How Do We Know if a Supplement or Its Ingredients Are Actually Working? Key Elements to Look for in Scientific Studies as a Consumer

When choosing a dietary supplement, many consumers wonder: “Does this really work?”

According to a 2019 national survey conducted for Pew Charitable Trusts (N=707),[1] “Potential benefits” had the highest percentage of participants reported as “important” (64%) when picking a dietary supplement, followed by “Cost” and “Quality of ingredients” (both 47%), “Safety” (41%), “Brand reputation” (36%), and “Product reviews” (28%).

In our own internal survey of 59 current and former supplement users (conducted July-August 2024), we found similar priorities.

Specifically, when asked what influenced their first purchase (59 responses), the most important factors included:

• Recommendation by my doctors or healthcare providers
• Findings from scientific research, and
• Recommendations from friends or family members

Top reasons to continue supplement use (19 responses) included:

• Product is working
• Recommended by my doctors or healthcare providers
• Have the desired quality certification, and
• Reasonable price

Conversely, users reported the following top reasons for switching supplements (38 responses):

• Price too high
• Not achieving desired benefit, and
• Recommended by my doctors or healthcare providers

These responses suggest that while cost matters, the perceived health benefit is often the primary reason people stick with or switch supplements.

 

Understanding Scientific Studies: What to Look For

Previously, we explored The Five Key Values of Peer-Reviewed Publications for Vitamin and Supplement Consumers in this blog.

Peer-reviewed publications are crucial because they form the foundation for understanding how much health support a supplement may truly offer.

In this post, we’ll take a closer look at the essential elements to examine within a peer-reviewed study.

These critical details are usually found in the Methods and Results section, while the Abstract (a brief summary of the entire study) often provides a high-level overview.

 

1. Who Was Studied

Start by looking at who participated in the study. This helps us understand how much the results might apply to us.

Key things to look for:

• Inclusion and exclusion criteria
  • These are the rules researchers use to decide who can or cannot participate in the study
  • For example, a study might include only adults over 50 or exclude people with certain medical conditions
• Participant characteristics
  • Look for details like age, gender, health status, and other traits
  • This information shows who the results are based on
  • The more diverse the group, the more likely the results may apply to different types of people
• Number of people in the study
  • Larger studies tend to produce more reliable data
  • They also help researchers estimate the average effect more accurately

These pieces of information are typically found at the beginning of the Methods and Results sections of a peer-reviewed publication.

 

Ingredient-Related Information: The IDOHS Framework

Use this simple framework to evaluate the supplement or ingredient:

Component	What It Means	Why It Matters to Consumers
Ingredient	What was in the product	Helps compare what was studied in research vs. what's in the supplement we're considering
Dose	How much was included	Helps determine if the supplement contains similar amounts used in research
Outcomes	What effect was measured, and for how long	Provides context on what benefits were observed and over what period
Health Support	What area of health was targeted	Shows which body system or function the supplement or ingredient is intended to support (such as heart, immune system, sleep)*

 

Why These Components Matter

In general, the more clearly and transparently these details are disclosed in a peer-reviewed publication, the easier it is for readers to assess how reliable and trustworthy the findings may be.

When key information is missing, it doesn’t automatically disqualify the study—but it can lower confidence in how much we can trust the results.

 

About Outcome Measures

For the “Outcomes” component of IDOHS, look for outcome measures that are clinically endorsed or consumer-relevant.

 

Why is it important to be clinically endorsed?

When outcome measures are clinically endorsed, it means they have been reviewed and agreed upon by recognized experts.

These measures are often included in clinical practice guidelines or routinely used in other studies.

These types of measures are generally more reliable, consistent, and meaningful.

On the other hand, measures that are not clinically endorsed or newly created by study teams may have several limitations:

1. They can be hard to interpret
2. Their results may be inconsistent or less stable
3. The way they are measured may not be well established or reliable

 

Why is it important to be consumer-relevant?

Consumer-relevant reflects real-life impacts—such as changes in quality of life, vitality, or how we feel day-to-day.

These types of outcomes are meaningful to us as individuals because they directly relate to our overall well-being.

 

Example: Outcome Measures in Heart or Metabolic Health Studies

Clinically Endorsed	Consumer-Relevant	Not Clinically Endorsed or Consumer Relevant
% (percent) change in LDL (bad cholesterol) levels from the beginning of the study to week 4	% (percent) change in vitality levels from the beginning of the study to week 4 based on responses to the SF-36 (a widely used health survey)	Maintain LDL or TG levels within 20%   Possible issues: 1. No clear starting point for measurement 2. Timeframe is vague or missing 3. Combines multiple outcomes, reducing clarity

*LDL: low-density lipoprotein; SF-36: Short Form (36) Health Survey; TG: triglycerides

 

Importantly, outcome measures should ideally address both potential benefits and risks, including any adverse events or side effects.

Supplements and their ingredients may not be automatically risk-free, even if they are naturally derived.

These kinds of details are usually found in the Methods section of publications or in the Abstract summary.

 

2. How the Study Was Designed

Study design is a complicated matter.

The strongest possible types of study design are:

• Randomized controlled trial (RCT): Participants are randomly assigned to groups and compared
• Systematic literature reviews/ meta-analyses: Combine results from multiple studies[2]

Less rigorous but still potentially useful designs include:

• Single-arm clinical trials
• Observational studies

Even with strong designs like RCTs, study quality can vary a lot.

Things like how much detail is shared, how well the study avoids missing data, and how outcomes are measured all affect the risk of bias (how likely it is that the results might be misleading).[3]

 

Why Design and Comparison Matter

To know if a supplement or ingredient may be effective in supporting our health, researchers need to make comparisons and run statistical tests.

• In an RCT, we compare a group taking the supplement or ingredient to a similar group that is not. This is the best way to tell if any changes are likely due to the supplement itself.
• In a single-arm trial, researchers compare results from before and after taking the supplement or ingredient. This design has more limitations but can still offer helpful insights when no RCTs are available.

To say that something “works,” researchers typically look for statistical significance—a result that is unlikely to be due to chance.

This usually means the chance of a false positive (or “error”) is less than 5%.

These details are usually found in the Methods section of publications or briefly described in the Abstract.

 

3. What the Results Are 

This is the heart of the matter. To understand the study results, we should focus on two things:

• Statistical significance: Were the results unlikely to be due to chance? (In other words, is the finding real?)
• Meaningful size of effect: how big or meaningful was the change?

Ideally, we’d like to see both:

• A statistically significant result
• A (clinically) meaningful size of difference between the groups being compared

 

What Statistical Significance Tells Us—and What It Doesn’t

Statistical significance helps answer “Is there likely a real difference?”

But it does not tell us how big or important that difference is.

To evaluate that, we need to look at the actual size of the change—for example, how much something improved in the group taking the supplement compared to the other group (or compared to before they started).

A larger difference usually means stronger evidence, but both the magnitude and meaning of the change matter.

Let’s say one group of participants starts with an average LDL level of 70 mg/dL, which is well within the optimal range.

Another group starts at 100 mg/dL, which is closer to the upper limit of the optimal range.

If both groups are measured over 8 weeks, their ability to maintain healthy LDL levels may differ—not necessarily because of what they took, but because of where they started.

It’s generally harder for individuals closer to the high end of a healthy range to stay within that range over time.

 

A Note on RCTs: Focus on the Right Comparison

In RCTs, the most important comparison is between the groups—such as between the supplement group and the control group.

Sometimes, RCT studies report improvements within a group (before vs. after taking the supplement) but don’t show whether the between-group difference was significant.

That can be misleading.

Why? Because the purpose of having two or more groups is to compare them. Ignoring that comparison weakens the interpretation of the results.

We’ll dive deeper into that topic in another post.

 

Table. Understanding Statistical Results in RCTs (Gold Standard Clinical Studies)

Scenario	Statistically Significant?		Does the ingredient or supplement show a real benefit over the control group — not just by chance?
	Between-Group Difference (Ingredient/ Supplement group vs. Control)	Within-Group Difference (Before vs. After Starting)
1	Yes	Yes	Yes
2	Yes	No	Yes
3	No	Yes	No*
4	No	No	No

*In Scenario 3, even though the group improved over time, we can’t say the supplement caused the change without seeing a difference between groups.

These types of results are usually found in the Results section of a scientific publication, and summarized in the Abstract.

 

Final Words

Published studies can offer valuable hidden gems that help consumers better understand the potential effects and risks of the supplements or ingredients they’re considering.

While a single study may be informative, consistent findings from multiple well-designed studies provide stronger scientific support.

Once we understand the findings from one study, we can begin looking at additional research involving the same ingredients or supplements that aim to support the same area of health. Over time, we can also explore studies of other ingredients for the same wellness goals.

This ongoing process can help identify which supplements or ingredients may be most appropriate for our individual wellness goals.

We understand that interpreting scientific studies can be a complex matter.

If you're unsure, speak with a healthcare provider or the supplement manufacturer for clarification.

At Truth Full Health, we’re committed to supporting you in your journey to better understand the science behind supplements and wellness.

We look forward to being a trusted source of clarity, evidence, and confidence as you navigate your wellness decisions.

 

Sincerely,

Derek Tang, PhD, MS, BSPharm

Truth Full Health

Your Trusted Supplement Partner

 

*Disclaimer: all blogged content is for informational purposes only and does not replace professional medical advice. The statements made regarding dietary supplements (vitamins and supplements) have not been evaluated by the Food and Drug Administration (FDA). These products are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare provider before beginning any new supplement, diet, or health regimen. Any references to specific products or studies are for illustrative purposes and do not constitute an endorsement or guarantee of effectiveness.

 

 

[1] The Pew Charitable Trusts. Dietary Supplement Survey: Topline Results. Pew Research Center; 2019. Accessed October 11, 2025. https://www.pew.org/-/media/assets/2019/10/dietary_supplement_survey_topline_results.pdf.

[2] Title: The levels of evidence and their role in evidence-based medicine. First author: PB Burns. Journal: Plastic and Reconstructive Surgery. Year of publication: 2011.

[3] Centers for Disease Control and Prevention. Chapter 8: Domains Decreasing Certainty in the Evidence. In: ACIP GRADE Handbook. Published April 22, 2024. Accessed October 11, 2025. https://www.cdc.gov/acip-grade-handbook/hcp/chapter-8-domains-decreasing-certainty-in-the-evidence/index.html