Bioavailability: The Reason Why Magnesium Oxide is Not in Our Drink Mix

TLDR (Too Long Didn't Read): Our bodies absorb 4-5x more magnesium from organic magnesium forms than cheap and inorganic magnesium oxide, in addition to being gentler on the stomach. Think of it as eating a rock. For 50mg (elemental) of magnesium oxide, our bodies only absorb 2-5mg.

Why the Form of Magnesium (Mg) Matters

Imagine you're at a buffet with a variety of dishes. Some dishes are your absolute favorites, easy to eat and digest, while others are not quite to your taste or might even upset your stomach. The 'form' of Mg in supplements is somewhat similar to these dishes. Just as you'd prefer a dish that's both delicious and easy on your stomach, your body prefers Mg in forms that are easier to absorb and use.

Different forms of Mg are paired with a variety different 'partners,' like citrate, oxide, glycinate, or malate to name a few. These partners affect how well magnesium can be absorbed by your body. For example, magnesium malate is like a favorite dish - it's easily absorbed and your body can use it efficiently, making it a great choice for athletes who need their muscles to keep contractive function and recovery after intense activities.

Bioavailability

Bioavailability is a term that refers to how much of what you consume is actually absorbed and used by your body. Going back to our buffet analogy, consider bioavailability as the portion of your favorite dish that you can eat and digest, gaining all the nutrients and energy from it. Some dishes might look appealing but if your body can't properly digest them, you won't get all the benefits.

In the context of magnesium supplements, a high bioavailability means that a greater amount of magnesium can be absorbed into your bloodstream and utilized by your cells. This is crucial for athletes because magnesium supports muscle function, energy production, and overall recovery, so they need a form of magnesium that their body can readily absorb and use.

Inorganic Forms (Mg-Oxide, Mg-Sulfate, Mg-Hydroxide, Mg-Chloride)

This is where we get into the differences in absorption. Cheap, inorganic forms of magnesium such as magnesium oxide do indeed contain magnesium which is why manufacturers use this form in their products. Although, because of its insoluble nature, it is like trying to eat a rock and expecting your body to process it. It's not going to happen. (Don't get us wrong, we love a good rock garden on the mountain bike but we prefer to not eat them.) It is estimated across literature that our bodies only absorb around 4-5% of the magnesium from magnesium oxide as measured in blood plasma concentration, which is the pathway to the muscles. The low solubility is also why you will see pixie dust amounts of magnesium oxide in some mixes or settling in the bottom of your bottle. In fact, solubility is directly related to how bioavailable the form is. (1) (2)

Although useful, other inorganic forms such as Mg Sulfate (aka Epsom Salt) are often used in bath soaks for muscle relaxation but are less commonly used in nutritional products or dietary supplements due to its laxative effects. Mg Chloride is easily absorbed by the body but imparts a vividly unpleasant taste that is quite off-putting. In addition, care must be taken to minimize its laxative effects at higher doses. Mg Hydroxide (aka Milk of Magnesia) is another common inorganic form. Magnesium hydroxide is not highly soluble in water. At room temperature, only a small amount of magnesium hydroxide can dissolve in water, which results in a relatively low bioavailability when ingested. This low solubility means that it's not readily absorbed by the digestive system, which is why it's effective as an antacid—it remains in the stomach and neutralizes acid without being quickly absorbed into the bloodstream.

Organic / Chelated Forms (Mg- Malate, Citrate, Lactate, Glycinate, etc.)

We found a form that is perfect for use in a sports hydration mix that excels in the criteria for bioavailability, solubility, taste, and GI tolerability. This stuff rocks, but is not made from rocks.

The high bioavailability of magnesium malate ensures that athletes can efficiently replenish the magnesium lost through sweat and exertion, supporting vital physiological functions such as muscle contraction and relaxation, energy production, and electrolyte balance. The chelated form of magnesium in conjunction with malic acid provides a synergistic effect that not only enhances energy production at the cellular level but also aids in the detoxification of lactic acid, reducing muscle fatigue and soreness post-exercise.

The malate / malic acid component of magnesium malate may exert additional metabolic benefits by facilitating the shuttle of reducing equivalents (NADH and FADH₂) into mitochondria for oxidative phosphorylation, thereby enhancing aerobic energy production. This unique combination makes magnesium malate especially effective in boosting energy production at the cellular level. For endurance athletes, this means improved stamina and performance during long-duration activities.  The malic acid in magnesium malate plays a role in the citric acid cycle, helping to convert lactic acid into energy. This can potentially reduce the accumulation of lactic acid in muscles, thus diminishing fatigue and speeding up recovery. This is why we have actually added additional malic acid in our endurance drink mix.