quality [5].
Headaches and migraines have a well-documented association with low magnesium. A 2020 review found that magnesium deficiency is present in up to 50% of people experiencing acute migraine attacks (Porri et al., 2020, Nutrients) [8]. For a deeper dive into these specific symptoms, see our article on what are the 7 signs your body needs magnesium.
What Are the 11 Signs of Low Magnesium?
Beyond the classic seven, there are additional — and often overlooked — symptoms that point to low magnesium status. Research identifies at least 11 distinct clinical signs when deficiency becomes moderate to severe [2], [3].
| Sign | Category | Notes |
|---|---|---|
| Muscle cramps / spasms | Neuromuscular | Especially nocturnal leg cramps |
| Chronic fatigue | Metabolic | Related to impaired ATP synthesis |
| Anxiety / low mood | Neurological | HPA axis dysregulation [5] |
| Poor sleep / insomnia | Neurological | Reduced GABA activity |
| Headaches / migraines | Vascular | Affects up to 50% of migraine sufferers [8] |
| Tingling or numbness | Neuromuscular | Peripheral nerve involvement |
| Heart palpitations | Cardiac | Risk of arrhythmia in severe cases [3] |
| High blood pressure | Cardiovascular | Magnesium relaxes blood vessel walls |
| Constipation | Digestive | Reduced smooth muscle motility |
| Brain fog / poor concentration | Cognitive | Neuronal signalling impairment |
| Increased stress sensitivity | Hormonal | Vicious cycle with cortisol [5] |
It is worth noting that many of these symptoms overlap with other conditions, and a blood test — specifically a serum magnesium test — is the standard diagnostic tool, though it does not always reflect intracellular magnesium stores [7]. A result below 0.75 mmol/L is typically considered deficient.
Natural dietary sources of are the signs of lacking magnesium that can complement supplementation.
"Many of my clients come in with a cluster of symptoms — poor sleep, anxiety, muscle cramps — and we find magnesium is a key piece of the puzzle. The challenge is that standard blood tests can appear normal even when intracellular stores are depleted, so symptoms should always be considered alongside lab results."
— Sarah Law, Naturopathic Nutritionist & Functional Practitioner | Optimised Female
If you're looking to try Magnesium Glycinate for yourself, our Magnesium Glycinate formula is third-party tested, free from fillers, and made in the UK.
What Do You Crave When Low on Magnesium?
The most commonly reported craving associated with low magnesium is chocolate — specifically dark chocolate. This is not coincidental. Dark chocolate is one of the richest dietary sources of magnesium, containing approximately 64 mg per 28 g serving. The body's appetite signalling may drive cravings for foods that contain what it lacks.
Some people also report cravings for salty or crunchy foods, which may be linked to the broader electrolyte imbalance that accompanies magnesium deficiency. Magnesium works in close relationship with sodium, potassium, and calcium, and a drop in one often disrupts the others [4].
However, it is important to be cautious here. The science of specific nutrient cravings is not conclusive — cravings are multifactorial and influenced by mood, habit, and blood sugar regulation. Chocolate cravings are not a reliable diagnostic tool, but they can be one piece of the picture worth noting alongside other symptoms.
What Organ Is Most Affected by Magnesium?
The kidneys are the primary organ responsible for magnesium regulation. They filter and reabsorb magnesium with remarkable precision, adjusting urinary excretion based on the body's needs [3]. When magnesium intake is low, healthy kidneys can reduce excretion to near zero to conserve stores.
Kidney dysfunction is therefore a leading cause of both deficiency and excess. Conditions such as diabetes, chronic kidney disease, and gastrointestinal disorders that impair absorption all dramatically affect magnesium status [2]. The heart is also significantly impacted — magnesium stabilises electrical activity in cardiac cells, and severe deficiency can trigger dangerous arrhythmias [3].
The brain and nervous system are affected at a functional level as well. Magnesium blocks NMDA receptors, preventing excessive stimulation of nerve cells. When levels fall, this neuroprotective effect is reduced, contributing to anxiety, poor focus, and heightened stress reactivity [5].
What Drains Magnesium from Your Body?
Several lifestyle and medical factors accelerate magnesium loss. Understanding these is essential for anyone trying to address deficiency.
Stress is one of the most significant drivers. Cortisol, the primary stress hormone, increases urinary magnesium excretion — and lower magnesium levels in turn raise cortisol, creating a self-perpetuating cycle [5], [10]. Alcohol is another major depleter, as it increases renal excretion while simultaneously reducing intestinal absorption.
Medications are a frequently overlooked cause. Proton pump inhibitors (PPIs), commonly used for acid reflux, are associated with clinically significant hypomagnesaemia with long-term use [9]. Diuretics, antibiotics, and certain chemotherapy drugs also deplete magnesium status.
High sugar and processed food diets are problematic because refined carbohydrates require magnesium for metabolism without replenishing it. Intense or prolonged exercise also increases magnesium losses through sweat, which is why active individuals often have higher requirements [6].
Man taking magnesium supplement.
Which Food Is Highest in Magnesium?
Pumpkin seeds top the list, providing approximately 156 mg of magnesium per 28 g serving — nearly 40% of the UK Reference Nutrient Intake (RNI) for adults. Other excellent dietary sources include:
- Dark chocolate (70%+ cocoa): ~64 mg per 28 g
- Boiled spinach: ~78 mg per 100 g
- Black beans (cooked): ~60 mg per 100 g
- Almonds: ~76 mg per 28 g
- Avocado: ~29 mg per 100 g
- Whole wheat bread: ~23 mg per slice
Despite these food sources being widely available, dietary surveys consistently show that large proportions of the UK population fall below recommended intakes [1]. Modern farming practices, food processing, and gut health issues that impair absorption all contribute to this gap.
What Drink Is High in Magnesium?
Mineral water can be a meaningful source of dietary magnesium, particularly certain European brands. Some mineral waters provide 50–100 mg of magnesium per litre, depending on the source. Water from magnesium-rich geological regions contains naturally dissolved magnesium bicarbonate, which is highly bioavailable.
Soy milk provides approximately 61 mg per 250 ml serving, making it one of the better drink-based sources. Freshly pressed green juices containing spinach or kale can also contribute meaningfully. Coffee, interestingly, contains small amounts of magnesium, though it can also increase urinary excretion in high doses.
It is worth noting that drinks alone are unlikely to correct a significant deficiency. Diet and targeted supplementation together provide the most reliable path to restoring magnesium levels.
How Much Magnesium Glycinate Per Day?
Magnesium glycinate is widely regarded as one of the most bioavailable and well-tolerated forms of magnesium supplement, making it a popular choice for addressing deficiency [6]. The glycine component also has calming properties that complement magnesium's role in sleep and anxiety.
The UK RNI for magnesium is 270 mg per day for women and 300 mg per day for men. In supplemental form, typical doses of magnesium glycinate range from 200–400 mg of elemental magnesium daily, usually split across two doses to improve absorption and reduce the risk of loose stools.
For sleep-specific benefits, many nutritionists recommend taking magnesium glycinate in the evening. For more detailed guidance, see our article on should I take magnesium glycinate in the morning or at night and how much magnesium glycinate per day.
If you are considering a magnesium supplement, Love Life Supplements Magnesium Glycinate provides a high-bioavailability form with no unnecessary fillers — a solid option for those looking to address dietary shortfalls.
Safety, Side Effects, and Who Should Be Cautious
Magnesium from food is considered safe for most people. Supplemental magnesium is also well-tolerated at recommended doses, though doses exceeding 400 mg of elemental magnesium per day from supplements can cause gastrointestinal side effects including diarrhoea, nausea, and abdominal cramping [3].
People with kidney disease should not take magnesium supplements without medical supervision, as impaired kidneys cannot efficiently excrete excess magnesium, raising the risk of toxicity [7]. Signs of magnesium excess (hypermagnesaemia) include low blood pressure, drowsiness, and in severe cases, cardiac arrest.
Drug interactions are also clinically relevant. Magnesium can reduce the absorption of certain antibiotics (particularly tetracyclines and fluoroquinolones) and bisphosphonates used for osteoporosis. It should be taken at least two hours apart from these medications [9].
It is also worth exploring whether pairing magnesium with other nutrients is appropriate for you. Our article on can magnesium glycinate and vitamin D be taken together covers this combination in detail, as magnesium is required to activate vitamin D in the body.
"For most healthy adults, magnesium glycinate at 200–300 mg of elemental magnesium in the evening is a safe and effective starting point. However, if you have kidney disease, are pregnant, or take prescription medications, please speak to your GP or a qualified practitioner before supplementing — individual needs vary considerably."
— Sarah Law, Naturopathic Nutritionist & Functional Practitioner | Optimised Female
Always consult your GP or healthcare provider before starting a magnesium supplement, particularly if you take prescription medication, have a chronic health condition, or are pregnant or breastfeeding.
If you're looking to try Magnesium Glycinate for yourself, our Magnesium Glycinate formula is third-party tested, free from fillers, and made in the UK.
References
- Magnesium: Are We Consuming Enough? — PubMed
- Magnesium Disorders. — PubMed
- Hypomagnesemia and hypermagnesemia. — PubMed
- Magnesium metabolism and deficiency. — PubMed
- Magnesium Status and Stress: The Vicious Circle Concept Revisited. — PubMed
- Magnesium: Biochemistry, Nutrition, Detection, and Social Impact of Diseases Linked to Its Deficiency. — PubMed
- Magnesium Disorders: Core Curriculum 2024. — PubMed
- Headaches and Magnesium: Mechanisms, Bioavailability, Therapeutic Efficacy and Potential Advantage of Magnesium Pidolate. — PubMed
- An overview of diagnosis and management of drug-induced hypomagnesemia. — PubMed
- [Magnesium deficiency and stress: Issues of their relationship, diagnostic tests, and approaches to therapy]. — PubMed