What is the difference between magnesium bisglycinate and magnesium glycinate?
Magnesium bisglycinate and magnesium glycinate are two names for the same supplement. Whether it is absorbed better than magnesium citrate is not yet clear: the studies in healthy people contradict each other, and citrate currently has the strongest evidence base.
Magnesium bisglycinate and magnesium glycinate are two names for exactly the same supplement. The word 'bis' simply means that two glycine molecules (a simple amino acid) are bound to a single magnesium atom. Some manufacturers use the shorter name, others the chemically more precise one: the product in the jar is identical.
Whether this chelate form is absorbed better than other forms is not yet clear. In a study of people who had had part of their bowel removed, magnesium bisglycinate performed significantly better than magnesium oxide in the patients with the poorest absorption, and the peak in the blood occurred earlier. However, in healthy people, a single study of 40 healthy participants funded by the manufacturer of a competing product showed no measurable rise in blood magnesium for magnesium bisglycinate, while magnesium oxide and magnesium citrate did produce rises at certain time points. Cell culture research using intestinal cells suggests that buffered magnesium bisglycinate passes through the intestinal wall better than the so-called sucrosomal form, but what works in a cell culture does not necessarily work the same way in humans.
The strongest evidence for absorption in healthy people belongs to magnesium citrate. In an independent study of 46 healthy participants over 60 days, citrate produced the highest concentrations in both blood and saliva, significantly better than magnesium oxide. A magnesium amino acid chelate (comparable to bisglycinate) performed better than oxide, but not better than citrate. On the label, look for 'magnesium (elemental)' and the salt form listed: oxide scores worst in all studies, and for absorption it therefore does not matter what price the supplement carries.
If you want to choose a magnesium form specifically for absorption, citrate is currently the best-supported choice. Magnesium bisglycinate has been too little studied in healthy people to recommend it with confidence: the results contradict each other. If you have a condition such as diabetes, hypertension or pregnancy, always discuss its use with your doctor first.
This answer is based on four randomised studies in humans, of which two were small (twelve and forty participants respectively) and one involved 46 participants over 60 days. One study was funded by a company with a commercial interest in the outcome. One source is purely laboratory research using cells, without human participants. The studies directly contradict each other on the point of absorption in healthy individuals, which makes the conclusions uncertain.
What exactly does magnesium glycinate do in your body?
Magnesium glycinate is well absorbed, but for most healthy people it is not demonstrably better than citrate. For those with poor intestinal function or a sensitive stomach, it is a worthwhile choice.
How much magnesium glycinate can you safely take per day?
In Europe the limit is 250 mg of elemental magnesium per day from supplements (350 mg in the United States), although more recent research suggests that higher doses do not cause diarrhoea in most people. How much magnesium glycinate specifically can be taken safely has not been well studied, so stick to the European limit and check your label.
Why does magnesium work for some people but not others?
Whether magnesium works for you depends strongly on which form you take and how high your dose is. Preferably choose an organic form such as citrate rather than oxide, and give it at least two months.
Which form of magnesium is best to take?
Magnesium citrate has the strongest evidence for absorption into the body. Magnesium oxide, the cheapest option, demonstrably performs the worst and is best avoided.
Does magnesium glycinate help you sleep better?
Research suggests that magnesium glycinate may modestly improve sleep, although the evidence on magnesium and sleep in general is contradictory and of low quality.
Can magnesium glycinate cause diarrhoea or gastrointestinal complaints?
At normal doses (around 5 mg per kilogram of body weight per day) gastrointestinal complaints are not to be expected, but at higher doses a laxative effect is a well-known side effect of oral magnesium.