Determining the correct 25-hydroxy Vitamin D level is still a work in progress. In the 8 years I have been attending meetings, we have made considerable progress. NOF 2007 was the first time any society proposed an intake above 400 IU daily and a 25-hydroxy Vit D level of more than 20 ng/ml.
At the 2015 U. Wisconsin “Bare Bones Symposium” the latest recommendations were discussed. I have summarized them here.
Take Vitamin D3. D3 is Cholecalciferol (what we make in sunshine). Vitamin D2 is Ergocalciferol (what plants make and use). D3 works much better in people than D2 becuse it is the right stuff. It lasts 5 times longer and the assay is more accurate.
Test for 25-hydroxy Vitamin D level and aim for between 40 and 80 ng/ml. At 40 ng/ml over 98% of people can absorb and utilize Calcium fully. You want to have some margin of safety since lab test results vary by at least 20%. If you are seriously deficient, we give 50,000 IU of D3 every M, W, F based on your level and size, to correct the level quickly.
If you do not want to test your level, and you are the “average person” of 154# or 70 kg, you should take 3800 IU daily. This should achieve the 40 ng/ml level – eventually. If you are very deficient, this could take a year or more. If you are larger than the old average, or you have digestive issues, you will need more.
Finally, some cancer researchers believe that 70 ng/ml is better for preventing and treating cancers. If they are right, you should go for the higher level. If they are wrong, you have done no harm by going for the higher level.
Take Control of your Bone Health. Take enough D3.
Jay Ginther, MD