Ng doesn't yet advocate vitamin D supplements as a means of preventing or treating cancer, however. "Definitive evidence that our results are due to vitamin D would require a randomized clinical trial," Ng said.
Clinical trials are planned to determine if adding vitamin D to chemotherapy after surgery improves colon cancer survival, the researcher said.
However, Ng believes that most people are probably not getting enough vitamin D anyway. "Patients should talk with their physician about whether vitamin D supplementation would be good for their health overall," Ng said.
Despite these and other findings, experts continue to debate the role of vitamin D in cancer treatment and prevention.
Dr. Michael F. Holick, a professor in the department of medicine's Endocrine Laboratory at Boston University, is convinced that high doses of vitamin D can reduce the risk of malignancy and aid in cancer treatment.
"This finding is outstanding," Holick said. "It is consistent with dozens and dozens of observations that have been made in the past decade," he said.
Holick believes that most people do not get enough vitamin D. "Vitamin D deficiency is the most common medical condition worldwide," he said. "Everyone, children and adults, should be on at least 1,000 International Units (IU) of vitamin D a day."
That level is far above current recommendations, Holick said. "Everybody now agrees that those recommendations need to be markedly increased," he said.
The recommended daily doses of vitamin D supplements range from 200 IU a day for those under 50 to 400 IU for those 50 to 70 and 600 IU for people over 70.
For clinical trials to really determine whether vitamin D is effective as a cancer preventative or treatment, the dose of vitamin D needs
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