The Importance of the Calcium Magnesium Ratio
When it comes to calcium and magnesium in the human body, it’s like a dance. The key is to make sure neither one is stepping on the other one’s toes! As with any good dance, it’s all about balance. When the ratio is right between these two, there is physiological harmony. But when the ratio is off, processes may fall out of step.
|The Cal/Mag Yin-Yang Effect|
|Calcium is found mostly outside the cells||Magnesium is found inside the cells|
|Calcium excites||Magnesium calms|
|Calcium contributes to clotting||Magnesium contributes to blood flow|
|Calcium is found in bones||Magnesium is found in soft tissue|
|Calcium helps muscles contract||Magnesium helps muscles relax|
Magnesium and calcium work together and yet they also antagonize each other. The same receptors that regulate calcium also impact magnesium. Studies have found that calcium directly or indirectly competes with magnesium for intestinal absorption and transport, especially if calcium intake is much higher than magnesium intake. For example, if the gut has more magnesium than calcium, the magnesium will be absorbed but if there is a much higher amount of calcium, the magnesium will not be absorbed. This is big information, with big impact, because high dose calcium supplementation is common, and we also know the dramatic necessity of adequate magnesium for optimal physiological function.
In a 1997 study published in the American Journal of Clinical Nutrition, children who consumed even the Recommended Dietary Allowance of magnesium were in negative magnesium balance if their calcium intake was high. The body of current evidence supports taking more frequent, lower doses of calcium (with meals if using calcium carbonate), and avoiding high doses above 250 mg at a time. This helps ensure both better magnesium absorption, and calcium absorption.
A 2013 population-based cohort based on the Shanghai Women’s Health Study and the Shanghai Men’s Health Study that was published in the journal BMJ Open eloquently illustrated that the amount of calcium and magnesium absorbed is dependent on the dietary ratio of calcium to magnesium. The two Shanghai studies that were featured in the cohort took place over a four-year period involving nearly 75,000 women and more than 61,000 men age 40 to 74. Calcium and magnesium intake was validated by food questionnaires and the follow-up rate for both of these studies was nearly 100%.
This 2013 BMJ Open study clearly demonstrated that calcium intake alone was not nearly as important as the calcium to magnesium ratio. The calcium to magnesium intake ratio among this Chinese population was on average 1.7 versus approximately 3.0 in the United States. In this study, intakes of magnesium greater than the US RDA of 320 mg/day for women and 420 mg/day for men was associated with poor health. Poor health was also associated with a calcium to magnesium ratio of greater than 1.7 for the men and greater than or equal to 1.7 for the women. Because this study was done on a population with a lower calcium to magnesium ratio compared to the United States, we are not sure how this can be applied to US populations. However, it does illustrate the importance of striking the proper balance of calcium to magnesium in both food and dietary supplements in clinical practice.
According to the Nutritional Magnesium Association, the 2:1 calcium-to-magnesium ratio was first discussed by French magnesium researcher Jean Durlach in an effort to help prevent excessive calcium intake, which can damage health. “It is important to note that this ratio is for weights of elemental calcium and elemental magnesium, not the weights of their compounds,” stresses the Nutritional Magnesium Association. “It is also for all sources of calcium and magnesium intakes including food, water and supplements.”
In dietary supplements the ratio of calcium to magnesium can vary with some manufacturers having an approximate 2:1 ratio and some having a 1:1 ratio. Practitioners typically have a preference of products they recommended based on the patients they are treating. But more practitioners are now choosing to dose calcium and magnesium separately, for optimal absorption of each. Especially since calcium may interact with certain medication, thyroid replacement for example, magnesium can be dosed in the morning and calcium later in the day, reducing the competition for absorption.
Two primary forms of calcium used in supplements are citrate and carbonate. Calcium carbonate is the type of calcium also found in over-the-counter antacid products. According to the National Institutes of Health, “People with low levels of stomach acid (a condition that is more common in people over age 50) absorb calcium citrate better than calcium carbonate.” And it is now accepted that calcium, in general, is better absorbed when taken with meals. But, does it matter what form of calcium one uses?
Microcrystalline hydroxyapatite concentrate (MCHA) is a highly absorbable, natural calcium source produced from bone. It contains all the minerals naturally occurring in healthy bone in the right proportions, along with the other active and supportive constituents of bone. A study comparing the absorption and efficacy of calcium carbonate, calcium citrate and MCHA, showed that all forms were absorbed and raised calcium levels in a similar manner but most importantly, similarly reduced the rate of bone resorption – the primary reason for calcium supplementation. Although the level of serum calcium was not elevated as much with MCHA, it still reduced bone resorption at the same rate. This shows that bone health is supported even with relatively lower serum levels of calcium, as long as calcium intake is adequate. These findings suggest that calcium supplements, in general, produce repeated sustained increases in serum calcium concentrations after ingestion of each dose and that calcium supplements with smaller effects on serum calcium concentrations may have equivalent efficacy in suppressing bone turnover.
In light of the body of research, now is a good time for all practitioners to re-examine their own beliefs and practices regarding calcium and magnesium supplementation, especially with regard to bone and heart health. High doses may do more harm than good. More is not better. Dietary intake is not insignificant – it must be assessed and considered before supplementation. Medication interactions must be considered to determine timing of dosing. And, they don’t need to be taken together at the same time. But, with a little extra effort, maintaining a physiologically healthy, 2:1 ratio of daily calcium intake to magnesium intake overall, is a very attainable goal.
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