This nutrient is available in supermarket staples and via sun exposure, yet many of us don’t get enough.  Why?


Vitamin D is a bit of an enigma.  It’s found naturally in grocery-store go-tos like eggs and fish and has been fortifying milk products, orange juice, and breakfast cereals for decades.  Technically it’s a vitamin, but it behaves more like a hormone, in that the body can create a certain form of it through exposure to sunlight.  And yet one in three Americans of European descent suffers from a deficiency of this vitamin, which is vital to bone health and may also support immune function and prevent certain cancers, diabetes, multiple sclerosis and heart disease.

So if it’s found in readily available foods, and a mere 5-10 minutes a day of sun exposure generate enough vitamin D for most people, what exactly accounts for such a widespread deficiency?  Over the centuries, people have migrated away from the equator and are exposed to less sunshine; industrialization has pushed many occupations indoors; then there is the aggravating habit of putting on clothes, which block the sunlight. Kidding aside, more recently, we’ve also been slathering ourselves with sunscreen.


How much do we need?

Adding to the confusion is the debate over the recommended daily allowance.  Vitamin D helps the body absorb and retain calcium and phosphorus, critical bone builders, which is reason alone to err of the side of more rather than less.  The current recommendation is that most adults get 2,000 IUs per day via a D3 (cholecalciferol) gelcap.  While this amount may seem high, you won’t be getting too much of the vitamin.  It takes several hundred thousand IUs to reach toxic levels.  While a healthy diet can get you off to a good start in meeting your needs, it’s difficult to get enough from food alone.  In addition, most of the vitamin D in fortified foods is D2, a much less absorbable form of the vitamin
synthesized from yeast.


Who’s at risk?

Groups that may not be getting enough D include people who work nine-to-five jobs as well as those living in the northern regions of the country (north of Philadelphia, on a line west to San Francisco). 
Your skin melatonin content is also a factor, since darker complexions require longer sunlight exposure to create the vitamin.  Weight matters, too, since body fat binds to vitamin D and prevents it from entering the bloodstream.  And the older you get, the harder it is to generate the vitamin from sun exposure. 
But everyone gets roughly the same amount via intestinal absorption.  So this is a health concern with a simple solution: Whether your skin is dark, pale, old or young; whether you hate the sun or love it, you can and should get enough vitamin D!


**The Not So Sunny Side: While most people meet some of their vitamin D needs through sunlight exposure, relying on the sun as your sole source of the vitamin is problematic and potentially dangerous.  For starters, there is the relationship between cumulative UV exposure and skin cancer (and photo-aging), which prompts many of us to cover up with sunblock before spending any time in direct sunlight. 
Most problematic, though, is that it’s impossible to gauge exactly how much vitamin D you’re receiving from the sun. You can’t get too much (the body regulates the amount it makes), but you may not be absorbing as much as you think. Unless you live near the equator, the sun isn’t intense enough between roughly November and April to trigger significant, if any, vitamin D production.  Even living in a sunny area does not guarantee that you’re getting sufficient amounts of vitamin D from the sun.  People tend to stay indoors or take refuge in the shade when temperatures rise.  Also, amounts of sunlight change with the weather, so it matters what time of day you’re outside and how brightly the sun is shining.  Overcast days can burn your skin, but they won’t ramp up the vitamin D.


For more information, talk with your Doctor or Registered Dietitian.

Sally Schultheiss