Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult your GP or a registered health professional before starting any new supplement.
Most people who start taking magnesium notice a difference within two weeks. Better sleep, less muscle tension, fewer headaches, a clearer head. And yet magnesium remains one of the most underappreciated supplements on the market — probably because it does not have the marketing glamour of collagen or the trending appeal of lion’s mane. It just quietly fixes things.
New Zealand surveys consistently show magnesium in the top three daily supplements Kiwis take, and for good reason: it is involved in over 300 enzymatic processes in the body, and many New Zealanders do not get enough from food alone. This guide covers the best magnesium supplements available in NZ, which form actually absorbs best, and what nobody tells you about magnesium dosing.
The Form of Magnesium Matters More Than the Brand
This is the single most important thing to understand before buying a magnesium supplement. The form of magnesium determines how well it absorbs and what it is actually good for. Here is the honest breakdown:
- Magnesium glycinate (bisglycinate): Bound to glycine, an amino acid. Highest bioavailability, gentlest on the stomach, and excellent for sleep, anxiety, and nervous system support. This is the form most worth spending more on.
- Magnesium citrate: Bound to citric acid. Good absorption, affordable, and a mild laxative effect at higher doses — which makes it useful for constipation but less ideal for sleep-focused supplementation.
- Magnesium oxide: The cheapest and most commonly used form in supermarket supplements. Poor bioavailability (roughly 4% absorbed). Avoid unless you specifically want the laxative effect.
- Magnesium malate: Bound to malic acid. Good for energy and muscle recovery. A solid choice if you are active.
- Magnesium threonate: Newer form, claimed to cross the blood-brain barrier more effectively. More expensive, limited but promising research for cognitive function.
The Best Magnesium Supplements Available in NZ (2026)
1. Clinicians Magnesium Bisglycinate — Best Overall
Clinicians, the Canstar Blue award-winning NZ supplement brand founded in 1997, makes one of the best magnesium glycinate products available locally. Each capsule delivers 100mg of elemental magnesium as bisglycinate — a well-absorbed form that is easy on the digestive system. The product is available from Healthpost.co.nz and most NZ health stores at around NZ$30-45 for 60 capsules. For sleep, stress, and muscle recovery, this is the form to choose.
Best for: Sleep, anxiety, nervous system support. Anyone who has tried cheaper forms and not felt results.
2. GO Healthy GO Magnesium — Best Everyday Value
GO Healthy’s magnesium range includes several forms, including their high-strength options. Their GO Magnesium + B6 500mg delivers elemental magnesium in a combination formula that supports both muscle function and energy. As NZ’s number one selling supplement brand, GO Healthy is widely available through Healthpost, Unichem, and health food stores, with pricing typically in the NZ$25-40 range. Check the form on the label — their premium options use more bioavailable forms than their entry-level products.
Best for: General magnesium maintenance and muscle support at good value.
3. BePure MagnesiCalm — Best NZ Practitioner Brand
BePure’s MagnesiCalm powder delivers magnesium in a drinkable form that many people find easier to take than capsules. It uses a combination of magnesium glycinate and magnesium oxide, with a pleasant taste and easy dissolving. The glycinate component makes it more useful than pure oxide products. Available direct from BePure at around NZ$55-65 for a month’s supply — the premium reflects the NZ-made formulation quality.
Best for: People who prefer powders over capsules, and those wanting a practitioner-quality NZ product.
4. Sanderson Magnesium Citrate 400mg — Best Budget Pick
Sanderson has been an NZ supplement brand since 1979. Their magnesium citrate 400mg capsules are solid value for those who want a more bioavailable form than oxide without paying glycinate prices. Magnesium citrate absorbs well and is particularly useful for muscle cramps. Available from Healthpost at around NZ$20-30 for 90 capsules.
Best for: Those wanting better-than-oxide absorption at an affordable price point.
5. Thorne Magnesium Bisglycinate (via iHerb) — Best International Option
Thorne’s magnesium bisglycinate is one of the gold-standard international options for anyone ordering through iHerb. NSF-certified, pharmaceutical-grade manufacturing, and 200mg of elemental magnesium per two-capsule serving. Priced at around NZ$35-50 delivered via iHerb.
Best for: Those prioritising the highest available testing standards and comfortable with international ordering.
What the Label Will Not Tell You
The milligram number on the label is often the compound weight, not the elemental magnesium content. For example, 500mg of magnesium citrate delivers around 75-80mg of actual (elemental) magnesium. Always look for the elemental magnesium amount — this is what actually matters for dosing. Good NZ brands like Clinicians clearly state this; cheaper products often bury it.
Most adults need 300-420mg of elemental magnesium daily from all sources combined (food plus supplements). Magnesium-rich foods include dark leafy greens, pumpkin seeds, almonds, and dark chocolate. If you eat a varied diet with plenty of vegetables, you may already be getting 200-300mg from food and only need a modest top-up.
Taking too much magnesium (above 350mg supplemental per day for most people) can cause loose stools. Start with a lower dose and increase gradually.
When to Take Magnesium
Magnesium glycinate is best taken 30-60 minutes before bed — the relaxing effect on the nervous system is genuinely useful for sleep quality. Magnesium citrate or malate can be taken any time. Avoid taking magnesium at the same time as calcium supplements, as they compete for absorption.
The Bottom Line
If you can only buy one form of magnesium, make it glycinate or bisglycinate. Clinicians is the standout NZ brand, and GO Healthy offers good value if you check the form on the label. Avoid anything labelled simply as magnesium oxide if results matter to you — the absorption difference is significant.
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Read the Elemental Magnesium, Not Just the Compound Weight
A label may advertise a large amount of magnesium glycinate or citrate while providing a much smaller amount of elemental magnesium—the amount that counts toward your intake. Compare products using the elemental-magnesium line on the nutrition panel and the number of capsules needed per serving. A transparent label also identifies the exact form rather than using a proprietary blend.
Which Form Fits Which Goal?
- Magnesium glycinate: often chosen when digestive tolerance is the priority. It is not a guaranteed sleep treatment, despite common marketing.
- Magnesium citrate: well absorbed and may loosen stools, which can be helpful or inconvenient depending on the person.
- Magnesium oxide: inexpensive and contains a high proportion of elemental magnesium, but it is less completely absorbed and commonly causes gastrointestinal effects.
- Magnesium chloride: another soluble option. Topical sprays are popular, but evidence that they reliably correct magnesium status through intact skin is limited.
Dose, Side Effects and Interactions
Start with food sources—nuts, seeds, legumes, whole grains and leafy greens—and use a supplement to fill a defined gap. The US National Institutes of Health sets an adult upper limit of 350 mg per day for magnesium from supplements and medicines, not including food, unless a clinician recommends otherwise. Higher supplemental amounts commonly cause diarrhoea, nausea or cramping.
Magnesium can interfere with absorption of some antibiotics and bisphosphonates, and kidney impairment can increase the risk of excess magnesium. Check timing with a pharmacist and seek personal advice if you have kidney disease, take regular medicine, are pregnant, or are supplementing for persistent symptoms. For a broader comparison of evidence and quality checks, visit our New Zealand supplement guide and our detailed glycinate vs citrate guide.
Source
NIH Office of Dietary Supplements: Magnesium fact sheet for health professionals