Dr. Zittermann’s new editorial on magnesium (Mg) and vitamin D is important. We have been saying for the last 7 years that you need to be getting enough Mg.
In his editorial, Dr. Zittermann highlights our great need to start looking at Mg deficiency as a serious and common health problem.
However, there are some barriers in making sure people are getting enough Mg, and there are some barriers in being able to measure what their Mg status is, adequate or deficient.
To date, we have no great way to measure Mg adequacy. Unfortunately, serum Mg represents only 1% of Mg stores. Mg is homeostatically controlled in the serum and measuring serum Mg levels miss many Mg deficient people. It is clear that by the time your serum Mg is low, you are very Mg deficient as the body can no longer maintain serum Mg levels.
In Mg deficient patients, bone Mg is mobilized to maintain serum Mg.
So that begs the question, how does one know if you are Mg deficient?
Perhaps the ratio of ionized Mg/total Mg in serum or plasma may be a better measurement of Mg depletion.
Durlach J, Pagès N, Bac P, Bara M, Guiet-Bara A. Importance of the ratio between ionized and total Mg in serum or plasma: new data on the regulation of Mg status and practical importance of total Mg concentration in the investigation of Mg imbalance. Magnes Res. 2002 Dec;15(3-4):203-5. Review.
But still, this is probably not reliable enough. As of today, a Mg intake assessment is the only way to know if one is Mg deficient. That means counting all foods in your diet and then looking those foods up on Mg content of foods table.
And when we assess Mg intakes, repeated studies show the average American has inadequate intakes of Mg. Mg consumption is particularly low among adolescent females, adult females, and elderly men, with one study showing that 85%, 80%, and 75%, respectively, of the population groups having mean Mg intakes below their respective RDA.
In one NHANES study, none of the African Americans studied met the RDA for Mg.
Fulgoni V 3rd, Nicholls J, Reed A, Buckley R, Kafer K, Huth P, DiRienzo D, Miller GD. Dairy consumption and related nutrient intake in African-American adults and children in the United States: continuing survey of food intakes by individuals 1994-1996, 1998, and the National Health And Nutrition Examination Survey 1999-2000. J Am Diet Assoc. 2007 Feb;107(2):256-64.
In another study, the actual intakes of Mg were 202 mg/day for children from 1 to 5 years old, 228 mg/day for women and 331 mg/day for men, well below the RDA for all three groups.
For older Americans, a study showed that both men and women had median diet intakes below the RDA for Mg. That is, less than half had adequate intakes.
But I stress, despite inadequate intakes, few of these people have low blood Mg levels; again, because it’s homeostatically controlled.
So we are left with the fact that more than half of Americans are Mg deficient, and we have no good way to assess Mg status. My recommendation is to take supplemental Mg 200-300 mg/day unless you are sure your Mg intake is adequate. Once you assess your Mg intake, you may decide you need even more. Up to 500 mg/day is certainly safe, unless one has renal failure. Too much Mg has a laxative effect, as in milk of Mg.
I’m glad Dr. Zittermann is clearly calling for more research in this area.