You can and should take magnesium and vitamin D together. In fact, the bioavailability of vitamin D is largely dependent on magnesium. Vitamins and minerals work in combination and depend on each other to be fully effective. This is important because there is an association between excess vitamin D and excess calcium in the blood (hypercalcemia), which can cause serious health complications.
Women who received vitamin D and magnesium had a significant increase in grip strength and overall mobility, compared to the placebo group. Taking vitamin D and magnesium orally, on an individual basis, can help treat or reduce the risk of many of the same health problems. It is recommended that adults take at least 10 micrograms (mcg) of vitamin D a day, especially during the fall and winter. Taking magnesium helps your body absorb and use minerals such as calcium, phosphorus and potassium, and vitamins such as vitamin D.
If not converted, vitamin D can increase calcium levels instead of regulating them as it should. This study showed that, in response to magnesium supplementation (without vitamin D), the number of women with vitamin D deficiency declined by approximately 20%. In observational studies, higher intake and blood levels of vitamin D and magnesium have been linked to a lower risk of insulin resistance and type II diabetes. In the kidneys (and other tissues), another enzyme, 1-alpha-hydroxylase, converts 25-hydroxyvitamin D to vitamin D.
Vitamin D levels also depend on the foods you eat and the vitamin D supplements you take (see the Magnesium and Vitamin D Intake section below). Laura Kunces, PhD, RD and director of nutritional research at Thorne Research, told Healthline that, given widespread vitamin D and magnesium deficiencies, the findings could support a broader use of supplements for both. Magnesium is one of several essential minerals that your body needs to stay healthy and work as it should. Like any vitamin or mineral, vitamin D cannot work without first being converted into a form that the body can absorb.
Vitamin D promotes the intestinal absorption of calcium and magnesium, which are vital components of bones that help prevent osteoporosis. Magnesium supplementation is also said to increase vitamin D levels in people with vitamin D deficiency, but causes a reduction in people whose intake is high.