The findings, published recently in the American Journal of Clinical Nutrition, indicated the importance of magnesium for regulating 25(OH)D levels, particularly in light of the fact that almost 80% of US adults are not hitting the RDA for magnesium.
“Vitamin D insufficiency is something that has been recognized as a potential health problem on a fairly large scale in the US,” explained Martha Shrubsole, PhD, research professor of medicine, division of epidemiology at the Vanderbilt-Ingram Cancer Cente
“A lot of people have received recommendations from their health care providers to take vitamin D supplements to increase their levels based upon their blood tests. In addition to vitamin D, however, magnesium deficiency is an under-recognized issue.”
‘Necessary for over 300 biochemical reactions’
The National Institutes of Health (NIH) lists magnesium as being necessary for more than 300 biochemical reactions in the body, from helping maintain normal muscle and nerve function, to keeping heart rhythm steady, supporting a healthy immune system, and keeping bones strong. The mineral is also needed for blood sugar management and healthy blood pressure.
The science and positive regulatory decisions have led to increased interest from consumers in magnesium and this has led to increasing sales. And with 70-80% of the US population not meeting their recommended intakes of magnesium, the market is expected to continue to grow. Indeed, some industry experts are predicting that magnesium sales in the nutrition market will surpass calcium by 2020.
The new study was part of the Personalized Prevention of Colorectal Cancer Trial, a double-blind 2 × 2 factorial randomized controlled trial examining whether magnesium plays a role in cancer. Participants aged between 40 and 85 were randomly assigned to either placebo or magnesium supplements with personalized doses based on their initialy intakes of calcium and magnesium as well as their calcium-to-magnesium intake ratio. The doses were designed to decrease the calcium-to- magnesium intake ratio to about 2.3.
The results showed that the impact of magnesium was dependent on the initial levels of vitamin D (25(OH)D). Specifically, if 25(OH)D levels were close to insufficient or lower (below 30 ng/mL), then magnesium supplementation increased vitamin D levels. However, if vitamin D levels were between 30 and 50 ng/mL, then magnesium was found to decrease vitamin D levels, particularly when levels were closer to 50 ng/mL.
“[T]he findings from the current study provide the first evidence in humans that magnesium supplementation reduces 25(OH)D3 and 24,25(OH)2D3 when 25(OH)D is higher but may increase 25(OH)D3 when 25(OH)D is lower,” wrote the researchers.
“The precise molecular mechanism is not clear. One possible explanation is that magnesium supplementation affects both vitamin D– activating enzymes (i.e., CYP27B1 and CYP2R1) and vitamin D–deactivating enzymes [i.e., CYP24A1 and CYP3A4].”
Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are transformed in the liver and kidneys into 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D).
While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.
Source: American Journal of Clinical Nutrition
Volume 108, Number 6, Pages 1249-1258
“Magnesium status and supplementation influence vitamin D status and metabolism: results from a randomized trial”
Authors: Q. Dai et al.