Magnesium activates the enzymes necessary for a number of physiological functions, including neuromuscular contractions, cardiac function, and the regulation of the acid-alkaline balance in the body. In a cross-sectional study involving 210 elderly individuals, optimal magnesium intake was associated with positive mood, lipid metabolism and lean body mass. Magnesium is necessary for the metabolism of carbohydrates, amino acids and fats, as well as energy production and the utilization of calcium, phosphorus, sodium, and potassium. In a 15-year study involving almost 5,000 young adults, higher intakes of magnesium were associated with healthy cardiovascular function and glucose utilization. Another large cross-sectional study found that magnesium intake was positively associated with bone mineral density in certain subgroups. This vital mineral also helps utilize some vitamins, including vitamin B6, vitamin C, and vitamin E.