A recent study published in JAMA Network Open determined the relationship between regular multivitamin (MV) supplementation and mortality risk among United States adults.
Record
One in three people living in the United States consumes multivitamins to maintain or improve health and prevent disease. Therefore, knowledge of the association between MV supplementation and mortality risk is crucial for public health guidelines.
The United States Preventive Services Task Force 2022 (USPSTF) reviewed data on multivitamin use and risk of death from randomized controlled trials and concluded that, due to short follow-up and external validation, there is insufficient evidence to determine risk-benefit ratios.
Observational studies provide conflicting results, and differences in multivitamin content or confounding factors may explain their varying results. Multivitamin users may be more health conscious, leading to healthier diets, increased physical activity, and reduced smoking. However, people aged >65 years with comorbidities are more likely to use multivitamins, as they have a higher risk of death.
About the study
In the present study, researchers investigated whether regular multivitamin use can reduce the risk of death in the US adult population.
The study included adults with no prior history of chronic medical conditions and cancer participating in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO, 42,732 subjects). the Agricultural Health Study (AHS, 19,660 subjects) or the National Institutes of Health-AARP Diet and Health Study (NIH-AARP, 327,732 subjects).
Each cohort study assessed baseline multivitamin use between 1993 and 2001, followed by follow-up assessments between 1998 and 2004 and characterizing confounders. Investigators followed participants until study termination (NIH-AARP and AHS: December 2019; PLCO: December 2020) or death. They ascertained mortality using the National Death Index (NDI) and cause-related deaths using International Classification of Diseases, Ninth Revision (ICD-9) or ICD-10 codes.
The study exposure was self-reported multivitamin use, and the primary study outcome was death. Participants completed baseline questionnaires to provide multivitamin use data. Time-varying analyzes incorporated dietary questionnaire follow-up data five years, three years, and nine years after initiation of the AHS, PLCO, and NIH-ARP studies, respectively.
The researchers performed Cox proportional hazards regression modeling to calculate hazard ratios (HRs), adjusting for variables such as age, biological sex, body mass index (BMI), race, ethnicity, education level, physical activity, marital status, alcohol consumption, smoking habits, coffee consumption, Healthy Eating Index 2015 (HEI-2015) scores and cancer among family members. They analyzed data between June 2022 and April 2024.
Investigators excluded proxy respondents: those who died before receiving study questionnaires. those who had registry-confirmed or reported cancer at baseline; those who had myocardial infarction, diabetes, end-stage renal disease or stroke at baseline (n=105,871). those with excessive caloric intake. or those with missing covariate data.
Results
The study included 390,124 people: 327,732 from NIH-AARP, 42,732 from PLCO, and 19,660 from AHS. There were 7,861,485 individual years of follow-up. The median age of the participants was 62 years and 55% were male.
In total, the researchers noted 164,762 deaths during the follow-up period. 41% had never smoked and 40% had obtained a university degree. Of the 164,762 deaths, 49,836 were from cancer, 35,060 from cardiovascular disease and 9,275 from cerebrovascular disease.
Among regular multivitamin users, 49% and 42% were college-educated women, compared with 39% and 38% among non-multivitamin users, respectively. In contrast, 11% of regular multivitamin users, compared to 13% of nonusers, were current smokers.
Multivitamin use was not associated with a lower risk of death from any cause at baseline or follow-up periods. Hazard ratios were comparable for leading causes of mortality and time-varying assessments.
The team observed qualitative effect modifications by age, BMI, and smoking status, but not by biological sex, HEI-2015 scores, race, or ethnicity. In the initial follow-up analysis (FP1), the HRs for regular multivitamin use and death from any cause were higher for those younger than 55 years (HR, 1.2).
In FP1, HR estimates for non-regular multivitamin use and death from any cause were higher for former and current smokers and subjects with normal BMI. The meta-analysis, incorporating time-varying estimates from all cohorts, showed that regular multivitamin use, compared with no use, was associated with a 4.0% higher risk of death from any cause in FP1 but not in FP2.
conclusion
The study findings provide no evidence of increased longevity among regular multivitamin users. However, one cannot rule out the possible effects of regular multivitamin use on other aging-related health outcomes. Further research should include non-observational study designs and more diverse populations to increase the generalizability of the study findings.
