Does magnesium glycinate cause a laxative effect like citrate?

The remainder arithmetic, because the laxative effect is what the gut did not absorb

Does magnesium glycinate cause a laxative effect like citrate is answered by the remainder, because the laxative effect of any magnesium salt is not a property of the salt but of what the gut left behind: the small intestine absorbs a fraction of a dose, the unabsorbed remainder travels to the colon within six to twelve hours, and the remainder draws water osmotically, softening stool and speeding transit in proportion to its size, the kinetics of every magnesium salt and the reason oxide, with most of its dose left behind, is the most laxative and the reason a bigger dose of anything is more laxative than a smaller one. So the question becomes which salt leaves the smaller remainder at the same elemental dose, and the comparative literature answers it. Citrate is absorbed reasonably well, better than oxide and roughly level with bisglycinate in some studies, and leaves a moderate remainder, so that a full 300mg elemental dose of citrate loosens stools in a fair share of people and a dose over the guidance level in most, the citrate downside page's first entry. Bisglycinate is absorbed well and, on the proposed mechanism, differently, the chelate travelling partly intact across the gut wall through the dipeptide transport route that carries small peptides, releasing its magnesium on the far side, which means less free magnesium ion sitting in the gut lumen to draw water, a smaller remainder at the same dose and the smaller laxative effect that every comparison and most users report, a 300mg elemental dose of bisglycinate with a meal loosening few people and a nightly habit staying out of the bathroom, the section's reason for recommending it.

The two cases where glycinate does loosen, the fix for each, and the arithmetic filed

Glycinate does loosen in two cases, and both are the remainder arithmetic applied. The first is a large dose: absorption is saturable, so the fraction absorbed falls as a single dose rises, and a bisglycinate dose well over the 400mg guidance level, a reader taking six capsules to hurry things or doubling a two-capsule product, leaves a remainder large enough to draw water whatever the salt, the too-much pages' second rung and the fix being the dose, back to 300mg and split across two meals so that no single sitting is large. The second is the buffered product: some tubs sold under the glycinate name are bisglycinate buffered with magnesium oxide, the ingredients list reading bisglycinate then oxide and the elemental figure per capsule being chemically implausible for true glycinate, the budget glycinate page's trap, and the oxide half of such a product behaves like oxide, poorly absorbed and heavily laxative, so a reader who bought glycinate for its gentleness and got loose stools anyway often bought a buffered product, the fix being the ingredients list and a pure bisglycinate with no oxide in it. A third, minor case is the fasted dose, any salt sitting worse in an empty stomach, the fix being a meal. The honest ranking, then, at the same elemental dose with a meal: oxide most laxative, citrate moderate, bisglycinate least, with a reader who wants the effect, for constipation, choosing citrate or a pharmacy hydroxide, and a reader who wants no effect choosing pure bisglycinate under the level. The arithmetic filed: the laxative effect is the remainder, bisglycinate leaves the smallest, citrate a moderate one and oxide the largest, and glycinate loosens only at a dose well over the level or from a product buffered with oxide, the worked example being pure bisglycinate with no oxide in the list, 300mg elemental, £19.99 for 90 days at 22p.

The verdict, far less, for a reason that is arithmetic

Does magnesium glycinate cause a laxative effect like citrate: far less, because the laxative effect of any magnesium salt is the unabsorbed remainder drawing water in the colon, and bisglycinate, absorbed well and proposed to travel partly intact through dipeptide transport, leaves a smaller remainder than citrate at the same elemental dose and a far smaller one than oxide, so that a 300mg dose with a meal loosens few people, with glycinate loosening only in two cases, a dose well over the guidance level where absorption saturates and the remainder grows, and a product buffered with oxide under the glycinate name whose oxide half behaves like oxide. The salt with the smallest remainder: Futuro Labs Magnesium Glycinate, pure bisglycinate with no oxide in the list, 300mg elemental at 80% NRV, £19.99 for 90 days at 22p a day.

What to check on the label

Questions people also ask

Is magnesium glycinate less laxative than citrate?

Yes, far less at the same elemental dose: the laxative effect is the unabsorbed remainder drawing water in the colon, and bisglycinate, absorbed well and proposed to travel partly intact through dipeptide transport, leaves a smaller remainder than citrate and a far smaller one than oxide.

Why does citrate cause diarrhoea but glycinate usually doesn't?

Because of what each leaves behind: citrate's moderate absorption leaves a moderate remainder that draws water at a full dose, while bisglycinate's good absorption and chelate route leave less free magnesium in the gut lumen, so a 300mg dose with a meal loosens few people.

Can magnesium glycinate ever cause loose stools?

In two cases: a dose well over the 400mg guidance level, where absorption saturates and the remainder grows whatever the salt, and a product buffered with oxide under the glycinate name, whose oxide half behaves like oxide; a fasted dose of any salt also sits worse.

How do I know if my glycinate is buffered with oxide?

Read the ingredients list: bisglycinate followed by oxide means a buffered product, and an elemental figure per capsule that is implausibly high for true glycinate, well over 100mg in one small capsule, confirms it.

Which magnesium should I take if I want a laxative effect?

Citrate at a labelled dose, or magnesium hydroxide from a pharmacy as the licensed laxative, since their larger remainders are the point for a constipated reader; bisglycinate is the salt for a reader who wants no effect at all.

Sources

1. The magnesium bisglycinate absorption literature: the chelate is proposed to be absorbed partly intact through dipeptide transport and to release its magnesium with less free ion left in the gut, consistent with the lower laxative effect and good bioavailability reported for bisglycinate against citrate and oxide. PubMed record
2. The magnesium absorption kinetics literature: oral magnesium is absorbed mainly in the distal small intestine over the hours after a dose, the unabsorbed remainder reaching the colon within six to twelve hours where its osmotic effect appears, and surplus absorbed magnesium is excreted by the kidneys within a day or two. PubMed record
3. Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research 2003;16(3):183-191. PubMed record
4. The magnesium absorption literature: fractional absorption of magnesium falls as the dose rises, so the same daily amount taken in divided doses is absorbed at a higher fraction and with less osmotic laxative effect than a single large dose. PubMed record

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