A randomized, double-blind, placebo-controlled, crossover trial to compare the bioavailability of magnesium from Natural Calm magnesium with three marketed magnesium supplements.
Natural Calm is a magnesium citrate supplement, made by combining magnesium carbonate and citric acid. When these ingredients are mixed in liquid, the magnesium carbonate converts to magnesium citrate.
It is widely held that magnesium citrate is three times better absorbed than magnesium oxide.
However, at Natural Calm, we wanted to demonstrate the efficacy of our magnesium citrate formula against other leading magnesium supplements of a high quality. Specifically, we wanted to demonstrate the absorbability of Natural Calm against other magnesium citrate brands, and against magnesium bisglycinate brands that do not contain magnesium citrate.
In 2016, Natural Calm Canada contracted with Nutrasource, a full-service contract research organization (CRO) specializing in clinical trials and product testing for the natural health industry, to compare magnesium absorption from four brands of magnesium supplements.
The results were released by Nutrasource in September, 2017, and presented at the Canadian Health Food Association by Dr. Alison Smith. This summary was prepared by Dr. Smith. A thorough explanation of the study findings can be found on our blog, here.
Nutrasource conducted a 10-week, randomized, double-blind, crossover study including 12 healthy, postmenopausal women, randomized into four different treatment sequences. All subjects took 150 mg of the four magnesium brands or a placebo; however, the sequence of treatment varied between subjects.
Study Duration: June 2016 – September 2017. Each subject visited the clinic 27 times plus two screening visits.
Supplement brands included in the study:
|Natural Calm||Magnesium carbonate powder with citric acid that converts to magnesium citrate once dissolved in hot water|
|Magnesium Glycinate 1.||Magnesium bisglycinate powder dissolved in water|
|Magnesium Glycinate 2.||Magnesium bisglycinate powder dissolved in water|
|Magnesium Citrate 2.||Magnesium citrate powder in a capsule|
|Placebo||Hypromellose and rice flour contained in a capsule. One capsule contained an estimated 0.26 mg of magnesium.|
Primary Measurement: The concentration of magnesium in the blood serum and urine between 0-8 hours following supplement ingestion. (For information on the rationale for measuring magnesium absorption via blood serum and urine tests, see our White Paper.)
Secondary Measurements: The concentration of magnesium in the blood serum and urine between 0-10 hours, 0-12 hours, 0-24 hours (urine only), as well as maximum concentration (Cmax) and time to maximum concentration (Tmax) of magnesium in the blood serum and urine.
10 Subjects completed the study and the following results were found.
- For the primary measurement, between 0-8 hours, Natural Calm magnesium citrate significantly increased magnesium concentration in both the blood serum and urine, compared to taking a placebo. The magnesium bisglycinate supplements and the magnesium citrate capsule did not significantly increase magnesium concentration in either the blood serum or urine during this time period.
- For the secondary measurement, between 0-12 hours, Natural Calm magnesium citrate significantly increased magnesium concentration in the urine compared to magnesium bisglycinate supplement.
- The maximum concentration of magnesium in the urine (Cmax) was measured after collecting urine over the course of 24 hours. Cmax was a secondary study measure. Results showed the magnesium citrate capsule to significantly increase magnesium concentration in the urine compared to magnesium bisglycinate supplement.
According to the primary measurement, Natural Calm magnesium citrate significantly increases the bioavailability of magnesium in the human body compared to magnesium glycinate competitors.
Overall, the statistical tests with a significant result showed that the magnesium citrate supplements from Natural Calm outperformed both magnesium bisglycinate supplements.
For the full study results, please contact firstname.lastname@example.org.
We acknowledge that the quality of magnesium glycinate used in the tested products may be a factor, despite that these are two leading magnesium glycinate brands. In 2017, it was revealed that a number of Canadian magnesium glycinate brands contained undisclosed magnesium oxide, a less absorbable form. This may have influenced the study results.