Experiment guides → Supplements → Glycinate vs citrate
Magnesium glycinate vs citrate: which is better for sleep?
Quick answer: nobody knows, because no sleep trial has compared them. What the absorption studies show is that both are organic salts absorbed considerably better than cheap magnesium oxide, with no convincing gap between the two. The real differences are practical: citrate loosens the bowels at higher doses; glycinate is gentler and delivers a substantial dose of glycine — an amino acid with its own small sleep trials — which may be where its reputation comes from. If you want a real answer for your body, run them back to back, 14 nights each, same elemental dose.
"I will take magnesium glycinate for 14 nights, then citrate for 14 nights, same dose."
What the research says
Citrate beats oxide on absorption; glycinate is in the same tier. In a randomized crossover study, Walker and colleagues compared magnesium citrate, amino-acid chelate and oxide over 60 days. Citrate produced the highest serum and salivary magnesium and was judged the most bioavailable; oxide was clearly the worst. The amino-acid chelate (the family glycinate belongs to) sat closer to citrate than to oxide (Walker et al., 2003).
A review of absorption reaches the same conclusion. A 2017 review of magnesium bioavailability concludes that organic salts (citrate, glycinate, aspartate, lactate) are generally better absorbed than inorganic ones (oxide, sulphate), but that head-to-head data among the organic salts are sparse and the differences small compared with dose, meal timing and your existing magnesium status (Schuchardt & Hahn, 2017).
The glycine may be doing some of the work. Magnesium bisglycinate is roughly 14% magnesium by weight, so a 300 mg elemental dose carries about 1.5–2 g of glycine. Small Japanese trials found that 3 g of glycine before bed improved subjective sleep quality and shortened the time to reach deep sleep on polysomnography — so a glycinate user is, in effect, running a half-dose glycine experiment at the same time (Bannai et al., 2012).
What this evidence doesn't say
The absorption studies measured magnesium in blood and saliva, not sleep, and none was designed around sleep outcomes. The glycine trials are tiny and industry-funded. Nothing here says one salt helps you sleep better than the other — that gap is precisely why a self-comparison is the only way to get an answer that applies to you.
Run it as an experiment
- Baseline five nights on nothing. Morning ratings for sleep quality, restedness and time-to-sleep. Both salts will be judged against this.
- Match the elemental dose. Pick 200–300 mg elemental magnesium and buy both salts at that level. Labels list compound weight in big type and elemental in small — read the small.
- Block one: glycinate, 14 nights. "I will take magnesium glycinate every evening for 14 nights." Same hour every night. Note any GI effects.
- Block two: citrate, 14 nights, straight after. Switch salts, keep everything else identical. If citrate loosens your bowels at that dose, note it rather than dropping the dose mid-block — a changed dose breaks the comparison.
- Compare all three. Baseline vs glycinate vs citrate, restedness first. If neither beats baseline, the salt was never the question. If one does, stop for a week and retest that one alone.
What to expect
Most people who run this find the two blocks look alike — which is itself a finding, and a cheap one, because it means you can buy whichever is cheaper or kinder to your stomach. If glycinate edges ahead, consider a follow-up test of plain glycine at 3 g to see whether the amino acid was the active ingredient all along.
Who should skip this
Kidney disease, bisphosphonates, tetracycline or quinolone antibiotics, pregnancy — doctor or pharmacist first. Citrate at 300 mg elemental and above can act as a laxative; if you have IBS with diarrhoea, start with glycinate only.
Frequently asked questions
Is magnesium glycinate better for sleep than citrate?
There's no trial showing that. Glycinate's sleep reputation rests on absorption data (which is roughly a tie with citrate) plus the glycine it contains, which has small trials of its own. The honest answer is "unknown for you until you test it".
Which magnesium causes less diarrhoea?
Glycinate, in most people. Citrate is an osmotic laxative at higher doses — that's why it's sold for constipation — and oxide is worse still. If GI comfort decides it for you, glycinate is the safer default.
Does the form matter more than the dose?
The absorption literature says dose, your current magnesium status and whether you take it with food matter more than the choice between two organic salts. Fixing the elemental dose is what makes a form comparison fair.
Related experiments
Sources
- Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res. 2003;16(3):183–191. PubMed 14596323
- Schuchardt JP, Hahn A. Intestinal absorption and factors influencing bioavailability of magnesium — an update. Curr Nutr Food Sci. 2017;13(4):260–278. PubMed 29123461
- Bannai M, Kawai N, Ono K, Nakahara K, Murakami N. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol. 2012;3:61. PubMed 22529837
Track this experiment in N of 1
A few baseline nights, then the change — and your own mornings deliver the result. No streaks, no guilt. Your first experiment is free.
Downloadon the App StoreThis page is general information about published research, not medical advice. Magnesium supplements interact with some medicines and are risky in kidney disease; talk to your doctor or pharmacist before starting one.