CALCIUM AND MAGNESIUM AND STROKE PREVENTION
Calcium is needed for bone health, muscle strength, blood clotting and cell-to-cell transmission. Several studies have suggested, though have not proven, that elevated serum calcium levels increase risk of vascular disease. Knowing this, is it wise to continue to promote use of calcium supplementation to prevent osteoporosis?
Low levels of magnesium, by contrast, may increase stroke risk. Magnesium affects blood pressure and insulin function. Interestingly, certain genetic variants increase serum magnesium, but do they prevent stroke?
A new study by Larsson et al, published in Neurology 2019, attempted to answer this question. It showed convincingly that several genes that increase serum magnesium do indeed reduce stroke risk by up to 40%. This is probably cause-and-effect but is limited to strokes of cardiac origin, mainly from atrial fibrillation. It found no consistent evidence that higher calcium levels raised risks of any type of stroke.
Keep in mind that no study has shown that taking magnesium supplements reduces risk of stroke or heart disease. It seems reasonable to take calcium and magnesium. That is, until the next study comes along.