Scientific Evidence for Supplements

3 Steps to Identify Supplements that Lack Scientific Evidence for their Reported Benefits

What is the Scientific Evidence for Supplements?

You read about a supplement that allegedly "Boosts your

mood and motivation!" That sure sounds good so your surf over to the company's web site.

The web site looks official--it's even got footnotes citing scientific journals. You're ready to purchase the supplement online until you ask yourself, "What is the scientific evidence for supplements in general and for this supplement in particular?"

Here are the 3 Steps to determine if there is evidence for a supplement:

Step 1: Go to

which is a National Library of Medicine (United States) web site where you can search for articles published in peer-reviewed scientific journals.

Why check PubMed? Because the National Library of Medicine carefully selects only high-quality journals that offer value to medical scientists around the world. Selection criteria are detailed on this web page:

Step 2: Once on the PubMed web site, search for research articles using the generic (scientific) name of the supplement in question. Supplement manufacturers must list the scientific name for their supplement's ingredients on the label and in advertisements. Supplements often contain many ingredients but usually only a few provide the purported benefits. Those are the ingredients you want to evaluate--they are often the same

Say the RIGHT Thing Every Time
ones the manufacturer highlights in advertisements. The scientific evidence for supplements can be aided by determining the scientific names of products (this is a good request that we

Step 3: This is the step some supplement companies don't want you to know. Before you click on the "Search" button at, limit your search to studies that utilize the right research methodology with the right population.

The right research methodology is a randomized controlled trial (the double-blind, placebo control group design fits under this category) and the right population is human beings.

Specifying human subjects is important because you want to know if the ingredients in a supplement have been shown to produce the advertised benefits in real live human beings--not just in rats pressing levers for food pellets or in a "case study" with one person.

This is not to say that basic science research, which is often conducted initially with animals, is unimportant. On the contrary, such research usually serves as a crucial building block for subsequent clinical research with humans. But basic science research does not provide scientific evidence for a supplement's beneficial health effects on human beings. Only research with human subjects, using randomized controlled trials, can offer such evidence.

On the search page, click on the "Limits" tab located under the "Search" box. You will see a number of drop-down menus. First click on the Publication Type menu and then select Randomized Controlled Trial. Next click on the drop-down menu labeled, Humans or Animals and click on Humans.

An Example

Morinda citrifolia is the scientific name for a popular ingredient in a nutritional supplement. First search on PubMed for Morinda citrifolia, without placing Limits on your search.

How many results did you receive?

The count was 69 at the time I wrote this article. Looks impressive, huh?

But now search for Morinda citrifolia after first placing Limits on the search as described above, so that you receive only those studies which provide more definitive scientific evidence for the positive effects of Morinda citrifolia

How many journal articles did you find searching with the specified limits? I found 1. Thus, out of 69 articles found on, only one provides some evidence forMorinda citrifolia's beneficial effects.

It's great that this study exists because it could end up being one of several studies demonstrating that Morinda citrifolia provides health benefits. However, at the present time, the most one could say about Morinda citrifolia is something like, "One study has provided very preliminary evidence of Morinda citrifolia's health benefits with a narrowly defined patient group. Further controlled trials are needed to determine if this result will be replicated by other research groups working with different populations."


By using the "Limits" function on the search menu, consumers can identify supplements that lack scientific evidence for their efficacy.

Mark Worthen, Psy.D. is a clinical/forensic psychologist trained at Baylor and Harvard who now makes a living from home via Internet & Network Marketing. You can contact Mark via one of his web sites:

Scientific Evidence for Supplements