USDA Certified Organic Vitamin D3 - An Excellent Way to Help Replenish Vitamin D Levels. Vitamin D is a fat-soluble nutrient that is produced through skin exposure to sunlight, which triggers vitamin D synthesis. Despite the importance of the sun to vitamin D synthesis, many experts agree it is wise to limit sun exposure to the skin, which often results in lower than ideal Vitamin D levels in the body. Vitamin D supplements are another option for helping to replenish vitamin D status. Each tablet of Bronson Organic Vitamin D supplies 5000 IU of Vitamin D3, the preferred form. Research has shown that Vitamin D supports bone, immune, colon, muscle, and breast health.* Vitamin D supplements are an excellent way to help replenish vitamin D levels. * These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.