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home:pathogenesis:vitamind:correlation [01.03.2012] – external edit 127.0.0.1home:pathogenesis:vitamind:correlation [09.03.2020] – [Researchers should also measure 1,25-D] sallieq
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-Many vitamin D studies suffer from methodological errors including [[home:pathogenesis:vitamind:observational_bias|bias inherent to using self-selected subjects]] and [[home:pathogenesis:vitamind:longterm|insufficient followup]], but perhaps their most egregious liability comes in mistaking correlation for causation. +Many vitamin D studies suffer from methodological errors including [[home:pathogenesis:vitamind:observational_bias|bias inherent to using self-selected subjects]] and [[home:pathogenesis:vitamind:longterm|insufficient followup]], but perhaps their most egregious liability comes in mistaking correlation for causation. (({{pubmed>long:27610068}}))
  
 It's undisputed that a wide array of studies point to the fact that 25-hydroxyvitamin D (25-D) – typically referred to in the media as vitamin D – is low in people with numerous chronic inflammatory diseases. However, these studies fail to prove that low 25-D //causes// disease. Even so, some studies assume that doubling serum levels of 25-D would drastically reduce mortality.(({{pubmed>long:21731036}})) It's undisputed that a wide array of studies point to the fact that 25-hydroxyvitamin D (25-D) – typically referred to in the media as vitamin D – is low in people with numerous chronic inflammatory diseases. However, these studies fail to prove that low 25-D //causes// disease. Even so, some studies assume that doubling serum levels of 25-D would drastically reduce mortality.(({{pubmed>long:21731036}}))
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 ===== Causation is not self-evident ===== ===== Causation is not self-evident =====
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 There are a number of examples where low levels of a substance are known to be associated with but not cause disease.  There are a number of examples where low levels of a substance are known to be associated with but not cause disease. 
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 <blockquote>Of course, the study does not suggest that low and high estradiol concentrations themselves were the cause of increased mortality. <blockquote>Of course, the study does not suggest that low and high estradiol concentrations themselves were the cause of increased mortality.
  
-//**Vasan Ramachandran, MD**//, [[http://www.theheart.org/article/971237.do|Heartwire]]</blockquote>+//**Vasan Ramachandran, MD**//, Heartwire</blockquote>
  
  
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 One of the reasons that 1,25-D isn't measured may be that it is harder to test. But another reason may be that a high 1,25-D is inconsistent with reports of vitamin D "deficiency." How can patients be said to be "deficient" in vitamin D when one of its metabolites, 1,25-D, is often several standard deviations greater than normal? One of the reasons that 1,25-D isn't measured may be that it is harder to test. But another reason may be that a high 1,25-D is inconsistent with reports of vitamin D "deficiency." How can patients be said to be "deficient" in vitamin D when one of its metabolites, 1,25-D, is often several standard deviations greater than normal?
  
-{{tag>Study_Design}}+<blockquote>“The idea that widespread vitamin D deficiency exists in the world has never had any credibility, and the idea that vigorous supplementation is necessary therefore has to be false.” 
 + 
 +“Nowadays it is virtually impossible to buy milk in the US that has not been laced (‘fortified’) with vitamin D. The amounts added, and the content, have been subject to dubious control, and a number of fatalities have occurred due to Vitamin D poisoning from milk.” 
 + 
 +“The mis-labeling of this compound as a vitamin is regrettable, as it gave a potential toxin an aura of undeserved innocence. Vitamin D is not a vitamin, but a steroid, which is, in its most active form, a powerful hormone with receptors widely distributed in the tissues of the body. As with other steroids, excessive consumption has risks.” Dr Hywel Davies</blockquote> 
 + 
 +{{tag>pathogenesis  Science_behind_vitamin_D Study_Design}}
  
  
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 ===== Notes and comments ===== ===== Notes and comments =====
  
-  * Legacy content +broken link [[http://www.theheart.org/article/971237.do|Heartwire]] 
-    *+ 
 +  * Jigsaw suggests: 
 +    * "There are hundreds of reports of groups of sick people who have low vitaminD status, that is low levels of serum 25D as compared with healthy controls. Very few of these studies have also measured 1,25D. Some of those that have found an even better correlation between sickness and high 1,25D than between sickness and low 25D. 
 + 
 +The best illustration of the chain of causation in relation to D levels and sickness is the study below where the sick group was otherwise healthy young adults who had knee reconstructions. 
  
 +Circulating interferon-γ correlates with 1,25(OH)D ... [Cytokine. 2012] - PubMed - NCBI 
 +Circulating interferon-γ correlates with 1,25(OH)D and the 1,25(OH)D-to-25(OH)D ratio.
 +Barker T, Martins TB, Kjeldsberg CR, Trawick RH, Hill HR.
 +Source The Orthopedic Specialty Hospital, Murray, UT 84107, USA. tyler.barker@imail.org
 +Abstract The mechanism responsible for the decrease in vitamin D status (i.e., plasma or serum 25-hydroxyvitamin D (25(OH)D) concentration) during inflammatory stress is unknown in humans. Interferon (IFN)-γ is an inflammatory cytokine that regulates vitamin D metabolism in isolated immune cells, but data suggesting this regulation exists in vivo is lacking. The purpose of this study, therefore, was to associate circulating IFN-γ perturbations with 25(OH)D and 1,25-dihydroxyvitamin D (1,25(OH)D) alterations during inflammatory stress in young adults recovering from anterior cruciate ligament (ACL) reconstruction. Plasma 25(OH)D, 1,25(OH)D and IFN-γ concentrations were measured in fasting blood draw samples obtained from twelve-male patients pre-surgery and 90-m, 3-d and 7-d post-surgery. 25(OH)D decreased significantly (p<0.05) after surgery, and strikingly, tended to inversely correlate (r=-0.32, p=0.058) with IFN-γ changes from pre- to post- (i.e., 90-m, 3-d, and 7-d) surgery. Additionally, 1,25(OH)D (r=0.37, p<0.05) and the 1,25(OH)D-to-25(OH)D ratio (r=0.52, p<0.05) changes from pre- to post- (i.e., 90-m, 3-d, and 7-d) surgery correlated with those of IFN-γ. These are the first reported in vivo findings suggesting that the 25(OH)D decrease and conversion to 1,25(OH)D increase with increasing IFN-γ in the circulation. We conclude that IFN-γ contributes to the decrease in vitamin D and the conversion of vitamin D to its active hormonal form in the circulation during inflammatory insult in humans.
 +Last edited on 18 Jul 2013 04:46 pm by Jigsaw
  
 ===== References ===== ===== References =====
home/pathogenesis/vitamind/correlation.txt · Last modified: 09.14.2022 by 127.0.0.1
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