Multivitamins Are Hurting Your Performance

Multivitamins Are Hurting Your Performance

February 13, 2015 1 Comment

Do you take a multivitamin? Or maybe some antioxidants? Perhaps you take a super-duper-one-a-day vitamin or even a whole pack of daily vitamins. Maybe you even take a vitamin/mineral blend that's been formulated specifically for athletes - or even more specifically formulated for CrossFitters, runners, or triathletes. If you're lucky, that vitamin is doing nothing...but more likely than not, it's hurting your performance.  

Here's some science:  

  • A study out of the University of Florida indicates that consuming antioxidants after training actually increases muscle damage and delays recovery (1)
  • According to a study performed at the University of Memphis, eight weeks of supplementation with a multivitamin/mineral produced no anaerobic performance benefit (2)
  • A double blind crossover study performed at Cape Town Medical School in South Africa recorded no measurable effect of multivitamin/mineral supplementation on competitive runners (3)
  • In exercising rodents, consumption of Vitamin C has been shown to significantly reduce muscle growth and lower muscle protein synthesis (4)
  • The University of Copenhagen has shown that physiological adaptations to strenuous endurance exercise is not aided by the consumption of supplemental antioxidants (5)
  • A human + rodent study conducted by the University of Valencia, Spain, showed that vitamin C supplementation decreased endurance training efficiency by impairing cellular adaptations (6)
  • Combined vitamin C & E supplementation neither reduced markers of oxidative stress or inflammation nor did it facilitate recovery of muscle function after exercise-induced muscle damage, in a study conducted at Loughborough University (7)
  • Finally, another study from The University of Florida, has shown that vitamin E supplementation depresses skeletal muscle force production (8)
  • Supplementation with either single or multivitamin preparations containing B-complex vitamins, vitamin C or E does not improve physical performance in athletes with a normal vitamin balance resulting from a well-balanced diet (9)

In the best of these studies, we're told that vitamin & antioxidant supplementation does nothing to aid training; in the worst, we're told that they're hurting our training. When we learned this, we were just as surprised as you probably are right now. Exercise is the process of inducing stress upon the body and allowing it to recover to a state of supercompensation (meaning we end up stronger, more powerful, and with more endurance). Anything we can do to help recover from the damage we've caused during training, should (logically) be a good thing. It should help us reach our goals more quickly. We know that training causes oxidative stress and that vitamins (especially antioxidants) can help us recover from that type of damage. But that's not what actually happens when you supplement your diet with a multivitamin/mineral. Not by a long shot.

Based on the available science, it seems that you are far more likely to impede your progress by taking a bunch of supplemental vitamins. We're not cherry picking studies here, either. They basically fall into one of two categories: 1. Vitamins do nothing, or 2. Vitamins will impair training adaptations. And we're not asking you to take our word for it either – we're inviting you to check our references. We're even asking you to do your own research, because what you'll find is that the preponderance of evidence is against the use of vitamin and mineral (and especially antioxidant) supplementation.

Unfortunately, while the science has been telling us that these kinds of dietary supplements will work against our goals, our community has recently seen a flurry of “sports” vitamins and vitamin-loaded recovery products hitting our market. These products are far more likely to be holding you back than helping you recover. That multivitamin/mineral product is keeping you from getting the most out of your training – even if it has “WOD” or “Rx” in the name. The so-called science that actually DOES support the use of supplemental vitamins or minerals is dubious at best.

Consider the original “study” that concluded Zinc + Magnesium aspartate + B6 (ZMA) elevates testosterone levels and subsequently, strength. That study (10) was actually conducted by the owner of the company who holds the trademark on ZMA (he is listed as a lead researcher and author of the study). But when outside studies (i.e. not written up by the parent company) were performed, there was no increase in strength (11) nor testosterone levels (12). Preached hard is the word of clean eating in the CrossFit community. It is talked about at the Level 1; it is discussed at SME seminars and on BLOGs all over the internet. But what is becoming increasingly commonplace is reliance on unproven diets and supplements - and just as commonplace is the amount of support that many of these formulas and companies are being given by athletes in our community. In many (or most) of these cases, not only our research, but the research of universities around the world (check out our references!), doesn't support any of these claims the companies are making. Do yourself a favor and Google CrossFit + Multivitamin, and you'll see what I'm talking about. All of the science is against it, but a quick Google search shows that many have forgotten their Level 1 training...In essence what we have is something that is a magic trick, and if the company can convince you that it will make you better, you will not only take this product, but you will support it and sell it for them. Welcome to the supplement industry my friends.

Vitamins and minerals, the kinds you find in food, in physiological amounts, high enough to prevent a deficiency, are good. The CrossFit prescription for eating whole, healthy foods is ideal for the hard-training athlete of any sport. But the healthy, natural, vitamins and minerals you're getting from the CrossFit prescribed diet, are enough – and trying to increase your performance by overloading on vitamin supplements is a recipe for disaster.  

  1. Free Radic Biol Med. 2001 Sep 15;31(6):745-53. Supplementation with vitamin C and N-acetyl-cysteine increases oxidative stress in humans after an acute muscle injury induced by eccentric exercise.Childs A, Jacobs C, Kaminski T, Halliwell B, Leeuwenburgh C.Biochemistry of Aging Laboratory, Center for Exercice Science, College of Human Performance, University of Florida, Gainesville, FL 32611, USA.
  2. Res Sports Med. 2006 Jan-Mar;14(1):53-64. Effect of a liquid multivitamin/mineral supplement on anaerobic exercise performance.Fry AC, Bloomer RJ, Falvo MJ, Moore CA, Schilling BK, Weiss LW.Human Performance Laboratories, The University of Memphis, Memphis, Tennessee 38152, USA.
  3. Am J Clin Nutr. 1988 Feb;47(2):192-5.Vitamin and mineral supplementation: effect on the running performance of trained athletes. Weight LM, Myburgh KH, Noakes TD.Department of Physiology, University of Cape Town Medical School, South Africa
  4. Acta Physiol (Oxf). 2012 Nov 26. doi: 10.1111/apha.12042. [Epub ahead of print]Vitamin C administration attenuates overload-induced skeletal muscle hypertrophy in rats.Makanae Y, Kawada S, Sasaki K, Nakazato K, Ishii N.Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
  5. Med Sci Sports Exerc. 2010 Jul;42(7):1388-95. doi: 10.1249/MSS.0b013e3181cd76be. Antioxidant supplementation does not alter endurance training adaptation. Yfanti C, Akerström T, Nielsen S, Nielsen AR, Mounier R, Mortensen OH, Lykkesfeldt J, Rose AJ, Fischer CP, Pedersen BK.Center of Inflammation and Metabolism at Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
  6. Am J Clin Nutr. 2008 Jan;87(1):142-9.Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance.Gomez-Cabrera MC, Domenech E, Romagnoli M, Arduini A, Borras C, Pallardo FV, Sastre J, Viña J.Department of Physiology, Faculty of Medicine, University of Valencia, Valencia, Spain
  7. J. Appl Physiol. 2011 Jun;111(6):925-36. doi: 10.1007/s00421-010-1718-x. Epub 2010 Nov 11. Oxidative stress, inflammation and recovery of muscle function after damaging exercise: effect of 6-week mixed antioxidant supplementation.Bailey DM, Williams C, Betts JA, Thompson D, Hurst TL.School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
  8. Appl Physiol. 2001 Apr;90(4):1424-30.Effects of vitamin E and alpha-lipoic acid on skeletal muscle contractile properties. oombes JS, Powers SK, Rowell B, Hamilton KL, Dodd SL, Shanely RA, Sen CK, Packer L. enter for Exercise Science, University of Florida, Gainesville, Florida 32611, USA.
  9. Sports Med. 1985 May-Jun;2(3):175-97.Vitamins and endurance training. Food for running or faddish claims?van der Beek EJ.
  10. Brilla LR, Conte V. Effects of a novel zinc-magnesium formulation on hormones and strength. J Exerc Physiol Online. 2000;3:26–36.
  11. Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and CatabolismColin D Wilborn, Chad M Kerksick, Bill I Campbell, Lem W Taylor, Brandon M Marcello, Christopher J Rasmussen, Mike C Greenwood, Anthony Almada, Richard B KreiderJ Int Soc Sports Nutr. 2004; 1(2): 12–20. Published online 2004 December 31. doi:10.1186/1550-2783-1-2-12
  12. Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplementK.Koehler, M K.Parr, H.Geyer, J.Mesterand W.SchänzerInstitute of Biochemistry, German Research Centre of Elite Sport, German Sport University Cologne, Cologne, GermanyInstitute of Training Science and Sport Informatics, German Research Centre of Elite Sport, German Sport University Cologne, Cologne, Germany

3FU3L is not sponsored or endorsed by CrossFit, Inc.

1 Response


May 31, 2017

Interesting article. I am a science guy (doctorate degree in pharmacy). While I haven’t checked your studies I generally support your conclusions that additional supplementation doesn’t offer a benefit. I have analyzed other studies that demonstrate that supplementation with Calcium and milk and other dairy products may actually be promoting Osteoporosis rather than helping it (presumably from the acidic changes in the body). What’s interesting is that over the years, successful athletes have mentioned common themes. Avoid processed food where possible. Put fruits, veggies, nuts, whole grain (debatable) into your mouth as the primary source for fuel. Sleep well. Don’t overtrain. Seems simple. What’s interesting is that I don’t recall anyone saying I take extra “this” or extra “that”. Thanks for sharing.

Leave a comment

Comments will be approved before showing up.