Thorne Magnesium Review UK: Bisglycinate Reviewed

By the time you factor in UK delivery and import duty, a tub of Thorne Magnesium Bisglycinate works out at roughly £1.00 per serving. The same elemental dose from a UK glycinate brand costs around £0.25-£0.35. That four-times price gap is the real Thorne magnesium review question, and the answer is not obvious in either direction.

I am Clemmie Rose, a registered Nutritional Therapist and BANT member, and the author of How to Talk to Kids About Nutrition. I assessed Thorne's two flagship magnesium products for UK buyers - the Magnesium Bisglycinate powder and the CitraMate - across form quality, dose, third-party certification, UK stockist availability, and true landed cost. The outcome is a clear verdict on who this brand is genuinely worth buying from.

In evaluating Thorne, I applied a nutritionist's framework rather than a marketing checklist. That means checking what form of magnesium is actually in the formula and why it matters, verifying the certification claims independently, calculating the real per-serving cost once shipping and import duty are included, and asking whether any of those credentials justify the premium against UK-available alternatives at a quarter of the price. Thorne earns credibility on form and purity. Whether that translates into a recommendation for a UK buyer depends on what they are buying it for.

Does the world's most certified supplement brand justify a four-times UK price premium? On formulation, Thorne earns it. The Magnesium Bisglycinate powder is a genuinely well-constructed product: a chelated glycinate form with strong tolerability evidence, no fillers, and NSF Certified for Sport status - among the most demanding third-party certifications available. CitraMate combines magnesium with citrate and malate, a useful formula for anyone prioritising energy metabolism over sleep support.

The limitation for UK buyers is logistical, not clinical. Thorne ships from the US. Import duty, variable delivery times, and limited UK stockist presence push the true cost per serving well above comparable UK glycinate options. For most UK buyers seeking glycinate-form magnesium for sleep and relaxation, the premium is hard to justify on formulation grounds alone - UK brands such as Pure Encapsulations and BetterYou's oral magnesium offer the same form at a fraction of the landed cost.

Buy Thorne Bisglycinate if: you are already buying from iHerb UK or Thorne's UK site, want NSF Certified for Sport status specifically, or are managing a diagnosed deficiency under clinical guidance and want the highest-purity format available.

Buy Thorne CitraMate if: you want magnesium combined with malate for energy support, and this combination is not available from a UK brand at the right dose.

Skip Thorne if: your priority is cost-per-dose efficiency and you have no specific certification requirement - a UK glycinate formula at £0.25-£0.35/serving will deliver equivalent elemental magnesium at the same form quality.

Few supplement brands carry the certification load Thorne does. Founded in 1984 and based in New York, it manufactures to both NSF Certified for Sport and NSF GMP (Good Manufacturing Practice) standards - meaning every batch is independently tested for banned substances and label accuracy. Sports medicine clinicians and US health practitioners cite it regularly, precisely because that certification burden is not common.

In the UK, Thorne is available through uk.thorne.com (direct) and iHerb UK, which ships from European fulfilment. The UK range covers the brand's core magnesium products:

Magnesium Bisglycinate (powder) - Thorne's flagship sleep and relaxation format. Each serving provides 200mg of elemental magnesium as bisglycinate, a chelated form where two glycine molecules are bound to each magnesium ion. This chelation improves intestinal absorption and reduces the laxative effect common with oxide and citrate forms. NSF Certified for Sport. Unflavoured powder designed to dissolve in water. The US retail price is US$52 for 60 servings. UK import adds shipping (typically £8-12) and potentially import duty, landing at approximately £52-58 for a tub, or around £0.90-£0.97 per serving.

Magnesium CitraMate (capsules) - A combination formula using magnesium citrate and malate. Citrate provides good bioavailability; malate (the salt of malic acid) is associated with energy metabolism support and is used clinically in fibromyalgia research. Each capsule delivers 135mg of elemental magnesium. US retail: US$26 for 90 capsules (90 servings). UK landed cost: approximately £28-32 for a tub, around £0.31-£0.36 per serving.

Magnesium Glycinate (capsules) - The 120mg-per-capsule glycinate form. US retail: US$26 for 90 capsules. Available from iHerb UK and some Amazon third-party sellers.

The two products this review centres on are Bisglycinate and CitraMate, as these represent Thorne's strongest clinical positioning in each use case: sleep/relaxation and energy metabolism respectively.

Getting hold of Thorne in the UK takes more planning than ordering from a domestic brand, and that friction is part of what this review assesses.

I priced the Magnesium Bisglycinate powder on uk.thorne.com (Thorne's own UK-facing storefront), including delivery, and priced an equivalent order through iHerb UK as a comparison. The CitraMate is available through iHerb UK, where European fulfilment means faster delivery and no separate import calculation.

For the formulation assessment, I cross-referenced Thorne's label claims against published bisglycinate absorption data (Siebrecht S., 2013, OM & Ernährung, Nr.144; available via Semantic Scholar) and the EFSA's authorised health claims for magnesium under Regulation (EC) No 432/2012, which covers claims on reduction of tiredness and fatigue, normal energy-yielding metabolism, normal functioning of the nervous system, and normal muscle function.

FRICTION MOMENT 1: sourcing. Thorne is not stocked in any major UK high street retailer as of July 2026. That means every purchase involves either direct import (uk.thorne.com or Amazon third-party) or using iHerb UK, which ships from its EU warehouse. If you are used to ordering supplements from Holland & Barrett, Boots, or Amazon UK's own catalogue, Thorne is a deliberate extra step.

What the chelated form actually means for your gut is the first thing worth understanding. Magnesium bisglycinate is a chelated magnesium compound where the mineral is bonded to amino acids (in this case, two glycine molecules) - a process that protects it through the digestive tract and supports absorption in the small intestine. The evidence for glycinate and bisglycinate forms is stronger for tolerability (fewer GI side effects) than for any specific superiority in serum magnesium outcomes over other well-absorbed forms, such as citrate.

Thorne's NSF Certified for Sport status is the primary certification differentiator. NSF Certified for Sport tests every production lot for 280+ substances banned by major sports organisations (WADA, USADA, NCAA), contaminants, and label accuracy. This is a materially higher bar than many UK supplements, which are sold under food supplement regulations without mandatory batch testing. For elite athletes, or anyone with a formal anti-doping obligation, this certification is not decorative.

For the general wellness buyer, the relevant question is whether NSF Certified for Sport equals better magnesium. The honest answer: it equals more reliably labelled and cleaner magnesium - the dose on the label is what is in the capsule, the product is free from heavy metals above safe limits, and there are no undisclosed ingredients. Whether that justifies four times the per-serving cost over a reputable UK glycinate product depends on how much that assurance is worth to you personally.

Unflavoured by design - and that design choice does actual work. Mixed into 200ml of water, the Bisglycinate powder dissolves within 30 seconds of stirring with no visible residue. The taste is very mildly salty with a faint mineral note - not unpleasant, and not sweetened, which suits the clinical positioning. It works equally well mixed into a small amount of juice if the mineral taste is a sticking point.

At the 200mg-per-serving dose, the powder lends itself to an evening wind-down routine - mixed and taken 30-60 minutes before sleep, which aligns with the glycinate form's research associations with sleep quality and relaxation. For anyone interested in the broader relationship between caffeine consumption and evening magnesium timing, there is relevant context in our guide to best coffee beans uk - specifically around caffeine half-life and when to stop consuming it relative to sleep.

The CitraMate capsules have no taste issue and are a standard one-capsule serving, which is an easy habit.

Four times the per-serving cost should buy a meaningfully better product. Whether Thorne clears that bar depends on what you are paying for.

FRICTION MOMENT 2: shipping and duty. When you buy from uk.thorne.com, the checkout price is in GBP and includes Thorne's UK shipping rate (typically £8-10 for a single tub). Orders over approximately £135 may attract import duty. For a single tub of Bisglycinate at around £48, the all-in cost lands at approximately £56-58, or £0.93-0.97 per serving at 60 servings. iHerb UK's EU warehouse avoids the import duty calculation on smaller orders, bringing the same product in at approximately £46-52 depending on promotion, or £0.77-0.87 per serving.

The value case for Thorne is real but specific. If you require NSF Certified for Sport status, you are not overpaying for a premium brand name - you are paying for a certification process that has genuine cost and rigour behind it. If you simply want a well-absorbed glycinate-form magnesium for sleep and relaxation, UK alternatives deliver that outcome at a fraction of the price.

The mid-market UK glycinate market has improved significantly. Brands such as Pure Encapsulations and collagen supplements competitors in the nutrient quality space have driven formulation standards upward. You no longer need to import from the US to access chelated magnesium in the UK.

Buy Thorne Magnesium Bisglycinate if:

Buy Thorne CitraMate if:

Skip Thorne if:

For context on where Thorne compares in the wider magnesium market, our best magnesium supplement uk roundup covers the full UK field. For anyone specifically comparing bisglycinate and glycinate forms, our magnesium glycinate vs malate guide covers the form differences in depth. And for a deep dive into the overall picture of best creatine and supplement quality standards in the UK market, the creatine cluster covers parallel certification questions.