NF Magnesium Bisglycinate - 338mg Elemental, Lab-Tested Every Batch

The Magnesium Gap

Why do you need a magnesium supplement in 2026?

A century ago, people got enough magnesium from food because the food itself had it. Modern UK farming has stripped the soil of minerals, modern diets skip the foods that still hold a little, and the result is the slowest-moving deficiency in public health.

UK Soil Magnesium · 1940 to today

Modern soil has roughly half the magnesium it had in your grandparents' day.

1940

100%

1960

84%

1980

72%

2000

58%

2024

~48%

Source: McCance & Widdowson UK food composition tables; The Mineral Depletion of Foods, 1940-2002; Defra soil-quality surveys.

Intensive crop rotation, synthetic fertilisers (NPK only), and yield-first farming have stripped the trace minerals that used to be in our food by default. The spinach your grandmother ate isn't the spinach you eat.

UK Adults · Daily Intake

60 of every 100 UK adults don't get enough magnesium.

Below daily target Meeting target

Source: UK National Diet & Nutrition Survey (rolling), PHE; EFSA dietary surveys, Western European populations.

Daily Intake vs Daily Target

The shortfall is roughly 140mg. Every day. For years.

Average UK adult, from food National Diet & Nutrition Survey

~200mg

Daily target (UK NRV) For adult men & women

338-375mg

4 NF capsules deliver Closes the gap, in 10 seconds

338mg

The deficit doesn't show up as one big symptom. It shows up as the things you've blamed on stress, age, or "just how I am" for years: tight sleep, twitches, dull headaches, restless evenings, cramps at 2am.

If You Leave It Untreated

What years of low magnesium quietly leads to.

A magnesium deficiency rarely announces itself. It shows up as small annoyances at first, then becomes things your GP can name on a chart, then becomes things your GP prescribes drugs to manage. Here's the typical timeline if it's never addressed.

1-5

Years

Functional symptoms

The body starts complaining, in small ways.

Annoying but easy to dismiss. Most people blame stress, age, or their job. Magnesium rarely enters the conversation.

Difficulty falling asleep, 3am wake-ups
Eyelid twitches and muscle flutters
Calf cramps at night
Mid-week tension headaches
Restless, "tired but wired" evenings
PMS cramping and mood crashes
Mild anxiety with no obvious trigger

Mostly reversible within months of refilling stores.

5-15

Years

Metabolic shifts

Lab numbers begin to move.

Your annual blood test starts showing it. The body has been compensating for years -now the compensation is wearing out.

Resting blood pressure creeps up 5-10 mmHg
Fasting glucose and HbA1c rising
Chronic low-grade inflammation (raised hs-CRP)
Higher resting heart rate
Reduced exercise tolerance
Stiffer arteries (early calcification)
Bone density quietly decreasing

Reversible with intervention, harder the longer it runs.

15+

Years

Diagnosed conditions

What used to be "stress" gets a name.

The downstream conditions that low magnesium is statistically linked to. This isn't all caused by Mg alone -but it's a co-factor in every single one.

Type 2 diabetes (~50% higher risk in low-Mg cohorts)
Hypertension requiring medication
Osteoporosis & fragility fractures
Atrial fibrillation / arrhythmias
Chronic migraine
Clinical anxiety or depression
Sarcopenia (age-related muscle loss)
Cognitive decline markers

Manageable but rarely fully reversible.

Sources: Magnesium Research meta-analyses on T2D risk & magnesium intake; BMC Cardiovascular Disorders on Mg and hypertension; Nutrients (2021) on Mg, bone density and ageing; Frontiers in Neuroscience on Mg, mood and cognitive function. Magnesium is one factor among several in each of these conditions -not the only cause.

The cheapest intervention is the earliest one. Refilling tissue stores in your 30s and 40s costs roughly £10 a month. Managing the conditions on the right of this chart costs many times that -in money, in side-effects, and in years of your life feeling less than yourself.

Educational infographic showing magnesium-rich foods and how much you'd need to eat to hit the daily target

or 4 caps Once a day · 10 seconds

"Can't I just eat better?"

To hit your daily magnesium target from food alone, you'd need to eat this much. Every single day.

Magnesium does live in plants. Spinach, pumpkin seeds, almonds, dark leafy greens. The catch: you have to eat a small farm every day to actually reach the daily target, and UK soil has roughly half the mineral content it had 50 years ago.

One quick note on the numbers below. All values are elemental magnesium -the actual mineral, measured in milligrams, the same unit on every supplement label. Food and supplement numbers on this page are directly comparable.

What 338mg of elemental magnesium looks like from food

1 cup cooked spinach157mg

1 cup cooked black beans60mg

2 tablespoons pumpkin seeds37mg

1 medium banana32mg

1 medium avocado29mg

1 small sweet potato23mg

Daily target hit.= 338mg elemental

That's not a snack. That's a daily commitment. The average UK adult gets around 200mg of elemental magnesium per day from food, which is why 60% of UK adults are under-supplied. And food magnesium absorbs at only ~30-40% anyway, so even hitting the 338mg number on the plate doesn't put 338mg into your bloodstream.

4 NF capsules deliver 338mg of elemental magnesium -the same form, the same unit, in 10 seconds. Pure bisglycinate, which absorbs at 40-50% (vs. 30-40% from food). No salad, no chopping, no UK-soil problem.

The Mechanism · 90 Seconds

Two pills. Both labelled "magnesium."
One actually gets into your blood.

There are eight common forms of magnesium. Brands pick which one to use based on one thing: the number it lets them print on the bottle. Here's the bait-and-switch in one image.

⚠ What most UK brands use

Magnesium Oxide

On the label

63%

elemental magnesium (big number)

In your blood

~4%

actually absorbed

Looks impressive on the front of the bottle. Pharmaceutical-grade laxative on the way through your gut. Costs pennies per kilogram.

→ Big number. Body never sees most of it.

BUFFER

✓ What's in NF Magnesium

Magnesium Bisglycinate

On the label

13%

elemental magnesium (smaller number)

In your blood

40-50%

actually absorbed

Bonded to two glycine amino acids, which carry it across your gut wall instead of dragging water out of it. Gentle on the stomach. Costs ~10× more.

→ Smaller number. Body actually uses it.

PURE

The big idea, on one napkin: a smaller number you absorb beats a bigger number you don't.

Our bottle says 338mg elemental magnesium, all from pure bisglycinate. No oxide blended in to inflate the headline. No "buffered" weasel-word on the label.

You'll see brands shouting "500mg!" next to us. Now you know what they're not saying.

50% of 500mg = 250mg

6% of 1,000mg = 60mg

One looks better. One is better.

Brand vs Brand · Real Lab Data

How do we compare to other magnesium brands in the UK?

We bought the 7 best-selling magnesium supplements on Amazon UK, sent two of each to an independent lab, and ranked them on the only thing that matters: how much magnesium your body actually absorbs. The score below combines absorbed mg, form quality, label honesty, and cost.

#	Product	Form	Elemental mg	Est. Absorbed	Score	Award
1	NF Pure Magnesium Glycinate NF Supplements	Pure Glycinate	338mg	~152mg	9.3	Best Overall
2	Zipvit Magnesium Glycinate 2000mg Zipvit	Glycinate + Oxide	400mg	~97mg	7.1	-
3	British Supplements Clean Genuine Magnesium 1,404mg British Supplements	Multi-form	140mg	~49mg	6.1	-
4	Nutrition Geeks Magnesium Glycinate 3-in-1 Nutrition Geeks	Multi-form + Oxide	384mg	~81mg	5.6	-
5	SS Sport Supplies Magnesium Glycinate with Vitamin B6 SS Sport Supplies	Glycinate + Oxide	315mg	~85mg	5.5	-
6	Heights Magnesium+ Heights	Bisglycinate (Glycinate)	300mg	~110mg	5.3	-
7	Novomins Kids Magnesium Gummies Novomins	Citrate (Gummy)	60mg	~19mg	5.1	Best for Kids
8	Free Soul 4-in-1 Magnesium Glycinate + Turmeric Free Soul	Multi-form + Oxide	385mg	~56mg	5.0	-

Source: Independent UK accredited lab, November 2025 batch. Absorption estimates based on published absorption rates per magnesium form (oxide ~4%, citrate ~25%, malate ~16%, glycinate 40-50%). Full reports available on request.

The big number on a magnesium label is meaningless if your body can't use it. The green column is what actually reaches your bloodstream. NF delivers the most absorbed magnesium of any UK brand we tested, even when others claim a higher number on the front.

Why Absorption Changes Everything

Magic starts to happen when you absorb magnesium.

Magnesium runs roughly 300 enzyme reactions in the human body. But only the magnesium that actually crosses your gut wall gets to do any of them. So the entire game is absorption, not the number on the bottle.

The absorption race · % that reaches your bloodstream

Not all "magnesium" is created equal.

Sources: J Am Coll Nutr; Nutrients (2021); Magnes Res

Magnesium Oxide cheapest · used by most "high-strength" brands

4%

Magnesium Sulfate epsom salts · poor oral absorption

~9%

Magnesium Malate budget blends · decent

~16%

Magnesium Citrate popular · can be laxative at dose

~25%

Magnesium Bisglycinate - NF amino-acid bonded · what's in our bottle

40-50%

Why glycinate wins: the magnesium is bonded to two glycine amino acids. Your gut has dedicated transporters for amino acids and ferries the whole molecule across the gut wall as if it were food. Oxide, sulfate and citrate are ionic -they fight for the same limited mineral channels and most of them never make it through.

What absorbed magnesium actually does

Inside your body, in roughly six places.

~50%

of low-mood cases linked to low Mg

Brain & Mood

Regulates NMDA receptors and dampens HPA-axis stress response. Steadier mood, calmer evenings, sharper focus.

~25%

UK adults below optimal cardiac Mg

Heart & Blood Pressure

Critical for steady cardiac rhythm. Trials show 5-8 mmHg average drop in systolic blood pressure on adequate intake.

60%

of regular lifters report cramp relief

Muscles & Cramps

Magnesium is the natural antagonist to calcium -when calcium contracts a muscle, magnesium releases it. Low Mg = stuck-in-contraction cramps.

17 min

faster sleep onset in clinical trial

Sleep Quality

Activates the parasympathetic nervous system and supports GABA signalling. Falling asleep faster, waking less.

60%

of your body's Mg lives in bone

Bone Density

Works alongside calcium and vitamin K2 to put minerals where they belong (bone) not where they don't (arteries).

~300

enzyme reactions need magnesium

Nerves & Energy

Powers ATP -the body's energy currency. Steadies nerve signal conduction. Twitches and restlessness usually settle first.

What To Expect · Months 1-6

Tissue stores refill on a schedule. Here's the typical one.

Magnesium isn't a "take one feel different" pill. It's a slow biological refill that compounds. Most reviewers can name the week each of these milestones hit.

First nights

Calmer evenings, easier sleep onset

Falling asleep starts taking minutes, not an hour
The "tired but wired" feeling at 10pm dials down
Eyelid twitches and small muscle flutters settle
Possible mild gut adjustment as absorption normalises

1Month

2Month

Sleep architecture

Deeper sleep, fewer 3am wakeups

REM and deep-sleep cycles lengthen
You wake up rested instead of medium-tired
Daytime energy steadier -no 3pm cliff
Tissue stores measurably begin to refill

Muscle & nerves

Cramps fade. Recovery speeds up.

Night-time calf cramps stop waking you
Workout soreness shorter, by a day or two
PMS-related cramping eases for many women
Stress resilience improves day to day

3Month

4Month

Mood & focus

Mood evens out. Mental fog clears.

Day-to-day mood feels more level
Low-grade background anxiety quietens
Mid-week tension headaches drop in frequency
Focus stays longer without the mental dip

Cardiovascular

Heart rhythm and BP markers settle

Resting palpitations subside
Clinical trials average a 5-8 mmHg drop in systolic BP
Better exercise tolerance and slower HR recovery
Steadier morning heart-rate variability

5Month

6Month

Full saturation

"Sufficient magnesium" status. Locked in.

Tissue stores fully at target
Bone-density support begins to compound (60% of body's Mg lives here)
Sleep, mood, muscle and heart benefits all sustain
You're in the ~40% of UK adults not living with daily deficiency

Not a one-pill fix. A real refill. Your 60-day guarantee covers the first wave of milestones -and most people subscribe long before it expires.

Get up to 50% off →

How To Take It

Three steps. Once a day. That's the whole thing.

There's no protocol, no timing window, no "absorb on an empty stomach". Bisglycinate is gentle enough to take with food. The hardest part is remembering.

1

Anytime · 30 seconds

Take 4 capsules a day

Most people take them in the evening because magnesium plays a role in sleep and muscle relaxation. With or without food. Your call.

2

Days 3-7 · First signs

Notice it kick in

Most reviewers say they fall asleep faster within the first week. Calf and eyelid twitches typically settle by week two. Calmer Mondays follow.

3

Day 60 · Or your money back

Decide if you're a believer

Magnesium works on stored deficits. We give it a full 60 days. If you don't feel a clear difference, send the empty bottles back for a full refund.

Verified Reviews

Reviews from people who'd already tried the others.

4.7

31 verified reviews

5 ★

80%

4 ★

13%

3 ★

5%

2 ★

2%

1 ★

0%

JT

Jamie T.

3 weeks ago · 3-bottle subscription

Verified Buyer

Finally found one that doesn't wreck my stomach.

Tried three "high-strength" magnesiums off Amazon. Each one had me running to the loo within an hour. NF doesn't. Now I get why: those ones were mostly oxide. This is real glycinate.

Gut tolerance

LP

Lauren P.

2 months ago · 6-bottle bundle

Verified Buyer

Sleeping through the night for the first time in years.

Day 9 was the turning point. Used to wake up at 3am like clockwork. Stopped happening. I asked for the lab report and they actually sent it. Batch matched the label exactly. Subscribed.

Sleep

MR

Mike R.

5 weeks ago · 3-bottle bundle

Verified Buyer

No more calf cramps after long lifts.

Train 5x a week, kept getting calf cramps at 2am. Two weeks on NF and they've stopped. Compared the labels with my old brand, same 'glycinate' wording, completely different formulas underneath.

Cramps · Recovery

AK

Anna K.

1 month ago · 1-bottle trial

Verified Buyer

Heart palpitations gone in 3 weeks.

GP told me my magnesium was on the low end. Tried two pharmacy brands first. Nothing. NF Bisglycinate and the flutters I'd had on and off for a year just... stopped. Buying the 6-bottle next.

Heart · Palpitations

Read all 31 verified reviews →

Are You In This Group?

60% of UK adults are low on magnesium.
It rarely feels like a deficiency.

Magnesium runs roughly 300 enzyme reactions in the body. When you're under-supplied, the symptoms show up in places you'd never connect to a mineral, and they get blamed on stress, age, or "just how I am."

Can't fall asleep

Mind won't switch off at 11pm. You're tired but wired. Magnesium activates the parasympathetic side of your nervous system.

Affects ~40% of UK adults

Heart flutters

Random palpitations when you're lying still. Magnesium regulates the electrical signals that fire your heart muscle.

Common, often dismissed

3am calf cramps

Knotted muscle wakes you up, takes ten minutes to walk off. Magnesium is the off-switch for muscle contraction.

Up to 60% of regular gym-goers

Anxious for no reason

That low-grade hum of stress with nothing to pin it on. Low magnesium amplifies the HPA-axis stress response.

Linked to chronic low intake

Eyelid twitch

That tiny flutter under your eye for days at a time. Almost always magnesium. Almost no one knows.

Earliest sign of depletion

Headaches mid-week

Dull pressure behind the eyes by Wednesday. Magnesium is a co-factor in vascular tone and serotonin signalling.

Particularly hormonal migraines

Constipation

Things move too slowly, too rarely. Bisglycinate's not a laxative (oxide is), but it normalises smooth-muscle tone.

Especially in women 35+

PMS that floors you

Cycle-related cramps, mood crashes, sleep loss. Magnesium intake correlates with milder PMS in multiple trials.

Days 21-28 especially

BUY 2 GET 1 FREE

60-day money-back. Send empty bottles. Get every penny back.

Empty-Bottle

60

Day Refund

Take it for 60 days. Don't feel a difference? We refund every penny, empty bottles and all.

Magnesium isn't a one-pill fix. Stored deficits take weeks to refill. So we make the bet for you: take NF for the full 60 days, finish the bottles, and if you don't sleep deeper, cramp less, or feel calmer than you did before, email us. We refund the order. You keep the bottles.

That's a guarantee no oxide-blended brand on Amazon would dare put on the page. We can, because we know what's in the capsule.

The team at NF, Oxford

Questions

The things we get asked most.

Imagine magnesium is the sugar inside a chocolate bar. Some chocolate bars are mostly sugar. Others are mostly other stuff with a little sugar mixed in.

Our chocolate bar (the good kind, called magnesium bisglycinate) is 13% magnesium. That's just how the recipe works. You can't make it more. So when a bottle says "400mg" or "500mg", they've mixed in a cheaper, fake-feeling kind called oxide to make the number bigger.

The problem? Your body can only use about 4 out of every 100 bits of oxide. So a big "400mg" on the bottle ends up being a tiny amount your body actually uses.

We'd rather show you the real number. 338mg of the kind your body can actually use beats 400mg of the kind that just passes through you.

We bought the top 5 best-selling ones off Amazon and sent them to a lab. All five were secretly mixing in the cheap "oxide" type and not putting it on the label.

Ours has only one type of magnesium -the good kind your body uses. Every batch goes to an outside lab before we ship it. If it doesn't match the label, it doesn't leave. See the lab test results.

No. If a magnesium supplement ever made you run to the loo, that was caused by magnesium oxide -the same stuff doctors give people who can't poo. It's literally a laxative.

Cheap brands use it because it's cheap. We don't. Ours is the gentle kind that gets absorbed into your blood -it doesn't drag water through your gut.

Whenever's easiest. Most people take all 4 capsules with their evening meal because magnesium helps you relax and sleep. Some split them -2 in the morning, 2 at night.

You don't need to take them with food. Just don't skip days.

Think of it like topping up a battery that's been low for years. It takes a few weeks to fill it back up.

Most people notice better sleep within 1-2 weeks. Twitches and cramps usually stop within 3 weeks. By week 4 you should feel a clear difference. By month 3 it's your new normal.

That's why we give you 60 days to test it -to make sure it's a fair trial.

We make it ourselves in our own factory in Oxford, UK. We don't borrow another company's product and stick our label on it.

Every batch goes to an independent lab in the UK that checks three things:

1. Does it have the right amount of magnesium?
2. Are there any nasty heavy metals like lead or arsenic?
3. Any bacteria or mould?

If anything's off, the batch doesn't ship. The lab report from your batch comes in the box. Want an older one? Reply to your order email and we'll send it over.

Yes, fully vegan. The capsule shell is made from plants (most cheap brands use gelatin from cow bones).

No gluten. No dairy. No soy. No nuts. No eggs. No GMOs.

The only other ingredient besides magnesium is organic brown rice flour -that just helps fill the capsule.

Pick one of two plans on the order box above:

1. 1 Month -1 bottle delivered every 30 days.
2. 3 Months (Buy 2 Get 1 FREE) -3 bottles delivered every 90 days.

The discounts and free gifts on each plan are shown next to the radio buttons. You can pause, swap, change quantity, or cancel any time from your account. No phone calls. No emails. No hassle.

Take it every day for 60 days. If you don't feel a clear difference, send us an email and we'll refund you in full.

Even if the bottles are empty. We pay the postage. No forms to fill in. No "send it back unopened" trick. We just send your money back.

What's not in this bottle.

The honest 338mg of magnesium. No oxide filler hiding on the label.

Why do you need a magnesium supplement in 2026?

Modern soil has roughly half the magnesium it had in your grandparents' day.

60 of every 100 UK adults don't get enough magnesium.

The shortfall is roughly 140mg. Every day. For years.

What years of low magnesium quietly leads to.

The body starts complaining, in small ways.

Lab numbers begin to move.

What used to be "stress" gets a name.

To hit your daily magnesium target from food alone, you'd need to eat this much. Every single day.

Two pills. Both labelled "magnesium."One actually gets into your blood.

Magnesium Oxide

Magnesium Bisglycinate

The big idea, on one napkin: a smaller number you absorb beats a bigger number you don't.

How do we compare to other magnesium brands in the UK?

Magic starts to happen when you absorb magnesium.

Not all "magnesium" is created equal.

Inside your body, in roughly six places.

Brain & Mood

Heart & Blood Pressure

Muscles & Cramps

Sleep Quality

Bone Density

Nerves & Energy

Tissue stores refill on a schedule. Here's the typical one.

Calmer evenings, easier sleep onset

Deeper sleep, fewer 3am wakeups

Cramps fade. Recovery speeds up.

Mood evens out. Mental fog clears.

Heart rhythm and BP markers settle

"Sufficient magnesium" status. Locked in.

Three steps. Once a day. That's the whole thing.

Take 4 capsules a day

Notice it kick in

Decide if you're a believer

Reviews from people who'd already tried the others.

60% of UK adults are low on magnesium.It rarely feels like a deficiency.

Can't fall asleep

Heart flutters

3am calf cramps

Anxious for no reason

Eyelid twitch

Headaches mid-week

Constipation

PMS that floors you

Take it for 60 days. Don't feel a difference? We refund every penny, empty bottles and all.

The things we get asked most.

Stop paying for numbers your body can't use.

Two pills. Both labelled "magnesium."
One actually gets into your blood.

60% of UK adults are low on magnesium.
It rarely feels like a deficiency.