Human Studies Behind Vitamins and Supplements: Single-Group vs. Randomized Controlled Trials

Scientific evidence is the foundation for how we evaluate supplements.[1]

In earlier posts, we briefly discussed why the type of research study used to evaluate supplements matters for consumers.

On a smaller scale, the type of study can influence conclusions about appropriate intake levels or whether differences in supplement absorption truly matter.

On a larger scale, it can influence how confidently we understand whether a supplement may support our health goals.

At Truth Full Health, we prioritize supplement ingredients that are supported by consistent and well-designed human research, particularly randomized controlled trials (RCTs) in humans, or meta-analyses of these studies.

Single-group human studies are worthwhile to consider in some situations.

Today, we will take a closer look at two common types of human nutrition studies: Single- group studies and RCTs.

Single-Group Human Studies: What They Are

A single-group human study is a type of research where everyone in the study takes the same supplement, and researchers track how their health measurements change over time.

Instead of comparing two different groups of people, the study compares participants’ results before they start the supplement with their results after they have taken it for a period of time.

For example, in some human studies of berberine, participants may take a set amount of berberine each day for several weeks.[2]

Researchers measure markers like cholesterol levels or blood sugar before and after participants take berberine.

Changes in, or maintenance of, these markers during the study can help us understand how the supplement may support normal heart and metabolic health.

Single-group studies can provide early clues about how a supplement might work in people, but they also have limitations.

As in real life, because everyone in the study takes the same supplement and there is no comparison group, other factors—such as diet or lifestyle changes—could also influence the results.

For this reason, scientists often follow these early studies with more rigorous studies that compare groups of people.

Randomized Controlled Trials (RCTs): What They Are

A randomized controlled trial (RCT) is a type of study designed to more clearly understand whether a supplement may influence certain health markers.

In an RCT, participants are randomly assigned to different groups.

For example:

• One group receives the supplement being studied
• Another group receives a placebo (a look-alike capsule with no active ingredient) or another supplement

Randomization helps make the groups more similar in factors that may affect health markers, such as diet, lifestyle, and overall health.

Because of this design, RCTs are widely considered the gold standard for studying health and nutrition.

So far, it is the best way to separate the effects of the supplement being studied from other influences.

This helps consumers better understand the true effects of supplements and decide whether to choose certain products.

For example, in an RCT studying BPF® bergamot extract, participants may be randomly divided into two groups:

• One group takes a daily BPF® supplement
• The other group takes a placebo

The two groups are similar in age, gender, and health profile.

Researchers measure markers such as cholesterol or triglyceride levels at the start of the study and again after several weeks or months.

By comparing the changes between the two groups, researchers can better understand whether BPF® help support normal markers of heart and metabolic health.

When Might Single-Group Human Studies Still Be Useful?

Although RCTs are considered the most rigorous design, single-group studies can still be informative in certain situations.

1. When placebo effects are expected to be small

If previous research shows that placebo effects are small in a certain health area, single-group studies may sometimes still provide useful information.

This is often the case when researchers are measuring laboratory markers such as cholesterol or blood sugar.

Even in these cases, it is still important to consider other factors that may influence the results, including:

• Participant age
• Gender
• Race or ethnicity
• Dose of the supplement
• Diet and exercise habits
• Study duration

For example:

Participants	What participants are asked to take or do	Health marker examined	Factors that may influence results
People above age 65	Berberine 1,000mg daily	Blood sugar	Age, dose
Men	Berberine 500mg daily	Blood sugar	Gender, dose
Women	Berberine 1,500mg with 30-min daily exercise	Blood sugar	Gender, dose, exercise
Caucasian	Berberine 1,000mg with 30-min daily exercise and low-carbohydrate diet	Blood sugar	Race, dose, exercise, diet

Differences like these make it important to carefully compare study conditions before drawing conclusions.

On the other hand, health areas that report how people feel—such as sleep, pain and mood—often have stronger placebo effects.

In these areas, RCTs are especially important.

3. When researchers are exploring potential effects

After supplement ingredients have enough pre-human science supporting their biological effect, we still don’t know whether they have any effects in humans or what intake amounts may be appropriate.

In these cases, researchers may first conduct a smaller single-group study to explore:

• Whether an ingredient shows signs of influencing health markers in humans
• What intake amount may be appropriate
• Whether it makes sense to conduct a larger study

This helps researchers determine whether conducting a larger RCT is worthwhile.

Final Thoughts

As supplement consumers, we are often busy and may not have much time to understand the science behind the supplements we take.

Supplement brands that clearly show when their products or ingredients are supported by well-designed human studies, such as randomized controlled trials (RCTs), can help save consumers’ valuable time.

For this reason, Truth Full Health focuses on supplements with ingredients supported by well-designed human studies and transparently shares the research sources behind them.

We sincerely hope that all supplement consumers can find products that support their individual health goals.

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. Statements made about vitamins or supplements (officially called “dietary supplements”) have not been evaluated by the U.S. Food and Drug Administration (FDA). Dietary supplements 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 lifestyle program.

[1] In this article, ‘supplement’ refers to dietary supplements, including vitamins.

[2] Title: Efficacy of berberine in patients with type 2 diabetes mellitus. First author: J. Yin. Journal: Metabolism. Year of publication: 2008.