The Sunshine Vitamin in Just One Drop Mom's Choice Awards - Honoring Excellence 1000 IU Per Drop 180 Drops A Factor in the Maintenance of Good Health Dietary Supplement Euro Dropper Technology GMP Quality Product Vitamin D is made in skin when exposed to summer sunlight (UVB), and is present in only a few foods. Vitamin D is necessary for healthy bones and normal muscle function. Vitamin D can be measured with a blood test for 25-hydroxyvitamin D. The Institute of Medicine recommends this level should be higher than 20 ng/ml. A vitamin D supplement may be required to raise 25-Hydroxyvitamin D to healthy levels. Research findings show a 25 (OH)D blood level above 20 ng/ml is related to better health. A vitamin D3 supplement may be especially helpful for anyone who avoids exposing skin to sunshine.