Introduction
Multivitamins are a source of much debate. Some believe a basic multivitamin is the bare minimum needed to optimize health, while others argue it offers no real benefits and could even cause harm. With numerous studies and analyses on the topic, is there a middle ground? Should anyone take a multivitamin, and if so, what should they consider? This article provides a basic overview of the topic and explores our current knowledge.
Let’s dig in!
What is a multivitamin?
According to the NIH, a multivitamin is a supplement that includes at least three vitamins and minerals, but no herbs, hormones1, or medications. For simplicity, this article focuses on multivitamin-mineral supplements (MVMs) that provide essential vitamins like A, D, and C, along with minerals such as calcium and zinc.
As you can see from the definition, a multivitamin could contain all essential micronutrients or a sparse few. So, in the first important point of this article, multivitamins cover a very broad space in the supplement category. Beyond basic definitions, there’s no standard for what a multivitamin must include, and as you’ll learn, there are minimal guidelines and regulations for what qualifies as a multivitamin.
Limitation of specific study
It’s also important to note that studies on multivitamins can be somewhat limited. This makes sense because, for example, if someone is dealing with an illness linked to a vitamin C deficiency, the logical approach would be to test outcomes using varying doses of vitamin C — not a multivitamin that happens to contain vitamin C. As a result, while some studies do examine multivitamin supplementation, the research can be “messy,” leading to less clear or direct conclusions.
Are people deficient in micronutrients?
Without diving too deeply into technical terms, US organizations assess whether we’re getting enough nutrients using a system of Dietary Reference Intakes (DRIs). These guidelines help ensure people meet their nutritional needs while also not exceeding safe levels. Below are a few key terms commonly used in this system and their meanings:
| Term | What It Means |
|---|---|
| EAR (Estimated Average Requirement) | Meets the needs of 50% of a specific group (e.g.; age, gender). Typically assesses nutrient intake for groups instead of individuals. |
| RDA (Recommended Dietary Allowance) | Meets the needs of 97-98% of healthy individuals in a specific group. Typically used for planning diets. |
| AI (Adequate Intake) | Based on what appears to keep people healthy. |
| UL (Tolerable Upper Intake Level) | The highest daily amount to avoid adverse effects from intake. |
Ideally, we should meet our micronutrient requirements through food intake. In developed countries, access to a wide variety of foods generally ensures that basic nutritional needs are met, as energy intake from food tends to scale with micronutrient intake. However, micronutrient intake can be more complicated in developing countries, and the need for fortified foods or supplements not only aids with optimization but also with actual livelihood.
That said, nutrient deficiencies can still occur even in high-income countries with better energy intake. In Europe, for example, vitamin D deficiency is prevalent across many nations, though it varies from country to country. Denmark and Sweden have notably lower selenium levels compared to Finland. In the United States, over 25% of adults fail to meet the Estimated Average Requirement (EAR) for several vitamins and minerals, including vitamins A, D, E, calcium, and magnesium. Even identical food items can differ in nutrient content due to soil health and farming techniques.
In short, it is possible that a person with a more varied diet could fall short of certain micronutrients.
If you’re concerned about nutrient deficiencies, I highly recommend tracking your micronutrient intake to see which ones you consistently meet. MacroFactor, for example, pulls data from high-quality sources like the USDA and NCCDB, providing detailed micronutrient information. For accurate tracking, focus on logging common foods rather than branded items. Below is a table highlighting nutrients that might need more attention and others that are likely less of a concern.
What would be the purpose of a multivitamin?
One key point is that a multivitamin is not a medication. While there are cases where vitamin intake has resolved medical conditions, a multivitamin should not be treated as medicine.
Multivitamins (or specific vitamin and mineral supplementation) could potentially improve health outcomes when someone has a micronutrient deficiency that isn’t already being treated in a more targeted manner. However, using multivitamins to address diseases or conditions unrelated to vitamin deficiencies doesn’t seem as effective. This might explain why several studies, including this well-known one from JAMA, have shown that multivitamin use doesn’t necessarily contribute to living a longer life. That said, vitamin deficiency can be dangerous.
This is where the distinction lies: “healthy adults” who take a multivitamin may not see much benefit, while others, particularly those with deficiencies, could experience notable improvements in quality of life or a reduction in illness. This also highlights the difference in nutritional needs between developed countries, where diets are generally more varied, and developing countries that rely on fortification and vitamin supplementation to address severe deficiencies.
For the average person eating a varied, healthy diet, multivitamins serve more as “nutrient insurance” (with caveats). They can assist in filling nutrient gaps but should not replace what your diet provides.
Do multivitamins work?
This is where the research becomes more abstract and harder to piece together. When we examine how individual supplements address specific deficiencies, strong evidence supports using a single micronutrient in supplement form (typically at the direction of a medical professional). However, the evidence becomes less clear when we look at multivitamins and their contribution to addressing specific (or even broader) issues. This is partly because multivitamins are not typically used to resolve a deficiency that would be better treated with a targeted micronutrient supplement.
With this in mind, it raises reasonable questions about the purpose and effectiveness of multivitamins.
Can multivitamins affect micronutrient levels?
A study on multivitamin/multimineral supplementation in healthy older men found that, while the participants didn’t initially have major deficiencies, the supplement helped prevent the typical decline in several key vitamins associated with aging. Specifically, levels of vitamins B6, D, E, and beta-carotene increased as a result of multivitamin use.
Blood micronutrient concentrations at baseline and completion (final) of the supplementation period for participants assigned placebo and MV/MM
| Biomarker | Placebo Group Baseline | Placebo Group Final | MV/MM Group Baseline | MV/MM Group Final | p-Value |
|---|---|---|---|---|---|
| Pyridoxal Phosphate, ng/mL | 14.6 (10.6) | 15.2 (12.9) | 11.9 (3.4) | 28.7 (9.2) | <0.0001 |
| Ascorbic Acid, µM | 42 (14) | 42 (19) | 54 (18) | 58 (14) | 0.52 |
| Cobalamin, pg/mL | 485 (134) | 501 (314) | 428 (129) | 480 (150) | 0.39 |
| Folate, RBC, ng/mL | 537 (155) | 504 (127) | 640 (209) | 695 (169) | 0.16 |
| α-Tocopherol, µM | 35 (9) | 31 (6) | 30 (9) | 35 (9) | 0.01 |
| Calcidiol, ng/mL | 28 (11) | 27 (11) | 32 (11) | 38 (13) | 0.0005 |
| Phylloquinone, nM | 2.0 (1.5) | 1.9 (1.6) | 1.5 (1.1) | 2.0 (1.5) | 0.80 |
| Retinol, µM | 6.2 (1.7) | 5.8 (1.3) | 6.3 (2.3) | 6.7 (1.9) | 0.06 |
| β-Carotene, µM | 0.41 (0.17) | 0.36 (0.19) | 0.39 (0.17) | 0.45 (0.23) | 0.01 |
| Lutein, µM | 1.8 (0.7) | 1.7 (0.6) | 1.9 (1.2) | 2.0 (0.8) | 0.18 |
| Lycopene, µM | 0.31 (0.23) | 0.24 (0.14) | 0.31 (0.29) | 0.36 (0.29) | 0.26 |
| Calcium, µg/mL | 55 (2) | 55 (2) | 55 (2) | 56 (3) | 0.13 |
| Copper, µg/mL | 0.62 (0.09) | 0.62 (0.08) | 0.66 (0.15) | 0.61 (0.06) | 0.41 |
| Magnesium, µg/mL | 11.5 (0.9) | 11.4 (0.7) | 11.6 (0.9) | 11.7 (0.9) | 0.47 |
| Zinc, µg/mL | 0.50 (0.12) | 0.53 (0.13) | 0.56 (0.13) | 0.53 (0.16) | 0.33 |
While MVM supplementation improved certain vitamin levels, it’s important to note that it did not affect all micronutrients uniformly, particularly minerals. Another study in older populations using MVM supplements found a similar pattern — some vitamin levels increased, but not all were impacted by the supplementation.
I’ll talk about this a little more in the section on bioavailability, but there are limitations on how certain micronutrients are absorbed from multivitamins (or supplements in general). Factors like how the multivitamin is taken, the digestive health of the individual, and the form of the micronutrient used by the manufacturer all influence the supplement’s effectiveness. From a study design perspective, there are many variables to consider — not just the multivitamin itself but also the specific forms of each micronutrient, their interactions, and other factors.
So, the short but complex answer is that while we can absorb nutrients from multivitamins, it may not be all of them, and the amounts of absorbed micronutrients can vary.
Can nutrient deficiency contribute to illness or disease risks?
Sure. Iron deficiency can lead to anemia, and low B12 can cause neurological issues. However, the logical response to these issues is to take iron if you’re low on iron rather than relying on a multivitamin. The broader, more abstract question is whether taking a multivitamin could prevent, for example, someone who is borderline anemic from developing clinically low iron levels. It’s possible, but the answer isn’t clear, as there aren’t many studies specifically addressing this.
Can a multivitamin help decrease nutrient deficiency?
Technically, the answer is yes. But as you can see, there are many caveats, and I don’t think this is a clear-cut topic.
For most people, including a quality multivitamin in your daily routine — alongside a well-rounded whole food diet and in reasonable dosages — could potentially be beneficial. That’s about as far as I’d go in endorsing multivitamin use, but I also think that means a lot. The specifics are more nuanced and, surprisingly, quite complex, making it difficult to determine how a multivitamin impacts your health. Ultimately, it comes down to making an informed decision about whether or not to take one and, if so, choosing a high-quality option.
I do think multivitamins could plausibly help optimize and supplement a whole-food diet. More specifically, I think a minimal and responsible multivitamin intake could help fill certain nutrient gaps, especially considering the variability in vitamin and mineral levels, seasonal changes in produce, or occasional suboptimal food choices.
That said, it’s important to recognize that the quality of your diet isn’t just about hitting your macro- and micronutrient targets. Even if multivitamins were flawless in every way, you’d still be better off aiming for a diet rich in diverse, whole foods, especially fruits and vegetables. Why? Because whole foods offer more than just vitamins and minerals. They provide fiber, phytonutrients, and other compounds that affect overall health — things you just don’t get from a pill.
A balanced, varied diet will do a lot more for your long-term health than relying solely on supplements. This companion article makes good points on avoiding micronutrient reductionism, which is an oversimplified approach to defining a healthy diet solely by meeting specific micronutrient targets. It often neglects the broader health benefits of consuming a diverse range of whole foods.
So, will a multivitamin compensate for a consistently low-nutrient, low-fiber diet? No. But could it help cover micronutrient gaps when you do your best to include nutrient-dense foods? I think it’s worth a shot, just with caveats.
What should someone look for (or avoid) when picking a multivitamin?
If you decide to take a multivitamin, there are a few factors to consider.
Bioavailability of oral vitamins
How well we absorb a micronutrient (especially from an oral supplement) depends on many factors. Our body’s ability to utilize what we consume is influenced by digestive health, other nutrients, and even the form the nutrient is consumed.
In general, the absorption of micronutrients depends largely on their interactions with other dietary components. Fat- and water-soluble vitamins may have their absorption enhanced or diminished based on how they interact with other vitamins and minerals. For example, vitamin E can enhance the uptake of vitamin A, but this combination can also slightly reduce the absorption of vitamin D. So, with combining nutrients, it’s not always straightforward.
Additionally, supplements often contain different forms of vitamins and minerals, which can vary in how well they are absorbed. For instance, magnesium oxide has relatively low absorption, while magnesium citrate is absorbed more efficiently. In cases like this, selecting the right form can make a difference in whether you benefit from the supplement.
While it would be overkill to list out every form of every micronutrient that may appear in multivitamins, these are some of the key nutrients to be on the lookout for (nutrients for which versions with poor bioavailability or poor efficacy are often used, when superior forms are available). If a multivitamin uses the lower-quality forms of most or all of these nutrients, that’s a decent indication that it’s a fairly low-quality multivitamin overall:
| Nutrient | Higher-quality form | Lower-quality form | Notes |
|---|---|---|---|
| Calcium | Citrate | Carbonate | While both can be useful, carbonate requires food for better absorption. |
| Iron | Ferrous | Ferric | Ferrous is absorbed more easily. |
| Magnesium | Chelated (e.g., Glycinate or Citrate) | Oxide | Chelated forms are typically easier on the stomach and better absorbed. |
| Vitamin D | D3 | D2 | D3 appears to be more effective |
| Zinc | Chelated (e.g., Citrate, Gluconate) | Oxide, Sulfate | Again, chelated forms are typically better absorbed. |
It can feel overwhelming to consider all the different micronutrients, their interactions, and the various absorbable forms. This is where choosing a vetted, high-quality multivitamin can help, as these products are more likely to include the best forms of each nutrient. Additionally, it’s ideal to take a multivitamin with a whole-food meal to enhance absorption potential.
Avoiding excessive intake
Using a multivitamin can carry the risk of exceeding recommended intake levels. While most micronutrients aren’t at risk of surpassing upper tolerance levels, some require caution. For example, men can easily consume too much iron. Vitamin A is another nutrient that can be overconsumed, even without supplements, making it important to monitor supplemental forms.
You can take too much of a micronutrient from supplements, so one of the best ways to avoid this is to choose reputable, responsible brands that take a reasonable approach to nutrient levels. While it’s fine for some micronutrients to exceed daily values, a red flag is when levels are significantly higher than recommended. More isn’t always better.
Lastly, MacroFactor has an excellent article detailing how to understand upper tolerance levels, which you can find here.
General supplement safety
Depending on your country, rules and regulations around supplements can vary. In the U.S., while there is some regulation, oversight is relatively limited. Dietary supplements are governed by the Dietary Supplement Health and Education Act (DSHEA). The FDA is responsible for ensuring supplements are safe, but only after products are already on the market. Manufacturers don’t need to prove their supplements are effective or safe before selling them.
In contrast, Europe has a few more pre-market safeguards. The European Food Safety Authority (EFSA) sets safe upper intake levels for vitamins and minerals, providing a more structured regulatory framework.
I recommend a combination of a few factors if electing to choose a multivitamin:
- Choose multivitamins that have been independently tested to verify their product claims. Several organizations (NSF, USP, Labdoor and ConsumerLab) conduct tests or certify supplements to ensure that the ingredients and dosages listed match the actual product. Additionally, you can check if your product is NSF certified (the search is a little daunting but free).
- Select multivitamins that provide appropriate serving amounts of the listed vitamins and minerals. This can be tricky, as most supplements list their contents based on daily values, which may not always align with your specific needs.
- Be cautious of additional ingredients in multivitamins that aren’t related to micronutrients. Some products may contain herbal ingredients or even drugs that aren’t immediately obvious, as the main label often focuses on the multivitamin claim. For example, it’s not uncommon for a multivitamin to include caffeine (a stimulant) or herbal ingredients like saw palmetto that in higher amounts can have pretty notable side effects.
Take home? A good multivitamin should contain only essential vitamins and minerals, come from a vetted and reputable organization, and provide reasonable, safe quantities of each ingredient.
Basic Recap
Multivitamins are probably unnecessary for most individuals with a varied diet that includes a balance of macro- and micronutrients. However, for those with less dietary variety or who are restricting certain macro- or micronutrients, in reasonable doses, multivitamins from an independently tested and reputable source could be helpful. They’re also a cheap and easy source of certain nutrients, especially if they include EPA/DHA.
TL;DR: I’m not shilling too hard for multivitamins, but I think they’re fine in small amounts as micronutrient insurance.
- Other than vitamin D, which is technically a hormone ↩︎
