NOW Foods Magnesium Citrate 400 mg provides one of the most bioavailable and well-tolerated forms of supplemental magnesium in convenient vegetarian capsules. Magnesium is the fourth most abundant mineral in the human body and is required as a cofactor for over 300 enzymatic reactions — including energy production, protein synthesis, muscle contraction, nerve transmission, and blood glucose regulation. Many adults are chronically deficient, contributing to muscle cramps, poor sleep, anxiety, fatigue, and cardiovascular issues. The citrate form is particularly well-absorbed and effective for both general magnesium repletion and supporting healthy bowel regularity. NOW Foods delivers a generous 400 mg elemental magnesium dose per two-capsule serving, manufactured in their GMP-certified facility with rigorous purity testing on all raw materials.