Getting Enough Vitamin D? In Summer or winter, our need for Vitamin D is often far greater than we are getting. Researchers now know that previous recommendations for optimal levels of Vitamin D were much too low! Vitamin D not only helps strengthen bones; Vitamin D also protects against dementia, and MS. Prairie Naturals Vitamin D3 is the most readily absorbed form. Be sure you get enough of this low-cost, highly valuable vitamin. You’ll soon feel the difference that Vitamin D makes.