Multivitamins May Slow Biological Aging in Seniors

A new study from one of America's most prestigious research institutions claims a humble daily multivitamin can slow the molecular machinery of aging. But dig beneath the headlines and a far more complicated picture emerges—one involving industry funding, conflicting data, and a scientific community wrestling with what "biological age" even means.

The Study That Launched a Thousand Headlines

On March 9, 2026, researchers from Brigham and Women's Hospital published a study in Nature Medicine that quickly ricocheted across newsrooms worldwide: a daily multivitamin-multimineral supplement appeared to slow biological aging in older adults [1][2].

The findings emerged from a prespecified ancillary analysis of the COcoa Supplement and Multivitamin Outcomes Study (COSMOS), a large-scale randomized, placebo-controlled clinical trial that enrolled 21,442 men and women beginning in 2014 [3]. For the epigenetic aging analysis, researchers focused on a subset of 958 participants—482 women aged 65 and older and 476 men aged 60 and older, with an average chronological age of 70—who provided blood samples at baseline and after two years [1][4].

Participants were randomly assigned to one of four groups: multivitamin plus cocoa extract, multivitamin alone, cocoa extract alone, or placebo. The multivitamin used was Centrum Silver, provided by Haleon (formerly part of GSK Consumer Healthcare), while Mars Inc. supplied the cocoa extract [2][5].

What the Clocks Revealed

The study measured five distinct "epigenetic clocks"—sophisticated biomarkers that estimate biological age by analyzing patterns of DNA methylation, the chemical modifications that accumulate on our DNA over time and regulate how genes are expressed [6][7].

Two of the five clocks showed statistically significant results in favor of multivitamin supplementation. Compared with placebo, participants taking the daily multivitamin showed:

• PCPhenoAge acceleration: Slowed by 0.209 years (approximately 2.6 months) per year
• PCGrimAge acceleration: Slowed by 0.111 years (approximately 1.4 months) per year [1][4]

Over the full two-year trial, this translated to roughly four months of reduced biological aging—meaning participants' molecular clocks ticked as though they had aged approximately 20 months rather than 24 [2].

Crucially, the effect was more pronounced among those who were already aging faster than their chronological age at baseline. For participants with accelerated GrimAge at enrollment, the benefit approximately doubled to 2.8 months per year [2][4].

However, three other epigenetic clocks included in the analysis—first-generation measures including the Horvath and Hannum clocks—showed no statistically significant changes [8]. And cocoa extract, the trial's other active intervention, produced no measurable effect on any of the five aging markers [1].

Source: Nature Medicine / COSMOS Trial

Data as of Mar 9, 2026CSV

The Promise and Limits of Epigenetic Clocks

To understand why this study matters—and why its implications remain fiercely debated—requires grasping what epigenetic clocks actually measure.

First-generation clocks, developed by researchers like Steve Horvath, were trained to predict chronological age from DNA methylation patterns. They are remarkably accurate at telling you how old someone is, but less useful for predicting health outcomes [6].

Second-generation clocks like PhenoAge and GrimAge represent a significant methodological advance. PhenoAge incorporates nine clinical biomarkers including albumin, creatinine, glucose, and C-reactive protein alongside methylation data, creating a multidimensional measure of aging [6]. GrimAge goes further, building its predictions from DNA methylation surrogates for plasma proteins and smoking history—factors with established links to mortality. Studies have shown GrimAge outperforms other epigenetic clocks in predicting death and age-related clinical decline [7][9].

"What it means is that your trajectory of health moving forward should stand to benefit," said Howard Sesso, an epidemiologist at Brigham and Women's Hospital and a lead author of the study. But he was careful to add: the results "don't mean a multivitamin adds four months to a person's lifespan" [2].

Daniel Belsky, an aging researcher at Columbia University, offered a similarly measured take: "Nobody thinks taking a multivitamin is going to rejuvenate them" [2].

A Demographic Tailwind

The study arrives at a moment when America's aging population is growing rapidly—and spending accordingly.

Source: World Bank

Data as of Feb 24, 2026CSV

The percentage of Americans aged 65 and older has risen from 12.3% in 2007 to 17.9% in 2024, according to World Bank data [10]. This demographic shift has fueled enormous growth in the supplements market. The global older adults health supplements industry was valued at $182.6 billion in 2024 and is projected to reach $314.2 billion by 2034 [11]. Multivitamin formulations are used by roughly 59% of elderly individuals [11], and nearly 40% of Americans aged 60 and over take a multivitamin-mineral supplement [12].

Three-quarters of all Americans now report using some form of dietary supplement, with multivitamins the single most popular category at 40% usage [12][13].

The Contradictory Evidence

The COSMOS epigenetic aging results do not exist in a vacuum. They must be weighed against a substantial body of research that has failed to find meaningful health benefits from multivitamin supplementation.

In June 2024, a landmark study published in JAMA Network Open followed 390,124 generally healthy adults across three prospective U.S. cohorts for over 20 years. The conclusion was stark: daily multivitamin use was not associated with a lower risk of death from any cause, nor from cancer, heart disease, or cerebrovascular disease specifically [14][15].

"These findings suggest that multivitamin use to improve longevity is not supported," the researchers from the National Cancer Institute wrote [15].

The U.S. Preventive Services Task Force (USPSTF) has maintained since 2022 that evidence is "insufficient" to determine whether multivitamin supplementation prevents cardiovascular disease or cancer in healthy, nonpregnant adults—an "I statement" reflecting genuine scientific uncertainty rather than a recommendation for or against [16]. The task force actively recommends against beta carotene and vitamin E supplements for disease prevention [16].

Johns Hopkins Medicine has been even more blunt. "Enough is enough: stop wasting money on vitamin and mineral supplements," researchers there wrote, concluding that multivitamins "don't reduce the risk for heart disease, cancer, cognitive decline... or an early death" [17].

The Cognitive Connection

Where the COSMOS trial has arguably produced its most consistent results is in cognition. Three separate analyses from the trial have found evidence that daily multivitamin supplementation improves memory and slows cognitive aging in older adults [18][19].

A meta-analysis of three cognitive substudies within COSMOS, published in the American Journal of Clinical Nutrition in January 2024, found that participants assigned to the multivitamin group had significantly higher cognitive test scores after three years than those on placebo. The cognitive benefit was estimated to be equivalent to slowing age-related decline by approximately three years [18][19].

These findings represent some of the strongest randomized trial evidence to date linking multivitamins to cognitive preservation—though the mechanism remains unclear. Researchers have hypothesized that B-vitamins and choline, which influence the one-carbon metabolism pathway responsible for providing methyl groups for DNA methylation reactions, could be driving both the epigenetic and cognitive effects [6][20].

Follow the Money

Any assessment of the COSMOS findings must contend with the study's funding structure. Haleon, which manufactures Centrum Silver, provided the multivitamin product, placebo pills, and packaging for the trial [5]. Mars Inc., maker of cocoa-based products including CocoaVia, funded the cocoa extract arm and provided infrastructure support through its Mars Edge nutrition research division [3][5].

The trial was also supported by multiple grants from the National Institutes of Health (grants AG050657, AG071611, EY025623, and HL157665), providing a degree of public funding and independent oversight [3].

Researchers at Brigham and Women's Hospital have emphasized that the study was investigator-initiated and that the funders had no role in data collection, analysis, or interpretation [3]. Nevertheless, the arrangement illustrates a perennial tension in nutrition science: randomized clinical trials are expensive and rare, and industry funding often fills the gap that public research budgets cannot.

As Centrum's own website notes, the brand positions itself as "the most clinically studied multivitamin brand in the world" [5]—a marketing claim that the COSMOS trial directly supports.

What We Still Don't Know

The limitations of the study are significant and have been acknowledged by the researchers themselves.

José Ordovás, a nutrition scientist at Tufts University, observed that "the multivitamin produced small favorable changes in two epigenetic aging markers, but not across all the clocks that were measured," and that "conclusions about broad anti-aging effects remain premature" [8].

Zachary Clayton of the University of Colorado Anschutz emphasized that "the magnitude of the observed differences was modest, and their clinical significance remains uncertain" [8].

Danica Chen of UC Berkeley raised perhaps the most fundamental question: "We do not know yet whether [multivitamins] have an effect in improving tissue function or reducing disease risk" [2].

Additional unresolved issues include:

• Narrow demographics: The study's participants were predominantly white, healthy, and over 70. Whether results generalize to younger, more diverse populations is unknown [2][8].
• Unclear mechanisms: Researchers cannot identify which specific vitamin or mineral—or combination thereof—drove the observed effects [2].
• No gold standard: There is no universally accepted measure of biological aging. Different epigenetic clocks can yield different results, as this study demonstrated [8].
• Clinical significance: Slowing a molecular marker by a few months does not necessarily translate to fewer diseases, better function, or longer life [2][8].
• Diet and lifestyle: The study did not control for participants' diets or physical activity during the two-year period [8].

As Sesso himself noted: "We still need to understand what an improvement in biological aging feels like beyond our DNA" [4].

The Bigger Picture

The tension at the heart of this story is not really about multivitamins. It is about the fundamental challenge of measuring aging itself—and the gap between what molecular biomarkers can detect and what patients actually experience.

Epigenetic clocks represent a genuine scientific advance, offering researchers a window into the biological processes that drive aging at the cellular level. But they remain a proxy, not a verdict. A clock that ticks slightly slower is not the same thing as a body that functions better or a life that lasts longer.

The supplement industry, valued at hundreds of billions of dollars and largely unregulated by the FDA, has every incentive to translate tentative findings into definitive marketing claims. Consumers, bombarded by a confusing mix of pro- and anti-supplement messaging, are left to navigate a landscape where a rigorous Nature Medicine study and a reassuring Centrum advertisement can cite the same data [5].

What the COSMOS trial has delivered is not a verdict but a provocation: the first randomized clinical trial evidence that a cheap, widely available supplement can measurably—if modestly—alter a molecular signature of aging. Whether that molecular signature matters for the outcomes people actually care about—fewer diseases, sharper minds, longer lives—remains the open question that only years of additional research can answer.

For now, the scientific consensus holds: a balanced diet rich in fruits, vegetables, and whole grains remains the gold standard for healthy aging [17]. A daily multivitamin may offer an intriguing hedge—but it is not yet a proven fountain of youth.

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