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, 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.
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
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.
Reviewed by Melissa Conrad Stöppler, MD on 6/18/2013
Yes, deficiency of vitamin D can cause bone pain and muscle weakness.
However, mild vitamin D deficiency is not necessarily associated with any
symptoms. Vitamin D has been referred to as the "sunlight vitamin" because it is
made in our skin when we are exposed to sunlight.
Sun protection is simply guarding a body from the adverse effects of sunlight. Aside from the hazards of heat, the sun poses the danger of
sunburn, which can permanently damage the skin and cause skin cancer,"...