A meta-analysis of 22 trials involving 1173 participants concluded that magnesium supplementation achieved a small but clinically significant reduction in blood pressure, and may therefore protect against heart disease. This reduction was most significant in those who were magnesium deficient or had elevated blood pressure. There is also evidence from meta-analyses that magnesium supplementation can improve insulin sensitivity and reduce blood sugar in those with or at risk of diabetes, though the blood sugar reduction is not always reliable.
Some studies suggest that magnesium supplementation may improve sleep quality in people who sleep poorly. Improved sleep quality is associated with reduced risk of developing neurodegenerative diseases such as Alzheimer’s.