Magnesium benefits, what magnesium does in your body
What magnesium does, which benefits UK law allows, and what trials found for sleep, blood pressure, stress, cramps and exercise.
- Written by
- Ben L.
- Last updated
- Reading time
- 9 min read
Overview
Magnesium helps turn food into energy and supports normal muscles, nerves, bones and teeth. In the UK it can be said to reduce tiredness and fatigue and support normal psychological function. Trials found a small average fall in blood pressure and a small sleep benefit in one trial. Most people can get enough from food.
Key points
- Over 600 enzymes in the body use magnesium as a helper.
- UK law allows 10 health claims for magnesium, including less tiredness and normal muscle function.
- A 2025 review of 38 trials found a 2.8 mmHg average fall in systolic blood pressure.
- Sleep evidence is early, with one small positive trial and mixed results overall.
- The NHS says 400 mg a day or less from supplements is unlikely to cause harm.
Over 600 enzymes in your body use magnesium to do their job [1]. That one number explains why magnesium turns up in so many claims, and why it's worth sorting the proven benefits from the hopeful ones.
The main magnesium benefits backed by UK law are less tiredness, normal muscle and nerve function, normal psychological function and healthy bones and teeth [2]. Trials also point to small effects on blood pressure and sleep, though the evidence there is mixed or early. Most people can get enough magnesium from food [3].
What does magnesium do in the body?
Quite a lot. An adult body holds roughly 20 to 28 g of magnesium, and about half to two-thirds of it sits in bone [1]. The rest works inside cells, where it helps store and use energy, build proteins and keep DNA stable, and supports normal nerve and muscle function [1].
The NHS puts it simply. Magnesium helps turn the food you eat into energy, and helps the parathyroid glands, which make hormones important for bone health, work normally [3].
UK law allows 10 health claims for magnesium, because the evidence behind each was formally checked [2].
| Area | What magnesium contributes to |
|---|---|
| Energy | A reduction of tiredness and fatigue, and normal energy-yielding metabolism |
| Mind and nerves | Normal psychological function and normal functioning of the nervous system |
| Muscles | Normal muscle function and electrolyte balance |
| Bones and teeth | The maintenance of normal bones and normal teeth |
| Cells | Normal protein synthesis, and a role in cell division |
These claims apply to magnesium in any form, as long as a product gives enough of it. Several other claims were turned down, including ones about blood pressure, blood sugar and hormones [2].
What are the health benefits of magnesium?
Beyond the authorised claims, researchers have tested magnesium supplements for sleep, blood pressure, stress, cramps and exercise. Each row has a label. Strong means several good trials agree, Moderate sits in between, Early means one or two small trials, and Mixed means the trials disagree.
| Benefit | What the research shows | Evidence |
|---|---|---|
| Tiredness and energy | An authorised claim, based on magnesium's role in making energy [2] | Strong |
| Blood pressure | A small fall on average across 38 trials, seen mainly in people with high blood pressure [4] | Mixed |
| Sleep | A small improvement in one 2025 trial, but a 2026 review of 12 trials found the results inconsistent [5][6] | Early |
| Stress and mood | Hints of benefit in people prone to anxious feelings, from poor-quality studies [7] | Early |
| Muscle cramps | A Cochrane review found magnesium unlikely to help cramps in older adults [8] | Moderate |
| Exercise and strength | No clear gain in strength for active people, who usually get enough magnesium already [9] | Early |
Blood pressure. A 2025 review pooled 38 trials with 2,709 people. Magnesium lowered systolic blood pressure by 2.8 mmHg on average compared with a placebo. The fall was larger in people already taking blood pressure medicines or with low blood magnesium, and wasn't clear in people whose blood pressure was normal [4]. The trials varied a lot, so the authors urged caution. If you take blood pressure tablets, our guide to magnesium side effects covers how they mix.
Sleep. In 155 adults who slept poorly, magnesium bisglycinate giving 250 mg of magnesium a day improved insomnia scores a little more than a placebo over 4 weeks, by 3.9 points against 2.3 [5]. A 2026 review of 12 trials rated the overall evidence low to very low in certainty [6]. Our guide to magnesium for sleep covers each trial.
Stress and mood. A 2017 review of 18 studies found that 9 reported less anxiety with magnesium. Every study recruited people already prone to anxiety, such as before a period, and the authors judged the evidence poor [7]. Our library of magnesium studies lists every trial in people.
In practice, the firmest benefit is the plainest one. Getting enough magnesium supports normal energy, muscles, nerves and bones.
Are there benefits of taking magnesium at night?
Possibly for sleep, but we found no trial that tested night against morning. The 2025 sleep trial gave magnesium daily, and its small benefit came from the magnesium rather than the time on the clock [5].
So take it when you'll remember it. Our guide on when to take magnesium covers timing, food and medicines.
Do you need a magnesium supplement?
Many people don't. The NHS says adults need 300 mg a day for men and 270 mg for women, and that a varied diet should provide it. Good sources include spinach, nuts and wholemeal bread [3].
Plenty of us fall a little short, though. The latest UK diet survey found men eat 273 mg a day on average and women 224 mg. About 20% of men and 15% of women were below the lowest intake level, the amount that's likely too little for most people [10].
Here's how that works out. A man eating the average 273 mg is about 27 mg short of 300 mg. A woman eating the average 224 mg is about 46 mg short of 270 mg. That gap is often a food question first. Our list of magnesium-rich foods shows how much each portion gives.
If you think you might be low, our guide to magnesium deficiency symptoms explains what to look for, and when to see a GP. There are separate guides for magnesium for women and magnesium for men.
Which type of magnesium is best?
For general use, the type matters less than the amount of magnesium you get. A 2017 review found the type of salt matters less than often thought, and that smaller doses spread through the day are absorbed better than one large dose [11].
Our guide to types of magnesium compares glycinate, citrate, malate, oxide and threonate side by side.
Is magnesium safe to take every day?
Yes, at sensible amounts. The NHS says taking 400 mg or less a day from supplements is unlikely to cause any harm. More than 400 mg for a short time can cause diarrhoea, and the effects of high doses over a long time aren't known [3].
In practice, add up the magnesium from every supplement you take, including multivitamins, and keep the total at 400 mg or less. Our guide to magnesium side effects covers medicines and who should check with a GP first.
Where Nooroots fits
Nooroots Triple Magnesium is a food supplement with magnesium glycinate, citrate and malate, in three capsules a day. Magnesium contributes to a reduction of tiredness and fatigue and to normal psychological function [2].
Frequently asked questions
What is magnesium good for?
Magnesium helps turn food into energy and supports normal muscles, nerves, bones and teeth. In the UK it can be said to reduce tiredness and fatigue and to support normal psychological function [2][3].
What are the benefits of taking magnesium supplements?
For people who don't get enough from food, a supplement helps cover the gap and brings the benefits of the authorised claims. Trials also found a small fall in blood pressure on average and a small sleep benefit in one trial [2][4][5].
Is it good to take magnesium every day?
Daily use is fine at sensible amounts. The NHS says 400 mg a day or less from supplements is unlikely to cause any harm [3].
Does magnesium help you sleep?
It may help a little. One 2025 trial found a small improvement in insomnia scores, but a 2026 review of 12 trials found the results inconsistent [5][6].
Which type of magnesium is best?
No single type suits everyone. The amount of magnesium you get matters more than the salt it comes in, and smaller doses through the day are absorbed better than one large dose [11].
Does magnesium give you energy?
Not like caffeine does. Magnesium contributes to normal energy-yielding metabolism and to a reduction of tiredness and fatigue, which matters most if your intake is low [2].
Read more about daily amounts in our guide to how much magnesium you need per day.
References
Every source here is listed so you can read it yourself. This guide is for general information and doesn't replace advice from your GP. We check it again at least every six months.
- Fiorentini D, Cappadone C, Farruggia G, Prata C (2021). Magnesium: Biochemistry, Nutrition, Detection, and Social Impact of Diseases Linked to Its Deficiency. Nutrients 13(4): 1136. PMID 33808247
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register, spreadsheet of 19 May 2026. Accessed 1 November 2026. gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register
- NHS. Vitamins and minerals: others (magnesium and zinc sections). Page last reviewed 3 August 2020. Accessed 1 November 2026. nhs.uk/conditions/vitamins-and-minerals/others
- Argeros Z, Xu X, Bhandari B, Harris K, Touyz RM, Schutte AE (2025). Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Hypertension 82(11): 1844-1856. PMID 41000008
- Schuster J, Cycelskij I, Lopresti A, Hahn A (2025). Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep 17: 2027-2040. PMID 40918053
- Lopresti AL, Smith SJ, Drummond PD (2026). Magnesium Supplementation for Sleep in Adults: A Systematic Review of Randomized Controlled Trials. Journal of Dietary Supplements 23(5): 553-581. PMID 42661485
- Boyle NB, Lawton C, Dye L (2017). The Effects of Magnesium Supplementation on Subjective Anxiety and Stress-A Systematic Review. Nutrients 9(5): 429. PMID 28445426
- Garrison SR, Korownyk CS, Kolber MR, Allan GM, Musini VM, Sekhon RK et al. (2020). Magnesium for skeletal muscle cramps. Cochrane Database of Systematic Reviews 9: CD009402. PMID 32956536
- Wang R, Chen C, Liu W, Zhou T, Xun P, He K et al. (2017). The effect of magnesium supplementation on muscle fitness: a meta-analysis and systematic review. Magnesium Research 30(4): 120-132. PMID 29637897
- Office for Health Improvement and Disparities (2025). National Diet and Nutrition Survey 2019 to 2023 (chapter 5 data, tables 5.26 and 5.41). Accessed 1 November 2026. gov.uk/government/statistics/national-diet-and-nutrition-survey-2019-to-2023
- Schuchardt JP, Hahn A (2017). Intestinal Absorption and Factors Influencing Bioavailability of Magnesium-An Update. Current Nutrition and Food Science 13(4): 260-278. PMID 29123461
