Lower Vitamin D Levels Correlated to Human Longevity
This research result is noted because it stands in opposition to the present consensus on vitamin D and long term health in humans; the evidence to date supports a correlation between higher levels of vitamin D, a lower risk of age-related disease, and a longer life expectancy. But here we see the opposite result. This sort of outright contradiction is usually indicative of some greater complexity under the hood yet to be outlined and understood - and there's certainly no shortage of complexity in metabolism:
Low levels of 25(OH) vitamin D are associated with various age-related diseases and mortality, but causality has not been determined. We investigated vitamin D levels in the offspring of nonagenarians who had at least one nonagenarian sibling; these offspring have a lower prevalence of age-related diseases and a higher propensity to reach old age compared with their partners.We [assessed] vitamin D levels, [dietary] vitamin D intake and single nucleotide polymorphisms (SNPs) associated with vitamin D levels. We included offspring (n = 1038) of nonagenarians who had at least one nonagenarian sibling, and the offsprings' partners (n = 461; controls) from the Leiden Longevity Study.
The offspring had significantly lower levels of vitamin D (64.3 nmol/L) compared with controls (68.4 nmol/L), independent of possible confounding factors. ... Compared with controls, the offspring of nonagenarians who had at least one nonagenarian sibling had a reduced frequency of a common variant in the CYP2R1 gene, which predisposes people to high vitamin D levels; they also had lower levels of vitamin D that persisted over the 2 most prevalent genotypes. These results cast doubt on the causal nature of previously reported associations between low levels of vitamin D and age-related diseases and mortality.
Very interesting. This is not the first study to query higher Vit.D levels - prostate cancer seems to be worse for both higher and lower levels of Vit.D.
However, the research here quoted also seem a bit odd: these levels are, in fact, somewhat unusual in that the two samples have similar means, implying a lot of overlap between the two. Both therefor probably include sub-optimal Vit.D levels.
See "Previous results from the same nationwide survey showed that 41 percent of men and 53 percent of women are technically deficient in the nutrient, with vitamin D levels below 28 nanograms per milliliter. [28ng/mL = 70 nmol/L]
http://www.sciencedaily.com/releases/2009/11/091115123715.htm
I find this study design to be less than ideal.
Inferring health outcomes from data from the offspring of nonagenarians rather than the nonagenarians themselves seems tenuous unless you limit yourself to offspring with both parents being qualifying nonagenarians.
The data does look interesting for reasons other than the stated conclusions. The offspring of nonagenarians do appear to have less metabolic disease (diabetes and hypertension) but this does not appear to significantly reduce their levels of heart attack, stroke nor cancer which ironically might be attributed to their lower vitamin D levels.
I would like to see a deeper examination of vitamin D status beyond the isoform that is most readily measured to draw any conclusions but if this study was extended longitudinally you could confirm whether the vitamin D status in these individuals is a determinant of their longevity.
To me it seems that this data is stretched beyond a reasonable amount to generate conclusions at odds with a substantial literature base.