Consumers often see references made to research studies about herbs and herbal supplements in advertisements and articles. Some will look for research studies about a particular herb they are interested in using. Research studies are an important part of adding to the collective knowledge about the uses of herbs and herbal supplements. Consumers turn to research studies about herbs to help make purchasing decisions, government uses them to assist with regulation, the medical community uses them to consider possible treatments, and industry uses them to help create products and sometimes in advertising.
Unfortunately many consumers don’t know or don’t remember from school the basics of how research studies are done and what makes a well-designed study. Often someone else (e.g. media writers, advertisers) is interpreting study results for the reader which may or may not be a good thing. Sometimes people jump to conclusions or insert assumptions that aren’t necessarily true when reading these interpretations. To be a savvy herbal consumer, it’s important to have a basic understanding of research studies and how they can be used in the marketplace.
Some Basics on Understanding Research Studies
Let’s start with a review of the scientific method. The scientific method is a set of steps for creating and testing out a hypothesis (a theory on why something is the way it is or happens the way it does). A simple version of the steps of the scientific method are:
- Ask a question.
- Do background research pertaining to the question.
- Construct a hypothesis.
- Test the hypothesis by designing and conducting an experiment.
- Analyze the data from the experiment and draw a conclusion.
- Communicate/publish the results.
There is a lot that goes into this set of steps and it can get very complicated. Any of these steps that are not properly executed could result in tainted and/or worthless results or in creating an experiment that is too expensive to conduct. One of the obstacles that consumers can run into is a limited number of research studies about a particular herb. One reason is because research studies are expensive to do, and funding sources can be difficult to find.
There are a few terms to become familiar with that can help make sense of a published study.
Intervention – A process or action that is the focus of the study. One example of an intervention is an herb or herbal supplement that is given to the study subjects.
Control group – The group in a study that receives a placebo, a standard known treatment or nothing at all.
Experimental group – The group in the study that receives the intervention being studied.
Confounding variables – Variables that the researcher failed to control or eliminate in the design of the study. These variables can influence the results.
Placebo – an inert substance that has no pharmacological effect on a person.
Published studies also have a set structure for how the information is presented. A published study will be broken up into six different parts:
- Abstract – A summary of the study.
- Introduction – The reason why the study is being done and the question(s) being studied.
- Method – The design of the study. This is described in great detail. This information can include who the study subjects were, how they were chosen, the dosage of the intervention, what the intervention was made of, how often it was administered, how long the subjects were involved in the study, any potential confounding variables and how they were accounted for or controlled, etc.
- Results – The data that was collected from the study and how it was collected.
- Discussion – The interpretation of the results and if they supported or didn’t support the hypothesis.
- References – Sources used in the research and design of the study or that were otherwise referenced in the study.
Types of Studies
Here are a few more terms to learn related to research studies. Some of these types of studies can be combined when designing a study. For example, you can have a randomized, double blind, placebo-controlled clinical study. This type of study is considered to be the gold standard of research studies.
Clinical study – A study that uses human volunteers. A human study and a clinical study are the same thing. This type of study includes intervention and observational studies.
+ Intervention – A study where the researcher controls whether the subjects receive the intervention. An example of an intervention clinical study is the control group receiving a placebo and the experimental group receiving the herbal supplement being tested.
+ Observational – A study where the researcher has no control over whether the subjects are/were exposed to the intervention. This type of study is seen as less optimal than an intervention study. An example of an observational clinical study is a group of people who took Echinacea last year during cold and flu season who are interviewed about how often they got sick.
An observational study can either be a prospective or retrospective study.
* Prospective observational study – A study where subjects are recruited BEFORE the outcome has occurred (i.e. development of a disease).
* Retrospective observational study – A study where subjects are interviewed and their records reviewed AFTER the outcome has occurred.
Cross-over study – A study where subjects are given a sequence of interventions (and possibly a placebo) in order to compare the effects of the different interventions in the subjects. There is typically a “wash out” period between interventions to allow the previous intervention to clear out of the subject’s system so it doesn’t influence the results of the next intervention.
Double blind study – A study where neither the subjects nor the research study staff know who is receiving the intervention treatment and who is receiving the placebo. Ideally this controls the researcher(s) and subject from inadvertently influencing the results.
In vitro study – A study where the experiment is conducted outside a living body (e.g. on tissue, cells, etc.) in an artificial controlled environment.
In vivo study – A study where whole, living organisms are used as the test subjects (e.g. animals, humans, etc.).
Meta-analysis – Where the results of multiple completed studies that have focused on a similar hypothesis (e.g. the ability of Echinacea to prevent colds) are systematically combined and evaluated. This, in a way, increases the number of test subjects and the statistical power of the research, however it does have limitations.
Peer-reviewed study – A study that is reviewed for content and research quality by others who are experts in the same field. A “blind review” is one where information on the study’s author(s) is removed before it’s reviewed to avoid any bias in the review.
Placebo-controlled study – A study where a placebo is provided to the control group in the same manner as the intervention is provided to the experimental group. (i.e. both groups receive the same size and color pill the same number of times a day for the same length of time.)
Randomized study – A study where the study subjects are randomly assigned to a group within the study (i.e. a control group and an experimental group). Ideally the randomization produces similar groups in terms of demographics and other variables.
Triple blind study – A study where neither the study subjects, research study staff nor researchers analyzing the data know which group received the intervention and which received the placebo.
Bonus term: Placebo effect – where an inert substance (placebo) given to a patient seems to improve a patient’s condition. The effect is attributed to the patient’s expectation for the substance to help them rather than a pharmacological effect.
Examples of Studies Used in the Media
In February 2015 the New York State Attorney General’s office announced their study on certain herbal supplements. They took a number of bottles of Echinacea, Ginseng, St. John’s Wort, and other herbal supplements from GNC, Target, Walmart and Walgreens retail stores and had them tested to see if the supplements contained the herbs. The testing was done by a biology professor at Clarkson University using DNA barcoding. The Attorney General (AG) said that the results showed that most had no evidence of DNA of the herbs in question along with some ingredients that weren’t listed on the label. Based on these results the AG concluded that many of the supplements did not contain the herbs and forced the retailers to pull the supplements from their shelves.
The herbal supplement industry responded by saying that the test used was not the appropriate test to determine if the herbs were included in the supplements. They said that with herbal pills and capsules, extracts of the herbs are commonly used (as opposed to the whole herb). With the extracting process, the DNA of the herb is broken down and therefore wouldn’t be detectable with DNA barcoding. They also pointed out that the person overseeing the testing is a biologist with a focus on evolutionary biology and not a botanist. This would call into question his ability to properly evaluate the data. Industry representatives called for the AG to have the samples tested by an appropriate independent laboratory and to have the AG’s office release the full results of the study for review. To the best of my knowledge neither has been done.
This is a real life example of the importance of a well-designed study. The quality of the design has a direct impact on the quality and validity of the results. It’s not enough to conduct a study; how the study is designed and executed matters.
Another example of how studies are used in the marketplace comes from the article 17 Herbs and Spices That Fight Diabetes from Prevention magazine. Below is an excerpt from part of the article that talks about curcumin which is an active component of the herb Turmeric.
According to a study published in the journal Diabetes Care, 240 people, all of whom had been diagnosed with prediabetes, were assigned to take either daily curcumin capsules (1,500 mg) or a placebo for nine months. At the end of the study, researchers found that 16.4% of subjects who took the placebo developed type 2 diabetes, while no one who took the daily dose of curcumin developed diabetes.
After reading this part of the article, someone worried about type 2 diabetes might seriously consider purchasing some 1,500 mg capsules of curcumin. Before doing that though, there are some questions worth asking:
- Were the study subjects eating their regular diets during the study? If so, were the daily caloric intakes about the same for each person? What about the levels of sugar?
- Were any of the participants exercising regularly? Did all maintain their starting weight throughout the study?
- Did everyone/anyone in the study have a family history of type 2 diabetes?
- Curcumin has a low bioavailability, which means it is poorly absorbed by the body. Was this accounted for in the study?
Many important questions are left unanswered by this short description of the study. It’s understandable that the magazine article, and other ones like it, doesn’t have space to go into all the details of a study. That’s not what this type of article is supposed to do. It’s up to consumers to realize the limitations of the information given in an article and, if they’re interested in the herb or study mentioned, to do their own follow up.
So What’s A Consumer to Do?
As a consumer, it’s good to be critical of how study results are presented regardless of whether they are coming from advertisers, researchers, the medical community, media, government or the herbal industry. Citing studies is often a tactic used to try to sway a consumer’s opinion. Sometimes advancing a particular agenda takes precedence over providing accurate unbiased information.
Studies are also used to try to prove that herbs and herbal supplements are either safe and effective or not safe and effective. The thing is that there are so many variables involved in the production and use of herbs and herbal supplements that neither answer will fit all situations.
When looking at a specific herb as a consumer, research studies can help broaden your knowledge and understanding of the use of that herb. Studies can’t give you a definite answer on whether the herb or herbal supplement will work for you. To some degree you are a guinea pig when using herbs and herbal supplements (and prescription and over the counter drugs too) because you are your own set of variables separate from any study.
Places to look for actual research studies include PubMed and Science Direct. Check out this blog’s Free Resources for Information on Herbs article for more information about these sources. There are other sources for this on the internet as well. Often you can find references to studies in articles (like the one by Prevention magazine mentioned earlier). For those, you will need to do a little more work to track down the actual studies. Herbal monographs are another potential source for references to research studies, as well as the reference section of any published research studies.
Next article – Commentary: Consumer Trust and the Herbal Marketplace
Links to Learn More
ClinicalTrials.gov – maintained by the National Library of Medicine and the National Institutes of Health. Provides access to publicly and privately supported clinical studies in a wide range of diseases and conditions.
Significance Test (II) – Explorable.com
A.G. Schneiderman Asks Major Retailers To Halt Sales Of Certain Herbal Supplements As DNA Tests Fail To Detect Plant Materials Listed On Majority Of Products Tested – Press release on NYS Attorney General’s website – February 2015
The Capabilities and Limitations of DNA Barcoding of Botanical Dietary Supplements – Report created by authentechnologies® and posted by Council for Responsible Nutrition (http://www.crnusa.org/) – March 2015
Is the 2015 Noble Prize a turning point for traditional Chinese medicine? – – The Conversation – October 2015