DDYSS,
I'm not sure, but I think I may have linked to this study in some of my intense debates with a former contributor who often objected vigorously to me suggesting vitamin D might be helpful for various health problems. But I don't know if the VITAL study ever got it's own thread until this one.
Earlier I mentioned that a lot of the previous non-RCT studies showed little influence on PC occurrence with higher blood levels of Vit D, but did indicate far more benefits for the more aggressive cancers and/or survival( just like this RCT did).
But I did just see this in a summary of the VITAL study from the OP(and again, keep in mind the relatively low dose):
https://www.vitalstudy.org/findings.html Somebody said...
Vitamin D
Cancer. During the trial, 793 cancers occurred among the 12,927 participants assigned to vitamin D, as compared with 824 cancers among the 12,944 participants assigned to vitamin D placebo, a small but nonsignificant reduction. Supplemental vitamin D also did not reduce the occurrence of breast, prostate, or colorectal cancers. However, there was a suggestive 17% reduction in cancer deaths, which became a 25% reduction in analyses that excluded the first two years of follow-up. Excluding early follow-up is a common practice in analyzing data from trials of dietary supplements and cancer because effects of nutritional factors on risk of cancer, a slow-developing disease, typically become clear only after several years.
Although vitamin D did not significantly lower the risk of developing cancer in the total study population, African Americans assigned to vitamin D did experience a suggestive 23% reduction in cancer risk. However, further research is needed to confirm this finding.
So, notice that last part. African Americans normally have the lowest levels of vitamin D, since their dark skin makes far less vitamin D in the lower sunshine conditions of North America, compared to more southern and equatorial regions. Less sunshine means less Vit D for every one, but some people(dark skinned folks) need a lot more sunshine than a pale face like me in order to make adequate vit D from the small amount of sunshine most folks are exposed to. So most likely they had the lowest levels at the start of the test, and most likely stood to benefit the most from an increase in blood levels of vitamin D after taking 2000 IU/day. And sure enough, when they looked at that sub-group they not only had a reduction in cancer deaths, but a suggestive 23% reduction in cancer risk. This group had less chance of getting cancer in the first place, from a mere 2000 iu/day.
If we are starting with a higher base line blood level of vitamin D, it seems likely that to show the same amount of improvement as those who are most deficient, we would need a higher dose. After all, doesn't it seem likely that if we already had near toxic levels of Vit D- say 100 ng/ml - that we would be unlikely to show any further improvement by supplementing with some additional vitamin D? If so, then most likely the folks who already had higher levels to start with compared with African Americans will have a smaller % increase by adding just 2000. If they increased an AA's level from 10 to 20, that is a 100% increase. If they increase a starting level of 30 by 10, that is only a 33.3% increase. In this study, the group that most likely saw the greatest % increase also showed an actual decrease in the diagnosis of cancer, and not merely a reduction in cancer deaths.
Once again, I was so glad to hear that my nieces doctor has had her on 10,000 IU/day of vitamin D since she was diagnosed with stage 4 breast cancer 8 years ago. It does not appear to have hurt her, and may well have helped her.
Post Edited (BillyBob@388) : 12/2/2018 6:22:15 AM (GMT-7)