Science Reveals Most Multivitamins Fall Short—Here’s What Makes Dr. Fuhrman’s Different

Q: Should I take a multivitamin—even if I’m already healthy?

It’s a common question. Nearly one-third of Americans take a daily multivitamin, hoping it might help them live longer, prevent cancer, and reduce their risk of chronic disease. Others rely on them to fill nutritional gaps in their diet.

But the truth is, not all multivitamins are created equal. And while the idea of “just taking a pill” sounds simple, the science is more complicated—and more revealing.

Over the past 70 years, the standard American diet has become increasingly processed and nutrient-poor. Multivitamins were developed to compensate for that. But today, the real question is: can the right multivitamin enhance an already healthy diet? The answer—if you follow the latest research—is yes, but only if it's done right.

What the Research Actually Shows 

Studies on multivitamins have delivered mixed results:
🧪 An analysis of data from over 390,000 U.S. adults followed for more than 20 years found that multivitamin use was not associated with a reduced risk of mortality.¹ 
The Physicians’ Health Study II (14,000+ U.S. male physicians) randomized controlled trial of multivitamin supplementation showed an 8% reduction in cancer risk over 11 years, which was stronger in men with a history of cancer or older than 70—but no effect on the risk of cardiovascular disease or deaths from cancer.^2,3
🧪 COSMOS, a randomized controlled trial of multivitamin and/or cocoa supplementation of 21,000 older adults over about 3.5 years, found no significant reduction  in total cancer, cardiovascular disease, or mortality. However, there was a decrease in lung cancer risk and  improved cognitive function  in the multivitamin groups.^4,5
🧪Multivitamin use has been associated with longer telomeres, a marker of slower biological aging, and slower epigenetic aging was observed in participants taking multivitamins in the COSMOS trial.^6,7

Why the variation? Because outcomes depend on the nutrient content of the participants’ diets, the nutrients included in the multivitamin, their doses, and the supplement quality itself. Also, looking broadly at mortality or cardiovascular disease might obscure benefits to cognitive function, immune health, or quality of life in older age. Finally, looking at the research on multivitamins doesn’t tell us the effects of the individual nutrients, some of which are health-promoting and some likely harmful. That’s why I took a radically different approach.

Dr. Fuhrman’s Guide to Smart Supplementation

Rather than rely on generic formulas, I build supplements from the ground up, guided by rigorous nutritional science. Every ingredient is selected based on its proven benefit for longevity and health—nothing more, nothing less.

My goal is to enhance a high-nutrient diet, not replace one- and help people live longer, healthier lives.

First, It Starts with Food

The Nutritarian diet is built around high-nutrient, plant-rich foods. It’s designed to fuel the body with powerful phytochemicals and antioxidants while reducing disease risk and slowing the aging process. Studies show those who eat more whole plant foods live longer.^8-13

But here’s the tradeoff: as we reduce or eliminate animal products, we also reduce our intake of nutrients like vitamin B12, zinc, iodine, and omega-3 DHA and EPA—all of which are harder to get from plants alone.

And seafood? It’s a poor solution. Fish may supply omega-3s and iodine, but also come with mercury, dioxins, and microplastics—not to mention unsustainable environmental costs.^14-16 That’s why smart supplementation, not seafood, is the better path forward.

What Makes a Multivitamin “Smart”?

The best diet only needs targeted, conservative supplementation to become fully protective. But most store-bought multivitamins are poorly designed for people who already eat healthfully: they underdeliver on what you need and overdeliver on what you don’t.

Even mild deficiencies in B12, iodine, DHA, or zinc can negatively affect immune health, cognitive function, and longevity. Nutrient gaps are common—even in those who eat animal products.^17,18 

Why Most Multivitamins Fall Short

Many conventional multivitamins still use outdated formulas packed with potentially harmful ingredients:

• Folic acid – Unlike natural folate, supplementing with synthetic folic acid may increase cancer risk.
• Vitamin A and beta-carotene – Linked to higher mortality and bone fracture risk.
• High-dose iron and copper – especially when one is not deficient, can accumulate and promote oxidative stress, especially as we age. 

Worse yet, many companies don’t update their formulations as new research emerges. Their products prioritize shelf life and profit over health outcomes.

Dr. Fuhrman’s Approach: Based on Science, Not Stock Formulas

My supplements are based on clinical science, not marketing trends. I created them to complement a nutrient-dense diet—never to replace one.

They are:

• Free of potentially harmful ingredients like folic acid, vitamin A, and copper
• Formulated with evidence-based doses of key nutrients
• Designed to optimize your health, not just cover the basics

When used wisely, formulas like Women’s Daily +D3 and Men’s Daily +D3 support healthy aging, brain health, immune function, and more—without compromising safety or purity.

Action Item:
My multivitamins are science-backed multivitamins designed with purity, safety, and effectiveness in mind.

Sources: 
Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts
Effect of multivitamin-mineral supplementation versus placebo on cognitive function: results from the clinic subcohort of the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial and meta-analysis of 3 cognitive studies within COSMOS.
Plant-Based Diets Are Associated With a Lower Risk of Incident Cardiovascular Disease, Cardiovascular Disease Mortality, and All-Cause Mortality in a General Population of Middle-Aged Adults 
Multivitamin use and telomere length in women
Differences in all-cause mortality risk associated with animal and plant dietary protein sources consumption
Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality
The association between overall, healthy, and unhealthy plant-based diet indexes and risk of all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

4 Vital Vitamins and Minerals

Even with a healthy diet, it’s difficult to guarantee optimal nutrient levels every day. Absorption varies from person to person, and some nutrients—especially on a plant-based diet—are harder to obtain in the right amounts. A high-quality multivitamin can help fill those gaps and ensure you’re getting the essential micronutrients your body depends on.

Here are four nutrients that should be present in your multivitamin—in effective, evidence-based forms and doses:

Vitamin B12

Vitamin B12 is essential for red blood cell production, nerve function, and DNA synthesis. A deficiency can lead to anemia, fatigue, mood changes, digestive issues, and even irreversible nerve damage.¹⁹ Low B12 levels are also linked to cognitive decline and raise homocysteine, a known risk factor for cardiovascular disease.^20-23 B12 is made only by microorganisms and is not found in plant foods. Deficiencies are especially common in vegans not taking supplements and older adults (about 20% of people over age 60 are deficient).¹⁹

Supplement tip: I recommend 75 mcg of methylcobalamin daily to ensure optimal absorption—especially for those on a vegan or plant-based diet.^24,25

Sources:
The metabolism and significance of homocysteine in nutrition and health 
Cognitive impairment and vitamin B12: a review 
Vitamin B12 in health and disease
Mechanistic Link between Vitamin B12 and Alzheimer's Disease

Vitamin D

While our bodies produce vitamin D from sun exposure, low levels are extremely common—particularly in people who work indoors, live in northern climates, or avoid excessive sun due to skin cancer risk. 

Related: Vitamin D is Crucial to Overall Health

Vitamin D does far more than support bone health—it also plays a critical role in immune function and may reduce the risk of certain cancers, heart disease, diabetes, and autoimmune conditions.^26,27 
Supplement tip: 2000 IU (50 mcg) of vegan vitamin D3 is generally effective for reaching ideal blood levels of 25(OH)D (30–45 ng/mL). D3 is more effective than D2.²⁸ Blood testing is recommended to confirm adequacy.

Sources:
Vitamin D Deficiency
Vitamin D for skeletal and non-skeletal health: What we should know
Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis

Iodine

Iodine is required for healthy thyroid function and hormone production. Most plant foods are low in iodine, and while kelp is rich in it, it’s not eaten regularly—and can sometimes provide excess amounts.

In the Standard American Diet, iodized salt is the primary source. But if you avoid added salt (which is advisable for blood pressure and heart health), you may be at risk for iodine deficiency.^29,30

Supplement tip: A multivitamin with around 150 mcg of iodine from a natural source (like kelp) can help maintain healthy thyroid function.

Sources:
Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Iodine 
Vegans, Vegetarians, and Omnivores: How Does Dietary Choice Influence Iodine Intake? A Systematic Review 

Zinc

Zinc is critical for immune health, wound healing, reproduction, and hundreds of biochemical reactions in the body. While zinc is found in whole plant foods, its absorption is blocked by phytate in beans, grains, nuts, and seeds.^31,32
Vegetarians and vegans typically have lower circulating zinc levels, and plant-based eaters may need up to 50% more zinc than omnivores. 33-35 Zinc is especially important for men, as it supports prostate health.³⁶

Supplement tip: Look for 7.5-10 mg of zinc in highly bioavailable forms like zinc bisglycinate or picolinate.³⁷

Sources:
Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans
The role of zinc in life: a review
Zinc Deficiency in Men Over 50 and Its Implications in Prostate Disorders
Comparative Absorption and Bioavailability of Various Chemical Forms of Zinc in Humans

An Important Note on DHA and EPA

While not typically included in multivitamins, the long-chain omega-3s DHA and EPA are essential for brain health and cognitive longevity. Most people—even those who eat fish—have suboptimal levels. Vegans and vegetarians are especially at risk.^38,39

For brain protection across all life stages, I recommend algae-derived DHA/EPA supplements as a cleaner, safer alternative to fish oil.

Related: Omega-3 fatty acids, DHA and EPA, are crucial for brain health through all stages of life 

Action Item:
Shop DHA+EPA Purity

3 ingredients you don’t want in your multivitamin 

Research shows you do not want to take a multivitamin containing folic acid, vitamin A, or beta-carotene. These nutrients are potentially dangerous to supplement and are unnecessary when consuming a heathy diet rich in vegetables, fruits, and other health-promoting plant foods.

Folic Acid

Folic acid is the synthetic version of folate, a vital B vitamin found naturally in leafy greens and other plant foods. While folate supports DNA repair and helps prevent birth defects, synthetic folic acid may pose health risks when taken in excess.

Multiple studies suggest that folic acid—because of its higher bioavailability and accumulation in the bloodstream—may promote cancer growth in some individuals.^40-43

Bottom line: If you eat a diet rich in green vegetables, you’re getting plenty of natural folate. Supplementing with synthetic folic acid is unnecessary—and potentially dangerous.

Sources:
Is folic acid good for everyone?
Folate and Its Impact on Cancer Risk

Vitamin A and Beta-Carotene

Vitamin A is important, but you don’t need to get it from supplements. A diet rich in colorful vegetables provides beta-carotene and other carotenoids that your body can convert to vitamin A as needed.

However, studies show that supplementing with synthetic vitamin A or beta-carotene may actually interfere with the absorption of other protective carotenoids and increase cancer risk.^44,45 These supplements have also been linked to osteoporotic fractures,46 and, at higher doses, a greater risk of premature death.^45,47

Bottom line: Get your vitamin A from food—not pills. Supplementing with these forms may do more harm than good.

Sources:
Beta-carotene, carotenoids, and disease prevention in humans
Vitamin A - discovery, metabolism, receptor signaling and effects on bone mass and fracture susceptibility
Dietary Supplements and Risk of Cause-Specific Death, Cardiovascular Disease, and Cancer: A Systematic Review and Meta-Analysis of Primary Prevention Trials

Caution: vitamin E, selenium, iron, and copper

While all of these nutrients are essential in small amounts, excess supplementation can cause more harm than good—especially as we age.

Vitamin E

Vitamin E occurs naturally in many plant-based foods, especially nuts and seeds. However, most supplements contain only alpha-tocopherol,  which—when taken in high doses—has been associated with an increased risk of mortality.47 This narrow formulation may also interfere with the absorption of other beneficial forms of vitamin E.

Selenium

Selenium plays a role in immune function and thyroid health, and is found naturally in nuts (especially Brazil nuts), beans, and whole grains. But excess selenium intake—common with multivitamin use—has been linked to a higher risk of type 2 diabetes, elevated cholesterol, prostate cancer, and cardiovascular disease, along with impaired immune and thyroid function.^48-53

Iron and Copper

These two trace minerals are necessary for oxygen transport, energy production, and enzyme function. However, iron and copper can accumulate in the body over time, particularly in adults over 40, contributing to oxidative stress, inflammation, and increased risk of heart disease and neurodegenerative conditions.^54-56
Supplemental iron should only be used when medically indicated—such as during pregnancy or if a deficiency is confirmed by bloodwork.^57,58

Related: Iron recommendations for pregnant women

Sources:
Meta-regression analyses, meta-analyses, and trial sequential analyses of the effects of supplementation with beta-carotene, vitamin A, and vitamin E singly or in different combinations on all-cause mortality: do we have evidence for lack of harm?
Adverse health effects of selenium in humans 
Metal Toxicity Links to Alzheimer's Disease and Neuroinflammation
New insights into the role of iron in inflammation and atherosclerosis 
Iron status during pregnancy: setting the stage for mother and infant 

Takeaway

These surprising scientific findings mean that most conventional multivitamins act as a double-edged sword, containing both helpful and harmful elements. Use the latest advance in nutritional research to your advantage by understanding the ingredients found in your multivitamin and making sure that they are present in optimal amounts. It is this reason I created my own multivitamins for my patients to ensure that they supplement wisely.