Simple SummaryMagnesium is an essential nutrient, also called an essential mineral or element. Magnesium is vastly important in all life, with vital roles for the healthy functioning of the human immune, metabolic, neurological, psychological, and heart and circulatory systems. Our bodies cannot “make” magnesium; rather, wemustget it from outside the body—from our environment, usually through food and water. In most modern cultures, magnesium intake has been low for decades. When the COVID-19 pandemic began, a group of international magnesium researchers were profoundly struck by the strong similarities between low magnesium status and the many risk factors for COVID-19, including older age, obesity, diabetes, kidney disease, cardiovascular disease, hypertension, and ailments that affect breathing. They began Zoom meetings to share ideas, data, and study plans and formed the MaGNet Global Magnesium Project. This review, written by several MaGNet members, discusses several peer-reviewed studies demonstrating the following: (1) low magnesium status is associated with the severity of COVID-19 outcomes, including mortality, and with several disease-related neurological symptoms, including loss of memory, taste, and/or smell; (2) inhaled magnesium as a therapy may improve oxygen status; and (3) magnesium therapy, alone or in combination with zinc, may increase the effectiveness of anti-COVID-19 medications.AbstractA large amount of published research points to the interesting concept (hypothesis) that magnesium (Mg) status may have relevance for the outcome of COVID-19 and that Mg could be protective during the COVID disease course. As an essential element, Mg plays basic biochemical, cellular, and physiological roles required for cardiovascular, immunological, respiratory, and neurological functions. Both low serum and dietary Mg have been associated with the severity of COVID-19 outcomes, including mortality; both are also associated with COVID-19 risk factors such as older age, obesity, type 2 diabetes, kidney disease, cardiovascular disease, hypertension, and asthma. In addition, populations with high rates of COVID-19 mortality and hospitalization tend to consume diets high in modern processed foods, which are generally low in Mg. In this review, we review the research to describe and consider the possible impact of Mg and Mg status on COVID-19 showing that (1) serum Mg between 2.19 and 2.26 mg/dL and dietary Mg intakes > 329 mg/day could be protective during the disease course and (2) inhaled Mg may improve oxygenation of hypoxic COVID-19 patients. In spite of such promise, oral Mg for COVID-19 has thus far been studied only in combination with other nutrients. Mg deficiency is involved in the occurrence and aggravation of neuropsychiatric complications of COVID-19, including memory loss, cognition, loss of taste and smell, ataxia, confusion, dizziness, and headache. Potential of zinc and/or Mg as useful for increasing drug therapy effectiveness or reducing adverse effect of anti-COVID-19 drugs is reviewed. Oral Mg trials of patients with COVID-19 are warranted.