To “D” or not to “D”…

…that is the question…okay, pretty lame, I know.  But today I want to talk a little bit about Vitamin D, which has been getting a lot of press lately, both positive and negative. 

First off, when you hear all the hype about vitamin D, it is about vitamin D3, one of five D vitamins.   If you decide to supplement with vitamin D, make sure it is this particular form.  Vitamin D3 is in fact, not a vitamin but a fat soluble hormone. Currently there are not a lot of rigorous scientific experiments that prove the merits of this vitamin; most of the positive reports about D3 are based on correlation and observational studies, which admittedly, are not as reliable.  However, when you consider the potential benefits, the cost of D3 and the downside of taking D3, all of which I will discuss, I think you might decide in favor of taking this supplement. 

Let’s start by talking about what vitamin D does for us…or why do we need it in the first place?  From Alona Pulde, MD:

Vitamin D is essential for the human body to function properly.  It regulates over 200 genes, in cells all over the body ~ including the brain, heart, kidney, bone, intestines, skin, gonads, prostrate, breast, parathyroid gland and immune system.  Vitamin D is [also] important for bone health as it regulates calcium and phosphorus levels in the blood. 

Vitamin D3 is often referred to as the “sunshine vitamin” as the best source of D3 is, in fact, the sun, or rather,  your body’s absorption of the sun’s ultraviolet-B (UVB) rays.  Dietary sources of vitamin D are primarily available through wild-caught oily fish (salmon, mackerel, bluefish and canned tuna) , eggs, and fortified milk and orange juice.  Unfortunately, it is almost impossible to obtain enough vitamin D3 via food sources…you just cannot eat enough.  Before the invention of sunscreen vitamin D deficiencies weren’t as common.  But with all the admonishments to wear sunscreen combined with the fact that people spend less time outdoors than in the past, vitamin D deficiency is on the rise.  Some estimates suggest that as much as 80% of the population has some form of vitamin D deficiency. 

Vitamin D deficiencies have been linked to increased rates of colorectal, ovarian, renal, breast and lung cancers, coronary heart disease and Type 2 diabetes.  And while these linkages are based on the previously mentioned correlative and observational studies, these are pretty serious health concerns.   Now if combating low vitamin D levels involved expensive pills, costly medical procedures, or risky supplements, then maybe I would advise to wait for more information.  But the reality is, it is cheap and easy to combat low vitamin D levels. 

Option #1:  Spend time out in the sun without sunscreen.  Yep, I said it.  Doctors who recommend this suggest being outside without sunscreen with minimal clothing (this can mean shorts and a t-shirt) between the hours of 10 AM and 3 PM, at a minimum of 2-3 times per week, for 5-10 minutes, and as much as 3-4 times a week for 30 minutes (recommendations vary ~ for me, I run and bike outside in the summer without sunscreen, so I am sure I get enough exposure).  Note that those who are darker skinned may need up to four times more exposure to obtain the same benefits.   If you get enough sun exposure in the summer, your body can store the vitamin D and it will get you through the winter months.  The body also has a built-in safe-guard with respect to vitamin D accumulation from the sun (not so with supplements) ~ if your body has enough, it will destroy any excess…pretty cool, the human body, huh?

Option #2:  Take a supplement.  While the Institute of Medicine has set a recommended intake of 200 I.U. per day from birth to age 50 (400 for adults age 50 to 70 and 600 for adults older than 70), most experts feel these recommendations are way too low.  While I have seen recommendations as high as 4000-5000 I.U. per day, the commonly accepted dosage seems to be 2000 I.U. per day.  For those with a confirmed Vitamin D deficiency (more on that in a minute), much higher dosages may be temporarily recommended…listen to your doctor.  While there are risks associated with excessive Vitamin D supplementation (unlike sun exposure, the body is not able to destroy excessive vitamin D via supplementation), the amounts necessary for negative effects to occur are very high, well over 5,000 I.U. per day. 

Personally, I see no real harm in supplementing with a daily 2000 I.U. Vitamin D3 capsule.  However, if you want to be sure you are indeed deficient, you can determine this through a simple blood test.  Make sure the test is looking for vitamin D3 levels, or 2,5-dihydroxy vitamin D.  What constitutes a healthy level varies by expert, but the bare minimum seems to be 30 nanograms/millilitre (ng/ml), with 40-60 ng/ml representing a more acceptable range.  If your levels are low, your doctor may prescribe some aggressive vitamin D3 supplementation (in the range of 50,000 I.U. per day…don’t be alarmed).  As a general rule, however, 1000 I.U. per day will lead to about a 10 ng/ml increase in serum concentration; 30 minutes in the sun is the equivalent of about 10,000 I.U. (although this is spread over all 5 forms of vitamin D). 

In the end, as always, it is up to you to decide.  All I am trying to do is consolidate the information, inform, and let you make a choice.  With this one, sun exposure costs nothing, and even if you chose to go the supplementation route, a year’s supply of vitamin D3 costs a whopping $13.  I recommend Carlson Vitamin D3 ~ available online through many sources ~ I use My Natural Market. 

What do you think about Vitamin D3?  Do you rely on the sun, do you supplement?  I would be interested to hear from readers.


About Lisa Van Dore

I have lived in Sherborn, Dover and most recently North Walpole, for a total of 15 years (and counting). Having recently been through the process of selling a home and buying (and renovating) a new one, I understand the conflicting emotions of excitement and anxiety inherent in the process, whether you are a seller or buyer, whether this is your first home purchase or your tenth. I have a BA from the University of Michigan and an MBA from Indiana University. My early career found me working as a CPA, and later as the controller of Crate & Barrel. More recently I spent seven years running my own personal training business. I understand the hard work and dedication necessary to build a business and a reputation...most of my personal training clients came to me by referral and my first client was still with me when I decided to leave personal training. This speaks to the level of effort I put forth for my clients, week after week. On a more personal note, I raced triathlon for seven years and more recently completed my first half marathon. In my free time I enjoy cooking, reading, Maine, hiking and, in the fall, following college teams are the University of Michigan (Go Blue!) and Texas Christian University (Go Frogs!).
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2 Responses to To “D” or not to “D”…

  1. Brian Dwyer says:


    I rely on the sun. As you know, I spend a lot of time outside. I have a rather un-informed opinion that vitamins and/or soluble hormones are best available to the body through natural means.
    Vitamins from food are more successfully utilized by the body vs. supplemented vitamins. I believe the same is true for D3. My 2 cents.

    Great blog!



    • Thanks, Brian. I imagine you are a bit more informed on this than some of the rest of us. I too rely on sun exposure, but I have my kids take vitamin D, especially my daughter who spends a lot of her time indoors.

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