Vitamin D Is An Essential Nutrient That Contributes To The Normal Function Of The Immune System And The Maintenance Of Normal Bones And Teeth. As Fear Of Sun-Exposure Has Grown And Lifestyles Have Become More Sedentary, Exposure To The Sun Has Dropped Dramatically And Vitamin D Deficiency And The Incidence Of Rickets Has Surged. As Dietary Sources Of Vitamin D Include Eggs And Fatty Fish, Many Vegans Prefer To Get Boost Their Intake By Using Supplements.