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The last study to determine whether vitamin D can prevent cancer is negative, but many trials of this type have occurred and the results have been contradictory.
The latest results come from New Zealand. the study on the evaluation of vitamin D (ViDA), which involved 5108 participants in the community. The main purpose of the ViDA study was to study cardiovascular outcomes.
He found that taking high doses of vitamin D for 4 years without calcium was not associated with a reduction in the incidence of cancer or cancer mortality. The cancer rate during a median follow-up of 3.3 years was 6.5% for those who received 100,000 IU of vitamin D3 each month. In comparison, the cumulative incidence of cancer during the same period was 6.4% among placebo participants (adjusted risk ratio [HR] 1.01; P = 95). Vitamin D supplementation may not be associated with cancer prevention and should not be used for this purpose, "says Robert Scragg, MBBS, PhD, of the University of Auckland, and his colleagues [19659004]. ] JAMA Oncology.
Scragg and colleagues note that other randomized clinical trials on vitamin D supplementation have yielded inconsistent results. They point out that these latest findings on cancer incidence are consistent with earlier randomized clinical trial results from community samples from the United States and the United Kingdom, and that they are also Consistent with the results of a recent meta-analysis of vitamin D supplementation trials
Asked for comments, Carolyn Y. Fang, Ph.D., Cancer Prevention and Control Officer, Fox Chase Cancer Center from Philadelphia, Pennsylvania, said that despite the null findings of the current study, "there are doctors should talk to patients who have vitamin D deficiency the way they can make dietary or behavioral changes healthy and if taking a vitamin D supplement is warranted, says Fang Medscape Medical News. "However," she added, "from a population health perspective, key questions about the appropriate vitamin D" dose "for cancer prevention and how long to take that dose to influence Positive health The results of previous studies on the question of whether vitamin D can reduce the risk of cancer are contradictory.
In the largest and most comprehensive observational study to date, An international research group concluded that prior to 1965, the SUNSHINE study showed that high-dose vitamin D supplementation significantly improved progression-free survival in patients with advanced colorectal cancer who were receiving chemotherapy.
Last month, results from an international collaborative meta-analysis indicated that higher levels of vitamin D in the blood can protect against cancer color In 2016, a review of the literature that included 28 new meta-analyzes and 100 trials published between 2013 and 2017 found that 10 to 20 μg per day of vitamin D can reduce all-cause mortality and cancer death in the women.
Study Details
The ViDA Trial was a randomized, double-blind, placebo-controlled clinical trial that was conducted from March 1, 2011 to July 31, 2015. The primary outcome was: the effect of vitamin D supplementation on the incidence of cardiovascular disease, but also the possible effects on acute respiratory infections, falls and non-vertebral fractures.
Scragg and colleagues report that the results of an earlier meta-analysis suggest that vitamin D supplements were "associated with a reduction in cancer mortality, but not at the incidence of cancer" .
The participants in the ViDA study were recruited from 55 family medicine practices in Auckland. The average age of the participants was 66 years, 58% men and 83% ethnic or European origin. The rest of the participants were of Polynesian or South Asian origin.
Of the participants, 320 (6.3%) used tobacco and 2173 (42.5%) said they had ever smoked.
About 1214 (23.8%) participants said that they had already been diagnosed with cancer. The cancer cases were evenly distributed between the two groups: out of 2558 participants in the vitamin D group, 622 (24.3%) had already been diagnosed with cancer, compared to 592 out of 2550 (23.3%) in the group placebo. In the vitamin D group, an initial bolus of 200,000 IU oral vitamin D3 was administered, followed by monthly doses of 100,000 IU. All participants were followed for a period of up to 4.2 years.
Initially, the average concentration of seasonally adjusted 25-hydroxyvitamin D (25 [OH] D) was 26.5 ng / mL. At follow-up, the mean concentration in a random sample of 438 participants was consistently greater than 20 ng / mL in participants taking vitamin D compared to those taking placebo.
The study showed that 375 participants had been diagnosed with cancer after randomization, there was no difference in the percentage of vitamin D intake compared to placebo. The most common cancers were in situ melanoma, diagnosed in 71 participants, and malignant melanoma, diagnosed in 55 participants. Prostate cancer was diagnosed in 64 participants, colorectal cancer in 38, breast cancer in 36 and lymphoid and hematopoietic cancer in 36.
There were no significant differences between men and women, in participants with serum 25 (OH) D concentrations greater than 20 ng / mL vs less than 20 ng / mL, or in the time of diagnosis after randomization. Similar results were observed for all secondary outcomes. These were defined as all malignant neoplasms reported more than 12 months after randomization until the discontinuation of the study drug on July 31, 2015.
The fact that 25 % of participants had vitamin D deficiency may have limited statistical power. subgroup, say the researchers.
Funding for the study was provided by the Health Research Council of New Zealand. Dr. Scragg and study coauthors revealed no relevant financial relationship.
JAMA Oncol. Posted online July 19, 2018. Abstract
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