Nutrition Fact: More than 25% of Americans are Vitamin D Insufficient

Are YOU Getting Enough Vitamin D?

It seems like Vitamin D has been the “fashionable” vitamin over the past few years mainly because there has been a trend in research suggesting vitamin D deficiency/insufficiency may play a role in various diseases other than just bone health.  Additionally, while the the Institute of Medicine (IOM) increased their recommendations and upper limits for vitamin D for optimum bone health in 2010,  other experts don’t agree with those recommendations and more and more research is showing increased intake may protect against several chronic diseases.  So, with all the controversy and inconclusive evidence out there how do you tease out what you really need to know about Vitamin D?  Let’s start by understanding what vitamin D is and where you get it from.     

What is Vitamin D? 

Vitamin D is a family of fat-soluble vitamins which functions to regulate calcium and phosphorus homeostasis.  Additional functions include:

  1.  Helps maintain bone health
  2. Aids in cell differentiation of hemotapoietic and epithelial cells
  3. Enhances immunity
  4. Helps reduce inflammation
  5. Aids in regulation of blood pressure and insulin

Aside from these known functions Vitamin D plays, new research suggests that vitamin D status may also be linked to chronic diseases including cardiovascular disease, certain cancers, cognitive decline, depression, diabetes, pregnancy complications, and some autoimmune diseases.  Although the link between Vitamin D and these chronic diseases is still inconclusive, it’s not surprising that there has been a dramatic increase in sales in Vitamin D supplements and manufactures of the vitamin dues to evidence of protection against certain chronic diseases.

Where do I get Vitamin D from? 

Vitamin D is mostly obtained through skin exposure to UV B light where it is converted to the active form for Vitamin D (D3) in our skin.   Some Vitamin D is also obtained from the diet in fortified foods such as milk, cereals, and juices as well as some natural foods such as some fish (i.e. salmon and sardines) and liver.  But more recently many have been receiving vitamin D from supplements which either come in the form of D2 or D3.

Because most of our Vitamin D supply comes from sunlight, there are certain populations that are at risk of deficiency because they convert less sunlight to Vitamin D from their skin.  This includes:

  • Those with darker skin tones.  The increased melanin reduces conversion of sunlight to Vitamin D.
  • Those that don’t expose skin in the sunlight or wear high levels of sunblock all the time.  Clothing and sunblock inhibit the conversion of Vitamin D from sunlight.
  • Those that live in geographies that have less sun exposure.
What are the recommendations for Vitamin D intake?  

The Institute of Medicine (IOM) who puts out the Recommended Daily Allowances (RDAs) for nutrients makes the following recommendations for Vitamin D:

Recommended Dietary Allowance (RDA) for Vitamin D
Set by the Institute of Medicine
Life Stage  Age  Males
mcg/day (IU/day)
Females
mcg/day (IU/day)
Infants 0-6 months 400 IU (AI) 400 IU (AI)
Infants 6-12 months 400 IU (AI) 400 IU (AI)
Children 1-3 years 600 IU 600 IU
Children 4-8 years 600 IU 600 IU
Children 9-13 years 600 IU 600 IU
Adolescents 14-18 years 600 IU 600 IU
Adults 19-50 years 600 IU 600 IU
Adults 51-70 years 600 IU 600 IU
Adults 71 years and older 800 IU 800 IU
Pregnancy all ages 600 IU
Breast-feeding all ages 600 IU

Credit: Linus Pauling Institute on Micronutrients 

The IOM also set the tolerable Upper Limits for Children 9 years and older at 4,000 IU/ day to prevent any toxicity from over consumption of Vitamin D.  It’s important to keep in mind that these are conservative recommendations based only on the IOM’s review of the research related to optimum bone health.  Many other experts are now recommending increased intake of vitamin D in light of new research linking increased Vitamin D status to lower risk of certain chronic diseases and based on data from a NHANES study showing that about 30% of Americans are Vitamin D deficient or at risk of being deficient according to IOM serum Vitamin D levels for optimum bone health.  I personally was tested two years ago and was severely deficient as well.  In order also project against some chronic diseases, some experts such as the Vitamin D Council are now recommending as much as 5,000 IU/day for adults.

SO WHAT DO I RECOMMEND?

I think it’s still too early to be recommending everyone to start taking high dose Vitamin D supplements to protect against various chronic diseases, however, there is promising research for additional benefits with increased Vitamin D coupled with the fact that many Americans are in fact not getting enough Vitamin D from sunlight or the diet so I would recommend the following to increase your intake of Vitamin D:

  1. Get tested.  Testing your Vitamin D level is a simple blood test and especially if your insurance covers it, I would recommend it.  That will give you a basis on how much Vitamin D supplements, if any you really need.  There are also tests you can do at home with a simple blood pinch that are fairly inexpensive with decent accuracy to give you some idea of your Vitamin D levels.
  2. Try consuming more Vitamin D rich foods from your diet.  Natural is ALWAYS better so make sure you’re including enough milk, salmon, and other fortified foods in your diet to help increase your Vitamin D intake.
  3. Try to expose enough skin (arms and/or legs) to at least 5-15 minutes of sunlight twice a day.  That amount of time without sunblock should provide you with more than enough Vitamin D while still minimizing risk to harmful side effects of sun exposure.  Additional plus is that you can’t get Vitamin D toxicity from Vitamin D synthesized from sunlight, only from too much supplement or intake from the diet.
  4. If you do wish to take supplements, or if your doctor recommends it, make sure you take Vitamin  D3 over D2 which research indicates may be up to three times more potent.

After I finished my prescription dose of Vitamin D to get me back to a healthy blood level,  my doctor recommends to get between 1,000- 2,000 IU/ day so I eat fortified foods and take a 1,000 IU supplement daily.  That recommendation is based on the fact that I don’t get much sun exposure living in Seattle, have darker skin, and that my levels were low.  So before you start popping 1,000 IU or 2,000 IU Vitamin D supplements per day, I would recommend you get your levels tested and try moderate sun exposure and diet before you choose supplements.  That will prevent any potential toxicity from too much Vitamin D intake and will save you money…and who doesn’t need to save money right?

1 Comment

Filed under Nutrition in the News, Recommendations, Uncategorized, Vitamins

One response to “Nutrition Fact: More than 25% of Americans are Vitamin D Insufficient

  1. So true…you need to get your levels tested before taking a supplement. I have mine tested every 6 months as I was really low at one point, but all better now with the supplement 🙂

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