Bioavailability Comparison Tool
Not all supplement forms are created equal. Compare absorption rates of different forms to find the most effective option for your needs. Data is based on published pharmacokinetic studies.
Magnesium bioavailability varies dramatically by form. The percentage represents how much elemental magnesium is actually absorbed into the bloodstream.
Relative Bioavailability
| Form | Absorption | Best For | Price | Notes |
|---|---|---|---|---|
| Magnesium Glycinate (Bisglycinate) | 80% | Sleep, anxiety, general use | $$ | Chelated with glycine. Gentle on stomach. Best overall form. |
| Magnesium L-Threonate | 75% | Brain health, cognition | $$$ | Only form proven to cross blood-brain barrier. Developed at MIT. |
| Magnesium Taurate | 75% | Heart health, blood pressure | $$ | Chelated with taurine. Both components benefit cardiovascular system. |
| Magnesium Citrate | 65% | General use, constipation | $ | Well-absorbed and affordable. Can have laxative effect at higher doses. |
| Magnesium Malate | 60% | Energy, fibromyalgia | $$ | Bound to malic acid (Krebs cycle). Good for energy production. |
| Magnesium Chloride | 55% | Topical use, general | $ | Available as oral supplement or topical (Epsom salt alternative). |
| Magnesium Oxide | 4% | Constipation only | $ | Highest elemental Mg per pill but almost none is absorbed. Primarily acts as laxative. |
Understanding Bioavailability
Bioavailability refers to the proportion of a nutrient or supplement that is absorbed into the bloodstream and available for use by the body. When you swallow a supplement, it must survive stomach acid, be absorbed through the intestinal wall, pass through the liver (first-pass metabolism), and reach systemic circulation before it can exert its effects. Each of these steps can reduce the amount of active compound that actually reaches your cells.
Several factors influence bioavailability: the chemical form of the nutrient, whether it's taken with food (especially fat for fat-soluble nutrients), the presence of enhancers (like vitamin C for iron or piperine for curcumin), individual gut health, and even genetic factors affecting enzyme activity. Understanding these factors can help you choose the most effective form of each supplement and maximize the value of your investment.
Chelated minerals (bound to amino acids like glycine) generally have superior bioavailability compared to inorganic salts (like oxide or sulfate forms). For fat-soluble vitamins (A, D, E, K), oil-based delivery systems significantly improve absorption. For compounds with inherently poor bioavailability (like curcumin), advanced delivery technologies such as phytosomes, nanoparticles, and liposomal encapsulation can increase absorption by orders of magnitude.
Note: Bioavailability percentages are approximate and based on published pharmacokinetic studies. Actual absorption varies between individuals based on gut health, genetics, diet, and other factors. For curcumin, values represent relative improvement over standard curcumin (set as baseline 1x).