Vitamin D Deficiency
Betty Kovacs, MS, RD
Betty is a Registered Dietitian who earned her B.S. degree in Food and Nutrition from Marymount College of Fordham University and her M.S. degree in Clinical Nutrition from New York University. She is the Co-Director and Director of nutrition for the New York Obesity Research Center Weight Loss Program.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
- What is vitamin D?
- What does vitamin D do for one's health? What are symptoms and signs of vitamin D deficiency?
- What causes a vitamin D deficiency?
- How is a vitamin D deficiency diagnosed?
- What is the treatment for a vitamin D deficiency?
- Can vitamin D deficiency be prevented?
- What are symptoms and signs of an excessive vitamin D intake?
- Vitamin D FAQs
- Patient Comments: Vitamin D Deficiency - Symptoms
- Patient Comments: Vitamin D Deficiency - Causes
- Patient Comments: Vitamin D Deficiency - Tests
- Patient Comments: Vitamin D Deficiency - Treatment
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What is vitamin D?
The "sunshine" vitamin is a hot topic. Should people be exposed to the sun for their vitamin D? Are the guidelines for how much vitamin D we need adequate? Is the tolerable upper limit too low? What benefits does vitamin D have on our health? This article will discuss and respond to all of these common questions.
There are two forms of vitamin D, known as D2 and D3. Vitamin D2, also known as ergocalciferol, comes from fortified foods, plant foods, and supplements. Vitamin D3, also known as cholecalciferol, comes from fortified foods, animal foods (fish, eggs, and liver), and can be made internally when your skin is exposed to ultraviolet (UV) radiation from the sun. Vitamin D is a fat-soluble vitamin. This means that it is stored in our fat cells for use when it is needed. It is constantly being used for calcium metabolism and bone remodeling.
The guidelines for how much vitamin D we need were updated in 2010 by the Institute of Medicine (IOM). They were set based on the evidence for bone health and assumed that there was limited sun exposure. The recommended dietary allowance (RDA) for vitamin D is as follows:
- 600 IU/day for ages 1 to 70
- 800 IU/day for over 70 years of age
- 600 IU/day for pregnant and lactating women
These recommendations have been met with a lot opposition by some experts, saying that they are too low. The evidence review that the IOM did was based on 1,000 studies. They were limited by the types of studies and availability of studies to support the benefits linking vitamin D to multiple sclerosis, heart disease, cancer, immunity and autoimmune diseases, cardiovascular and respiratory health, pregnancy, obesity, erythropoiesis, diabetes, muscle function, and aging. They looked for randomization, double-blinding, placebo-controlled studies. The studies take a lot of time and money, and enough subjects have not yet been studied in regard to vitamin D and its effects on each one of these medical conditions. The RDA is set to meet the requirements of 97%-98% of healthy individuals, so the argument for greater levels stems from the fact that higher levels are needed for people with health issues. Still, there is a fine line between what we hope will work and what we know will work.
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