Are YOU getting enough vitamin D3? The recommended daily amount for an adult during the winter months is up to 4,000 IUs. The amount is often more if you are severely deficient in vitamin D3, or have underlying health conditions. Often times, people swallowing an oral vitamin D3 supplement are not able to absorb it properly. The most effective way to absorb vitamin D3 (other than naturally from the sun) is to take a sublingual supplement. The word ‘sublingual’ is Latin for “under the tongue”. By letting it sit under your tongue, it gets directly absorbed into your bloodstream through the lining of your mouth. This eliminates the need for it to pass through the entire gastrointestinal tract, the liver, and THEN on into your bloodstream, decreasing the effectiveness of the supplement.