Nature Made Magnesium 250 mg uses magnesium oxide as its sole form of magnesium. Magnesium oxide is one of the most common and inexpensive forms of magnesium available in supplements. It contains a high percentage of elemental magnesium by weight, which allows for a smaller pill size for a given dose.
However, the primary drawback of magnesium oxide is its low absorption rate for systemic benefits. A large portion of it passes through the digestive tract unabsorbed, where it can exert a laxative effect. This makes it more suitable for addressing occasional constipation than for significantly raising magnesium levels throughout the body.
For those primarily seeking a very budget-friendly option, or for mild digestive regularity, this product could be considered. But for widespread magnesium support for functions like muscle relaxation, nerve health, or bone density, other, more bioavailable forms would likely be more effective.