The bad pun is not mine. It belongs to Michael F. Holick, writing in June's Mayo Clinic Proceedings [1].
Holick is one of the big names in Vitamin D research [2]. His article is a commentary on the research of Dr Daniel Dudenkov.
Dudenkov uses 20-50 ng/mL as his reference range. Deficiency is <20 ng/mL. {The reference range is usually split between insufficiency & sufficiency where the split is usually at 32 (sometimes 30).}
"... important was the observation that the {mortality} HR for those who had a 25(OH)D level greater than 50 ng/mL was 1 and thus not different from the reference range."
"For white patients who had 25(OH)D levels of less than 12 and 12 to 19 ng/mL .., their unadjusted all-cause mortality hazard ratios (HRs) were 2.6 and 1.3, respectively, when compared with their reference range of 20 to 50 ng/mL."
"The observation by Dudenkov et al1 is thus supportive of a multitude of studies worldwide reporting that the maintenance of vitamin D sufficiency can result in substantial reductions in cancer, cardiovascular, and all-cause mortality rates. However, is too much of a good thing bad for you? The Institute of Medicine in its report10 also recognized that there was an inverse relationship of all-cause mortality and serum 25(OH)D levels less than 30 ng/mL. In addition, on the basis of a few studies, the Institute of Medicine raised the concern that when 25(OH)D levels are greater than 30 ng/mL, there is an increased risk of all-cause mortality. They concluded that a blood level of 25(OH)D greater than 50 ng/mL potentially increases the risk of mortality, thereby profiling a J-curve or U-curve phenomenon. More recent studies have challenged this notion of the J or U curve pertaining to serum 25(OH)D levels that are either salutary or potentially injurious. Garland et al11 in a meta-analysis of 32 studies found a dramatic decrease in all-cause mortality with higher 25(OH)D levels; the maximum benefit was observed when blood levels of 25(OH)D were greater than 30 ng/mL, and this benefit extended above 70 ng/mL. Dudenkov et al1 in their cohort confirmed that there is no increased mortality risk when blood levels of 25(OH)D are greater than 50 ng/mL."
Here is a brief video of Dr Daniel Dudenkov
youtube.com/watch?v=CEp8ZRz...
-Patrick
