Vitamin Supplements: Which Ones Are Proven And Which Ones Are Placebo?

When it comes to staying healthy, people are always looking for the next greatest thing to add to their routine. With the modernization of health marketing running rampant on both traditional and social media advertising, health supplements and vitamins have become incredibly popular over the past few decades. But with little long-term data, minimal science-based research, and no government requirements for efficacy testing, how can we be sure that the vitamins we take every day are actually doing us any good?

Originally identified in 1912 by food researcher Casimir Funk, vitamins have forever changed how we approach eating a balanced and nutrient-dense diet.¹ With the first vitamin supplements entering the market as early as 1916, over the following century health supplements would grow to become a massive player in the health industry. According to the Food and Drug Administration (FDA), there are an estimated 29,000 different dietary supplements available to the general public, with an additional 1000 supplement options being added every single year.²

With thousands of different options available and minimal research available about the efficacy of each individual supplement, consumers can easily get lost in the seemingly never-ending sea of “important” dietary supplements. With the vitamin and supplement industry having an estimated market size of $36.6 billion in 2021, it seems that a large majority of us are willing to spend our money on supplements, whether or not they have been proven to actually offer us any proven health benefits.³

According to the CDC, vitamin supplements are popular amongst almost all age groups across America. With 57% of Americans aged 20-29 using vitamin supplements regularly, the percentage increases to nearly 75% of adults aged 60 or over.⁴

So, as the supplement industry continues to create and market the next best vitamin supplement that we all need to try, how can consumers become more conscious about which supplements are actually delivering on the health benefits that they claim?

What is a vitamin supplement?

A dietary supplement is officially defined as a product taken to supplement (or add to) your regular dietary intake. Capable of containing a variety of different ingredients, most dietary supplements are made from one or more vitamins, minerals, herbs, botanicals, and amino acids.⁵ Marketing to different age groups and for their different health benefits, vitamin supplements come in a variety of different forms, including tablets, capsules, gummies, liquids, topical creams, patches, powders, drinks, energy bars, and more.⁶

Despite the extensive number and variety of vitamins available on the market today, it is important to note that not a single dietary supplement is required to go through the same extensive testing that prescription-based medications do.⁵ Because of this, little information about the efficacy, safety, and overall impact of dietary supplements is known by the general public and researchers alike.

Supplements are not well-regulated, so adverse reactions go unreported

If you or someone you love is taking any prescription medications, there is a very high likelihood that drugs they are taking have undergone extensive clinical and medical testing. Regulated by the FDA, for a prescription or over-the-counter medication to be widely available to the public, the drug manufacturing company must submit a detailed data report containing information about the medication’s safety and efficacy. While every medication takes a slightly different path to approval, the most common steps to FDA approval include:⁷

  • Initial science and research (2-5 years) — During this phase, research and scientific testing are done into the creation of a medication. Depending on the success of initial research, research time can be significantly longer in this phase if delays occur.

  • Preclinical testing (1-2 years) — Initial testing is required to be done before conducting large-scale clinical trials. The goal of this testing is to answer basic questions about how the medication interacts with the human body.

  • Clinical trials (~9 years) — If the medication passes through these first two steps, it can enter the clinical trial phase. The longest phase of the process is broken up into three distinct sections:

    • Phase 1 — Early testing on a small group of healthy patients. The goal of this phase is to test for safety concerns with the medication.

    • Phase 2 — If it is approved, the drug is then tested on a larger group of patients living with the disease the medication is designed to treat.

    • Phase 3 — Finally, if the drug is effective, it is tested on a larger group of patients to identify possible adverse reactions and learn more about its efficacy.

  • FDA approval (6 months - 2 years) — If, and only if, a medication can be proven safe and effective for its designed treatment, then finally the FDA begins to assess and approve the medication for widespread use, completing the multi-year process.

Despite all of this testing, an FDA approval does not always mean that the medication is safe to use for everyone. Additional monitoring and recording of adverse reactions are conducted by the FDA for years after a medication is approved, and at any time medication can be removed if the statistics show that it is not safe or effective for treatment.

So, if medications that take this long to be approved can still be removed from the market for safety concerns, how are we sure that dietary supplements and vitamins, which are not FDA approved or tested, are safe to consume?

Currently, there is no great answer to this question. With the Dietary Supplement Health and Education Act restricting the FDA’s ability to restrict or monitor any vitamin labelled as a “dietary supplement,” there is no fail-safe testing done on these products to ensure quality, purity, potency, or safety of the supplement.⁸ In addition to this, there is currently no law requiring the information on the nutrition label of dietary supplements to be truthful and accurate. While the FDA can swoop in and remove a product on the market that has been identified to be misbranded or proven to cause injuries, finding the information needed to do this is nearly impossible. Because no formal monitoring is required for dietary supplements, it is estimated that as many as 50,000 supplement-related adverse reactions go unreported every single year in the United States alone.⁹

How do we know that vitamins even help?

In an attempt to learn more about the value, safety, and efficacy of vitamin supplements, some researchers have taken on the task of conducting full-fledged scientific studies about the most popular vitamins. Starting as simple observational studies, research projects about vitamins can turn into properly managed clinical trials. With the use of volunteers, proper testing with control groups (taking a dummy placebo supplement) and groups taking the supplement can be compared to learn more about the validity and benefits claimed by the vitamin supplement.

Despite the limited research and information about supplements, millions of people around the world still take multiple supplements every single day. While vitamin use is common across all age groups, it appears that the largest demographic of dietary supplement takers are senior citizens. With nearly 25% of Americans over the age of 60 taking four or more dietary supplements daily, the risk of developing adverse reactions and interactions with prescription medications is a serious concern.⁴

Supplements that you can go without

So which vitamins have been tested and proven to have health benefits, and are they the most popular supplements used around the world?

According to the CDC, the most popular dietary supplement in the United States are multivitamins, followed by vitamin D, OMEGA 3 fish oil, vitamin C, and other botanicals.⁴

Unfortunately, not all of these popular supplements have been proven to offer health benefits.

With more information about the at times questionable efficacy of dietary supplements, more research has been able to shed some light on which vitamins might be worth skipping in your daily routine. These supplements, which have only been proven to cause health benefits through the placebo effect, are more likely than not a waste of your time and money:


Commonly prescribed by healthcare professionals or taken by people because they feel like they should, multivitamins have become the most commonly taken dietary supplement in America. Often taken as a tablet or gummy, the appeal of these supplements is that you can get a wide variety of vitamins from one single dose. While multivitamins are commonly taken to improve overall health, studies have shown that they do not result in any risk reduction of developing cancer, heart disease, or mental decline with age.¹⁰ Additionally, because many multivitamins contain a large selection of different supplements in one, the strength of each vitamin is often too low to result in any health benefits.⁹


As a supplement that has become increasingly popular recently, the dietary supplement market is now saturated with antioxidant vitamins. Capable of being man-made or found naturally in our food, antioxidants such as vitamin C, vitamin A, vitamin E, and carotene are said to help delay or prevent damage to our cells. Unfortunately, recent research has shown that taking antioxidant supplements may not be as safe as we originally thought. Dangerous at high doses and capable of interacting with prescription medications, antioxidant dietary supplements may be more harmful than helpful in the long run.¹¹

As a safer option, many health professionals encourage people to supplement their diet with naturally occurring antioxidants that occur in foods. By eating foods such as green tea, spinach, blueberries, and dark chocolate, a person can reap all the benefits from antioxidants in a safer and healthier way.

Tried and Tested Vitamins

In contrast to the dietary supplements that have not been proven to offer many health benefits, there is a selection of vitamins that have shown promising results from scientific testing. While it is always important to stay connected to the most recent research about the supplements you are taking, here are a few vitamins that have been proven to have some health benefits:

Vitamin D

Commonly referred to as the sunshine vitamin, humans predominantly get the amount of vitamin D they need from exposure to the sun. Created within our body as a result of exposure to the sun’s ultraviolet rays, people living in colder and darker climates are at an elevated risk of developing symptoms of vitamin D deficiencies such as mood changes, muscle cramps, brittle bones, and fatigue.¹²

Because very little of our daily requirements of vitamin D come from food, dietary supplements have proven to be helpful in those at risk of deficiencies. It is recommended that adults take anywhere from 600 IU - 1000 IU of vitamin D supplements a day, with higher dosages possibly becoming toxic in large quantities.⁹


Fibre is a type of carbohydrate commonly found in fruits and vegetables that is not digestible by the human body. Passing through the body until it is removed, fibre is an essential component of a healthy gastrointestinal tract. For those with gastrointestinal diseases or nutritional deficits, fibre supplements have been proven to be a great help in reducing the severity of symptoms.⁹ Capable of being taken by those without an existing medical condition, increased fibre intake has minimal risks and is considered to lead to many health benefits.

Vitamin B12

Found only in animal products, vitamin B12 is a water-soluble vitamin that is involved in the healthy function of our metabolism. For vegans, vegetarians, and those who do not eat animal products, taking a vitamin B12 supplement is necessary to prevent the development of deficiencies.⁹ Proven to be safe and effective at replacing the missing nutrient for these groups of people, vitamin B12 supplements are worth taking for specific groups of people.

Choosing Quality of Quantity

At the end of the day, quality is one of the most important determining factors of the safety and efficacy of any supplement. While there are a few vitamin manufacturers who spend the time to rigorously test and perfect their products, many dietary supplements are made cheaply and quickly to make money from unaware consumers. Paul Garcia, a former marketing director for the vitamin company Theralogix explains:¹³

“The brands people buy most often are junk. Vitamins mass-marketed to consumers may or may not match the ingredients listed on their labels or be bioavailable to have an active effect at the time that they enter the body.”

With this in mind, it is heavily encouraged that all consumers spend some time researching and evaluating the brands and types of supplements they are choosing to purchase and take. With safety and efficacy concerns still incredibly present in the dietary supplement industry due to limited laws and regulations on production, the burden of research and education, unfortunately, falls on the general public for the time being. Hopefully, in the future, increased involvement from regulatory bodies such as the FDA can be implemented to protect consumers from purchasing mislabeled or potentially dangerous supplements.

  1. The discovery of the vitamins (2012)

  2. Dietary supplements: A framework for evaluating safety (2005)

  3. Vitamin & Supplement Manufacturing in the US - Market Size 2005–2027 | IBIS World

  4. Dietary Supplement Use Among Adults: the United States, 2017–2018 | Center for Disease Control and Prevention

  5. Definition of health terms: vitamins | MedlinePlus

  6. Dietary supplements: What you need to know | NIH: National Institutes of Health

  7. Rush to judgment? | Optum

  8. Dietary supplements | U.S. Food & Drug Administration

  9. Supplements: a scorecard | Harvard Health Publishing

  10. Is There Really Any Benefit to Multivitamins? | Johns Hopkins Medicine

  11. Antioxidants: in-depth | National Center for Complementary and Integrative Health

  12. Vitamin D Deficiency | Cleveland Clinic

  13. Multivitamins Don’t Provide Many Health Benefits, Researchers Say | Healthline

The author, Claire Bonneau, is a medical writer and certified trauma operating room nurse.

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