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Table of contents
Introduction
See also Overview Meta-analysis of Vitamin D
Unfortunately, a meta-analysis will frequently fail to consider one or more of the following
- Dose size (Some gave the same importance to 40 IU as 10,000 IU)
- Dose frequency (Some ignore differences between daily, weekly, monthly, and annual dosing)
- Duration, (Some gave same importance to 4 weeks as 4 years)
It takes 3 to 12 months for vitamin D levels to come to a new plateau
and it often takes months for the body to then utilize it - Pre-existing Vitamin D blood level
adding vitamin D does not provide much benefit if person alrady has a good level - Cofactors (Most meta-analyses ignore the importance of Magnesium, Omega-3, Vitamin K2, etc)
- Type of Vitamin D - D3 far better than D2
- Those with poor guts need a different type of vitamin D
- Those who are Obese need 2.5 X more vitamin D
- Many drugs, such as statins deplete vitamin D or the Magnesium needed by Vitamin D
- For some health problems pulsed vitamin D, not daily, is far better (gets over possible Vitamin D receptor limitation)
See also Proof that Vitamin D Works
See also All items in category Intervention Vitamin DSee also Clinical Trials of vitamin D can have “biological flaws” – Jan 2015
See also Nice description of Meta-Analysis in Scientific American Jan 2014
See also The Misuse of Meta-analysis in Nutrition Research JAMA Sept 2017
". . . they have mixed apples and oranges—and sometimes “apples, lice, and killer whales”—yielding meaningless conclusions"
"In a 2007 review of 111 industry-funded (nutrition) studies, funding source was significantly related to study conclusions"
It does not mention the major problems of Vitamin D Meta-analyses.
1) Dose sizes are ignored: Studies assume benefit from 400 IU is the same as for 4,000 IU
2) Durations are ignored: Studies assume benefit of 1 month dosing is the same as 1 year dosing
3) Existing Vitamin D levels are often ignored.
Studies ignore that a 20 ng addition to a 10 ng person has vastly more benefit than a 20 ng addition to a 40 ng person
A rare example of a good meta-analysis is: one on depression - April 2014
Really great medical studies do not blindly give a single supplement/drug to a group, but rather treat the patients as individuals and provide extra Magnesium, Vitamin K2, Omega-3, Vitamin C, etc as needed. These studies, which have the best results, are not Random Controlled Trials and are virtually never included in a meta-analysis.
Likewise, the trials which give vitamin D to an entire country, or to all of the patients (immoral not to do so) are never considered by any meta-analysis
Vitamin D has climbed the pyramid for decades, but has not yet reached the top
International prospective register of on-going systematic reviews: 569 reviews of Vitamin D as of March 2020
Intervention - Vitamin D includes the following:
Studies in VitaminDWiki
| Year | Randomized Controlled Trials | Interventions | Meta- analyses |
| 2022 | 900+ | 700+ | 600+ |
| 2017 | - | 48 | 52 |
| 2015 | 69 | 82 | 35 |
| 2012 | 41 | 38 | 39 |
Note: Govt recommendations in 2015 often ignored data after 2011
Meta-analysis category is associated with 52 other VitaminDWiki categories (>4 each)
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Summary of Associations
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