Writing in Current Developments in Nutrition, researchers from the National University of Singapore, the University of Birmingham, the University of Bristol, and SingHealth Duke-NUS Global Health Institute have urged the re-evaluation of clinical endpoints and tools used in multivitamin clinical trials.
They pointed out that clinical trials on multivitamins often focused on evaluating endpoints such as disease reduction or prevention. However, consumers are more interested in aspects such as health maintenance, quality of life, and specific health functions such as cognitive health and fatigue, as reflected in their purchasing behavior.
The researchers also argued that the design of multivitamin clinical trials was often geared toward a pharmaceutical model, where the intervention used was intended to produce a large effect on a specific “hard” clinical endpoint, which would not be suitable for multivitamin research.
“In essence, the scientific approach has been to give a subtle supplement to a healthy population and then measure the effect with an instrument that is psychometrically incapable of detecting subtle, positive changes in well-being,” the researchers wrote.
Such an approach, based on the researchers’ point of view, is “ill-suited” for clinical trials assessing low-dose multivitamins’ effects in a general population.
The paradox
According to the researchers’ review, there is a current paradox between public health advice, research findings and consumer behavior.
For instance, although meta-analyses on multivitamins did not show significant effects on disease reduction or prevention, including cardiovascular diseases or cancer, leading to health officials advising against the routine use of multivitamins for disease prevention, consumers have continued to purchase and take multivitamin supplements.
In the United States, multivitamins are the most popular supplements, taken by more than a third of adults.
In Europe, 88% of adults have taken a dietary supplement at some point in their life, the researchers said, citing findings from the IPSOS 2022 survey of 14 European Union countries.
“This creates a significant paradox: continued investment in a practice that is not supported by scientific evidence. What needs to be addressed is whether this paradox is due to consumers being misinformed and/or if the scientific community has failed to measure consumer-relevant endpoints,” the researchers wrote.
They hypothesized that, despite mixed clinical outcomes in multivitamin trials, consumers have continued to take multivitamins, potentially due to their positive impact on quality of life.
A literature review was thus conducted on PubMed, EMBASE, Web of Science and Cochrane CENTRAL using the search terms “MVM,” “multivitamin,” “mineral supplementation,” “quality of life,” and “HRQoL”.
The findings
A key finding from the literature review was that consumers do not necessarily take multivitamins to prevent a disease from occurring, but to preserve their current health and enhance their quality of life.
Citing findings from the 2012 National Health Interview Survey involving over 21,603 American adults, the researchers highlighted that multivitamin users self-reported 30% better overall health than nonusers.
This was despite the fact that no differences were seen between users and non-users in clinically measurable health outcomes.
“This suggests the consumer’s goal is not necessarily the prevention of a future, abstract clinical event like a myocardial infarction, but the preservation of their current health and the enhancement of their subjective quality of life,” the researchers wrote. “If this is true, then large-scale RCTs, while methodologically sound, may fail to address this question. The public is asking, ‘Will this help me feel better?’ The scientific community has been structured to answer, ‘Will this prevent disease or death?’”
The idea that consumers are taking multivitamins for general health can also be gleaned from two U.S. surveys conducted in 2013 and 2014.
Based on the surveys, it was revealed that improving and maintaining overall health and wellness was the most prevalent reason for taking multivitamins.
What could be done?
In view of the findings, the researchers have urged a shift in the focus of multivitamin studies from disease prevention to the preservation of health and subjective quality of life in healthy adults.
In this case, clinical trials could assess the effects of multivitamins on areas such as cognition, positive mood, perceived energy, sleep quality, and resilience to stress as part of evaluating improvements to the quality of life.
“These components align more closely to the lived experience of adults, rather than disease-related limitations in physical, social, and role activities as in HRQoL (health-related quality of life) tools such as SF-36,” the researchers wrote.
For instance, they have proposed the use of WHO Well-Being Index (WHO-5) and ICEpop CAPability measure for Adults (ICE CAP-A), instead of SF-36 to evaluate the quality of life.
The researchers added that future trials should consider resilience as a study outcome, and this could be measured both subjectively through self-reported tools and objectively through acute or longitudinal responses to stressors.
“Resilience is associated with mental health and well-being and aligns with consumers’ motivations for taking MVM supplements. Overall, nutritional supplement trials that measure resilience outcomes are still limited and warrant further exploration,” the researchers wrote.
Source: Current Developments in Nutrition. doi: 10.1016/j.cdnut.2026.107708. “Consumer-Relevant Endpoints in Nutritional Supplement Research: A Case of Multivitamin and Mineral Supplements.” Authors: R. Sheldon et al.
