Vitamin D levels

[cdamaden]

Article in NY Times, skeptical on current trend to raise Vitamin D levels

https://www.nytimes.com/2017/04/10/heal ... hone-share


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[circular]

I apologize for not having a link or a title, but I saw a paper in the last several months that indicated that new blood levels of vitamin D don't stabilize after supplementation begins until three years after starting. It was saying that supplementing and checking a year later and then staying at that supplementation level may not be good. Your levels could keep rising to a higher level than you want to go.

(I had the paper open in my browser for some time and never got around to posting. Now it's gone and I can't find it online but thought I'd mention it in case someone wants to look for it )

[Julie G]

The article focuses primarily upon heart disease and cancer. It never mentions cognition, not once. We have a plethora of studies suggesting higher vitamin D levels are positively associated with cognition. Here's the latest:

Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults.
https://www.ncbi.nlm.nih.gov/pubmed/28167237

Nonverbal (visual) memory seems to benefit from higher doses of vitamin D supplementation, particularly among those who are insufficient (<75nmol/L) at baseline, while verbal memory and other cognitive domains do not. These findings are consistent with recent cross-sectional and longitudinal studies, which have demonstrated significant positive associations between 25(OH)D levels and nonverbal, but not verbal, memory. While our findings require confirmation, they suggest that higher 25(OH)D is particularly important for higher level cognitive functioning, specifically nonverbal (visual) memory, which also utilizes executive functioning processes.

[Rob]

The heart attack study they link in the article (here) was providing 100,000 IU on a monthly basis for ~ 3 years. They didn't find significant differences between placebo and intervention groups.

I find using 100,000 odd. I haven't looked up to see what the efficacy of using that vs a daily lower dose (~3,000 IU) would be, but I would be surprised if there weren't differences, e.g. why monthly doses - why not year doses? Also, 3 years isn't that long of a time, perhaps they've continued watching the cohort and have a longer timeline.

The cancer study they link (here) followed postmenopausal women for 4 years, with the intervention group getting 2,000 IU per day D3 and 1,500 mg per day calcium. The other group got placebo. Total diagnosis of confirmed cancer was 109 participants, 45 (3.89%) in the treatment group and 64 (5.58%) in the placebo group, P = .06. They then say in their conclusion that:

... supplementation with vitamin D3 and calcium compared with placebo did not result in a significantly lower risk of all-type cancer at 4 years.

My initial reaction is the same as the commenter in Pubmed, below the abstract, Kenneth J Rothman:

Lappe et al. (1) reported that women receiving vitamin D and calcium supplementation had 30% lower cancer risk than women receiving placebo after four years (hazard ratio (HR)=0.70, 95% confidence interval (CI): 0.47 to 1.02). Remarkably, they interpreted this result as indicating no effect. So did the authors of the accompanying editorial (2), who described the 30% lower risk for cancer as “the absence of a clear benefit,” because the P-value was 0.06. ...

Although, I do get annoyed by people overplaying relative risk vs absolute risk - if anything this study hints that there is a beneficial effect. The whole P < 0.05 as a test of "significance" is important, but arbitrary.