He may know a lot about the biochemistry of vitamin D but his understanding of natural selection leaves something to be desired, if “two-thirds of the people are vitamin D-insufficient” outside Europe and North America it’s because those places are inhabited by non Europeans who have a natural homeostasis of vitamin D which is lower than whites. These are people who live nearer the equator remember. Think it’s down to more pigment in the skin?
,’Common genetic determinants of vitamin D insufficiency: a genome-wide association study’ found none of the genes identified are linked with skin pigmentation
‘A systematic review of the association between common single nucleotide polymorphisms and 25-hydroxyvitamin D concentrations’ “‘We speculate that recently identified U-shaped relationships between 25OHD concentrations and disease outcomes (i.e. increased risk at both high and low concentrations) may reflect a mixture of genotype-defined subgroups. Further research is required in order to clarify the genetic architecture underlying 25OHD serum concentrations, and to unravel the mechanisms of action responsible for these associations.”
So how do these COMMON polymorphisms persist in those subgroups eh?
Complex regulatory mechanisms control metabolism, recent epidemiologic evidence suggests that there is a narrow range of vitamin D levels in which vascular function is optimized. Yes, levels below this natural homeostasis of vitamin D increase mortality but if you look at the study it’s clear humans have evolved limitations on vitamin d levels that have stood the test of hatural selection.
Taking supplements will take you higher than is good for you because it’s not just deficiency in the calcipherol system that causes abnormal functioning and premature aging – excess does too. Oh and you may be interested to know that"Freedman et al. (2010) have found that serum vitamin D correlates in African Americans with calcified atheroscleratic plaque." Which is something that should have been learnt from the antioxidant fiasco
He may know a lot about the biochemistry of vitamin D but his understanding of natural selection leaves something to be desired, if “two-thirds of the people are vitamin D-insufficient” outside Europe and North America it’s because those places are inhabited by non Europeans who have a natural homeostasis of vitamin D which is lower than whites. These are people who live nearer the equator remember. Think it’s down to more pigment in the skin?
ReplyDelete,’Common genetic determinants of vitamin D insufficiency: a genome-wide association study’ found none of the genes identified are linked with skin pigmentation
‘A systematic review of the association between common single nucleotide polymorphisms and 25-hydroxyvitamin D concentrations’
“‘We speculate that recently identified U-shaped relationships between 25OHD concentrations and disease outcomes (i.e. increased risk at both high and low concentrations) may reflect a mixture of genotype-defined subgroups. Further research is required in order to clarify the genetic architecture underlying 25OHD serum concentrations, and to unravel the mechanisms of action responsible for these associations.”
So how do these COMMON polymorphisms persist in those subgroups eh?
Complex regulatory mechanisms control metabolism, recent epidemiologic evidence suggests that there is a narrow range of vitamin D levels in which vascular function is optimized. Yes, levels below this natural homeostasis of vitamin D increase mortality but if you look at the study it’s clear humans have evolved limitations on vitamin d levels that have stood the test of hatural selection.
Taking supplements will take you higher than is good for you because it’s not just deficiency in the calcipherol system that causes abnormal functioning and premature aging – excess does too. Oh and you may be interested to know that"Freedman et al. (2010) have found that serum vitamin D correlates in African Americans with calcified atheroscleratic plaque."
Which is something that should have been learnt from the antioxidant fiasco