Vitamin D-Supplement in the Winter?

The Sunshine Vitamin
Vitamin D is considered the “Sunshine” Vitamin.  In all reality, vitamin D is a hormone that effects nearly every organ system in the body.  Vitamin D deficiency has been a hot topic and there are calls for supplementation and screening.  Low vitamin D has been reported to be linked with cancer risk, multiple sclerosis, depression, and of course, bone disease.  Recently, though, the vitamin D craze has been tempered by lack of evidence.  The United States Preventive Services Task Force (USPSTF) called the evidence for screening for vitamin D deficiency, “insufficient” and calls for more studies. [1]
 vitd1
Sources of Vitamin D
There are only 2 natural sources of vitamin D that are in creation.  Sunshine and food.  For those living way North of the equator (or South), then your exposure to the Sunshine vitamin is limited.  Also those with darker skin (including Asians, African Americans and Hispanics) can’t absorb vitamin D.
The other issue is that there are really not many “natural” sources, or of vitamin D in food.  Most of what we think are supplemented with Vitamin D.  Specifically milk and other dairy products. There are several foods that are high in Vitamin D.  A nice chart in the NEJM is shown here. [2]  Bottom line, to get more Vitamin D through food, eat Fatty Fish (wild over farmed if possible), the mushrooms (sun dried over fresh, when possible) and egg yolk.  It is notable to see that Omega-3s that are more abundant in fatty fish also has higher levels of vitamin D.  So, eating salmon, mackerel, sardines, and tuna can give you more of omega-3s and vitamin D.
What does Vitamin D do?
Vitamin D precursor in your skin gets transformed by UV rays to vitamin D.  Or you ingest foods rich in vitamin D.  This then goes to the liver where a hydroxy group (OH) gets added to the 25-carbon, making it 25-OH Vitamin D.  Then the kidney processes it and adds another hydroxy group (OH) on the 1-carbon, making it 1,25 dihydroxy-vitamin D.  (as a side note, this is probably the best thing I got from organic chemistry).
What are the benefits of Vitamin D?
There are numerous purported benefits, but not many scientifically proven benefits.  Perhaps the strongest benefit is for bones and muscles.  After that, the evidence for heart disease, diabetes, cancer and autoimmune diseases are still being worked out.  Let’s take a closer look at these.
Muscles and Bones
The best evidence for Vitamin D are bones.  Rickets is a disease of children and it was this “essential vitamin” that was found to be lacking in children who had rickets.  Children had bow legs and “rachitic rosaries” on their chests due to ineffective bone growth.  Children exposed to UV light was found to improve.  (Not sure who thought of lighting kids up with lamps back in the 1800’s, but it sure worked).  Then researchers found this compound essential to life.  This was the 4th essential nutrient found in food, so they named it a Vitamin “D”  (after Vitamin A, B and C).

Once this vitamin was found, supplementation and food fortification helped basically eliminate rickets. However, recently, reports of a reemergence of rickets appeared in the medical literature. Black children were especially found susceptible. This prompted guidelines to recommend increase levels of vitamin D in infants, especially those who are primarily breastfeeding since absorption of vitamin d is poor from breast milk.

For adults, the rickets version is called osteomalacia. Similarly, adults with osteomalacia has severe bone pain, in the chest and shins. Theories abound regarding if atypical chest pains, costochondritis and even shin splints have relationship to vitamin d deficiency. To this date, there is limited evidence, but it makes sense.    Taking care of patients, I kept seeing those with atypical chest pain, worked up and eventually found to have vitamin d deficiency. I wrote about a case report [3] of patients with chest pain which appeared to be linked to vitamin D deficiency since I was seeing this apparent connection in my clinic.

Even patients with chronic shin splints, chronic who do not get quickly better with rest and rehab, consider vitamin d deficiency!  A recent reported article demonstrated that low vitamin D levels were related to stress fractures.  [4]

The Controversy
After that, the research gets murkier. Those clinicians who propose vitamin D for everyone, are very shortsighted. There are theoretical benefits, even a RCT that demonstrated reduced cancer risk. However, there are other studies that suggest that high vitamin D levels increases heart disease. (Probably by building up coronary calcium). Even for musculoskeletal benefits, an Institute of Medicine article felt that research only supported optimal bone health with levels up to 20ng/ml. However, the endocrine guidelines recommends to supplement up to 30ng/ml.

UPDATE:  Just recently JAMA published an article that showed no benefits of high dose VitD supplementation 60,000 IU vs. 24,000 IU monthly to get levels over 30g/dl in falls.  This was accompanied by an editorial that stated that we should be cautious when recommending supplementation. [5]

Prevention
So, can we prevent this from vitamin D supplementation?  There’s not enough research beyond prevention of rickets, but here are some thoughts.

Children
To prevent rickets, 400 int. units daily is recommended. This is either in 4 glasses of milk daily or through salmon, (wild) twice a week or 15 minutes of direct sunshine for caucasian skin. Everyone else should supplement. Read labels of the vitamins, and ensure you are getting up to 400 iu.  My kids love the gummy vitamins but ensure you get the ones with adequate vitamin D!  Read the labels.

For adolescents, recommendations are higher, 600iu
For general adults, 600-800 iu are recommended

For older adults at risk for falls, good research shows that vitamin d is useful for falls prevention.  800 int. units should be adequate to prevent falls for both men and women.

Conclusion
My take is that vitamin D, which is essential for bone health, should ideally be from natural, God made sources.  That is, sunshine, fish and mushrooms.  IF you can’t get it from these sources AND you are having symptoms, then it is when supplementation should be considered.

REFERENCES

  1.  USPSTF Recommendation for Vitamin D screening.  http://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/vitamin-d-deficiency-screening
  2. Hollick, MF.  Vitamin D Deficiency.  NEJM 2007;357:266-281.  Found at: http://www.nejm.org/doi/full/10.1056/NEJMra070553
  3. Oh RC, Johnson JD. Chest pain and costochondritis associated with vitamin d deficiency: a report of two cases.  Case reports in Medicine 2012: 375730.  Found here: http://www.hindawi.com/journals/crim/2012/375730/
  4. Miller JR et al.  Association of Vitamin D with Stress Fractures.  A retrospective cohort study.  Journal Foot Ankle Surgery 2015;55:117-120.  Found here:  http://www.jfas.org/article/S1067-2516(15)00374-9/abstract
  5. Cummings SR.  Vitamin D Supplementation and increased risk of falling: A cautionary tale of vitamin supplements retold.  JAMA 2015, January 4 2016.  Found here:  http://archinte.jamanetwork.com/article.aspx?articleid=2478893
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Posted on December 28, 2015, in Nutrition and tagged , , , . Bookmark the permalink. Leave a comment.

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