April 17, 2017
416 Vitamin D & Cancer [17 April 2017
A randomized clinical trial of 2,300 postmenopausal women in Nebraska looked at the effects of vitamin D supplementation on all types of cancer. The test group received 2,000 IU of D3 and 1,500 mg calcium while the control group was given placebos. After four years 109 of the women had developed cancer, 3.9% in the treatment group; 5.6% in the control group. While this amounts to a 30% decrease in the vitamin D group, the small numbers made the finding not statistically significant.
A similar study by the same researchers published in 2007 found a 77% decrease in cancer incidence in the vitamin D group (statistically significant that time!). [see #367]. Other studies have found similar results [#254].
It was interesting to see how different online journals reported this current study. Medical News Today headline reads “Clinical trial finds that vitamin D, calcium, have no effect on cancer risk”. Predictably Mercola’s headline reads “Higher Vitamin D Levels Lower Cancer Risk”. A more honest headline appeared in Science Daily which simply posed the question “Does Vitamin D decrease risk of cancer?”
What do the authors themselves say about the study? The principal author Joan Lappe, a professor of medicine at Creighton University, Omaha, said “This study suggests that higher levels of [vitamin] D in the blood are associated with lower cancer risk. These results contribute to a growing body of scientific findings…that vitamin D is a critical tool in fighting cancer.”
There are some limitations to the study that need to be discussed. The participants in both Nebraska studies were menopausal women so the findings can’t be extrapolated to men or to younger women. Also most of the participants were Caucasian so results for people with darker skin may be different. Also some adverse effects were noted in the treatment group that may be related to the vitamin D and calcium supplementation: 16 of the treatment group vs 10 of the control group developed kidney stones, and 6 vs 2 developed high serum calcium levels.
And, as always, the authors conclude with a call for more research: “The results of this study lend credence to a call for more attention to the importance of vitamin D in human health and specifically in preventing cancer”.
For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.