Pure Encapsulations Magnesium Glycinate: The 4-Capsule Catch

Pure Encapsulations is the magnesium glycinate people search for by name, usually because a doctor, a dietitian or a friend recommended it. The questions that follow are the practical ones: how much magnesium is in a capsule, how many to take, and what else is in it.

We answered them from the source that does not change with the marketing: the product’s own label, as recorded in the National Institutes of Health’s Dietary Supplement Label Database. We then pulled every other magnesium glycinate label in the same database to see how this one compares.

What one capsule contains

Every Pure Encapsulations Magnesium (Glycinate) capsule label in the NIH database lists the same thing:

Item	Per capsule
Magnesium (elemental)	120 mg
Magnesium source	Magnesium glycinate
Other ingredients	Vegetarian capsule (cellulose and water on newer labels), ascorbyl palmitate

The 120 mg is the magnesium itself, not the weight of the glycinate compound, which is much heavier. That matters because some glycinate products put the compound weight in large type on the front. Ascorbyl palmitate is a fat-soluble form of vitamin C used to protect the contents from oxidation; it is a small quantity, not a vitamin C dose.

For context, the recommended intake from all sources is 400 to 420 mg a day for men and 310 to 320 mg for women, according to the NIH fact sheet. One capsule supplies roughly a third of that.

The 4-capsule catch

This is the part most pages skip. Four Pure Encapsulations capsule labels are in the NIH database, and their directions differ:

Bottle	Entered in database	Directions	Magnesium at the top of the range
180 capsules	July 2019	1-4 capsules daily, with food	480 mg
90 capsules	May 2020	1-4 capsules daily, with food	480 mg
360 capsules	July 2023	1-4 capsules daily, with food	480 mg
30 capsules	September 2023	1 capsule daily, with a meal	120 mg

The US Tolerable Upper Intake Level for magnesium from supplements and medicines is 350 mg a day for adults. It is set where diarrhea becomes a risk: the NIH fact sheet says high doses from supplements or medications “can cause diarrhea, nausea, and abdominal cramping.” Four capsules, 480 mg, is 130 mg over that limit, and that is before any magnesium in a multivitamin, an antacid or a sleep blend.

The limit does not count magnesium from food, because healthy kidneys clear the excess. It also does not mean four capsules is dangerous for a healthy adult; it means that above 350 mg the chance of loose stools rises, and the reason most people choose glycinate, its gentleness on the gut, starts to disappear. Higher doses are sometimes used under medical supervision, which is a different situation from following a bottle.

So the label is not wrong to allow a range. But the top of that range is above the limit, and the newest label in the database, for the smallest bottle, asks for one capsule.

Add up the magnesium from every product you take in the checker above. The full tool covers 15 nutrients on our supplement upper limit checker page.

How it compares with 146 other glycinate labels

To see whether Pure Encapsulations is typical, we pulled every on-market product in the NIH database with magnesium and glycinate in its name, kept those listing magnesium in milligrams, and dropped multi-nutrient products. That left 146 labels.

What we counted	Products	Share
More than 350 mg magnesium in one listed serving	41	28%
120 mg or less per serving	31	21%
Magnesium oxide listed alongside the glycinate	11	8%
Glycinate described as “buffered”, buffer not named	10	7%
No magnesium form named at all	19	13%

Two of those rows explain why the label is worth reading.

The 41 above 350 mg sell a single serving, usually two tablets or capsules of “Magnesium Glycinate 400”, that is over the upper limit on its own. The most common serving sizes in the set were 200 mg (37 products) and 400 mg (35 products). Pure Encapsulations, at 120 mg a capsule, is one of the lower-dose options, which makes it easier to take less, not harder.

The 11 with magnesium oxide are products sold as magnesium glycinate in which part of the magnesium comes from oxide, the form glycinate is usually bought to avoid. The label shows this only in the “as” line under magnesium. Pure Encapsulations lists glycinate alone.

“Buffered” glycinate is a related case: the word means something else has been added, and 10 labels in the set used it without saying what.

This is our count from the database on 9 October 2026, not a lab test. The database records labels as they were submitted, and a product may have changed since.

What glycinate actually does well

The case for glycinate is narrower than most product pages say, and we went through it in our article on the trials of magnesium glycinate itself. The short version:

• Absorption: in the only isotope study, glycinate was absorbed about the same as oxide overall, 23.5% against 22.8%, in 12 people who had part of their small bowel removed. It did better in the four patients who absorbed oxide worst.
• Tolerance: the same study found glycinate better tolerated by every patient. This is its real advantage.
• Sleep: the one sleep trial gave 250 mg of magnesium a day as bisglycinate to 155 adults with poor sleep. Insomnia scores fell 3.9 points against 2.3 on placebo after four weeks, a small effect, and the improvement was larger in people who ate little magnesium.

Two Pure Encapsulations capsules, 240 mg, sit close to that trial dose and under the upper limit. No trial has tested this brand specifically.

How to take it

1. Start with one capsule a day, with food. That is 120 mg, and it is what the newest label asks for.
2. Go to two if you want the sleep-trial dose. 240 mg is close to the 250 mg tested.
3. Count other magnesium. Check the magnesium line on any multivitamin or sleep blend you take. Keep all supplemental magnesium at or under 350 mg a day.
4. Do not use four a day without medical advice. It exceeds the limit and makes diarrhea more likely.
5. Space it from some medicines. The NIH fact sheet advises separating magnesium from oral bisphosphonates by two hours, and taking tetracycline or quinolone antibiotics two hours before or four to six hours after it.
6. Skip it with kidney disease unless your doctor advises it, because impaired kidneys cannot clear excess magnesium.

The liquid version

Pure Encapsulations also sells a Magnesium Glycinate Liquid. Its label in the NIH database lists 165 mg of magnesium per 10 mL serving (two teaspoons daily), with 20 calories, 2 g of carbohydrate and 1 g of protein. One serving is a little more than one capsule and well within the limit. It may suit people who have trouble with capsules.

The bottom line

Pure Encapsulations Magnesium (Glycinate) has a clean label: 120 mg of magnesium per capsule, all from glycinate, with no oxide mixed in, which cannot be said of every product sold under that name. The thing to watch is the dose. Three of its four capsule labels allow up to four capsules, 480 mg, which is above the 350 mg daily limit for supplemental magnesium. One or two capsules a day is the range the evidence and the limit support.