As high vitamin D and ambient UV levels are known to be associated with lower colorectal cancer mortality, a group of scientists from the University of Leiden, Netherlands, investigated in mouse experiments whether this could be a causal relationship. Besides an inhibitory effect on tumor growth, they found that moderate UV exposure also resulted in fewer tumors turning malignant - an effect not seen with vitamin D supplementation. Thus, their study suggests that there is an effect from UV exposure not mediated by vitamin D that reduces progression to malignancy.
The scientists put mice, prone to develop intestinal tumors, on an vitamin D-deficient diet. Apart from a control group, one group was vitamin D supplemented, another group was UV irradiated every day. After six weeks of treatment vitamin D statuses were markedly increased.
The tumor load was significantly reduced in both the vitamin D-supplemented and the UV-exposed group compared to the control group. While only UV exposure slowed down malignant progression.
"The Dutch scientists demonstrate with their study that regular moderate sun exposure reduces the risk of intestinal cancer. Obviously this study could only be done with animals, but the results provide biological evidence for a causal effect on colon cancer in humans as the scientists state in their study: 'As epidemiologic data suggest that our results can be translated to colon cancer in humans, our findings lend support to stimulation of regular moderate sun exposures to lower the risk of colorectal cancers.'", Ad Brand, spokesperson for the Sunlight Research Forum (SRF), explains.
Source:
Heggert Rebel, Celia Dingemanse-van der Spek, Daniela Salvatori, Johannes P.T.M. van Leeuwen, Els C. Robanus-Maandag and Frank R. de Gruijl: UV exposure inhibits intestinal tumor growth and progression to malignancy in intestine-specific Apc mutant mice kept on low vitamin D diet. Article first published online: 5 JUN 2014, DOI: 10.1002/ijc.29002
The scientists put mice, prone to develop intestinal tumors, on an vitamin D-deficient diet. Apart from a control group, one group was vitamin D supplemented, another group was UV irradiated every day. After six weeks of treatment vitamin D statuses were markedly increased.
The tumor load was significantly reduced in both the vitamin D-supplemented and the UV-exposed group compared to the control group. While only UV exposure slowed down malignant progression.
"The Dutch scientists demonstrate with their study that regular moderate sun exposure reduces the risk of intestinal cancer. Obviously this study could only be done with animals, but the results provide biological evidence for a causal effect on colon cancer in humans as the scientists state in their study: 'As epidemiologic data suggest that our results can be translated to colon cancer in humans, our findings lend support to stimulation of regular moderate sun exposures to lower the risk of colorectal cancers.'", Ad Brand, spokesperson for the Sunlight Research Forum (SRF), explains.
Source:
Heggert Rebel, Celia Dingemanse-van der Spek, Daniela Salvatori, Johannes P.T.M. van Leeuwen, Els C. Robanus-Maandag and Frank R. de Gruijl: UV exposure inhibits intestinal tumor growth and progression to malignancy in intestine-specific Apc mutant mice kept on low vitamin D diet. Article first published online: 5 JUN 2014, DOI: 10.1002/ijc.29002
