A recent study published in JAMA Network Open found an association between regular multivitamin (MV) supplementation and risk of mortality in US adults.
Study: Multivitamin use and risk of mortality in three prospective US cohorts. Image credit: Sergii Sobolevskyi/Shutterstock.com
background
One in three US residents takes a multivitamin to maintain or improve health and prevent disease, so knowledge of the relationship between multivitamin supplementation and mortality risk is critical for public health guidelines.
The 2022 United States Preventive Services Task Force (USPSTF) examined data on multivitamin use and mortality risk from randomized controlled trials and concluded that due to short follow-up periods and external validation, there was insufficient evidence to determine a risk-benefit ratio.
Observational studies have produced conflicting results, and differences in multivitamin content and confounding factors may explain the varied results. Multivitamin users may be more health conscious, which may lead to healthier diets, increased physical activity, and reduced smoking. However, people aged 65 years and older with comorbidities are at higher risk of mortality and therefore more likely to use multivitamins.
About the Research
In this study, researchers investigated whether regular consumption of multivitamins could reduce the risk of death among US adults.
The study included adults with no history of chronic disease or cancer who were enrolled in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO, n=42,732), the Agricultural Health Study (AHS, n=19,660), or the National Institutes of Health-AARP Diet and Health Study (NIH-AARP, n=327,732).
Each cohort study assessed baseline multivitamin use from 1993 to 2001, followed by assessments and characterization of confounders from 1998 to 2004. Researchers followed participants until study completion (NIH-AARP and AHS: December 2019; PLCO: December 2020) or death. Mortality was determined by the National Death Index (NDI), and cause-specific mortality was ascertained by International Classification of Diseases, Ninth Revision (ICD-9) or ICD-10 codes.
The study exposure was self-recorded multivitamin use and the primary study outcome was death. Participants completed a baseline questionnaire to provide multivitamin use data. Time-varying analyses incorporated follow-up dietary questionnaire data 5, 3, and 9 years after initiation of the AHS, PLCO, and NIH-AARP studies, respectively.
The researchers calculated hazard ratios (HRs) using Cox proportional hazards regression models, adjusting for variables including age, biological sex, body mass index (BMI), race, ethnicity, education, physical activity, marital status, alcohol intake, smoking habits, coffee intake, Healthy Eating Index 2015 (HEI-2015) score, and family cancer. They analyzed data from June 2022 to April 2024.
The researchers excluded proxy respondents, those who died before receiving the study questionnaire, those with registry-confirmed or self-reported cancer at study entry, those with myocardial infarction, diabetes, end-stage renal disease, or stroke at baseline (n=105,871), extreme calorie intakes, or those with missing covariate data.
result
The study included 390,124 participants: 327,732 from NIH-AARP, 42,732 from PLCO, and 19,660 from AHS. Follow-up was 7,861,485 years. Participants' mean age was 62 years, and 55% were male.
The researchers recorded a total of 164,762 deaths during the follow-up period. Of these, 41% had never smoked and 40% had a college level education. Of the 164,762 deaths, 49,836 were due to cancer, 35,060 to cardiovascular disease, and 9,275 to cerebrovascular disease.
Among those who regularly take multivitamins, 49% and 42% of women have a college level education, compared with 39% and 38%, respectively, of those who do not use multivitamins. In contrast, the prevalence of current smoking among those who regularly take multivitamins is 11%, compared with 13% of those who do not use multivitamins.
Multivitamin use was not associated with a reduced risk of death from any cause at initial or subsequent follow-up. Hazard ratios were similar for leading causes of death and time to death.
The research team observed qualitative effect variation by age, BMI, and smoking status, but not by biological sex, HEI-2015 score, or race or ethnicity.In the first follow-up analysis (FP1), the HR value for regular multivitamin use and mortality from any cause was higher in individuals younger than 55 years (HR, 1.2).
In FP1, HR estimates for nonregular multivitamin use and all-cause mortality were higher for former and current smokers and for those with normal BMI. A meta-analysis incorporating time-varying estimates from all cohorts showed that regular multivitamin use, compared with non-user, was associated with a 4.0% higher risk of all-cause mortality in FP1, but not in FP2.
Conclusion
The findings do not provide evidence that people who regularly take multivitamins live longer. However, we cannot rule out the possibility that regular multivitamin intake may affect other health outcomes related to aging. Further studies should include nonobservational study designs and more diverse populations to increase the generalizability of the findings.
