Vitamin D: Should You Be Taking Supplements?

December 27, 2010/Stephanie Hofhenke//

By Torey Jones, MS RD LDN

Vitamin D

December 21, 2010 marked the shortest day of the year.  For those who are deficient in Vitamin D, a vitamin whose sources include sunlight exposure on the skin, don’t plan on getting your daily recommended allowance outside.  Experts believe that individuals who live at latitudes above 37˚north or below 37˚ south cannot produce adequate Vitamin D synthesis during the winter months.  Chicago sits at 41˚ north, just above this invisible cut-off.  Even in summer months, wearing sunscreen reduces the skin’s ability to synthesize Vitamin D by 95%.  Due to the risk of skin cancer, ample sunscreen use is still recommended to protect against dangerous UVA and UVB rays.

Vitamin D plays a variety of roles in the body.  The most understood is its role in bone health and calcium balance to maintain bone density.  Vitamin D helps to regulate blood pressure and the immune system.  Some studies have found that Vitamin D may also play a role in cancer prevention.

Risk factors for vitamin D deficiency include aging, dark skin complexion, individuals who cover their skin for religious or cultural reasons, exclusively breast-fed infants and obesity.  Obesity increases risk of Vitamin D deficiency because Vitamin D, a fat-soluble vitamin, becomes sequestered in fat tissue and thus unavailable for use by the body. Sources of Vitamin D

Low levels of vitamin D may impair the immune function and reduce bone density, leading to increased risk for osteoporosis and osteopenia.  Severe Vitamin D, although rare, causes rickets and primarily occurs in exclusively breast-fed infants not receiving supplementation.
 
The Institute of Medicine (IOM), a non-profit organization that provides advice on health and public policy, released its much-anticipated calcium and Vitamin D guidelines in November.  They declared that bone health is the only conclusive benefit of Vitamin D supplementation.  Although the IOM did increase the recommendation to 600 International Units (IU) of Vitamin D for most adults, many experts believe that 1000-2000 IU/day is required.
 
Natural dietary sources of Vitamin D are rare, primarily in fatty fish.  However, many foods such as milk, yogurt, cereal, some juices and infant formulas are now fortified with Vitamin D.   Still, consuming these foods may not be enough.  One cup of milk contains 100 IU of Vitamin D, just one-sixth of the IOM’s recommendation.  Not surprisingly, oral supplementation of Vitamin D (usually in the active D3 form cholecalciferol) is becoming increasingly common.

There are mixed messages for consumers regarding Vitamin D.  If you have any of the risk factors listed above, the best approach is to have your Vitamin D levels checked.  If you are part of the estimated 60% of Americans who are deficient, plan on taking an oral supplement to replenish your levels.  Aim to supplement between 600-2000 IU/day and avoid the mega-doses (such as 50,000-500,000 IU/day) unless prescribed by your doctor.  Both deficiency and excess are harmful; know your Vitamin D status and supplement moderately if necessary, especially during the winter months in Chicago.

 

Resources:

Linus Pauling Institute at Oregon State Univeristy. Vitamin D.  Last modified January, 2008, http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/.

Pellicane, A.J., Wysocki, N.M., & Schnitzer, T.J. (2010). Prevalence of 25-hydroxyvitamin D deficiency in the outpatient rehabilitation population.  American Journal of Physical Medicine & Rehabilitation 89 (11): 899-904.

CAND Instagram

Recent Posts

8 Ways to Shop and Eat with Less Packaging

8 Ways to Shop & Eat with Less Packaging

Dia De Los Muertos: Food and Culture

10 Ways to Eat More Plants

Meet the Author

Stephanie Hofhenke

Stephanie Hofhenke

Bringing you the best nutrition information...

Our Academy Bloggers

CAND has several professional and student bloggers.  They write about a range of topics for the public.

Meet the Bloggers

Comment on this post