The Many Forms of Magnesium
by Zach Trowbridge on February 12, 2025Magnesium is easily one of the more underrated supplements in the fitness industry – it contributes to more than 300 chemical reactions in the body, including energy production, maintaining insulin sensitivity, protein synthesis, and much, much more. It should be one of the most abundant minerals in the body, but deficiencies in magnesium are common for a few reasons:
- Many food sources that should be high in magnesium are grown in depleted soil, which means the actual mineral content is less than it should be
- As one of the electrolytes, it’s depleted through sweat and hard training
- High stress and cortisol production tends to “steal” magnesium from being available for other functions
Deficiencies can cause issues such as poor sleep, lower energy levels, low levels of inflammation, increased blood pressure, insulin resistance, and cardiovascular problems.
I like to see most all of my clients on some form of supplemental magnesium, but with some important distinctions. There are primarily two different varieties of magnesium in supplemental form – the form where it’s bonded to salt (magnesium oxide), and the form where it’s chelated, or bonded to an amino acid.
Magnesium oxide is a very cheap and poorly absorbed form of magnesium, with only around 5% of the magnesium being absorbed. That means that if you were to take 500mg of magnesium oxide, only around 25mg would actually be absorbed. Because of its poor bioavailability, magnesium oxide can cause loose stool or diarrhea, especially in higher doses. In fact, magnesium oxide is often used in prenatal vitamins for that particular “benefit,” as constipation is a regular problem in the later stages of pregnancy for many women.
Chelated magnesium, however, tends to be absorbed at a much higher rate, and comes in many different forms depending on which amino acid it’s bonded to. Different forms can have affinities for different tissues in the body, so while some forms work well as a general magnesium supplement, there are some that function more as “specialty” supplements that may help with issues above and beyond what you would see with standard magnesium deficiencies.
I highly recommend that you use a high-quality magnesium – you absolutely get what you pay for, and the supplements you see at grocery stores and discount supplement retailers will not be nearly as good as what you’ll see from companies that produce pharmaceutical-grade products.
Here are a few of the more commonly found forms along with dosage guidelines:
Magnesium citrate and magnesium malate
These are two commonly found forms, bonded to citric acid and malic acid respectively. These are relatively inexpensive and work well as a general magnesium supplement. They also work as options to use for magnesium’s ability to help improve quantity and quality of sleep. A daily dose of around 400-800mg in divided doses works well – start smaller and increase every few days to assess tolerance.
A note to prevent confusion: you can find high-dose liquid forms of magnesium citrate at most pharmacies next to other types of laxatives in cases of constipation. However, its use for constipation would have you taking significantly more than a normal daily dose – a typical bottle contains 10oz, and each ounce contains 1.745 grams of magnesium citrate. So taking the whole bottle at once would give you 17.45 grams – roughly 22 days of magnesium if you were taking 800mg per day.
Magnesium sulfate
This is the form of magnesium found in Epsom salt, and the typical administration is to use 2 cups in a hot bath and soak for 20-30 minutes. The magnesium absorbs through the skin, which increases the bioavailability and bypasses any concerns about digestive disruption. 2 cups contains about 475mg of magnesium sulfate.
Magnesium glycinate or bisglycinate
Magnesium glycinate is bonded to the amino acid glycine, which has an array of benefits – it improves liver detoxification, promotes muscle protein synthesis, increases quality of sleep as a neurotransmitter, and acts as an antioxidant. Because of its detoxification effects, you should work the dosage up gradually to assess tolerance, but for the same reason, it’s a great form of magnesium to use if using oral anabolics or if presenting with elevated AST, ALT or GGT lab markers. A daily dose of around 300-500mg in divided doses works well.
Magnesium bisglycinate has a higher absorption rate, but is slightly more expensive. This is an ideal form if you have issues with stomach sensitivity as it will allow you to use less for a similar effect. 200-400mg in divided doses would be a good starting point here.
Magtein (magnesium threonate)
This trademarked form of magnesium is the only one shown to cross the blood-brain barrier, which makes most of its additional benefits cognitive in nature. There seems to be potential to help manage brain disorders such as depression, Alzheimer’s disease, and cognitive decline relating to aging. A fairly standard dosing is 2,000mg of magnesium threonate, which provides 144mg of elemental magnesium.
Creatine MagnaPower (magnesium creatine chelate)
This is another trademarked form of magnesium bonded with creatine – you’ll often find this in different types of intra-workout supplements as the combo of magnesium and creatine plays off of magnesium’s ability to increase energy levels through production of ATP. A dose of 5g provides 2.25g of creatine and 400mg of elemental magnesium.
One note about dosing
You may have noticed that in the descriptions for Magtein and MagnaPower, that the doses discuss elemental magnesium. This simply means the amount of actual magnesium in a given amount of powder – you could think of it similarly to how you measure protein – 100g of cooked chicken breast doesn’t give you 100g of protein, it only gives you around 30g of protein.
Quality magnesium supplements should specify the amount of elemental magnesium in a certain capsule or powder serving size – that’s the amount you want to base your dosing on. For example, Thorne’s Magnesium CitraMate lists its magnesium per capsule as:
Magnesium (55mg as Magnesium Citrate and 80mg as Albion DiMagnesium Malate) – 135mg
That simply means that each capsule provides 135mg of elemental magnesium, which means it would take 6 capsules daily to provide just over 800mg (the higher end recommendation for that particular form of magnesium).
If you aren’t already using some kind of daily magnesium supplement, I highly recommend you consider adding it to your routine.
Zach is the co-owner and head strength coach of All Strength Training, a personal training center specializing in busy professionals located in Chicago, IL. He is also a competitive physique athlete, having earned his pro card in the WBFF in 2016, and currently competes in the NPC classic physique division.
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