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>In the analysis of the entire 25,000-person group, the risk of cancer was not significantly reduced. However, evidently higher vitamin D levels take time to ha

>In the analysis of the entire 25,000-person group, the risk of cancer was not significantly reduced. However, evidently higher vitamin D levels take time to have an effect, because when the data from the first one or two years were omitted, there was a 25% significant reduction in the all-cancer mortality rate. The original article [0] mentions the "exclude early years" analysis was post hoc. This wasn't a formal result, but it is a good idea for a new experiment. Same with the first study mentioned. It would be cool if the hazard decrease showed up in a larger study, but a confidence interval of 0% to 90% isn't much to rely on. [0] https://www.nejm.org/doi/full/10.1056/NEJMoa1809944?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed https://www.nejm.org/doi/full/10.1056/NEJMoa1809944?url_ver=...

danesparza 7y ago
The body produces Vitamin D when exposed to sunlight. This article indicates that specifically _supplements_ do not significantly reduce cancer rates: https://www.cancer.gov/news-events/cancer-currents-blog/2018/vitamin-d-supplement-cancer-prevention https://www.cancer.gov/news-events/cancer-currents-blog/2018...
- corprew 7y ago
  Although it should be noted in that article: "Over the follow-up period, there were 341 deaths from cancer: 154 among participants who took vitamin D (1.1%) and 187 among those who took the placebo (1.4%). Although this difference was not statistically significant, the difference in cancer deaths between the groups started to widen over time, the researchers reported. The researchers plan to follow the participants for another 2 to 5 years, to see if a statistically significant difference in cancer deaths emerges. Laboratory studies have suggested that high blood levels of vitamin D may decrease the aggressiveness of cancer cells and the likelihood of metastasis, explained Dr. Manson. If so, longer follow-up will be needed to assess its effects on the risk of death from cancer, she added. Other studies have suggested that regular use of vitamin D supplements may reduce the risk of dying from cancer, she said." So they're still continuing to follow that up long term to see if it has a longer term effect.

danesparza 7y ago

The body produces Vitamin D when exposed to sunlight. This article indicates that specifically _supplements_ do not significantly reduce cancer rates: https://www.cancer.gov/news-events/cancer-currents-blog/2018/vitamin-d-supplement-cancer-prevention https://www.cancer.gov/news-events/cancer-currents-blog/2018...

corprew 7y ago
Although it should be noted in that article: "Over the follow-up period, there were 341 deaths from cancer: 154 among participants who took vitamin D (1.1%) and 187 among those who took the placebo (1.4%). Although this difference was not statistically significant, the difference in cancer deaths between the groups started to widen over time, the researchers reported. The researchers plan to follow the participants for another 2 to 5 years, to see if a statistically significant difference in cancer deaths emerges. Laboratory studies have suggested that high blood levels of vitamin D may decrease the aggressiveness of cancer cells and the likelihood of metastasis, explained Dr. Manson. If so, longer follow-up will be needed to assess its effects on the risk of death from cancer, she added. Other studies have suggested that regular use of vitamin D supplements may reduce the risk of dying from cancer, she said." So they're still continuing to follow that up long term to see if it has a longer term effect.