Vitamin D, What can it do for you?

Pittsburgh Dietitian Blog Posts
December 17, 2014

Vitamin D has been a major topic of discussion recently. Over the past 5 years this vitamin has been the focus of many scientific communities. While some of the areas of impact need more research, there is quite a bit of promise from repeated data, which makes the case for increasing daily Vitamin D intake.

A General Background

Vitamin D is a fat-soluble vitamin that is produced in the body when the skin is exposed to UV rays. It is also available in low levels from some foods. Vitamin D in foods has two common forms, D2 and D3. D2, or ergocalciferol, is a fungus or yeast derived product that is created when certain fungi or plants are exposed to UV light. D3, or cholecalciferol, is what our skin, as well as the skin of other animals produce when exposed to UVB light. It can be produced synthetically and added to foods or produced as a supplement. Once in the blood stream, Vitamin D is transported to the kidneys, where it becomes Calcitriol, the biologically active form of vitamin D.

Why should I care?

Vitamin D has many functions in the body, many of which are well established and understood. Calcitriol (active Vitamin D) circulates as a hormone in the blood and regulates the concentrations of calcium and phosphate. This helps promote important processes, such as bone growth and remodeling. Calcitriol also has an effect on immune function and neuromuscular function.

The most well known link to vitamin D is its role in the prevention of rickets, a bone disease in children. This was discovered in 1922, and the addition of vitamin D to dairy in the 1930’s virtually eliminated rickets from the United States. For years, the levels of adequate consumption for Vitamin D (%DV, RDA, DRI), easily attained by three servings of dairy daily, have been based on the prevention of rickets. Recently however, studies have emerged suggesting that an increased serum vitamin D level beyond the levels currently recommended, can translate to reduced incidence of many diseases and disorders, which are noted in the chart below:


There are many notable areas of research. The most established is still bone health. Rickets in children, and reduction of fall risk, fractures and low bone mineral density in late adults and elderly, especially women, are the most significant. In addition to bone health, deficiency of vitamin D has been linked to higher risk of viral infections. Low levels are also associated with gestational diabetes, pre-eclampsia and low birth weight in pregnant women.

Multiple Sclerosis (MS)

Vitamin D has shown great potential in Multiple Sclerosis. Prevention and management of Multiple Sclerosis, as well as some other autoimmune disorders, are the main areas of the newest research. The study of nutritional genomics is working to better establish this link. Initially, it was observed that the farther away from the equator you get, there is an increase in both vitamin D deficient persons (less sunlight), and incidence of Multiple Sclerosis.

The most popular theory is vitamin D deficiency is an environmental trigger that turns a gene coding for MS ‘on’. With this theory, increasing vitamin D consumption and raising serum levels would succeed in turning the gene ‘off’. More studies are needed, but multiple have been done and some show very promising results.

The map is from an article titled 'Time for more vitamin D', which appeared in the September 2008 issue of Havrad Women's Health Watch. The article and this image discuss the difficulty obtaining enough vitamin D from sunlight and diet. The grey area on the map shows latitudes above 37 degrees north, where very little vitamin D is synthesized, except in the summer months. People who live in these areas are at relatively greater risk for vitamin D deficiency. The article can also be found on the Harvard Harvard Health Publications website, or by clicking the picture!


Some other good articles on Multiple Sclerosis and Vitamin can be found in the following links:

Vitamin D Council: Multiple Sclerosis

Overcoming Multiple Sclerosis: Sunlight and Vitamin D

Neurology: Lower serum vitamin D levels are associated with higher relapse rates in MS

Seasonal Affective Disorder (SAD)

Ever notice that the months of January-March often leave people feeling depressed. My Dad always says that February is the worst month and he would be happy to see it missing from the calendar. Are you someone who just goes through the motions when it’s snowing and overcast? Seasonal Affective Disorder (SAD) is another area of promising research for vitamin D intervention. Though the link between vitamin D and depression is not fully understood, it is established that low serum levels of vitamin D are linked with depression. It is also understood that a lack of vitamin d in the blood makes you more likely to develop depression, and taking a vitamin D supplement can improve symptoms of depression. There is direct evidence that the prevalence of SAD, the most appropriate acronym ever, is most concentrated in areas with the most extreme weather changes.

Journal of Nutrition and Healthy Aging: Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorder.

Vitamin D Council: Depression

Where do I get my Vitamin D from?

As suggested earlier, our primary source of vitamin D is what we make ourselves. Vitamin D3 is synthesized from cholesterol in the body, when an adequate UVB exposure exists. Ideal scenarios include 15 minutes of daily sun exposure to approximately 40% of the total body during the middle of the day to synthesize 10,000-25,000IU. That’s easy enough right? (Not.) In reality, this is a very real problem. First, most people work indoors during peak hours of sunlight. This instantly reduces chances of exposure to evenings, weekends and vacations. To make matters worse sunscreen, the vacationers best friend, reduces vitamin D synthesis (SPF 15 reduces vitamin D synthesis up to 98%). Then you consider location and seasonality. If you live in the Northeast United States like me, chances are there are 4-6 months each year that are cloudy and cold. Not only are you inside mostly, when you do go out, your entire body is covered with clothing. We live in a world that greatly reduces our ability to synthesize vitamin D. All of these factors become quite the D-ilemma (pun intended).

There are very few foods that are a great source of vitamin D. Currently, our best sources are dairy products that have added D3, fish that have some naturally occurring D3, or in mushrooms that have been UVB irradiated for enhanced vitamin D2 content.

How much am I getting from my diet?

o Dairy is fortified with D3 (30% DV = 120IU)o Cod Liver Oil (1390IU/15mL)o Catfish: 425IU/3-4ozo Salmon: 360IU/3-4ozo Tuna canned in oil: 235IU/cano Whole egg: 20IU/60g eggo Mushrooms§ Shiitake: 154IU/100g§ Portabella: 10IU/100g§ Portabella exposed to UV light: 420-525IU/100g


National Institute of Health Office of Dietary Supplements: Vitamin D Fact Sheet

Current studies suggest vitamin D3 is better utilized in the body, which makes sense since it is what we can synthesize. D3 binds better to receptors, which ultimately leads to a more effective raise and maintenance of serum levels. In addition to being better utilized, it is more shelf-stable and has a longer half-life. Since there is no real price difference between D2 and D3 on the shelf, I would recommend Vitamin D3 to those looking to increase consumption. Attention Vegetarians! Vitamin D3 is from animal sources. If representatives at supplement companies tell you it is synthetic, it is still likely a product with ingredients of animal origin that were processed synthetically.

How much do I need?

The amount of vitamin D a person needs is another ‘Case Specific’ value. It varies based on sun exposure, diet, genetics, gender, age, activity level, along with many other factors. The best way to know is to get your serum 25(OH)D level checked.

The current ‘normal range’ for serum 25(OH)D is 30-100ng/mL. As the chart above notes, levels above 20ng/mL are what virtually eliminated rickets. That is what a typical person will have if they consume 3 servings of dairy daily. An additional reference to the chart suggests there are benefits from serum concentrations as high as 55ng/mL. A lot of those values are either extrapolated or very preliminary research, but show great promise. Since this test has a standard deviation (potential error) of 10ng/mL, I would recommend at least getting your levels above 40ng/mL. Levels above 50ng/mL are what I strive for, and what I would recommend to my clients. To do this, there is a generic formula for quick reference.

Generally, 100IU of D3 will raise serum 25(OH)D approximately 1ng/mL.

So for someone with a vitamin D level of 25ng/mL, to get to 45ng/mL, you would need approximately 2,000IU in addition to your current lifestyle’s consumption and sun exposure. I would like to repeat that this is formula is not fact or scientifically proven. It is more of a general reference tool to help gauge a starting point.

For those concerned with over consumption, serum levels above 150ng/mL have been associated with negative effects. The Vitamin D Council often notes that there are no issues associated with a serum level around 70ng/mL, so if there is potential benefit why not? I personally supplement 2,000IU in the summer, when I am outdoors running frequently, and 3,500IU in the winter when I am bundled up and bogged down by the Pittsburgh winters. These amounts are in addition to what I consume from dairy, eggs, and other dietary staples.

Talk to your doctor about getting your serum 25(OH)D levels checked. Ask to know the value, not just the generic ‘you are fine’. If you are below 40ng/mL, I would still recommend getting at least an addition 1,000IU of daily D3. If you are deficient (below 30ng/mL), many doctors will write a prescription for a weekly 50,000IU D2 supplement. This is an unnecessary prescription. Not only do I advise clients to buy D3 instead of D2, Vitamin D can be purchased in a much cheaper, daily dose at any supplement store, website, or chain store that carries supplements. Let your doctor know you will instead buy a D3 supplement (2,000IU-5,000IU are very easy to find), and would like to retest in 3 months.

Support of Recommendations

Compared to the DRI of 600 IU for adults set by the IOM and Food and Nutrition Board, the levels I am referencing seem high. The Vitamin D Council, an organization solely focused on Vitamin D research would suggest otherwise:

Recommended daily intakes from various organizations: Vitamin D CouncilEndocrine SocietyFood and Nutrition BoardInfants1,000 IU/day400-1,000 IU/day400 IU/dayChildren1,000 IU/day per 25lbs of body weight600-1,000 IU/day600 IU/dayAdults5,000 IU/day1,500-2,000 IU/day600 IU/day, 800 IU/day for seniors

As you can see, the Vitamin D Council actually recommends 5,000IU per day. They also work to convince the FNB and IOM to increase the Tolerable Upper Limit (TUL) from 4,000IU to 10,000IU. This request is heavily based on the evidence that our bodies synthesize around 10,000IU daily from proper sun exposure without issue of toxicity. I am a great supporter of this council and their devotion to research and health. I also have a great deal of respect for the Endocrine Society. According to their documentation, the average adult will need around 1,500-2,000IU per day to receive the full benefit of vitamin D. Supplementing more than that should be based on individualized serum results, or done by those who wish to supplement with the hopes of receiving benefits hypothesized in very new research.

Final Comments:

  1. My recommendations are based on the areas I feel are well established. Those are the areas I discussed in greater length. Many of the links and charts I provided may discuss information or topics I feel need more data are not ready for application to populations yet. Remember moderation, balance, and variety rule the day.
  2. If I had to pick one vitamin for the general population to supplement, it would be vitamin D. It is the only vitamin I supplement daily.
  3. Get your Serum 25(OH)D levels checked immediately, 3 months later to track progress.
  4. Levels are typically at their lowest in March, due to the lack of sunlight experienced since approximately November. If you wish to know you low and high throughout the year, March and September (respectively) are the best times.
  5. Increase your dose in the winter months, or in periods when you have further reduced sun exposure. Decrease supplemented dose in time periods when you are getting more sun exposure.
  6. Stay updated on the latest research using the Vitamin D council or myself website for reference. Vitamin D is being studied intensely. Current areas in need of more research will be updated frequently. This topic is one that will be updated constantly.

Personally, I take a Vitamin D3 liquid by Metagenics. Just 2 mint flavored drops in the morning for my 2,000IU. The best part is one bottle contains over 2,200 drops, so it is by far the most cost effective Vitamin D3 supplement I have ever found. If you would like a high quality Vitamin D3 product 20% OFF with FREE shipping Click Here!


  1. ‘How to Make Sure That You are Getting Enough Vitamin D’. Dr. Ben Kim, Natural Health Care. 2013.
  2. ‘Vitamin D and Sunlight Exposure: Review’. Compiled by Walter Sorochan. 2011.
  3. Garland C.F., Baggerly C.A. Clinical Education. ‘Disease Incidence Prevention by Serum 25(OH)D Level’.
  4. Gloth III F.M., Alam W., Hollis B. J Nutr Healthy Aging. 1999;3(1):5-7. ‘Vitamin D vs Broad Spectrum Phototherapy in the Treatment of Seasonal Affective Disorder.
  5. Harvard Health Publications: Harvard Medical School. ‘Time for more Vitamin D’. September 2008.
  6. Mark A. Moyard, MD, MPH. Medscape Multispecialty. Dermatology Nursing. 2009;21(1). ‘Vitamin D: A Rapid Review’.
  7. National Institutes of Health: Office of Dietary Supplements. ‘Dietary Supplement Fact Sheet: Vitamin D’. 2011.
  8. Overcoming Multiple Sclerosis. ‘Sunlight & Vitamin D’. 2010.
  9. Runia T.F., Hop W.C., de Rijke Y.B., et al. Neurology. 2012 Jul 17;79(3):261-266. ‘Lower serum vitamin D levels are associated with a higher relapse risk in multiple sclerosis.
  10. Vitamin D Council. ‘Depression’. June 2013.
  11. Vitamin D Council. ‘Multiple Sclerosis’. March 2013.
  12. Vitamin D Council. 2013.
  13. The Endocrine Society. 2013.

Andrew Wade, RDN, LDN

Case Specific Nutrition logo
Stay Up To Date

Sign up for our newsletter

Sign up for our newsletter to stay up-to-date on new products, special offers, and exclusive content from the CSN team.

Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form. Please check your submission and try again.
An image of a Case Specific Nutrition® office.
The Case Specific Nutrition® East Liberty office.
Case Specific Nutrition logo
Find Us

Find Your Location

Embarking on your wellness journey has never been easier. With multiple Case Specific Nutrition® locations, a healthier lifestyle is right around the corner. Visit our Locations page to find the Case Specific Nutrition center nearest to you and step into a world of tailored health and wellness support!

An image of a glass of water and delicious, healthy food.
Case Specific Nutrition logo
Want more?

Get Started

At Case Specific Nutrition®, we believe in providing personalized support every step of the way. Get in touch with our team today to get more information about our services, answer your specific health questions, or just say hello! Our friendly team is eager to hear from you.