Monthly Archives: April 2012

I have recently been asked a lot about the media hype over vitamin D. Is it really necessary to take vitamin D? If so, how much is necessary? Why is vitamin D necessary and lastly, can I take too much vitamin D?

Lets start by explaining a few things. Vitamin D deficiency is very common amongst all age groups, especially in populations of people living above the 35 degree latitude. Vitamin D is either taken in through dietary means or converted from a precursor in the skin when exposed to sunlight. The deficiency then results from a diet relatively deficient in vitamin D and/or diminished outdoor activity along with the widespread use of sunscreens. More than 90% of our vitamin D requirement comes from casual exposure to light. Wearing a sunscreen with an spf of 8 reduces the ability of the skin to produce vitamin D by 95%. The ability of the sunlight exposure to produce vitamin d is also dependent on the intensity of the light which may be altered by the ozone layer, seasonal changes, geographic latitude, skin pigment, clothes worn and time of day. At higher latitudes, above the 35 degree, winter sunlight is unlikely to produce sufficient vitamin D even if exposure were appropriate. Vitamin D was declared a vitamin in the 1950ʼs when its role as a dietary factor that cured Rickets was found. Vitamin Dʼs well understood role in bone health has made it an important supplement in preventing osteoporosis. It is now widely accepted that vitamin D is more like a steroid, with hormone like properties and receptors on many tissue types throughout the body including muscles, heart, brain, bone, liver, kidney, pancreas and immune cells, like macrophages, and lymphocytes. The wide ranging actions of active Vitamin D (known as D3) help explain why Vitamin D deficiency has been associated with several chronic diseases.

There is exciting data that suggest that improving vitamin D levels can have significant effects on preventing and improving many disease states. Here are a few of the latest:

1. Cancer prevention-Vitamin D deficiency and living at higher altitudes increases the risk of development of colon, breast ,prostate, ovarian and esophageal cancers.
2. Diabetes prevention- Vitamin supplementation and replacement may help prevent both types I and II.
3. Hypertension-a recent study of hypertensive patients received ultraviolet irradiation from a tanning bed for 3 months not only increased their blood level of vitamin D by more than 100% but also completely resolved their hypertension.
4. Multiple Sclerosis-people living at higher latitudes are at higher risk of developing MS.
5. Rheumatoid arthritis-a study in 2004 showed an inverse relationship between vitamin D levels and cases of rheumatoid arthritis
6. Obesity-Fat tissue-may take up circulating vitamin D and thus obese patients may require higher doses.
7. Osteoporosis-anyone with osteopenia or osteoporosis should have their Vitamin D level checked periodically.
8. Fibromyalgia-many patients with vitamin D deficiency are mislabeled as having fibromyalgia. Symptoms may disappear with replacement of vitamin D.

Baseline measures of vitamin D should be performed in everyone on an annual basis at the yearly physical. Levels of vitamin D below 30 nmol/L are generally considered to be inadequate and a target level between 50 and 60 is desirable. Be certain of the unit of measurement your lab uses. Some labs use units ng/ml. This target level has not been agreed upon by experts yet. Many researchers feel that higher levels may be desirable for cancer and chronic disease prevention, while others worry about levels getting too high. Normal levels for most labs are between 30 and 100 nmol/L. I think shooting for the middle is appropriate, again between 50 and 60 nmol/L.

The Institute of Medicine published new guidelines for the RDA of vitamin D in 2010. For people age 19-69 the RDA is listed at 600 IU/day. I think personally this is too low. In clinical practice, the majority of people require a minimum of 1000 IU daily to maintain normal range. If someone starts off at a low level, say between 25 and 30 nmol/L I will start them at a minimum of 2000 IU daily and recheck the level in 3 months. For people with starting levels of < 25 nmol/L I may use up to 4000 IU daily. For those with levels less than 20 I will use 25,000-50,000 one to two times weekly for up to 12 weeks depending on the initial level. The response to oral intake of vitamin D should always be documented. A follow up level may be checked usually 3-6 months after initiating vitamin D replacement .

So letʼs summarize

1. Everyone needs to get their vitamin D level checked at least once and preferably annually at their physical exam.
2. Many people are deficient in Vitamin D and require supplements.
3. The Institute of Medicine recommends 600 IU/day. Realistically I have found a minimum of 1000 IU to 2000 IU/day to be therapeutic.
4. Levels on supplements should be documented to ensure they are reaching target zone.
5. Vitamin D is a hormone-we are going to hear much more about it as research continues to examine its role in the management of chronic disease-STAY TUNED!!