Vitamin D is a fat soluble vitamin that is obtained from food, sun exposure, and dietary supplements. Once vitamin D is ingested or synthesized in the skin, it undergoes two hydroxylation reactions in the body, first in the liver to calcidiol (25-hydroxycholecalciferol), and then in the kidney to calcitriol (1, 25-dihydroxycholecalciferol). Vitamin D is critical for healthy bone development, remodeling, and maintenance.* It is also known to play a key roll in the maintenance of many other organ functions.*

Obtaining sufficient vitamin D from food and daily sun exposure can be difficult for many people. The National Health and Nutrition Examination Surveys (NHANES) have reported that the average intake of vitamin D has been declining and that many children and adults in the United States are likely to be vitamin D deficient. This trend may be due to increased body mass index (BMI), reduced dairy consumption, lactose intolerance, milk allergy, increased use of sun protection, and vegetarianism.

In breast-fed infants, human milk alone is not sufficient to provide the required amount of vitamin D. The American Academy of Pediatrics (AAP) recommends vitamin D supplementation in both infants and mothers. Women and older individuals also tend to have vitamin D levels that are lower than recommended levels. In the population above age 50 in particular, this may be caused by a slowed or compromised metabolism and poor absorption of vitamin D. Adequate vitamin D is essential for optimal health. Supplementation of vitamin D with Jarrow Formulas Vitamin D3 can contribute to the required daily vitamin D intake and thus promote healthy bones, immune function, and cell protection in both the young and the old.*

Vitamin D plays an important role in stimulating the absorption and maintenance of proper blood levels of calcium and phosphorous, critical minerals for bone development and preservation.* Numerous studies have shown that vitamin D3 supplementation may support bone strength and reduce the risk of falls, fractures, and bone loss in elderly individuals, especially those with inadequate calcium and/or vitamin D intakes, postmenopausal conditions, and difficulty exercising.* Vitamin D3 supplementation can support not only healthy bone development and growth in young children and adults, but also promote balanced remodeling of bones in a mature population.*

Vitamin D has been shown to regulate immune-modulating effects of immune cells and factors.* Interactions among vitamin D receptors and other molecules on the immune cells enhance the communication between various signaling pathways, resulting in efficient and appropriate immune responses. In addition, this basic vitamin may play a significant role in cardiovascular health by regulating blood pressure (through balanced hormone secretion), heart and vessel muscle function, and normal immune response.* A growing body of research on vitamin D also suggests benefits of this vitamin to normal mood and blood sugar regulation, and overall mortality and well-being, although additional studies are necessary for better understanding of the modes of action.*