When you take a Vitamin D supplement, your body doesn’t use it immediately. It has to convert it into an active form that can help your cells fight off viruses, bacteria, and inflammation. This conversion process heavily depends on magnesium. Without enough of it, the Vitamin D you’re taking might just be sitting idle in your system, not doing much. “A combined magnesium and vitamin D treatment may be more effective in increasing serum 25-hydroxyvitamin D concentrations compared with vitamin D supplement alone in the overweight or obese population,” a 2022 study had found.

And here’s the shocking fact—most of us are unknowingly low on magnesium too! Blame it on processed foods, stressful lifestyles, too much caffeine, and not enough greens in our diet. Magnesium hides in foods like leafy vegetables, nuts, seeds, whole grains, and even dark chocolate. But the way we eat today, it’s pretty easy to fall short.