Vitamin D, like all nutrients, is essential for life. Our bodies need it from our environment (sunlight and food in this case) to function. It also plays an important role in building and maintaining strong bones. But that’s not all. Every cell in our body has receptors for vitamin D, meaning it can affect virtually everything that happens inside our cells. Research shows that people with higher blood levels of vitamin D live better for longer, with immune and cardiovascular systems that function better.