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I attended the recent 11th annual Speaking of Women’s Health event in Cleveland, but I did not get an opportunity to ask a question during the Q &A panel. We were encouraged to use this site to ask questions.

I currently see a Nurse Practitioner and she encouraged me to take a daily supplement of 2000 iu of Vitamin D3. During the warmer months I believe I get plenty of sunshine while not wearing sunscreen, so I’m not sure if this is something I should only take during the winter months. There is always talk about taking too much of a vitamin or supplement so I want to know if it’s okay for me to take the Vitamin D3 year-round or just when I feel I may not get enough sunshine. Another concern is whether to take the Vitamin D3 alone, with a meal or with calcium. I’m not sure what’s best.

Thank you.

Thank you for attending our 11th annual Speaking of Women’s Health event. I am so glad you were able to submit your question online.

Vitamin D is an important player in bone metabolism. Its most important biological action is to facilitate the intestinal absorption of calcium. Vitamin D deficiency interferes with bone metabolism and is associated with osteoporosis, increased risk of falls and possibly fractures. Vitamin D (Cholecalciferol also known as D3) is synthesized in our skin under the direct influence of sunlight. Cholecalciferol is then converted to 25-Hydroxy Vitamin D (Calcidiol 25OHD) in the liver then to 1,25 Dihydroxyvitamin D (Calcitriol 1,25 OHD) in the kidney - which is the most active form of Vitamin D.

Most clinicians agree that Vitamin D deficiency occurs at levels < 15ng/mL. However, there is no true consensus on what the optimal Vitamin D concentration level should be for healthy skeletal health.

  • The Institute of Medicine supports levels greater than 20ng/mL.
  • The Endocrine Society and the National Osteoporosis Foundation suggest a minimal level of 30ng/mL to minimize risk of falls and fractures.

Vitamin D deficiency can occur as a result of the following:

  • decrease in intake
  • decrease in absorption
  • decrease in sun exposure
  • decrease in synthesis in the liver and/or kidney

The recommended dietary allowance of vitamin D for adults is 600-800IU per day. However, the Institute of Medicine has defined the tolerable upper intake level to be 4,000 IU per day in healthy adults. The exact intake dose at which Vitamin D becomes toxic is not clear. Vitamin D toxicity is possible secondary to hypercalcemia and in those individuals who consume large doses of supplements and exceed 60,000 IU per day.

If you are taking Calcium supplements, it is best to take your Vitamin D with your calcium as Vitamin D facilitates the absorption of calcium. If you take your Vitamin D supplement without calcium, it can be taken either with or without meals. There is no harm in taking Vitamin D year-long considering you are not exceeding 4,000 IU per day, which is the tolerable upper intake level. Please keep in mind that use of sunscreen also decreases the penetration of sunlight in our skin, resulting in less production of Vitamin D.

November 1, 2012 at 3:32pm

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