Thursday, April 03, 2008
Anti-Cancer
Two Studies Examine Vitamin D Intake and Pancreatic Cancer Incidence
Abstracted by Marcia J. Egles, M.D., October 9, 2006 from Halycion G. Skinner, Dominique Michard, et al, "Vitamin D Intake and the Risk for Pancreatic Cancer in Two Cohort Studies" in Cancer Epidemiology Biomarkers a& Prevention Vol. 15, 1688-1695, September 2006.
Pancreatic cancer is the 4th leading cause of cancer deaths in the United States. Every year over 30,000 people are diagnosed. Less than 5% of those diagnosed survive to five years, distinguishing pancreatic cancer as one of the most deadly cancers. As with any disease, prevention is most desirable. Identified risk factors include cigarette smoking and diabetes, but currently there is no known sure way to prevent pancreatic cancer. However, results reported in a recent analysis of dietary information from two major American studies show an association between vitamin D intake and the incidence of pancreatic cancer.
Extensive data collected by mail-in questionnaire in two medically well-known American studies was combined in this new analysis. The first set of data was from 46,771 men aged 40 to 75 years as of 1986 in the Health Professionals Follow-up Study. The second set of data, the Nurses' Health Study, came from 75,427 female nurses aged 38-65 as of 1984. Baseline dietary information was collected in a 131-question food frequency questionnaire. Information on multivitamin usage was included in two studies. In 16 years of follow-up through the year 2000, 365 deaths from pancreatic cancer were identified.
Estimates of vitamin D intake were calculated from the dietary and supplement data. These estimates were validated by actual vitamin D blood levels, which were measured in sample groups of 57 men and 82 women. Factors such as smoking history, which could affect pancreatic cancer rates, were considered in the statistical analysis. Adjustments were made for potential vitamin D intake by sunlight exposure by controlling for subjects who came from similar latitudes. Sunlight exposure was not specifically part of the questionnaires.
The researchers found reductions in the cancer rates of those with the highest vitamin D intakes. In data pooled from the two sets, pancreatic cancer rates were 20% less in those whose vitamin D intake was 600 IU per day compared with those who consumed less than 150 IU per day. The association was even stronger in men, with a 51% reduction in those who consumed greater than 600 IU per day compared to those with the lowest intakes. (The Recommended Daily Allowance(RDA) of vitamin D is 400 IU per day.) After adjusting for vitamin D intake, no link between retinol or calcium and pancreatic cancer rates were observed in this study.
Prior laboratory studies have shown 1,25 dihydroxyvitamin D3 receptor expression in pancreatic cell lines. Forms of vitamin D have also been reported to inhibit pancreatic cell growth. The results of this new dietary study point to an important association between vitamin D and the incidence of pancreatic cancer.
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