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Why many vitamin D trials fail to find benefits - Nov 2016

.1) Trials rarely allow modifying the dose size - so as to compensate for
  obesity
   health problems - especially those which consume Vitamin D
   pre-existing deficiency
   gut problems
   no gallbladder
   use of drugs such as statins
   smoking etc

2) Trials often do not last long enough
  About 1/3 of the trials which I read would have had a benefit it they had only lasted longer
  but to minimize trial costs trials are kept short

3) Trials essentially must be monotherapy -no cofactors such as Magnesium permitted
  Meta-analyses never consider trials with co-factors, so if a researcher wants his data to be used he does not use cofactors

4) Many trials use too small a dose to possibly make a difference
  Have seen many trials just using 1,000 IU
  One trial used just 200 IU - and did not find a difference!!
  Imagine a trial using 1/20 a dose of Aspirin - it would be very unlikely to find any benefit

5) RCTs require a placebo group, but many researchers now find it unethical to not give vitamin D to all participants
  so their trial is not an RCT - note that an increasing Percentage of the Vitamin D proofs are not RCT

6) Some RCTs are now terminated because
   Researchers found too much pain/suffering in those getting the placebo
   Too many participants getting the placebo dropped out as they noticed the other group feeling much better and having fewer health problems

7) Some countries (about 30%) consider a mere 20 nanograms to be sufficient
   When they compare those with < 20 nanograms to those with > 20 nanograms they do not see any benefit
   Occasionally they include charts of the data - in which the benefits of vitamin D can be seen at 30 or 40 nanograms

8) RCTs ignore gene differences
   There is at least a 3 times increased risk for 12 diseases for people having just a Vitamin D Receptor problem
   Note: There are 5 additional important Vitamin D genes

9) RCTs sometimes use long time between doses
   > 3 week dosing interval provides less benefit
   > 6 month dosing invervals can result in problems (negative benefits)

10) RCT researchers are occasionally rewarded for NOT finding a benefit
   Example; Professor who concluded that vitamin D (800 IU) does not help bones got 324,000 dollar prize- Nov 2015

11) RCTs rarely use loading doses to restore vitamin D levels in a week or so
   Without loading doses many people will fail to show a benefit/get repleted within the typical short RCT length

12) Some RCTs mistakenly continue to use Vitamin D2
   D2 is significantly less effective the D3 - especially for non-daily doses
   Sometimes D2 actually reduces the level of D3
   Over a decade ago Vets decided that Vitamin D2 should not be used on any mammal - guess we hsve to remind Doctors that humans are mammals

See also VitaminDWiki

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