Both age and sex have a bearing on the latest guidelines on the recommended dietary allowance (RDA) for magnesium for adults. For males age 19-30, the RDA is 400 mg/day and for females, age 19-30 the RDA is 310 mg/day. For older adults, the RDA increases slightly to 420 mg/day for males and 320/mg/day for females. The upper tolerable upper limit, applicable to supplements only, is stated as 350 mg/day.
7 out of 10 Americans, (and at least 7.5 out of 10 who are over 70), while not necessarily in serious jeopardy due to magnesium deficiency, do not receive enough magnesium in their daily diet to meet the recommended levels. Older adults are especially vulnerable since absorption is less efficient and also since the increased bone mass loss associated with aging places them at high risk for osteoporosis. For adults with heart problems, maintaining an adequate level of magnesium in the body is crucial.
Optimal health is contingent, in addition, to maintaining the recommended calcium to magnesium intake ratio of about 2 to 1. Therefore, when it is medically advisable to take calcium supplements, it is also medically advisable to take magnesium supplements. High calcium, protein, Vitamin D, and alcohol intake all increase the need for magnesium.