and endothelial function. Magnesium increases prostaglandins, decreases thromboxane, and decreases angiotensin II, microvascular leakage, and vasospasm through its function similar to calcium channel blockers. Convulsions are the result of cerebral vasospasm. The vasodilatatory effect of magnesium seems to be the major mechanism. Asthma Magnesium exerts a bronchodilatatory effect, probably by antagonizing calcium-mediated bronchoconstriction. Neurological effects reducing electrical excitation modulating release of acetylcholine antagonising N-methyl-D-aspartate (NMDA) glutamate receptors, an excitatory neurotransmitter of the central nervous system and thus providing neuroprotection from excitoxicity. Diabetes mellitus Magnesium deficiency is frequently observed in people with type 2 diabetes mellitus, with an estimated prevalence ranging between 11.0 and 47.7%. Magnesium deficiency is strongly associated with high glucose and insulin resistance, which indicate that it is common in poorly controlled diabetes. Patients with type 2 diabetes and a magnesium deficiency have a higher risk of heart failure, atrial fibrillation and microvascular complications. Oral magnesium supplements has been demonstrated to improve insulin sensitivity and lipid profile. A 2016 meta-analysis not restricted to diabetic subjects found that increasing dietary magnesium intake, while associated with a reduced risk of stroke, heart failure, diabetes, and all-cause mortality, was not clearly associated with lower risk of coronary heart disease (CHD) or total cardiovascular disease (CVD). A 2021 study on blood from 4,400 diabetic patients over 6 to 11 years reported that "People with higher levels of magnesium in the blood were found to have a significantly lower risk of cardiovascular disease", and also of diabetic foot and diabetic retinopathy. The researchers, however, stated that "we have [not] demonstrated that magnesium supplements work. Further research is needed." Homeostasis Magnesium is abundant in nature. It can be found in green vegetables, chlorophyll (chloroplasts), cocoa derivatives, nuts, wheat, seafood, and meat. It is absorbed primarily in the duodenum of the small intestine. The rectum and sigmoid colon can absorb magnesium. Forty percent of dietary magnesium is absorbed. Hypomagnesemia stimulates and hypermagnesemia inhibits this absorption. The body contains 21–28 grams of magnesium (0.864–1.152 mol). Of this, 53% is located in bone, 19% in non-muscular tissue, and 1% in extracellular fluid. For this reason, blood levels of magnesium are not an adequate means of establishing the total amount of available magnesium. The majority of serum magnesium is bound to chelators, including proteins and citrate. Roughly 33% is bound to proteins, and 5–10% is not bound. This "free" magnesium is essential in regulating intracellular magnesium. Normal plasma