Clinical trials in humans are essential to substantiating the health benefits of supplements; they provide important scientific evidence of effectiveness and safety. To determine initial safety and dosing information, new nutrients are tested for toxic effects in model systems, typically in three stages: acute, sub-chronic, and chronic.

Acute toxicity studies help researchers understand the side effects (often referred to as adverse effects) of a substance after a single dose or multiple doses given over a short period of time (usually 24 hours). The information obtained from these studies is used to determine the appropriate dose for repeat-dose studies and can reveal target organs to investigate for toxicity in future trials.

Once acute toxicity studies are completed, sub-chronic toxicity studies investigate adverse effects and toxicological and physiological parameters in model systems, such as changes in body weight, cardiovascular function, and behavior. These studies provide the data needed to confidently move into chronic dosing studies, where study subjects consume the substance over a longer period of time.

Chronic toxicity studies, provide a very thorough look at the effects of a substance on health, bodily function, and, the long-term effect of a test substance in animals. Once this is complete, a nutrient manufacturer has the data required to submit a report called a dossier of all the information to the U.S. Food and Drug Administration (FDA) in hopes of being granted what is called a New Dietary Ingredient (NDI) designation.  This designation is required prior to selling a dietary supplement containing that new nutrient. This process was designed by FDA to ensure the safety of consumers.

Chronic dosing studies in animals also pave the way for clinical testing in humans. Many critical factors must be considered in the design of these clinical studies to ensure that the results collected will effectively measure how well the nutrient works to achieve the pre-determined endpoints or stated measurements. Proper study design also protects study participants and can help scientists and clinicians assess how credible the results are.

Investigation into clinical research by supplement companies indicates that up to one third of companies do not fund their own studies but “borrow” results from studies on similar products to support their health and safety claims.[1] It is critical for consumers to know which companies perform their own clinical research, as it is vital to responsible dietary supplement development and accurate marketing.

Careful research design is imperative to producing significant results that are applicable to the consumer. Fortunately, many supplement companies are engaging in clinical research, and the designs of their studies are developed in collaboration with leading experts in the field. As new companies come online, it will be important for consumers to know how they are approaching clinical research, whether they are funding their own research, and how their studies are designed. Perhaps most important is what companies do with the results of clinical research and how they develop marketing and health claims based on results.

  1. Myers, S. (2015, November 12). Clinical Trials: Two-Thirds of Supplement Companies Support Research. Retrieved from