Dietary Supplement Vitamin D3 can be synthesized by humans in the skin upon exposure to ultraviolet-B (UVB) radiation from sunlight. But due to the winter season, weather conditions, and sun block, the body’s ability to produce optimal vitamin D levels may be inhibited. These factors point to the value of taking a daily vitamin D supplement — and Life Extension now offers a convenient, mint-flavored liquid vitamin D formula! Benefits at a Glance 2,000 IU of convenient, liquid-dose vitamin D Supports healthy bone density Promotes healthy cell differentiation and immune function Supports healthy bone density Perfect complement to multivitamins with 1,000 IU to 3,000 IU vitamin D Supports Optimal Health Vitamin D has long provided significant support for healthy bone density. However; scientists have also validated the critical role that vitamin D plays in regulating healthy cell division and differentiation, and its profound effects on human immunity. These findings link a deficiency of vitamin D to a host of common age-related problems. Dosage The current recommended daily allowance (RDA) for vitamin D is only 600 IU, which has resulted in startling evidence of a widespread deficiency for this vitamin. Most experts in the field now recommend intakes between 1,000−10,000 IU for adults to achieve a serum 25(OH)D level above those indicative of vitamin D deficient levels, at approximately 80 nmol/L or 32 ng/mL. Increased Blood Levels Life Extension suggests that healthy adults supplement each day with 5000−8000 IU of vitamin D with the objective of achieving an optimal 25-hydroxy vitamin D blood level between 50−80 ng/mL. A vitamin D blood test can help you determine the additional amount of vitamin D you may need to achieve an optimal level.