Jarrow FORMULAS® Vitamin D3 provides cholecalciferol, the most bioavailable form of vitamin D. Vitamin D3 is converted by the kidneys into the hormone calcitriol, the active form of vitamin D3. Calcitriol enhances calcium and phosphorous absorption, stimulates the synthesis of osteocalcin (an important structural protein in bone), and is involved in proper cell differentiation (changing of cell function), including in prostate cells.  Adequate calcium and vitamin D as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis later in life.

Vitamin D is synthesized in the body from sunlight. But, due to the winter season, weather conditions, and sunscreen blockers, the body’s ability to produce optimal vitamin D levels may be inhibited.¹ In fact, it has been proposed that annual fluctuations in vitamin D levels explain the seasonality of influenza.² All of these factors point to the value of taking a daily vitamin D supplement to ensure optimal vitamin D intake.

Vitamin D has long provided significant support for healthy bone density.^3-8 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.^9-12 These findings link a deficiency of vitamin D to a host of common age-related problems. As a result of startling evidence of a widespread vitamin D deficiency, prominent nutritional scientists are calling on Americans to increase their vitamin D intake to 1000 IU per day and higher.