Vitamin D3 by Natural Factors $8.99 90 Tablets - $8.99 Size 90 Tablets 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart Vitamin D3 is essential for strong bones and teeth as it increases the body’s absorption of calcium from food.* Its role in regulating calcium levels also helps regulate the immune system and maintain healthy nerves and muscles.*