Nearly a year ago now we reported data from one relatively large study that suggested there was no direct connection between intake of vitamin D (in its 25-hydroxy vitamin D formulation) and risk for prostate cancer.
A new paper by Gilbert et al. has now reported results of a systematic review and meta-analysis of data from 25 key papers that have explored the relationships between prostate cancer, dietary intake, and circulating levels of 25-hydroxy vitamin D and 1,25-dihydroxy vitamin D.
The 25 key papers included in the meta-analysis were selected from 24,000 papers initially identified in seven electronic databases (through October 2010).
Gilbert et al. found that:
- In six prospective studies, the odds ratio (OR) for a finding of prostate cancer was 1.14 for each 1,000 IU increase in dietary intake of vitamin D.
- In three prospective studies, the OR for a finding of aggressive prostate cancer was 0.93 for each 1,000 IU increase in dietary intake of vitamin D.
- Five case-control studies examined dietary intake of vitamin D, but there was a high degree of inconsistency between the studies.
- In a total of 14 studies, the OR for a finding of prostate cancer was 1.04 for each 10 ng/ml increase in dietary intake of 25-hydroxy vitamin D.
- In a total of six studies, the OR for a finding of aggressive prostate cancer was 0.84 for each 10 ng/ml increase in dietary intake of 25-hydroxy vitamin D.
- In a total of seven studies, the OR for a finding of prostate cancer was 1.00 for each 10 pg/ml increase in dietary intake of 1,25-dihydroxy vitamin D.
- In two studies, the OR for a finding of aggressive prostate cancer was 0.86 for each 10 pg/ml increase in dietary intake of 1,25-dihydroxy vitamin D.
The authors conclude that, “Published literature provides little evidence to support a major role of vitamin D in preventing prostate cancer or its progression.”
While The “New” Prostate Cancer InfoLink concedes that there may well be an association between vitamin D levels, overall health, and overall survival, it appears to be improbable that there is a direct correlation between vitamin D levels and prostate cancer-specific risk or prostate cancer-specific survival.
Filed under: Diagnosis, Living with Prostate Cancer, Management, Prevention, Risk | Tagged: Prevention, risk, vitamin D |
THE "NEW" PROSTATE CANCER INFOLINK 
In such studies, I am concerned about the possibility that many subjects were low in vitamin D, as so many people are by the prevailing standard (never mind the recent Institute of Medicine report), i.e., too low to have shown the postulated benefit. This possibility is hinted at by Gilbert et al., who note that “Only three studies included only men with a dietary intake greater than the recommended daily allowance of 400 IU in their highest exposure group.” A table of 14 studies lists mean “vitamin D levels” of 19 through 33.1, except for one of 42. There is also the possibility of so-called U-shaped associations, which can be of two kinds, i.e., where either an adverse or protective effect of vitamin D bottoms out at a certain, possibly rather low level and goes up on either side of it.
Appropriately, the authors mention a number of other limitations of their analysis (too numerous for me to mention).
Anyway, I’m still taking about 5,000 IU/d of D3 and aiming for a 25-hydroxy vitamin D level of 50 or so ng/ml, for all its presumed benefits, proven or not.
Herb
AMEN, Herb! My 25-hydroxy vitamin D level on initial testing was very deficient at 25.5 ng/ml. With total daily intake of 9,600 IU, it still took a year before I finally arrived in the 60 to 75 ng/ml range recommended by Stephen Strum and Charles Myers. With a daily total intake of 6,600 IU I have been able to remain within that range. I consider vitamin D supplementation as well as pomegranate extract and omega-3 fish oil as contributing factors to my over 18 years of longevity despite having continued prostate cancer. There are numerous other “studies” that herald the health effects of vitamin D, including prostate cancer. (See also a report that I compiled myself and this article on Dr. Geo’s Natural Health Blog.)
Let’s keep open minds and hope for more high-quality evidence.