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Frequently Asked Questions

 


I have recently seen a lot of news articles about the relationship between vitamin D and cancer prevention. Should we all run out and get more Vitamin D supplements?

I agree that information related to vitamin D and cancer prevention and also cancer treatment has recently seen a lot of press! In fact, I recently heard Dr. Robert Heaney (a leading vitamin D researcher) speak about new research related to vitamin D. I came away from that presentation thinking “Wow, there is a lot of new information since I last studied vitamin D in depth!”

The role of vitamin D for human health and the best way to achieve optimal vitamin D status is a controversial area of ongoing scientific and medical research. Rather than repeat a substantial amount of information about the newer understanding of vitamin D metabolism and suggested intakes for optimizing human health, not just its effects on cancer, I am going to share several links to excellent articles that have already done that.

From Muscle Strength to Immunity, Scientists Find New Vitamin D Benefits
ScienceNews.org – October 9, 2004
http://www.sciencenews.org/articles/20041009/bob8.asp

Vitamin D – What’s Enough?
ScienceNews.org – October 16, 2004
http://www.sciencenews.org/articles/20041016/bob9.asp

Vitamin D Boosts Calcium Potency
ScienceNews.org – November 12, 2005
http://www.sciencenews.org/articles/20051112/food.asp


At Dr. Heaney’s presentation (October 2005), he recommended that everyone have a serum vitamin D level checked as part of an annual physical. Vitamin D is present in many forms in the body, and the recommended (and standardized) form to have evaluated is 25-hydroxy-vitamin D. Many labs can do this test although it may need to be sent out from your local facility (the University of Michigan sends this lab test out to The Mayo Clinic).

Dr. Heaney recommends a achieving a serum 25-hydroxy vitamin D level of approximately 75-80 nanomoles/liter. (Note – The reference range indicated as normal may be substantially less than this on the test results returned to you.) The goal of 75-80 nanomoles/liter is based on research that demonstrated maximum calcium absorption at this serum level of 25-hydroxy vitamin D plus optimal activity of vitamin D in several tissues in the body. (Note – If your lab results are shown in nanograms/milliliter, multiply that result by 2.5 to convert to nanomoles/liter – personal communication with Dr. Heaney).

Although there is not much evidence that higher levels will provide benefit, serum levels of 25-hydroxy vitamin D as high as 150 nanomoles/liter have been observed in outdoor construction workers in the tropics without evidence of vitamin D toxicity.

The means of achieving a serum level of 25-hydroxy vitamin D at a level approaching 80 nanomoles/liter are debatable in regards to how much is possible from sunlight versus food sources versus dietary supplements. If using a dietary supplement source of vitamin D, Dr. Heaney showed research demonstrating that the form called vitamin D3 or cholecalciferol (in contrast to the plant form of vitamin D2 or ergocalciferol) is more effective at optimizing calcium absorption along with its impact on an important hormone in calcium metabolism called parathyroid hormone (or PTH).

So, I have had my blood level tested for 25-hydroxy vitamin D. With an intake of approximately 1000 IU/day of vitamin D3, my level is right up there at the level Dr. Heaney is recommending. I obtain 1000 IU’s of vitamin D3 from dietary supplements (400 from a multi-vitamin, 400 from a separate vitamin D3 supplement, 200 from additional calcium supplements) plus whatever I might eat from the few food sources of vitamin D are available (fortified milk, soy milk, and OJ, egg yolks, some fish, and liver-which I do not eat) plus whatever my body makes from the sunshine I receive (not much in Michigan from November until April).

Also be aware that sunscreens and windows block the formation of vitamin D in the skin. Dermatologists are very concerned about the use of tanning beds and unprotected skin exposure due to the increased risk of skin cancers.
(The vitamin D questions: how much do you need and how should you get it? Wolpowitz D ,Gilchrest BA, J Am Acad Dermatol. 2006 Feb;54(2):301-17. Epub 2006 Jan 4.)

Another word of caution, cod liver oil may be a high source of vitamin D, but it is too high in vitamin A for me to recommend. (See my faq about risks associated with high intakes of vitamin A http://www.cancerrd.com/faqs/faq46.htm )

It is anyone’s guess at this point what would be the optimal intake and blood level of vitamin D needed to minimize the risk of recurrence for cancer. I think it is sensible and prudent to try to achieve the current suggestions for optimizing overall health of 1000 IU’s per day. I will be paying attention to this field of research closely and will update this faq with new information as it develops.

Some additional sources of information on the topic of vitamin D and cancer:
(1) Vitamin D deficiency can increase cancer risk
http://www.nlm.nih.gov/medlineplus/news/fullstory_29041.html

(2) Vitamin D needed to cut cancer risk
http://www.sciencedaily.com/releases/2005/12/051228012407.htm

(3) Vitamin D may lower some cancer risk
http://www.webmd.com/content/article/116/112304?src=RSS_PUBLIC

Excellent evaluation and discussions of the following research articles are available for viewing at http://www.CancerNutritionInfo.com (fee for full access but free trial subscription available):

(4) Benefits of Vitamin D Supplements for Prostate Cancer Patients
This article discusses the results of a study on the potential benefits of a dietary vitamin D supplement for men who have been treated for prostate cancer (Nutr Cancer. 2005;51(1):32-36).

(5) Vitamin D Status, Calcium Supplements & Colorectal Cancer
This article review discusses the findings of a recent study on vitamin D levels in the body, calcium dietary supplements and colorectal adenomas, which are believed to be precursors to colorectal cancer (J Natl Cancer Inst 2003;95(23):1765-1771).

(6) Dietary Vitamin D, Calcium & Breast Cancer Risk
This article review discusses the findings of a study on how dietary vitamin D and calcium may affect risk of breast cancer (Review of Cancer Epidemiol Biomarkers Prev. 2004;13(9):1466-1472).

Posted 02/06

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Vitamins

Soy Shake I have recently seen a lot of news articles about the relationship between vitamin D and cancer prevention. Should we all run out and get more Vitamin D supplements? posted 2/06
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Soy Shake Do you have recommendations for herbs and vitamins that children should use to recover from a bone marrow transplant? posted 3/05
Soy Shake Can you provide a list of all chemotherapy drugs called alkylating agents that may potentially have interactions with antioxidant supplements during chemotherapy? posted 10/02
Soy Shake Should I consume antioxidants during my cancer therapy? posted 12/01, updated 10/02
Soy Shake Should I stop drinking green tea during chemotherapy to avoid consuming too many antioxidants? posted 7/05
Soy Shake I have recently heard that Vitamin A may be linked to osteoporosis. I see Vitamin A in nearly everything on food labels, even my soymilk. What is the connection and how much should I be consuming? posted 5/02, updated 2/03

 


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These questions and answers are intended to be of a general informative nature. Please consult with the Registered Dietitian in your cancer center or your health care provider for nutritional advice that can be individualized to your specific medical condition.

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Phone/Fax: 734/996-9260

P.O. Box 130221, Ann Arbor, MI  48113

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