Vitamin D3 is important for a number of reasons. In fact, there are vitamin D receptors in every cell of the body. Having adequate vitamin D is important for immune function, your mood, bone health, and at optimal levels also has anticancer benefits. In neonates, the lowest vitamin D levels are associated with higher rates of respiratory infections. In children, lower vitamin D levels are associated with higher rates of juvenile diabetes. Therefore vitamin D may be supplemented in infants and children at doses of 2000 IU per day, and in adults, at doses of 4000 IU per day (the upper limit of safety according to the US Institute of Medicine). Nutritional practitioners, in actual practice may use higher doses of 6,000 – 10,000 units per day when levels are being checked. The sun is our natural source of getting adequate vitamin D, because vitamin D is activated in the skin when we are exposed to sunlight. In our clinic we check all pregnant patients routinely, and offer testing to all GYN patients as well. After years of checking vitamin D levels, it is clear to me that it is almost impossible to get adequate vitamin D for most without supplementation. This is because in our modern world we are simply not exposed to the sun enough to achieve adequate levels. Cancer protection begins at blood levels of over 50, and optimal levels are felt to be 60-90. Vitamin D testing is an easy blood test, and vitamin D3 is easy to find, inexpensive, and helps move you toward optimal wellness in more ways than one. Vitamin D comes from a number of natural food sources live cod liver oil, and comes in a variety of forms over the counter, as in a soft gel capsule, an emulsion, or as drops in oil, which may be placed in other foods or taken directly by mouth or even in a baby bottle. If you are considering supplementing with vitamin D3, consider getting tested, and also talk to your pediatrician as well concerning getting started with supplementing your children, to get their views on supplementation.