Magnesium is an essential mineral that helps your body turn food into energy, keeps muscles and nerves working normally, and supports healthy bones. Malaysian women need about 310 to 320 mg a day and men 400 to 420 mg, according to the Ministry of Health's Recommended Nutrient Intakes (RNI 2017), and most of this can come from nuts, seeds, wholegrains, legumes and leafy greens. Magnesium supplements are popular, especially magnesium glycinate (also sold as bisglycinate) and citrate; studies show forms such as citrate are absorbed much better than magnesium oxide. Research shows modest benefits for blood pressure and migraine prevention, weak evidence for sleep, and little benefit for leg cramps in older adults. The upper limit from supplements is 350 mg a day; more can cause diarrhoea. This guide explains what magnesium does, how much you need, the best food sources, how the different forms compare, what the evidence says, and who should be careful.
What does magnesium do?
Malaysia's RNI describes magnesium as a cofactor in more than 300 enzyme reactions. An adult body contains about 25 g of magnesium, 50% to 60% of it in the bones. Its main roles (fungsi magnesium) include:
- Energy: it helps turn the food you eat into energy, as the NHS also notes.
- Muscles and nerves: it is involved in normal muscle contraction and nerve signalling.
- Bones: it supports bone formation and the parathyroid glands, which produce hormones important for bone health.
- Making proteins, fats and DNA: it is needed for many basic building processes in cells.
How much magnesium do you need?
Upper limit: the RNI adopts the US Institute of Medicine's tolerable upper intake level of 350 mg a day from supplements for adults, including during pregnancy and breastfeeding. This applies only to magnesium from supplements and medicines, not food; magnesium naturally present in food has not been shown to cause harm. The UK NHS similarly says that 400 mg or less a day from supplements is unlikely to cause harm.
Makanan tinggi magnesium: best food sources
Malaysia's own food composition table does not yet include magnesium, so the RNI lists values from the USDA database. Foods rich in fibre are generally good sources, while refining grains removes much of their magnesium.
Simple ways to eat more magnesium: snack on a small handful of nuts, swap white bread for wholemeal, mix brown rice into white rice (see our guide to nasi putih and brown rice), and add leafy greens and dhal to meals.
Signs of low magnesium
Malaysia's RNI notes that symptomatic magnesium deficiency from low diet alone is uncommon in healthy people, because the kidneys reduce how much magnesium is lost in urine. Deficiency is more likely with long-term low intake, chronic alcohol use, some medicines, type 2 diabetes, and gut conditions that cause chronic diarrhoea or poor absorption, such as Crohn's disease or coeliac disease.
According to the RNI, early signs include loss of appetite, nausea, vomiting, tiredness and weakness. More severe deficiency can cause numbness, tingling, muscle cramps, seizures and abnormal heart rhythms. Blood tests do not always reflect body stores well, so a doctor may combine tests with your symptoms and history. See a doctor rather than self-treating if you think you have these symptoms.
Magnesium glycinate vs citrate vs oxide
Supplements contain magnesium bound to another substance, which affects how well it is absorbed and how it affects your gut.
Tip: labels may list either the total compound weight or the elemental magnesium. Compare products by elemental magnesium per serving, and keep supplement intake within 350 mg a day unless a doctor advises otherwise. Choose a product registered in Malaysia; our guide to checking KKM registration and halal status shows how.
What can magnesium supplements actually do?
If poor sleep or stress is your main concern, start with sleep habits; our guides to susah tidur (insomnia) and ashwagandha for stress and sleep cover what the research shows.
Side effects and who should be careful
- Diarrhoea is the main side effect of too much magnesium from supplements or medicines. In the Cochrane cramp trials, stomach side effects such as diarrhoea affected 11% to 37% of people taking magnesium.
- Kidney disease: the RNI warns that people with impaired kidney function are at greater risk of magnesium build-up (hypermagnesaemia), most often from magnesium-containing antacids or supplements. Do not take magnesium supplements without medical advice.
- Medicines: antacids and laxatives that contain magnesium can interfere with some medicines, including the antibiotic doxycycline and the osteoporosis medicine alendronic acid. Ask a pharmacist how to space them.
- Pregnancy: keep supplements within the 350 mg a day limit unless your doctor advises otherwise.
Frequently asked questions (FAQ)
What is magnesium good for (magnesium untuk apa)?
Magnesium is a mineral involved in more than 300 enzyme reactions in the body. It helps turn food into energy, supports normal muscle and nerve function, and is needed for healthy bones. Most people can get enough from foods such as nuts, wholegrains, legumes and leafy greens.
How much magnesium do I need a day?
Malaysia's Recommended Nutrient Intakes (RNI 2017) set 310 mg a day for women aged 19 to 30 and 320 mg for women aged 31 to 50, and 400 to 420 mg for men. The upper limit for magnesium from supplements is 350 mg a day for adults; magnesium from food does not count towards this limit.
What is the difference between magnesium glycinate and bisglycinate?
They are generally the same thing: magnesium bound to the amino acid glycine. 'Bisglycinate' describes one magnesium attached to two glycine molecules, and many labels use the two names interchangeably. Compare products by the amount of elemental magnesium per serving, not the name.
Which form of magnesium is best?
In studies, magnesium citrate, chloride, lactate and aspartate were absorbed better than magnesium oxide, which had only about 4% fractional absorption. Oxide is mainly used as a laxative. Glycinate is often chosen because it is considered gentler on the stomach, but direct human comparisons with other forms are limited.
Does magnesium help with sleep?
Possibly, but the evidence is weak. A 2021 meta-analysis of three small trials in older adults found magnesium helped people fall asleep about 17 minutes faster than placebo, but the studies were low quality. Good sleep habits remain the most reliable approach.
What are the side effects of magnesium supplements?
The most common side effect is diarrhoea, especially at doses above 350 to 400 mg a day from supplements. People with kidney disease should not take magnesium supplements without medical advice, because their kidneys may not remove the excess.
When is the best time to take magnesium?
There is no single best time. Many people take it in the evening, and taking it with food can reduce stomach upset. If you take antibiotics such as doxycycline or osteoporosis medicines such as alendronic acid, ask your pharmacist how to space them, because magnesium can interfere with how they are absorbed.
Disclaimer
This article is for general information only and is not a substitute for advice, diagnosis or treatment from a doctor or pharmacist. Health supplements are not intended to diagnose, treat, cure or prevent any disease.
References
- Recommended Nutrient Intakes for Malaysia (RNI 2017), Chapter 25: Magnesium — National Coordinating Committee on Food and Nutrition, Ministry of Health Malaysia
- Others (magnesium) — NHS
- Taking doxycycline with other medicines — NHS
- Taking alendronic acid with other medicines — NHS
- Zhang X, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension. 2016;68(2):324-333.
- Holland S, et al. Evidence-based guideline update: NSAIDs and other complementary treatments for episodic migraine prevention in adults. Neurology. 2012;78(17):1346-1353.
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysis. BMC Complement Med Ther. 2021;21(1):125.
- Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 2020;9(9):CD009402.
- Lindberg JS, et al. Magnesium bioavailability from magnesium citrate and magnesium oxide. J Am Coll Nutr. 1990;9(1):48-55.
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res. 2001;14(4):257-262.
