Calcium-magnesium balance is important. It is usually suggested that when we supplement calcium we take about half that amount in magnesium. If we increase calcium intake, we should likewise increase magnesium. We should also increase magnesium intake when we consume more phosphorus, vitamin D, or protein or when we have higher blood cholesterol. Those on birth control pills or diuretics, postmenopausal women, and those who drink alcohol need more magnesium.
The levels of magnesium used by physicians are commonly in the range of 600-1,000 mg.; however, the researchers in the kidney stone studies used only 200-300 mg. of supplemental magnesium oxide. Calcium and magnesium are both alkaline minerals, so they are not taken with or after meals, as they can reduce stomach acid as well as being absorbed poorly when taken with food. They are absorbed better when taken between meals or on an empty stomach, especially with a little vitamin C as ascorbic acid. Many calcium-magnesium combinations are formulated with hydrochloric acid and vitamin D to aid the mineral absorption. And taking them before bedtime may be very helpful in increasing utilization of both these important minerals and lead to a sleep-filled night.