What Vitamin D Level “Should” I Have?

February 27, 2012

What Vitamin D Level “Should” I Have? 

ReferenceHaddad in Jr Clin Endo Meta Dec 2012 and Vit D Council 

 Now that we are in the final throes of winter, and our eyes are turning to spring break and the return of the sun, the question that arises is “What level of Vitamin D “should” I have?”.   The logic that we usually apply to this is “What happens naturally?” when we have lifeguards exposed to the sun, or folks go to tanning booths or farmers work outdoors in the tropics.  But that’s not what humans did in their “early years”.  When we were in Africa, wearing few if any clothes, and exposed to the sun all day long, what was our D level?  (Doesn’t that sound like Spring Break in Florida to you?) 

That should be what we had in our evolutionary era for many million years. Well, that’s just what Haddad and his team reported back in December.  They took 35 Massai and 25 Hadzabe adults who lived in Tanzania, just about on the equator, who wear few clothes and have exposure to tropical sun year around.  Their levels of Vitamin D should be as close as we can hypothesize to our “natural state” as they represent some of the last humans on this planet who live outdoors, with few clothes on the equator in the parts of Africa where humans come from.  They all had skin type 6, which is just about as ebony black as you can get.  That would mean that they need the most sunlight to get Vitamin D production.  The authors mentioned that none of their study subjects used any sunblock (tongue in cheek).   They do wear some coverings on their legs and torsos and do stay out of the hottest mid-day sun in the shade of trees or their modest dwellings. 

 The levels of Vitamin D that they obtained was lower than you might think.  The Masai ranged from 23 to 67 with an average of 48 ng.   The Hadzabe are more traditional hunter-gatherers, have no possessions, wear fewer clothes than the Masai, and also stay out of the sun when they can. Their levels of D were 44, with a range of 28-68. This is the best study we have to date of Vitamin D levels in folks living in Africa in traditional lifestyles.  And considering how important Vit D is to arming your immune system (and all it’s other benefits), it suggests that we want to get our D levels to 45-50 year around.  

In Wisconsin, our D levels will drop to 20 if we are Caucasian and 6-10 if we are African American.  And then we get Vitamin D deficiency diseases.  I believe one of those is influenza is one.   As we ponder spring break, and look to the end of winter, we are at the last months of low sunlight.  How much D should you take?  To get to a level of 50 ng, most adults need about 4000 IU a day.  It takes 6-12 months to get to a new steady-state when you change doses, so loading doses are needed to get started.   (The reason for this loading dose is the concept of "volume of distribution".   Vitamin D is fat soluble and enters fat tissue.  It then behaves as though your body really had 10,000 gallons of volume whereas, just looking at you, you like like about 15 gallons to me. )

 WWW.  What will work for me.  A loading dose of D? That would be a week on the beach, with little clothing, and lots of sunblock to prevent sunburn.  Or 4000 IU a day.   Folks who are heavy store more D in fat tissue. They need more! 

Pop Quiz

1.   Folks living in Africa in hunter-gatherer groups wearing few clothes have optimal exposure to the sun in the environment we evolved in.  What is their D level?             Answer:   Two different groups were tested: their levels were 44 and 48 on average.

2.  What happens to D levels during winter in Wisconsin?                       Answer:  Caucasians with skin type 3 (mid-European: French, English, German, Swiss, Austrian, get to levels of 16-20.   African Americans get to levels of 6-10,  

3.   Why do Africans have less Vitamin D?                  Answer: That's what skin pigment does. It blocks UV radiation thereby protecting folate.   Caucasians lose folate with no pigment, and get more spina bifida in their offspring.

4.   Why do you need a loading dose when you get a different dose of D.                Answer:   You have a huge volume of distribution to fill up with more D when you raise a dose. It takes months and months to fill up that extra volume.

5.   If you are overweight, is your volume of distribution larger?                  Answer:  Hugely so.  It can take years to get to new homeostasis in overweight folks.  

 Written by John E Whitcomb, MD  Brookfield Longevity and Healthy Living Clinic, 17585 W North Ave, Suite 160   Brookfield, WI 53045   262-784-5300 www.LiveLongMD.com