A recent trial at the Vanderbilt-Ingram Cancer Center has shown that magnesium optimizes vitamin D status and that magnesium had a regulating effect in people with high vitamin D levels.

"Magnesium deficiency shuts down the vitamin D synthesis and metabolism pathway," Dai, one of the researchers, said.

Eureka states, “Foods with high levels of magnesium include dark leafy greens, beans, whole grains, dark chocolate, fatty fish such as salmon, nuts and avocados.”