How to Determine Your Optimal Dose of vitamin D.
The only way to know is by testing your blood. Fortunately, testing vitamin D is now very convenient. You simply order the test, prick your finger, send in the blood and wait for the results to come back to you.
Here are some basic guidelines:
- You must test for 25(OH)D, not 1,25(OH)D. They look similar, but 1,25(OH)D is a measure of kidney function, and is not the test you want for measuring vitamin D levels.
- Ideally, your blood level should be around 60-80 ng/ml, as this allows the body to have some vitamin D in reserve, and it duplicates the higher levels found in young, healthy individuals who spend a decent amount of time in a sun-rich environment.
- Begin taking vitamin D about eight weeks prior to being tested. This will help you customize your dose once you receive your test results. To determine a basic, starting dose, it has been suggested, as per Dr. John Cannell of the Vitamin D Council that you take 1,000 IU per 25 pounds of body weight. A person who weighs 150 pounds, for instance, would take 6,000 IU per day as a starting dose (150/25 = 6. 1,000 x 6 = 6,000). Do this for about eight weeks, and then test. Perhaps this dose will put you in the ideal range, but there`s no guarantee since we are all so different, and have unique vitamin D receptor genotypes.
- The idea is to hopefully get somewhere in the ballpark with this method and then tweak your daily dose once the test results come back. If your results are still suboptimal, Dr. Cannell has estimated that each 1,000 IU increase in supplemental vitamin D will generally produce a 10 ng/ml increase in the vitamin D blood level. For example, if you have been taking 5,000 IU per day for 8+ weeks, and your results come back at 40 ng/ml, you would want to increase your dose to at least 7,000 IU (2,000 IU = ~20 ng/ml rise in blood level) to achieve a minimum of 60 ng/ml.
- Supplementation is not recommended for everyone. Certain conditions, such as sarcoidosis and some lymphomas, can produce excessive amounts of vitamin D, and in these instances, one should move forward cautiously under the supervision of a healthcare professional.
vitamin d: the sunshine vitamin
"We estimate that vitamin D deficiency is the most common medical condition in the world."
- Michael Holick PhD, MD
Professor of Medicine, Physiology, and Biophysics
Boston University School of Medicine