Studies have shown that with higher latitude there is a decreased blood level of vitamin D3, which is associated with a much higher rate of pancreatic cancer. A group of researchers under Cedric F. Garland from the University of California San Diego used 2008 data from 107 countries and determined a cloud-adjusted ultraviolet B (UVB) exposure and related this to the incidence of pancreatic cancer. Residents in countries with low UVB exposure were found to have cancer of the pancreas rates that were six times greater when compared to countries with high UVB exposure rates. This was after adjustments were made for other risk factors like smoking, obesity and alcohol consumption.
This leaves the question whether the pancreatic cancer rate would go down, if people with low vitamin D3 levels were taking in vitamin D3 supplements. Studies have shown that in fact oral supplementation with vitamin D3 reduces rates of pancreatic cancer with the rates of cancer being lower, the higher the supplementation with vitamin D3 is.
One of the problems in the past were the minute doses of vitamin D that were recommended. In the past the common recommended supplementation dose was 400 IU of vitamin D3 per day. Now doses of 2000 to 4000 IU units of vitamin D3 are usually recommended. But the better way to proceed is to start supplementing with 4000 IU of vitamin D3, then measure the 25-hydroxy level of vitamin D in the blood and readjust the dose up or down. If the level is found to be low, the dose needs to be increased; if the level is high, a lower dose has to be taken. In the population people are different: there are poor absorbers and good absorbers of vitamin D3. The optimal level of vitamin D3 in the blood is 40 to 60 ng/ml of 25 hydroxy vitamin D as measured in the US, which translates to 100 to 150 nmol/L measured in metric units in other countries. LifeExtension recommends as optimal range 50-80 ng/ml (Ref. 1).
Vitamin D3 has been shown in other publications to have a beneficial broad-spectrum effect against the development of many cancers. It is one of the supplements that should be considered essential for health and longevity.
More info on vitamin D3: http://www.askdrray.com/the-super-powers-of-vitamin-d/
Ref. 1. LifeExtension: “Disease Prevention and Treatment”, 5th edition, published 2013 by LE Publication Inc. in the US.