The Essential Guide to Multivitamins

Why write this?

I am beyond confused when it comes to multivitamin supplements! And I have an extensive background in Biology, so what this tells me is that the industry has been extremely successful with blurring the lines between fact and fiction for one of the most commonly consumed supplements. I started by taking a simple one a day multivitamin, found a lot of material saying you don’t actually absorb anything from these and that I should find a multivitamin specially made for athletes. Then I went down the rabbit hole of 4 a day, 6 a day and even 8 a day multivitamins. So. Many. Pills.

With all the frustration I just stopped taking them for a while and tried to get most of my micronutrients and minerals from vegetables. This seemed okay but recently I’ve seen some of the exercise scientists and doctors that I actually trust (it isn’t a very long list) mention the benefits of a multivitamin. So now I’m going to finally do the research for myself and find out whether or not I should take a multivitamin. For the purpose of this article I am sticking to research done on supplements providing multiple vitamins and minerals.

Cliff Notes

  1. The most common deficiencies in the US are Vitamin B6 (and B12 in vegetarians), iron, vitamin D and Vitamin C.
  2. Performance multivitamins are shown to increase blood serum levels of B6, B12, Folic Acid, Vitamin C, Vitamin E, β-carotene and some trace minerals.
  3. Iron and Calcium are antagonists of many vitamins and minerals, any quality multivitamin should contain minor amounts of both, no super doses! If Calcium or Iron needs supplementation it should be done separately from multivitamin and taken at a different time of day.
  4. Iron and Vitamin C are synergists and are best taken together.
  5. Calcium and Vitamin D3 are synergists and are best taken together.
  6. Multivitamins have been shown to improve anaerobic performance and may have some positive impact on high volume weight training.
  7. Multivitamins do not improve memory but may improve depression symptoms by raising B12 and folate levels, which are commonly low in depression sufferers.

First things first: Why would you need a multivitamin?

Multivitamins are often advertised as being the wonder pill for filling in the deficiencies of your diet. So theoretically if you have a complete diet there’s no need for a multivitamin at all. Unfortunately we don’t live in theory. According to the center for disease control the largest vitamin deficiencies are B6, Vitamin D, Iron and Vitamin C (8). Additionally if you are regularly active you may find yourself using an increased amount of the available folate in your body due to its role in DNA transcription (good for building babies and building muscle). These common deficiencies provide an idea of what we may need in a multivitamin to cover our bases but the only way to be absolutely sure is to get a blood test done and test for deficiencies.

Let’s also keep in mind that deficiencies and daily percentages are all based on the recommended daily allowance (RDA) which is the minimum recommendation. This isn’t going to be the optimum level, so we don’t necessarily want something that just keeps are heads above water if we want positive benefits from our multivitamin. For this reason we primarily want to look at performance oriented multivitamins geared towards athletes.

Actual Effectiveness

Multivitamin ingredient lists look like an amazing catch-all for any holes in our nutrition. This is the appeal of multivitamin supplements, however due to the action of certain Synergists and Antagonists certain ingredients may not be absorbed at effective levels. In one study significant increases in the amount of vitamin B6 (as pyridoxal-5′-phosphate), vitamin B12, folic acid, vitamin C, vitamin E, and β-carotene were found in the blood serum of the experimental group participants (3) (It’s worth noting that the contents of the supplement in the study were low in iron and calcium).

Taking a multivitamin seems to have the greatest effect on B6, B12, Folic Acid, Vitamin C, Vitamin E, β-carotene and some trace minerals (minerals that we only need a small daily amount of such as copper or selenium). Even though some multivitamins may boast 300+% of the daily need for minerals, like calcium, iron, magnesium, zinc and vitamin D, it may be more effective to take supplements for these separately and as needed. Overall it seems that a daily multivitamin does help fill the deficiencies laid out in the previous section.

What I wish I knew right away: Synergists and Antagonists

When it comes to multivitamins many of us think of one-a-day multivitamins. These were what I started with until I was inundated with claims like “it’s too many nutrients at once! You can’t possibly absorb them all!” Or “the minerals will compete for uptake! You’ll only get calcium and iron out of it!” The science behind these statements comes in the form of Synergists and Antagonists. Synergists are combinations that help each other with uptake, like iron with Vitamin C or Zinc with vitamin D (5). In these cases taking the combination is better. Antagonists on the other hand compete for, or even completely halt, uptake of some vitamins and minerals. Calcium is an antagonist for a large array of vitamins and minerals (5) so it makes sense that we may wish to choose a multivitamin without calcium or other minerals that antagonize the majority of nutrients found in multivitamins. You can find a comprehensive list of antagonists and synergists here.

So now that we know certain minerals/vitamins may actually just stop us from absorbing everything listed on the bottle we should find out what to avoid. For instance, many of us that imbibe dairy products rarely have to deal with hypocalcemia, low levels of blood serum calcium, so there really isn’t a need to supplement with calcium. On the other hand if you’re diet is low in calcium it is preferable to take a calcium supplement on it’s own at a separate time of day than the multivitamin. This case also applies to some other minerals such as iron.

When I learned about the synergist/antagonist relationship I really began to see the importance of analyzing the contents of my multivitamin. Some multivitamins contain more than 100% of the RDA of ALL of the minerals my body needs. Needless to say the fact that Calcium and Iron will outperform the rest in terms of uptake means that I’ll continue to need a separate supplement for magnesium, zinc, manganese, etc… As an extension of this it made more sense that 1-a-day pills containing super high doses of everything are not the most efficient way to ensure I actually fill in the gaps of my nutrition.

Athletic Benefits

There’s a lot of disagreement in the gym if multivitamins are necessary. If your goal is optimal muscle synthesis then nutritional deficiencies are going to be a major hindrance, period. You can eat a ton of veggies to make up for it, down a kale smoothie or take a quality multivitamin, it’s up to you. But not all possible benefits are just about muscle size, let’s talk about performance a bit.

In a study in which a liquid multivitamin was given to participants and their improvement in power and anaerobic exercises was measured researchers found no significant difference between placebo and experimental groups when it came to back squat improvement. However there was statistically significant difference for anaerobic improvement (6). It could be from the addition extra minerals increasing the amount of neurotransmitters available for repeated firing of motor neurons we see during anaerobic exercise. Researchers theorize that multivitamins could have a positive impact on high volume weight training.

Something I’ve come across in my research among anecdotal reports is that multivitamins replace the minerals lost to sweat. This does have some validity to it: when we sweat we tend to lose sodium, potassium and a minor amount of zinc (higher in hot climates) (7). Fortunately most of the food we eat is loaded with both sodium and potassium, so much so that many multivitamins don’t even include these electrolytes.

Multivitamins and Cognitive Function

It’s easy to think that if we’re deficient in some set of minerals or vitamins that we may not actually function at our mental best. Herbal supplements have been touted about as being able to strengthen our memory and clarify our thoughts. In a study testing whether or not multivitamins could aid in mental performance researchers found no significant evidence that those that took multivitamins had any better ability to recall past events than their placebo counterparts (1). In fact in reviewing the data for these mental tests I was quite shocked at just how similar the results from each group were.

Multiple studies have found links between vitamin B12 and folic acid deficiency and depression (2). Supplementation with a multivitamin has been shown to significantly increase serum levels of B12 and folic acid (3) among others. Since B12 is found in animal sources it is especially common for vegetarians to have a deficiency in B12 (4). For vegetarians supplementation with multivitamins is almost necessary. There has also been some anecdotal evidence for the rise in serum B12 and folic acid due to multivitamin supplementation the need for lithium treatments of depressed patients is severely reduced.

An Outside Perspective

Since multivitamin usage is so prevalent, especially in the fitness world, I wanted to reach out to someone in the fitness world to answer a few questions on their view of multivitamins. The following is an email between myself and Corey Menzinger: a YouTube fitness star, buff guy and all around good dude. While Corey and I may not agree 100% on everything having to do with multivitamins I found his answers insightful and wanted to share. Corey

Just for context what kind of training do you most often engage in?

I most engage in bodybuilding training with small strength training blocks every few months.

In your opinion, what are some of the biggest benefits to taking a multivitamin?

The biggest benefits would have to be just bridging the gaps of basic nutrients that we miss out on in our diet. Most people’s diets are filled with food that has no nutritional value and some that even has a negative impact on our body, such as lots of fast food.

What, if any, are some possible negative side effects to taking a multivitamin?

Negative side effects would be taking one if you do not actually need one. Most people should take a multivitamin, but not everybody needs one. For some, it is just a waste of money, and if that vitamin tends to have too high numbers of certain fat soluble vitamins it is, but would be very hard to, possible to take too much and have adverse effects. The most common experience with this is too much iron with women that do not have regular menstruation cycles.

Many multivitamins now leave out, or minimize, iron and calcium content due to their ability to inhibit other vitamins from being absorbed. Do you think it’s necessary to supplement with iron and calcium on their own if you are taking such a multivitamin?

In my opinion, the only time you should be taking iron and calcium separately is if you were told by a doctor to do so. If you’re taking a multivitamin for the iron or calcium, in most cases it’s not going to be enough, more so in the case of calcium.

Do you recommend a one a day vitamin or a multiple times a day vitamin? Why?

I’m a big fan of nutrient timing, so personally I do take my multivitamin 3x a day, spaced in 5 hour intervals. It’s not absolutely necessary, but there are benefits as far as absorption goes, specifically in water-soluble vitamins. However, a one a day for an average person is usually fine.

What, if any, other vitamin supplements do you use other than a multivitamin?

On top of a multivitamin I also supplement extra vitamin D3. In my opinion D3 is the most important vitamin there is and it’s nearly impossible to find someone in a northern country that is not deficient. I also supplement fish oils for it’s incredible health benefits for cardiovascular and brain health as well as being a proven anti-inflammatory. I take turmeric year round for antioxidant and anti-inflammatory purposes as well. Turmeric is in my opinion, one of those supplements that anybody can take and would find benefit from. Lastly, I also take an echinacea & goldenseal complex just for extra immune support. My body takes a beating from training 3-4 hours a day usually 7 days a week, so I do whatever necessary to keep myself healthy enough to train and keep making progress, especially in flu season.

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Trust-Worthy Multivitamins

Hopefully now we have some idea of what we are actually looking for, but now it isn’t just about the label: it’s about honest business. Consumer Labs found that the contents of nearly 32% of multivitamins did not meet the labels (9). Below are my two top recommendations for multivitamins based on my experience and the general trustworthy-ness of the brand. There are probably quite a few trustworthy brands that I’m leaving out, feel free to suggest any to me via Twitter (@brawnforbrains). Click the name to be taken to the Amazon page for that multivitamin.

Legion’s Triumph

This is my number one to recommend. Is it because it tastes definitively garlicky? Because you have to consume 8 pills a day? Neither. It’s because the folks over at Legion painstakingly created a description of this product that goes ingredient by ingredient, informs you of why they put each in, lists clinically effective doses and they even provide links to ALL the research they reference. You can read this beast of a multivitamin description here.

Alive Max3 Multivitamin

This is Corey’s go to multivitamin that covers all bases and is a great nutritional insurance. At around $20 for 60 servings it’s difficult to find a better deal on quality multivitamins. Personally I’m ordering a bottle of these tonight because the bang for your buck you get with ease just excites me.

“What about Centrum?”

That’s right I left the most well known multivitamin off this list. Besides the fact that I think 1-a-day pills are pretty much ineffective they were left off because their website claims to have over 30 years of scientific support and research but I couldn’t find links or references anywhere on the site!


  1. Grodstein, Francine (12/17/2013). “Long-Term Multivitamin Supplementation and Cognitive Function in Men: A Randomized Trial”. Annals of internal medicine
  2. Coppen A1, Bolander-Gouaille C. “Treatment of depression: time to consider folic acid and vitamin B12.” J Psychopharmacol. 2005 Jan;19(1):59-65.
  3. Earnest, Conrad, et al. “Efficacy of a Complex Multivitamin Supplement.” Nutrition 18.9 (2002): 738-42.
  4. Hunt, Alesia, Dominic Harrington, and Susan Robinson. “Vitamin B12 Deficiency.” BMJ (Clinical research ed.) 349 (2014): g5226. Web.
  5. “Vitamin and Mineral Agonists and Antagonists.”
  6. Fry, Andrew C (01/01/2006). “Effect of a liquid multivitamin/mineral supplement on anaerobic exercise performance”. Research in sports medicine
  7. Tipton K., Green NR, Haymes EM, Waller M. “Loss in sweat of athletes exercising in hot and neutral temperatures.” Int J Sport Nutr. 1993 Sep ;3(3):261-71.
  8. Center for Disease Control. “Second Nutrition Report.”