Vitamin D: The Need for Supplement and Sunshine

Vitamin D is one of the most common nutritional deficiencies affecting 70 to 97% of adults across all ethnicities. Many are aware of the integral role vitamin D plays in regards to bone health, but it is also essential when it comes to hormones and how they influence metabolic pathways, cellular functions, and gene expression (approximately 2,000 of them!). 

Proper levels of vitamin D- >30ng/ml- have been associated with:

  • prevention of certain cancers
  • prevention of upper respiratory tract infections, asthma and wheezing disorders
  • support to muscle strength
  • prevention of autoimmune disorders such as type 1 diabetes, crohn’s, and rheumatoid arthritis 
  • help with mood-related health including SAD (seasonal affective disorder) and sleeping disorders
  • reduction of heart attack risk by 50%

Contrary to major belief, the sun - in moderation - is not bad. After all, sun exposure is what helps our skin make vitamin D! As little as 5 to 30 minutes of sun exposure between 10am and 3pm at least twice a week to the face, arms, legs or back, without sunscreen, is usually enough to prevent deficiencies. Another trick is to estimate the amount of time it takes for you to get “mildly pink” skin, which is the equivalent to 10,000-25,000 IU of vitamin D. 

Note: Even using SPF 8 reduces your skins ability to make vitamin D by 90%! 

But… what can we do in the colder months? 

Unfortunately, there are not a lot of options when it comes to vitamin D-rich foods. Shitake mushrooms (sun-dried), fresh/wild salmon, and cod liver oil are probably the highest dietary sources of vitamin D. The rest you can get from supplements. 

My suggestion is to check your vitamin D at your yearly check up. Based upon your serum levels (measured by 25 (OH)), the dosing guidelines are as follows. Dosage is per day and for adults only.  

  • < 20ng/ml   =    Deficient 
  • 21-29ng/ml =    Insufficient/ At risk 
  • ≥30ng/ml    =    Adequate/ Sufficient 
  • Adequate: 600 IU  
  • At Risk: 1500-2000 IU 
  • Deficient: 4000 IU 

Tolerable upper limit has been set at 4000 IUs per day for >9 years old, although this is a conservative level. 

Vitamin D3 (cholecalciferol) is the preferred form. If you’d like suggestions on over the counter supplements, write to me directly at 


  • -Office of Dietary Supplements. National Institutes of Health  
  • -Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC. The National Academic Press. 2010.  
  • -Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, Treatment, and Prevention of Vitamin D Deficiency: and Endocrine Society Clinical Practice Guideline. J Endoclin Metab. July 2011.
  • - Holick M. The vitamin D solution. Pair supplementation with sensible sun exposure. HealthETimes. 2012. 2 (5):14-17.