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home:pathogenesis:vitamind:correlation [07.19.2013] – [Notes and comments] joyfulhome:pathogenesis:vitamind:correlation [02.13.2019] – [Causation is not self-evident] 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}}+ 
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 +{{tag>pathogenesis  Science_behind_vitamin_D Study_Design}}
  
  
home/pathogenesis/vitamind/correlation.txt · Last modified: 09.14.2022 by 127.0.0.1
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