Evidence, evidence ...?

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Is there evidence?

It's a common question, but most non-scientists use it without understanding it.

Is there any evidence for this supplement?


What should I answer when asked?

In the first place, no matter how much you answer, you will not be able to tell if you do not understand the meaning of evidence and that there is a level of evidence.

In general, the evidence level is considered as follows.

The Juntendo University Graduate School of Medicine doctoral course also teaches this idea.


There are various levels of evidence. If a supplement such as 1a is required, huge funds will be required and the manufacturing corporation will fail.

Are you saying evidence on the 4th and 5th levels?

There may be some products that are sold as evidence based on the opinions of the six experts.

Can 4, 5, 6 really be evidence?

Is it evidence if it is presented at a conference? Yes?

Evidence if the paper is published? Yes?

I feel that the word “evidence” is walking alone and the society is confused.


In my opinion, it is impossible to seek high-level evidence for supplements, no matter how much evidence exists in the ingredients, the manufacturing method and required amount, the manufacturing process (slow or low temperature heating, high temperature heating), thickener, colorant , The balance and influence of additives, such as preservatives and fragrances, the quality of the ingredients, etc ..


Is there always evidence? Do you understand the meaning of the evidence? I don't think I'm the only scientist who feels like to ask.



Evidence level classification


Level Message
1a Randomized controlled trial OfMeta-analysis
1b At least oneRandomized controlled trial(RCT)
2a With simultaneous control without random assignmentCohort study(Prospective study, prospective study, concurrent cohort study, etc.
2b Cohort studies with past controls without random assignment (historical cohort study, retrospective cohort study, etc.)
3 Case-control study(Case control, retrospective study)
4 Pre- and post-treatment comparisons such as pre- and post-treatment comparisons, studies without a control group
5 Case report, case series
6 Expert opinion (including expert committee report)