Vitamin D and Pancreatic Cancer

The prevailing thought is that higher vitamin D levels offer protection against many cancers. Here is one possible explanation or method, Then this finding pops up as recently mentioned in a Wall Street Journal Blog by Katherine Hobson:

"...A recent editorial in the American Journal of Epidemiology discussing the issue of anti-cancer claims for various vitamins over the years notes that an analysis of existing research found no association between levels of vitamin D in the blood and several cancers. But it did find that “the risk of pancreatic cancer was doubled for those in the highest quintile of circulating vitamin D levels.” The editorialist, Tim Byers of the  University of Colorado Comprehensive Cancer Center and the Colorado School of Public Health, continues:

This observation is disconcerting both because pancreatic cancer is now the fourth leading cause of cancer death in the United States and because the proponents of the vitamin D hypothesis are now arguing that substantially elevating circulating blood concentrations into that range should be a nutritional policy objective for the general population.

Brannon (Patsy Brannon, a professor of nutritional sciences at Cornell University and member of the IOM panel that produced the report) tells the WSJ that the panel also saw a tentative association between death from prostate cancer and other causes in men with high blood levels of the vitamin, though it may not ever be possible to test the validity of those connections...."  end of aricle copy

Other studies have arrived at just the opposite result. There may have been errors in the above pancreatic cancer study. This vital dilemma needs to be settled. Remember that cancers reduce vitamin D levels so when vitamin D measurements are taken is critical. The Nurses Health Study found higher Vitamin D levels gave a 41% protection against pancreatic cancers. One has to remember that in many of these studies the range for vitamin D was only that achieved from sunlight and diet, while in other studies, supplements were used. A vital fact that maintaining a range of vitamin D levels within certain parameters may be the most optimal approach. A review report of studies on vitamins and cancers> ref  ref

Below is another study on sun exposure D production and reduced risk with one exception as noted above:  

Ann Epidemiol. 2009 Feb;19(2):89-95. Epub 2008 May 27.

Vitamin D and pancreatic cancer.

Stolzenberg-Solomon RZ.

Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department Health Human Services, Rockville, MD, USA. rs221z@nih.gov

Abstract

"Sun exposure has been associated with lower death rates for pancreatic cancer in ecological studies. Skin exposure to solar ultraviolet B radiation induces cutaneous production of precursors to 25-hydroxy (OH) vitamin D (D) and is considered the primary contributor to vitamin D status in most populations. Pancreatic islet and duct cells express 25-(OH) D(3)-1alpha-hydroxylase that generates the biologically active 1,25-dihydroxy(OH)(2) D form. Thus, 25(OH)D concentrations could affect pancreatic function and possibly pancreatic cancer etiology. Serum 25-(OH)D is the major circulating vitamin D metabolite and is considered the best indicator of vitamin D status as determined by the sun and diet. Although recent prospective epidemiologic studies of higher predicted vitamin D status score and vitamin D intake and pancreatic cancer risk suggest protective associations, a nested case-control study showed a significant 3-fold increased risk for pancreatic cancer with higher vitamin D status. Limitations of these studies include the former do not measure vitamin D status on pancreatic cancer cases and the later was conducted in a male smoker population. More research is needed, particularly examination of pre-diagnostic vitamin D status and risk of pancreatic cancer, prior to conclusions for vitamin D's potential role in the etiology of this highly fatal cancer." end of copy

ANALYSIS:

While making it seem difficult, it appears these contradictory results reveal some facts to aid wise supplement choices.

1. Do not take vitamin D if you smoke. Since the hormone form of vitamin D offers cancer protection, smoking may interfere with this conversion and thus raise the amount of the nonactive vitamin D which is the measured form. The hormone form is made from the nonactive form.
2. Men need to be a little more cautious taking vitamin D according to results of some studies on prostate. Women seem to exhibit less adverse effects at higher doses.
3. Do not consume extra vitamin D if there is a family history of pancreatic cancers. There may be a genetic link to a missing or inactive gene. Plus, especially if undergoing treatment for pancreatic cancer since vitamin D could block chemo drugs cancer cell killing action. ref
4. Maintain accepted ranges (25-35 ng/mL, 60-80 nmol/L) until science satisfies unanswered questions, unless under supervision of your health professional.
5. Some cancers produce a mechanism to destroy hormone vitamin D and prevent conversion of the storage form into the active hormone form. Other cancers do not. ref 

Reference: www.cancer.gov/cancertopics/factsheet/prevention/vitamin-D 

More facts are needed. The recent explosion of higher Vitamin D dosages, 2500 up to 10,000 IUs (label says 1 per week) is not without some controversy. Just because toxicity of vitamin D is not often seen until 40,000 or more units taken over a period of time doesn't mean the actions of the higher D amounts are not without some adverse ramifications due to increased actions, other than from vitamin D toxicity. Read the vitamin D article on this website. An once of precaution is better than a pound of undoing future adverse effects. These effects may initially be positive and only later turn negative. Science is finding vitamin D relationships in many areas outside of bone health: Autoimmune conditions, cardiovascular health, diabetes, autism, depression, prostate and breast tissues, and the list is still growing.