What You Don’t Know About Vitamin D

By: Lucinda Miller, Mary Beth Gudewicz CNTP, MNT

Vitamin D is important in many aspects of our health from healthy bones to protection from cancer, heart disease, and autoimmune diseases.  Although it is known as the “Sunshine Vitamin” you are not always getting Vitamin D when the sun is shining.  In fact it is estimated that 50% of the population in North America are Vitamin D deficient.  Our mechanism for making Vitamin D depends on the availability of UVB rays and as you will read in this article from the Vitamin D Council, anyone above latitudes of 37° north of the equator and below latitudes of 37° south of the equator experience what is known as a “Vitamin D Winter” in which no UVB rays can penetrate the ozone and thus shuts down our ability to make our own Vitamin D.

What you need to know:

  • Your body is designed to make its own Vitamin D with exposure to the UVB rays of the sun.
  • Just 10-15 minutes of sun exposure depending on your skin color (chest, arms, legs, torso- think 40% of your body) between 10 AM-2 PM will give you 10,000 IUs of Vitamin D.
  • When your skin is pink to the touch, you’ve made 10,000 IUs of Vitamin D, do not overexpose.
  • Keep in mind sunscreen with as little as SPF 8 can block your Vitamin D production by 100%.
  • Burning leads to skin cancer so be mindful of your time in the sun and when you do apply sunscreen be sure to refer to EWG’s sunscreen guide (www.ewg.org) for the latest research and recommendations of the safest sunscreens available.
  • Reasons for deficiency include:
    • Too little exposure to sunlight without sunscreen
    • Diets low in vitamin D
    • Low fat diets
    • Poorly functioning digestive system
    • Obesity
    • Darker skin
    • Living at northern latitudes
  • Vitamin D deficiency can adversely affect the immune and cardiovascular systems, mood, neurological imbalances, asthma, blood pressure and may cause other systemic problems. (Blood Nutrition Institute, 2007)
  • Vitamin D levels – the only way to monitor your Vitamin D levels is through a 25-Hydroxy-vitamin D blood test
    • 60-80 ng/mL is recommended
    • 80-100 ng/mL for people with autoimmune disease
  • 1,25-dihydroxy vitamin D
    • Vitamin D is metabolized in the liver to form 25-hydroxy (OH) vitamin D.  Additional hydroxylation takes place in the kidney by 1-alpha hydroxylase, under the control of parathyroid hormone, which yields 1,25-dihydroxy vitamin D.[1]
    • 1,25-dihydroxy vitamin D is the most potent vitamin D metabolite.  It stimulates calcium absorption in the intestine and its production is tightly regulated through concentrations of serum calcium, phosphorous, and parathyroid hormone.[2]
    • When calcium is high or a person has a disease that might produce excess amounts of vitamin D, such as sarcoidosis or an enlargement of lymph nodes (because immune cells may make 1,25-dihydroxyvitamin D), 1,25-dihydroxyvitamin D usually is ordered. Rarely, this testing may be indicated when abnormalities of the enzyme that converts 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D or renal disease are suspected.[3]
  • 10-75 ng/mL is recommended
  • Vitamin D Supplementation
    • There are many factors that affect vitamin D levels such as the season, time of day, and skin color so it is important to monitor your blood levels while supplementing.
    • Vitamin D is fat soluble and is best absorbed in liquid form not through pills.
    • We recommend Liqui-D3 by Rx Vitamins
    • For those without a gallbladder we recommend a micellized form for better absorption, we use Klaire Labs Micellized Vitamin D3
    • It is essential to supplement and eat foods high in Vitamin D throughout the winter when your body is not able to make its own from the sun.  Here in Denver that is November through March.
  • Vitamin D food sources
    • Wild caught salmon
    • Eggs
    • Mushrooms
    • Sardines
    • Halibut liver oil
    • Wild caught mackerel

Sources:

http://www.health.harvard.edu/newsweek/time-for-more-vitamin-d.htm

http://health.usnews.com/health-news/family-health/heart/articles/2008/06/23/time-in-the-sun-how-much-is-needed-for-vitamin-d

https://labtestsonline.org/understanding/analytes/vitamin-d/tab/test/

http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8822

[1] http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8822

http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8822[2]

[3]https://labtestsonline.org/understanding/analytes/vitamin-d/tab/test/

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