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Do Multivitamins Work and Are They Worth It?

Written by Markita Lewis, MS, RD

Reviewed by Anthony Dugarte, MD 

Published on June 18, 2021

Most people believe they need a multivitamin to help fill in nutrition gaps in their diet. But is this true? What does the research say about these popular supplements?

Do Multivitamins Work and Are They Worth It?

Multivitamins are among the most common dietary supplements out on the market today.

A recent CDC report states that in 2017–2018, the most common type of dietary supplement used by all age groups was multivitamin-mineral supplements.

Despite the popularity of multivitamins, many consumers still wonder if they should take a multivitamin and if they actually work.

This article will look into what a multivitamin is, what the research says about multivitamins, special populations who may benefit from vitamins, and potential safety concerns to help you determine if taking a multivitamin is right for you.

What Is a Multivitamin

What we know today as a “vitamin” comes from the phrase “vital amines” coined by Dr. Casimir Funk in 1912.

They are vital because they are small nutrient compounds that are essential to life. There are 13 essential vitamins, and deficiencies of these vitamins can increase the risk for a number of diseases.

A multivitamin is a supplement that can contain several vitamins, minerals, botanical substances, and other ingredients.

Different multivitamin supplements exist for various age groups, disease states, and lifestyles.

There are no current standards or regulations for what a multivitamin is required to provide, making it difficult to determine how effective they truly are.

Multivitamins can come in multiple forms – capsules, liquids, gummies, tablets, and powders.

The ingredients within multivitamins can be sourced from whole foods or made from synthetic processes.

Multivitamins and Healthy Aging

Some researchers believe that even moderate vitamin and mineral deficiencies can accelerate aging and increase the risk of age-related diseases.

A 2009 cross-sectional study found that telomere length was longer among women who used multivitamins than those who didn’t.

Telomere shortening in our chromosomes is a marker of biological aging, and this shortening is often accelerated in age-related diseases.

Not all of the research implies a connection between multivitamins and mortality risk.

A 2013 meta-analysis of clinical trials did not find multivitamin-multimineral supplementation to have any significant impact on reducing the risk of all-cause mortality.

National Health and Nutrition Examination Survey (NHANES) data from 1999–2010 also failed to show a relationship between vitamin and mineral supplement use and decreased mortality.

Instead, researchers found that adequate intake of certain nutrients from food sources reduced mortality risk.

Summary:
There is limited research for the effectiveness of multivitamins on anti-aging, and healthy aging may be more likely from having adequate nutrient intake from foods.

Multivitamins and Cardiovascular Disease

Multivitamins have been widely studied for their effects on cardiovascular disease, but the research doesn’t definitively support the use of multivitamins to reduce risk.

A 2018 systematic review and meta-analysis of vitamin and mineral supplements on cardiovascular disease outcomes found that multivitamins did not have any preventative benefits.

Only low to moderate evidence was found to support folic acid and B vitamin supplementation for stroke prevention and folic acid for overall cardiovascular disease prevention.

Another 2018 meta-analysis examining the effects of multivitamin use on hypertension found that supplements were effective at lowering systolic blood pressure.

But overall, the magnitude was not enough to effectively prevent a future occurrence of hypertension.

Summary:
Certain vitamins such as folic acid and other B vitamins may reduce the risk for cardiovascular disease, but multivitamins have limited effectiveness for lowering systolic blood pressure.

Multivitamins and Eye Health

Multivitamins appear to be helpful in promoting eye health for age-related eye diseases.

The Physician’s Health Study II, with a cohort of over 14,000 middle-aged and older male physicians, found that long-term multivitamin use decreased the risk of cataracts.

The Age-Related Eye Disease Studies find that targeted multivitamins containing antioxidants, minerals, and other nutrients reduced the risk of age-related macular degeneration.

Summary:
Research finds that general multivitamins can decrease the risk of cataracts, and vitamins targeted for improving eye health can reduce the risk of age-related macular degeneration.

Multivitamins and Cognition

Taking a daily multivitamin may be beneficial for supporting a healthy brain, but the effects aren’t consistent.

A randomized trial published in 2020 found that healthy young exercisers experienced several benefits from taking a multivitamin for 28 days.

Women experienced reduced stress in cognitive tasks and reduced mental tiredness during exercise. However, in men, the multivitamin only helped decrease mental tiredness.

Other studies on the effectiveness of multivitamins on cognitive function have not found a benefit over placebo, as noted in a 2018 systematic review.

Summary:
Multivitamins may help cognition during cognitive and exercise-induced stress, but this is not a consistently seen effect.

Multivitamins and Cancer

In 2013, The U.S. Preventive Services Task Force (USPSTF) did a meta-analysis of primary prevention studies to see if vitamin and mineral supplementation could be helpful for preventing cancer.

At the time, they found limited evidence to support vitamin and mineral supplementation to prevent cancer, but two studies included in the review found a lower incidence of cancer in men with vitamin supplementation.

The task force is currently in the middle of updating its recommendations.

Current research suggests that vitamin D supplementation may benefit cancer-related mortality and may have a small but statistically insignificant benefit in reducing all-cause mortality.

Data from the Physicians’ Health Study II suggest that multivitamin supplementation may reduce cancer incidence in men who have a history of cancer.

Summary:
Recent research suggests that multivitamins may reduce cancer incidence in men, and vitamin D may potentially reduce cancer-related mortality.

Special Populations

There are certain populations who have increased nutrient needs and benefit from multivitamin supplementation.

Research supports the use of dietary supplements to reduce the risk of nutrient deficiencies in individuals who have limited access to food or poor diet quality.

The American College of Obstetricians and Gynecologists recommend that pregnant persons take a prenatal multivitamin daily to meet increased needs during pregnancy.

A 2017 meta-analysis on the effects of multivitamins on natal outcomes found that regular multivitamin use during pregnancy reduced the risk of small for gestational age infants, neural tube defects, and other birth defects.

Older adults are more likely to have nutrient inadequacies and deficiencies due to decreased nutrient absorption and food intake. Therefore, they may benefit from a multivitamin.

NHANES data from adults ages 51 years and older found that multivitamin-multimineral supplements increased overall nutrient intake, decreased the prevalence of nutrient inadequacies, and reduced clinical nutrient deficiencies of multiple vitamins.

A recent 2020 study randomized trial that multivitamin supplements improved self-reported length and severity of illness in older adults compared to a placebo.

Vegetarians and vegans are at risk for having an inadequate intake of certain vitamins and minerals (including B12, vitamin D, zinc, and calcium) and would likely benefit from vitamin supplements.

There are also some chronic diseases and conditions that may either increase nutrient needs or impact the absorption of nutrients, and multivitamins may be necessary to help individuals meet their nutrient needs.

Summary:
Multivitamins can be useful for individuals with higher nutrient needs, decreased nutrient intake and absorption, decreased availability of certain nutrients in the diet due to dietary choices, or maybe experiencing food insecurity and insufficiency.

Safety Considerations

When people are deciding if they should take a multivitamin, there are inevitable concerns about whether they are safe to use.

A 2017 review on the safety of multivitamins found that multivitamins were generally safe to take long-term (more than 10 years). However, there are risks and potential side effects to consider.

Common side effects from taking multivitamins are usually mild and include nausea, abdominal pain, diarrhea, loss of appetite, and rash.

There is a higher risk of having an excessive intake of vitamins through multivitamin use than with food alone, especially if the composition of the multivitamin contains high doses of nutrients.

Single vitamin supplementation may present bigger health risks than multivitamin use.

In their review, the USPSTF found that beta-carotene supplementation was associated with cardiovascular and lung cancer mortality and should be avoided.

Studies find increased cardiovascular risks from taking vitamin E and niacin, with a trend towards greater mortality while taking antioxidant supplements.

Supplementation of vitamin D, vitamin E, or vitamin K can cause drug-vitamin interactions, so it is important to speak with a physician prior to starting a new supplement.

When choosing a vitamin, taking care to find a high-quality vitamin with independent testing is important.

The FDA classifies multivitamins as dietary supplements. However, because of DSHEA (the Dietary Supplement Health and Education Act of 1994), the FDA is not authorized to review dietary supplements for safety and effectiveness before they are sold.

Manufacturers are responsible for maintaining the quality of their supplements and following current Good Manufacturing Practices. However, quality errors can still be made, and your multivitamin may not contain what it says on its label.

Third-party testing from independent labs can help with assuring quality control.

Before starting a new supplement, I recommend having a conversation with your doctor to see if it is appropriate for your care and lifestyle.

If you experience any symptoms from taking a multivitamin, seek medical attention and speak with your doctor as soon as possible, as these symptoms may be related to other potentially serious underlying conditions.

Should You Take a Multivitamin?

If you’re a generally healthy person who has a varied diet based on whole foods, there may not be a big benefit to taking a multivitamin.

That being said, multivitamin supplementation appears to be worth it for maintaining eye health and possibly for reducing cancer risk.

The benefits of a multivitamin are greater if you either have existing micronutrient deficiencies in your diet or if your body requires more nutrition for pregnancy or other conditions.

In their 2018 position paper on micronutrient supplementation, the Academy of Nutrition and Dietetics advises against the indiscriminate use of multivitamins.

Intake of supplements should not take the place of foods in the diet and should be used to fill gaps in the diet.

The Bottom Line

Before taking a multivitamin, increasing the nutrient density of your diet can provide a number of health benefits and should be a starting point for supporting your health.

Choosing whole grains, fruits and vegetables, lean protein, and healthy fats daily can reduce your risk of vitamin deficiencies.

Proper supplement selection and use should be guided with the assistance of a health professional such as a doctor or registered dietitian.

Speak with your doctor before starting a multivitamin to see if it is safe and necessary for your health.

If you have concerns about nutrient deficiencies, your doctor can order labs and other tests to see what plan of action is best to help your nutrient status.

If you are experiencing any negative health symptoms, it may be related to a more serious underlying condition that may require medical care.

A discussion with your doctor can prevent delays in obtaining proper management of potential medical issues.

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