In the first study, researchers relied on data from the National Health and Nutrition Examination Survey (NHANES), a nationally representative study which has been continuously monitoring the health status of the U.S. population since 1959. The scientists examined the diets of adults aged 17 or older who, from 1999 to 2000, did not take magnesium in supplement form and found that 68% consumed less than the recommended daily allowance (RDA) for magnesium—which for adults is 310 mg to 420 mg per day—and 19% consumed less than half the RDA.
Compared to adults whose diets contained at least the RDA for magnesium, those who consumed less than the RDA were 48% to 75% more likely to have elevated CRP levels. Overweight adults over age 40 who consumed less than half the RDA for magnesium were more than twice as likely (124%) to have elevated CRP levels than were adults whose diets met or exceeded the RDA.
In the second study, the MUSC researchers wanted to gauge CRP levels in those who took magnesium supplements of at least 50 mg per day. Using NHANES data, doctors examined 10,024 adults and found that from 1999 through 2002, 25.6% took a magnesium supplement of at least 50 mg per day. Those whose total magnesium from all sources was less than the RDA—from diet and/or supplements—were 40% more likely to have elevated CRP compared to those whose diets met the RDA. Among those whose diets had less than half the RDA for magnesium, those who took magnesium supplements were 22% less likely to have elevated CRP than were those who did not take a supplement. Doctors noted that only 21.9% of those who did not take magnesium supplements met the RDA compared to 60.2% of those who took a magnesium supplement.