New study below.
I do wish Scandinavians would stop doing vitamin D studies on their own populations. For goodness sake - go to the Mediterranean where some men manage to be D-sufficient year round. Why look at a population where the majority are deficient or insufficient for much or the year, & the rest are mostly at the low end of sufficiency.
We have had a series of studies that identify vitamin D as a risk factor for PCa. The "reverse J-shaped association" mentioned in the new paper. Typically, using quartiles of serum D (calcidiol), the lowest quartile would include severely deficient (<15 ng/mL), the second quartile wold be a mix of deficient (<20 ng/mL) & insufficient (<32 ng/mL), the third would be all insufficient & the top quartile would be mostly barely sufficient, for a great part of the year. Oddly, the 4th quartile has higher risk than the lowest in those studies. As though deficiency were protective.
One possible explanation is that men who feel that they are at increased risk for PCa, might be inclined to supplement. Education has been found to be a PCa risk factor - perhaps because of the number of working hours spent indoors. Education + poor D status due to indoor work might lead to supplementation.
Those studies looked at incidence, the new Norwegian/Swedish study looked at mortality. Edward Giovannucci (Boston) was also involved.
"In men with prostate cancer (n = 2282), there was a significant inverse association between {calcidiol} and total mortality after controlling for potential confounders" ("during more than two decades of follow-up from the blood sample collection")
25% extra mortality for D below 50 nmol/L. To convert nmol/L to ng/mL, divide by 2.5. So there was 25% excess mortality for those under 20 ng/mL - which happens to be the cutoff for deficiency. Big surprise - deficiency is not a good place to be, after all:
"In this study population, {calcidiol} was inversely associated with total mortality during more than two decades of follow-up, despite, as previous reported, high {calcidiol} was associated with increased risk of prostate cancer."
A nitpick - the word "high", used in the sentence above, has also been used in the studies I mentioned. It doesn't actually mean high, except in comparison with the lowest group. In the new study, here are the number of men by serum D range:
<12 ng/mL - 160 - severely deficient
12-<20 ng/mL - 1,141 - deficient
20-<28 ng/mL - 1,561 - insufficient
28-<36 ng/mL - 1,023 - insufficient/sufficient (cutoff for sufficiency is 32 ng/mL)
>=36 ng/mL - 494 - sufficient
Total = 4,379 men (~1095 per quartile)
As can be seen, 1,301 are deficient (<20 ng/mL), which places 206 deficient men in the 2nd quartile.
The 4th quartile likely contains some insufficient men.
Less than half of the 4th quartile was >=36 ng/mL.
"... few men in our study had very high concentration {1.1% had concentration ≥ 50 ng/mL and 6% had concentration ≥ 40 ng/mL}"
Deaths:
<12 ng/mL - 32.4%
12-<20 ng/mL - 30.1%
20-<28 ng/mL - 25.6%
28-<36 ng/mL - 26.3%
>=36 ng/mL - 24.1%
Too bad the data is insufficient to see what happens in the 50-100 ng/mL range.
-Patrick
FULL Text: journals.plos.org/plosone/a...
ncbi.nlm.nih.gov/pubmed/269...
PLoS One. 2016 Mar 17;11(3):e0151441. doi: 10.1371/journal.pone.0151441.
Long Term Association between Serum 25-Hydroxyvitamin D and Mortality in a Cohort of 4379 Men.
Meyer HE1,2,3, Støer NC2,4,5, Samuelsen SO2,4, Blomhoff R6,7, Robsahm TE8, Brustad M9, Giovannucci EL3,10, Bjørge T8,11.
Author information
1Department of Community Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
2Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
3Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America.
4Department of Mathematics, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway.
5Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
6Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
7Division of Cancer, Surgery and Transplantation, Oslo University Hospital, Oslo, Norway.
8The Cancer Registry of Norway, Institute of Population-based Cancer Research, Oslo, Norway.
9Department of Community Medicine, UIT The Artic University of Norway, Tromsø, Norway.
10Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America.
11Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
Abstract
OBJECTIVE:
A number of observational studies have shown an inverse association between circulating 25-hydroxyvitamin D and total mortality, but a reverse J-shaped association has also been reported. In a large nested case-control study, serum-25-hydroxyvitamin D (s-25(OH)D) was positively associated with incident prostate cancer. Based on the same study population, the primary aim of the present study was to investigate the association between s-25(OH)D and total mortality.
METHODS:
Men participating in population based health screenings during 1981-1991 and enrolled in a nested case-control study were followed throughout 2007 with respect to all-cause and cause-specific mortality. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated using Cox proportional hazards regression.
RESULTS:
In men with prostate cancer (n = 2282), there was a significant inverse association between s-25(OH)D and total mortality after controlling for potential confounders (HR = 1.25 (95% CI 1.05-1.50), s-25(OH)D <50 nmol/l versus s-25(OH)D ≥50 nmol/l). The corresponding figure among controls (n = 2147) was HR = 1.15 (95% CI 0.88-1.50) and in the total study population HR = 1.19 (95% CI 1.03-1.38). For cause-specific deaths, we found no significant associations.
CONCLUSIONS:
In this study population, s-25(OH)D was inversely associated with total mortality during more than two decades of follow-up, despite, as previous reported, high s-25(OH)D was associated with increased risk of prostate cancer.
PMID: 26986958 [PubMed - as supplied by publisher]