Scientists make controversial conclusion about daily multivitamins in recent study

A new analysis of 390,124 healthy U.S. adults, tracked for more than 20 years, reports no link between taking a daily multivitamin and living longer. 

Plenty of people reach for a daily pill to cover nutritional gaps. The new results point in a different direction for longevity in generally healthy adults.

Studying daily multivitamin use

The research team followed participants in three large U.S. cohorts that began in the 1990s and early 2000s, all free of cancer and major chronic disease at the start.

This design is called a cohort study, which observes people over time and links their habits to later health outcomes.

After accounting for age, sex, race and ethnicity, education, smoking, body weight, and diet quality, the team compared daily multivitamin users with nonusers. The headline result did not change after these adjustments.

The study recorded 164,762 deaths during follow-up, including deaths from cancer, heart disease, and cerebrovascular disease.

Daily multivitamin (MV) use showed no reduction in all cause mortality or these major categories.

The work was led by Erikka Loftfield, PhD, National Cancer Institute (NCI). She and colleagues also checked whether results looked different by age, smoking status, and diet quality.

What the results mean

In the first half of follow-up, daily users had a 4 percent higher risk of death compared with nonusers. The study showed a “multivariable adjusted hazard ratio” of 1.04 and a 95 percent confidence interval of 1.02 to 1.07.

In the later years, the risk estimate was similar and not statistically different from 1.00.

“MV use was not associated with a mortality benefit,” wrote Loftfield. That conclusion fits the overall pattern of the data.

A hazard ratio compares risk between groups over time, with 1.00 indicating no difference. Values just above or below 1.00 suggest small differences that may or may not be meaningful after considering uncertainty.

How this fits with prior research

“The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the use of multivitamin supplements for the prevention of cardiovascular disease or cancer,” stated the U.S. Preventive Services Task Force (USPSTF).

That 2022 study reviewed randomized trials.

In the Physicians’ Health Study II, a large randomized trial in more than 14,000 male physicians, a daily multivitamin did not reduce major cardiovascular events or cardiovascular mortality after about 11 years.

That trial aligns with the new observational findings on longevity.

Editorial commentary characterized the mortality finding as consistent with mostly negative prior results. The pattern across methods, randomized and observational, tells a similar story for lifespan in well nourished adults.

Why people still take multivitamins

Many adults still use multivitamins for peace of mind or to backstop uneven diets. About one third of U.S. adults report recent use, according to an NIH Office of Dietary Supplements fact sheet.

Behavior can complicate research in this area. People who take supplements often exercise more and eat better, a form of healthy user bias that can make pills look better than they are in simple comparisons.

Reverse causation can also creep in when people start supplements after health problems appear. The new analysis tried to address both issues by adjusting for lifestyle and by examining time windows across decades.

Who might consider supplements

The study focused on generally healthy adults without major chronic disease at the start. Its findings do not apply to people with documented deficiencies or special needs.

The CDC has a longstanding recommendation that all women capable of becoming pregnant get 400 micrograms of folic acid daily to help prevent neural tube defects.

Clinicians also consider targeted supplements for specific conditions, such as vitamin D in people with low blood levels, or vitamin B12 in those with absorption problems.

Talk with your clinician before starting or stopping supplements, especially if you take medications. Labels can look simple, yet ingredients and doses vary a lot.

Daily multivitamins and human health

Multivitamins may still play a role in areas beyond mortality. Researchers have noted interest in how certain nutrients could affect cognition, eye health, or immune function.

Trials testing targeted outcomes, such as the impact of vitamin C or zinc on colds, have found mixed evidence, but these remain active areas of study.

Some studies suggest multivitamin use could influence short term measures like fatigue or mood, though findings vary.

Evidence on these fronts is less consistent than for mortality or chronic disease, yet they highlight that supplements may have benefits unrelated to lifespan.

The best supported steps for longer, healthier life remain familiar. Do not smoke, keep moving, eat a varied diet rich in plants, sleep well, and manage blood pressure and blood sugar.

Supplements can be useful in narrow, evidence based situations. For most healthy adults, a daily multivitamin does not appear to extend life.

The study is published in JAMA Network Open.

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