 And not only is it important for bone health, but there is a vitamin D receptor on every organ in the body, your heart, your blood vessels, your brain. Vitamin D is pivotal for mental focus. It also improves your mood. People who are low on vitamin D have depression, anxiety. So it goes far beyond just bone health. Vitamin D is a vital vitamin that sustains life of almost every single cell in the body, just like omega-3s does.