Ted Hutchinson
12-08-2007, 04:53 PM
25-hydroxyvitamin D, insulin-like growth factor 1 and metabolic syndrome at age 45y: a cross-sectional study in the 1958 British birth cohort. (http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=18003755)Objective: Hypovitaminosis D and reduced insulin-like growth factor-1 (IGF-1) are associated, individually, with metabolic syndrome. Physiologic interactions between vitamin D and IGF-1 are reported; this is the first study to investigate their combined associations with metabolic syndrome prevalence. Research Design and Methods: Data on 25-hydroxyvitamin D [25(OH)D], IGF-1, and metabolic syndrome abnormalities (abdominal obesity, raised HbA1c, blood pressure and triglycerides and low HDL-cholesterol) were collected from 6810 British whites in the 1958 cohort, surveyed 2002-2004 (age 45y). Results: IGF-1 concentrations increased with 25(OH)D up to approximately 75-85nmol/l, but not thereafter. Both 25(OH)D and IGF-1 were inversely associated with metabolic syndrome. There was an interaction between 25(OH)D and IGF-1 (p=0.025) on metabolic syndrome prevalence: IGF-1 was not significantly associated with metabolic syndrome among those with the lowest levels of 25(OH)D [p>0.09] whilst higher 25(OH)D was associated with metabolic syndrome at all IGF-1 concentrations (p</=0.006). Metabolic syndrome prevalence was lowest for participants with the highest concentrations of both 25(OH)D and IGF-1 [OR for highest vs. lowest third of both = 0.26 (0.17, 0.40), p<0.0001; adjusted for sex, month, hour, inactivity, alcohol consumption, smoking and social class]. 25(OH)D was associated with the prevalence of high HbA1c, blood pressure and triglycerides after adjustment for IGF-1, obesity and social and lifestyle variations (p</=0.004 for all comparisons). Conclusions: Serum 25(OH)D is inversely associated with metabolic syndrome, while the inverse association with IGF-1 was found only among those without hypovitaminosis D. These results suggest that metabolic syndrome prevalence is the lowest when both 25(OH)D and IGF-1 are high.
Hyppönen has previously report that most of this group of people are on Vitamin D insufficient. The average UK 45yr olds white adult having only 40nmol/l Vitamin D3 for most of the winter and never getting much over 75nmol/l at the end of summer. In order for all systems of your body to funciton without restriction from lack of the active metabolite of vitamn D3 Calcitriol, you require at least 100nmol/l (http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=17218096) if you look at figure 2 carefully you will see the curve of Calcitriol status levels off at 100nmol/l and the bulk of the spots from then on are between 125-150nmol/l. As this is all under the levels you would achieve naturally (if you lived naked outdoors all through the day) it seems likely that this is the status we elvoved to function at ideally. To achieve those levels they used 7000iu/daily/D3. Perfectly safe see Risk Assessment Vitamin D (http://www.ajcn.org/cgi/content/full/85/1/6) which argues for 10,000iu as a safe upper limit.
Hyppönen has previously report that most of this group of people are on Vitamin D insufficient. The average UK 45yr olds white adult having only 40nmol/l Vitamin D3 for most of the winter and never getting much over 75nmol/l at the end of summer. In order for all systems of your body to funciton without restriction from lack of the active metabolite of vitamn D3 Calcitriol, you require at least 100nmol/l (http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=17218096) if you look at figure 2 carefully you will see the curve of Calcitriol status levels off at 100nmol/l and the bulk of the spots from then on are between 125-150nmol/l. As this is all under the levels you would achieve naturally (if you lived naked outdoors all through the day) it seems likely that this is the status we elvoved to function at ideally. To achieve those levels they used 7000iu/daily/D3. Perfectly safe see Risk Assessment Vitamin D (http://www.ajcn.org/cgi/content/full/85/1/6) which argues for 10,000iu as a safe upper limit.