The CrossFit Supplements Guide: What Science Actually Shows

Written By Andy -  |  Nutrition 

Disclaimer: WODprep is not associated with CrossFit® in any way and these opinions are separate from the CrossFit® brand. 

As we discussed in “The Only CrossFit® Nutrition Article You’ll Ever Need”, supplements are the least important part of your success as a CrossFit athlete. They aren’t necessary, barring that you do not have some type of nutritional deficiency or condition that requires them.

In fact, in the grand scheme of things, the vast majority of CrossFit supplements on the market don’t do anything except burn a hole in your wallet.

That said, some are based on sound science and are therefore worth discussing as they can provide a small benefit. And because there are so many ineffective or unnecessary supplements on the market, we also need to discuss how to differentiate between the useful ones and the not so useful ones. Once we’ve learned how to evaluate them, I will present a list of supplements for your education, broken into categories based on the quality of evidence, and relevance to strength and physique goals as CrossFit athletes.

*Note the wording there, I am not an RD, I am not recommending anything, just educating you on the options for your consideration. However, before I get to the list, I first want to tell you about how to avoid the two most common scams in the industry.

How to Avoid Protein Powder Scams

If you’re a CrossFit athlete, you probably like protein powder. It’s a quick, convenient, and cost-effective way to hit your daily protein targets. Whey protein is not the cheapest, but it is popular due to the high BCAA content, particularly leucine, which is critical to the muscle building process.

Now, with consumers becoming wiser there is a rising demand for products that claim to have been lab tested, but this comes at a time of overall rising global demand (and thus prices). With consumers becoming sensitive to these price increases, and a lack of general education about what they should be looking for on the packet, the incentives for companies to cut costs by cheating the system are all there, and many do.

I’m talking about the rise of the phenomenon known as ‘protein spiking’.

This is how it works:

  • Some labs test for quality by measuring the nitrogen content of protein powder rather than the amounts of the individual amino acids (the building blocks of protein).
  • Under normal circumstances, as every amino acid contains nitrogen, measuring the nitrogen content of a powder should indicate how much protein it contains.
  • So, manufacturers can cheat the system by dumping cheap, low-quality amino acids like glycine and taurine into the mix. (Robbing us of some of the ones that are critical to the muscle building process.)
  • They can also add other nitrogenous, but non-proteinogenic (protein creating) acids into the mix, such as creatine and beta-alanine. These are cheaper by the gram, and gives the manufacturer the benefit of being able to list these on the packet, knowing that consumers have enough general awareness of these to think they are good, but not be educated enough to realize that, in fact, they are just being robbed of the protein they should be getting.

Here are some red flags to look out for when choosing a protein powder for CrossFit:

  1. The cost per pound/kilo of claimed protein content is considerably cheaper than average. Whey is a commodity traded on the open market. You can be ripped off and pay way too much (I’ve seen 11x market price protein from one “luxury brand” gym in Japan), but you won’t ever find it significantly cheaper than everything else without there being something dodgy going on.
  2. It has a proprietary blend or doesn’t list leucine content. (More on proprietary blends in a moment.)
  3. Leucine content, when listed, is lower than 2.7 g per 25 g of protein content (the BCAA content of whey is 25%, leucine should be 11%).
supplements research

So, pick up the tub next time before you buy and check the back label. If your protein powder doesn’t pass those checks, you’re rolling the dice with the quality of what you’re getting and I would advise you choose another product. This holds true for protein bars and ready-made protein shakes also, and I have yet to see the BCAA or leucine content listed there.

whey protein for crossFit

Lastly, for those who are vegan or lactose intolerant, a 70:30 mix of pea and rice protein closely mimics the amino acid profile of whey.

Protein Powders: Proprietary Blends

I would also recommend not getting products with so-called ‘proprietary blends’. A proprietary blend is where a company trademarks a combination of substances that they mix together and then gives that mixture a name of their choosing. Manufacturers are required to list the ingredients, but not the dosages. For example, a label might say it includes 30 grams of a “muscle blend” and lists all the ingredients, but doesn’t tell you the individual amount of each ingredient.

This is basically a way to say, “Look, this is our special sauce, we don’t want people to reproduce it, and so we’re not going to tell you exactly what’s in it.” Too often this becomes a way to disguise the fact that the individual ingredients are too underdosed to be effective. I recommend avoiding proprietary blends altogether.

Be Cautious with New Supplements

As a final note before moving onto the recommended CrossFit supplements, a word of caution on purchasing new supplements that are released with only minimal scientific support for their use.

New supplements come out all the time; most are not supported by any studies whatsoever. Less commonly, some supplements that come out are supported poorly by an animal study, short-term study, or an in vitro study that doesn’t directly measure fat loss, muscle gain or performance, but measures an outcome that is related to fat loss, muscle gain or performance. Even more rarely, a new CrossFit supplement will come out that actually does have a scientific study that supports its effectiveness directly.

Researcher bias, small sample sizes, and dare I say it, financial influence from the industry, can all potentially influence study outcomes. The smart thing to do would be to wait until there is a LOT of evidence supporting the use of a supplement before you decide to take it.

Think I’m being overly cautious? Let me give you a specific example.

Do you remember D-Aspartic acid? A study came out in 2009 that found it increased testosterone production in men to a rather impressive degree [8]. Immediately, supplement companies jumped on the bandwagon and started selling this commercially as a muscle builder, libido enhancer, and performance enhancer (despite the fact that the study did not measure changes in muscle mass, performance, or libido).

Over and over, I cautioned for people to wait until further studies had been performed before taking the supplement, considering this was the one and only human trial. Many ignored me, and then to their surprise (certainly not to my surprise) a study came out in 2013 that found D-Aspartic acid not only failed to increase testosterone levels but most importantly it had no effect on body composition or strength [9]. Once again, another supplement proves to just be a waste of money right? Wrong. A 2015 study came out that actually found D-Aspartic acid decreased testosterone levels in resistance-trained men [10]! So not only did this compound end up being a waste of money, it was found to potentially be counterproductive to the goals of those taking it.

Even the most effective supplements that have been tried and tested time and time again for decades that can help you reach your goals, make only a very small impact. Likely, the impact they will make might not even be discernible to you. So, don’t get caught up in marketing hype of some new dodgy supplement and think that by waiting a year or two until more research comes out that you’d be missing out on potential gains by not taking it. In fact, jumping on a bandwagon too early could be much worse of an idea. Remember, 1000’s of supplements have come out over the years, and 99.9% of them have disappeared because they proved useless. Assuming that a new supplement is the “next big thing” without sufficient proof is illogical and is just buying into marketing hype.

What Supplements Should CrossFit Athletes Take?

Keeping in mind how adamant I am regarding the combined quality, validity, and effectiveness of any substance, I’d like to present a compiled list of the few supplements that have adequate research showing they might be useful for CrossFit athletes.

Now there’s always subjectivity in deciding whether CrossFit supplements are worth considering or not, and as with all of my advice, feel free to disagree with it based on your own judgement. Additionally, it is quite likely that this list will prove to be outdated in a few years as more research comes out.

That said, what follows are three supplement lists:

  1. The A-list of supplements with an impeccable research record that are relevant to almost all athletes.

  2. The B-list of supplements that either are only worth considering in certain circumstances, or have a mixed but overall positive research record (just know, this could change as more data emerge).

  3. The C-list of supplements are not worth your time, despite their popularity or common use. (Furthermore, if a supplement you are considering is not mentioned, consider it to belong in this category.)

The A-list — Supplements with an Evidence Basis

the best supplements for CrossFit

Performance Supplements

Now that our basic daily supplements are covered, let’s dive into the performance supplements that made the A-list.

Creatine Monohydrate

Creatine is naturally produced in the human body from the amino acids glycine, methionine, and arginine, and is used in the phosphocreatine energy system which helps power the first ~10 seconds of activity. Supplemental creatine thus aids your ability to perform strength and power based activities, and reliably results in increased strength, power, and muscle mass when used chronically.

So, is creatine good for CrossFit?

Creatine monohydrate is the most tried and true, affordable, and effective of all the creatine variants [34]. It is the original, and many subsequent variants of creatine are either inferior [35], or cost more without giving any additional benefit [36]. So every time I refer to creatine, creatine monohydrate is the specific type that I am referring to.

Creatine is produced in the body and thus, is already present. We get it from animal products, mostly in meat, and it is more abundant in raw meat. When meat is cooked it degrades the creatine content [37], which is why it is difficult to get the performance-enhancing benefits without consuming this as a supplement.

To get creatine stores up to levels where they can benefit strength, power production, and ultimately your long-term ability to produce more muscle mass over time, an intake of 0.02 g/lb of bodyweight per day (0.04 g/kg/day) is what has been shown to be effective. (This is around 3-5 g per day for the average person.) It will take a couple weeks of ingesting this amount per day to reach supplemental creatine levels, but after that point, you can just maintain those levels by continuing to take the dose, like topping off your gas tank.

It’s important to note that for long-term consumption, timing doesn’t matter. It doesn’t need to be taken with carbs, it doesn’t need to be loaded, it doesn’t need to be taken pre-workout, and it doesn’t need to be taken post workout. All the benefits associated with creatine timing, whether it’s taken with carbs, or if creatine is loaded in large amounts, are strictly related to the first couple weeks of consumption where the goal is to get to supplemental levels. It has nothing to do with long-term use and whether it takes you 5 days or 21 days to reach supplemental levels of creatine has a less than negligible effect on long-term gains. So, if you decide to supplement, you can just use the aforementioned daily dose to receive its benefits.

Loading creatine is actually a good idea if you start taking creatine while dieting, because it limits the time period of your weight going up (due to increased muscle cell hydration as water is stored with creatine), which can confound your weigh-ins (if taking them). When you do this, simply use your new bodyweight post-loading as your new baseline to measure changes from.


Caffeine is the workhorse that provides 90% of the acute effects most pre-workout supplements provide (some also have other ingredients with an evidence-basis, but those typically provide chronic effects). Indeed, for purely the acute stimulatory effects,  you could just take caffeine and save yourself some cash, as most pre-workout supplements use low doses of lesser proven supplements piggybacked with caffeine. There are some pre-workout supplements that might be effective, but I’d stick to caffeine as there is a multitude of research behind its effectiveness for enhancing performance and suppressing tiredness, while other stimulants don’t have nearly as much behind them.

is caffeine a crossfit supplement?

Regarding the evidence-basis for caffeine, I’m going to break this down by discussing two different effects you might be trying to achieve: a suppression of tiredness or enhancement in performance. Then I’ll address the use of caffeine in “fat burners”, before concluding with a discussion on caffeine tolerance.

Caffeine is a stimulant, but the initial, cognitive stimulatory effects of caffeine fade with continued use. Fortunately, the suppression of tiredness remains even with continued use and does not appear to be affected by caffeine tolerance [38]. To suppress tiredness doses of 0.5-1.4 mg/lb/day (1–3 mg/kg/day) are appropriate. Also, caffeine can improve acute resistance-training performance, including strength and muscular endurance [39]. To get this effect, take 1.8–2.7 mg/lb (4-6 mg/kg) approximately 60 min before training.

It’s also worth noting that caffeine is often included in so-called “fat burners” with the claim it can enhance fat loss, either through thermogenesis or appetite suppression, leading to a lower energy intake. While the performance and tiredness-suppression effects of caffeine are very well proven, the claims that caffeine produces fat loss or reduces energy intake are inconsistent at best [40-46]. While the tiredness-suppressing effects of caffeine can be useful for dieters, it is not a dieting aid from a fat-loss perspective.

Athletic Benefits Of Caffeine

If your goal is performance enhancement for CrossFit, it might be wise to moderate your habitual, non-pre-workout caffeine intake both in magnitude (~1 mg/kg as a decent cap) and frequency (~2 x/week at most), as tolerance can inhibit the performance-enhancing effect of caffeine to some degree. Caffeine tolerance develops quickly with regular use. However, the pain-suppressing and local-muscle ergogenic effects of caffeine don’t seem to diminish with tolerance [47, 48]; although the endurance training benefits do diminish in some [49, 50], but not all studies [51].

In aggregate, this means that caffeine tolerance will likely diminish the ergogenic benefits for endurance training, but caffeine still probably aids resistance training performance to some degree even in habitual caffeine consumers (but maybe not quite as much as it does for caffeine-naive consumers).

So given tolerance is a reality, if you feel great and you’re ready to train, you might not need to take caffeine pre-workout at all. But if you are feeling down and are anticipating a terrible workout, then it might be a good day to maybe take some. It’s a valuable strategy to keep your caffeine intake as low as possible in order to allow yourself the ability to get those stimulatory effects when it is truly needed. Also, think about the times where suppressing tiredness might be more beneficial than enhancing performance. If you are on an extended, rather aggressive diet, it may be more beneficial for overall performance to take a tiredness-suppression dose regularly to maintain performance on all days, even if it means a slightly diminished effect when you take caffeine pre-workout to aid your lifting.

Additionally, even though the above information is specific for achieving maximal effectiveness, if you do decide to supplement it may be wise to start with half of these dosages for either suppressing tiredness or enhancing performance because of individual response. If you are not used to stimulants, or if you take too much you may feel jittery and unfocused, which can be an equally undesirable effect to feeling tired or low in energy. In general, it’s wise to consider the minimum effective dose to get the effect desired. It’s also a good idea to taper caffeine intake down towards the end of the day to avoid sleep disruption.

Health Supplements

While this is primarily an article about performance supplements for CrossFit, I’ll should cover the three ‘health’ supplements worth most people’s consideration. After all, if your health is down the drain that will affect performance.

This is a much abbreviated version from what we have in our book though.


  • A regular one-a-day pill multivitamin should cover your bases and protect against deficiencies. More is not better.
  • You can also find many basic multivitamins that are geared toward common deficiencies for a certain population, like those specifically made for women or vegetarians with emphasis on calcium, magnesium, zinc, and iron.
  • Multivitamin use appears to be not harmful and may confer a small protective health benefit to long-term users [11].
  • Taking a multivitamin is not a better solution than consuming adequate micronutrients (mainly, fruits and vegetables). Plant-based foods contain phytonutrients and animal-based foods contain zoonutrients; nutrients not classified as vitamins or minerals, but have beneficial effects for health.
  • Consider getting blood work done before consuming in any vitamin or mineral supplement to ensure you aren’t potentially providing micronutrient in excess or neglecting an unknown deficiency.

Essential Fatty Acids — (EPA and DHA)

  • Of the essential fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been found to have a host of potential health benefits [13].
  • The range of 1–2 g of combined EPA and DHA covers the bases for achieving the vast majority of health benefits shown in research (reducing symptoms of depression [14], decreases the risk of cardiac death [15], decreases blood pressure [16], and decreases waist circumference [17]).
  • However, examinations of fish oil as a performance enhancer for training or to augment muscle growth are few and generally mixed [18-22].
  • If you don’t eat fish or don’t like taking fish oil, you can also get EPA and DHA from an algae supplement, which is what the fish eat that gives them the EPA and DHA that we are looking for.
  • Taking more than the recommended range is not necessary, and could plausibly blunt inflammation to the point of being detrimental to skeletal muscle remodeling.
  • Read the label of a supplement to determine the EPA and DHA content per serving.
fish oil supplements for crossfit

In this brand, there are 750 mg of EPA/DHA per 1 g softgel. So you would need to take three daily to reach ~2 g.

Vitamin D3

  • If sun exposure is lacking, dietary sources of Vitamin D become increasingly important for health (and performance). 
  • Severe deficiency can cause osteoporosis and can be a contributing risk factor for cancer, hypertension, and a number of autoimmune diseases.
  • Sources of foods containing significant amounts of Vitamin D include fatty fish and Vitamin D fortified products (cereals, dairy products, and orange juice being most common). Beef, pork, and eggs contain small amounts of Vitamin D (a relatively sparse list) [23].
  • Vitamin D insufficiency, frequently classified as having serum 25(OH)D levels (a metabolite of Vitamin D) below 75 nmol/L (30 ng/ml) [24], is surprisingly common in the world at large [23, 25, 26].
  • Taking a broad view of the literature, correcting a Vitamin D insufficiency may improve immune function and reduce your incidence of illness [27, 28], but research assessing the efficacy of Vitamin D as an ergogenic aid for resistance training is hit and miss [25, 29, 30, 31]
  • Before you consider supplementation, get a blood test to confirm you are actually below the 75 nmol/L cut-off and also get checked after you begin supplementation to determine your individual dosing.
  • Vitamin D3 is the form best taken up by the body and recommendations for insufficient athletes are between 20-80 IU/kg of D3 (there are vegetarian forms of D3 these days, by the way) taken daily.
  • You could also just try to get some more sun, but unfortunately, sunlight through a window doesn’t provide you vitamin D [32]. However, be aware that during winter months, depending on your climate, Vitamin D dosing strategies may need to change or cease altogether.
  • Once you have corrected the insufficiency, there is no evidence to support improved health or performance by going higher, and it is possible that going too high could be harmful.

The B-list — Conditionally Effective or Mixed-Evidence Supplements

supplements for performance


Beta-alanine can be thought of as the muscular endurance version of creatine monohydrate. If you think of creatine for power, strength, and hypertrophy, think of beta-alanine for longer anaerobic performances.

Beta-alanine is a precursor to carnosine. Carnosine is abundant in skeletal muscle tissue and is made up of the amino acids histidine and beta-alanine. While carnosine can’t enter muscle cells to a significant extent, beta-alanine can, and is the rate-limiting step in carnosine synthesis. Beta-alanine serves to buffer acidity, regulating the pH levels in muscle, which can subsequently improve performances that are limited by metabolite build up.

Thus, I consider beta-alanine as a conditionally beneficial supplement because it only has a small performance-enhancing effect when efforts reach a duration of ~0.5–10 minutes [52, 53].

Thus, CrossFit athletes could benefit from taking beta-alanine and it is worth considering. If that is the case, taking 3-4 g/day may result in a potential small benefit.


Citrulline-malate is a supplement that combines the non-essential amino acid citrulline and the Krebs cycle intermediate (meaning, it can help with energy production) malate.

Citrulline may aid performance by increasing blood flow to working muscles through an increase in nitric oxide (a vasodilator) [55], and by helping to clear ammonia (a marker of muscle fatigue) [56]. Additionally, malate augments energy production during exercise while reducing the rate at which lactic acid accumulates [57]. In combination, citrulline and malate, therefore, could assist with both energy production and waste removal during training.

Based on the mechanisms of action, you would expect citrulline-malate could have a role in aiding muscular endurance, inter-set recovery, and thus, the ability to perform volume in a training bout and over time. However, when assessing the available literature relevant to resistance training, the evidence is split down the middle for citrulline-malate showing a positive [58-62] or null effect [63-67]. While there are currently no meta-analyses published on citrulline-malate, one will likely be published in the future that may give a more definitive answer. Such an analysis, if published, will help us elucidate what dosages, time frames, and expectations we should have for citrulline-malate as an ergogenic aid (if any).

For what it’s worth, I’m currently of the opinion (barely) that the evidence slightly leans in favor of its efficacy, as one of the studies showing null effects is underdosed [65]. Also, I’ve seen no indication of any potential harmful effect on performance.

In studies which show an ergogenic effect of citrulline-malate, 8 g is consumed ~60 minutes prior to training.

The C-list — CrossFit Supplements Without an Evidence Basis

supplements that probably don't work

Glutamine is the most abundant amino acid in the body, and is a non-essential, but sometimes conditionally-essential amino acid. Meaning, that in times when tissue breakdown is abnormally high, such as in clinical situations (disease states, following surgery, among burn victims, etc.), breakdown rates can outpace synthesis rates.

Indeed, in clinical scenarios glutamine delivered via injection in a hospital setting has been shown to help with reducing infections, speeding healing rates, reducing mortality rates, and reducing the length of hospital stays [68].

Glutamine is also a popular supplement in the bodybuilding and fitness community, as the effects observed in clinical literature (delivered via injection) are assumed to also somehow enhance hypertrophy or improve performance (when taken orally as a powder). However, to date, there is no evidence that supplementary glutamine improves body composition or performance [69, 70]. At best, there is a theoretical argument that glutamine could possibly aid in gastrointestinal health among physique competitors during contest preparation, although this is speculative at best [69].    

Branched Chain Amino Acids (BCAAs)

Whether you are cutting or lean gaining, I would have to say that BCAAs probably aren’t going to provide a benefit to you if your protein intake is already high enough. A high protein diet (such as recommended in this article) will provide you with ample amounts of BCAAs.

Despite this fact, BCAAs are one of the most frequently used supplements for bodybuilding [69]. However, what limited evidence exists that could be construed to support the use of BCAA is flawed in my opinion.

  • One study on BCAAs showing they outperformed whey or carbohydrate supplements was never published as a journal article, only as a conference presentation that had not undergone full peer review [71]. 
  • Additionally, the BCAA supplement consumed contained glutamine and citrulline-malate, confounding our ability to isolate the effects to BCAA.
  • Finally, dietary controls weren’t put in place to account for total daily protein intake (which is important since a high protein diet contains a high content of BCAAs).
  • Outside of this poster presentation, a study on dieting lifters showed better fat loss, lean mass maintenance and strength gains between groups on identical diets, one supplementing with a carbohydrate powder and the other BCAAs [72]. However, in a letter to the editor of the publishing journal it was noted that there were significant data reporting errors and inappropriate statistical analyses used, which draw into question the veracity of the findings [73].
  • Finally, both of these studies [71, 72] were funded by a company whose flagship product is a BCAA-based supplement—while this is certainly not proof of wrongdoing or shady research, it still is prudent to await reproduction of the findings from a second research group with more rigorous design and analysis.

Looking more broadly, a 2017 meta-analysis reported that BCAA reduced markers of muscle damage more than placebo [74]. However, the included studies simply compared BCAAs to a placebo (typically flavored water, nothing, or carbohydrate), not to protein. Critically, this tells you that BCAAs are better than nothing, but not better than protein for reducing exercise-induced muscle damage.

Should I Take BCCAs For CrossFit?

If we really stretch the definition of “evidence” we can look at a few other papers that some might cite as supporting BCAA use. Specifically, a 2015 paper came out that found handball athletes had a reduction in fatigue while taking a combined arginine and BCAA supplement compared to placebo during a multi-day simulated competitive event [75]. However, it is unclear whether this effect can be isolated to BCAAs (rather than arginine or the two combined) and the fatigue-reducing effects may only manifest during multi-day efforts, considering a similar study on wrestlers found no effect during a single, protracted competitive effort [76].

In terms of body composition, an older study found a greater reduction in abdominal fat in dieting wrestlers who replaced the vast majority of their daily protein intake with BCAAs compared to another group of wrestlers who replaced the vast majority of their daily protein intake with soy protein [77]. However, neither condition was representative of a normal diet. The extreme intakes of both soy and BCAAs in this experiment make it difficult to draw meaningful conclusions from this study.

Finally, there is evidence that aerobic exercise performance can be improved when consuming isocaloric amounts of BCAAs compared to carbohydrate, but only when glycogen depleted [78]. When not glycogen depleted, BCAAs may reduce perceived exertion, but are not as effective at aiding performance as an isocaloric amount of carbohydrate [79]. However, cardio for strength and physique athletes is not about performance, it’s about energy expenditure or maintaining a minimal amount of aerobic fitness, which certainly doesn’t need any ergogenic aid.

So, the take-home here is that if you are consuming a diet adequate in carbohydrates, protein, and total calories, you are unlikely to get any benefit from supplemental BCAAs, especially if you are hoping they will improve resistance training performance. On the other hand, if you are performing cardio and have to do so fasted or while consuming a low-calorie or low-carbohydrate diet (which could potentially result in glycogen depletion), you might potentially benefit from BCAA supplementation if you have endurance exercise performance goals. However, this is a very narrow rationale for BCAA supplementation indeed...and even then, I would counter that it would be cheaper to simply take a scoop of whey protein prior to training, or better yet if your goal is to improve aerobic endurance, don’t train in a fasted, glycogen-depleted state.

Despite the label claims, there are calories in BCAAs. For regulatory reasons, in many countries isolated amino acids, such as BCAAs, can’t be listed as having calories. Any difference in the energy content of whey vs BCAA is minimal, and both are quickly digested. If anything, you could make an argument that whey might be a better choice, as it has the entire spectrum of essential amino acids, which theoretically would provide better support for the build and repair of muscle [80].

Beta-hydroxy-beta-methylbutyrate (HMB)

A metabolite of leucine—β-hydroxy-β-methylbutyrate (HMB)—has been investigated for over two decades as an ergogenic aid for improving resistance training performance and increasing lean body mass via a reduction in muscle protein breakdown. Research on HMB is not new, as the first study on performance in humans was conducted in 1996 [81]. In it, the authors reported promising results for both resistance training performance and body composition changes in untrained individuals.

As further studies came out on HMB over the next few years, positive data mounted. In fact, in a meta-analysis of studies conducted up to 2001 on the effects of dietary supplements on muscle and strength gain, it was concluded that among all the supplements assessed, only HMB and creatine produced significant changes [82]. However, as more research was conducted on trained individuals, the findings became less impressive. Indeed, a 2009 meta-analysis reported that while small positive effects for strength in untrained lifters supplementing with HMB were found, trained lifters gained no such benefits, and only trivial changes in body composition were found, regardless of training experience [83].

While research regarding the clinical uses for HMB in muscle-wasting conditions continued [84], sports performance research waned after this point. However, in 2011, Fuller and colleagues reported that a free-acid gel capsule form of HMB resulted in nearly two-fold greater plasma concentrations and a 25% improved clearance rate of HMB from plasma, compared to the traditional calcium salt form of HMB [85]. This spurred a resurgence of interest in HMB (in free-acid form) for performance and body composition changes; however, the only investigations showing positive outcomes for free-acid HMB were funded by a company that sells free-acid HMB and have been called into serious question in three separate letters to the editor [86-88] —for transparency, my co-author Eric was among the 17 authors of one of these letters [87].  

Specifically, in these letters to the editor, the veracity of the findings was questioned on the basis that:

  1. The HMB group gained more muscle mass than is seen in studies on anabolic steroids, how this was incongruous with previously published data on HMB;
  2. The lack of a plausible mechanism for these changes (simply being more bioavailable shouldn’t take a supplement from doing nothing to being more effective than anabolic steroids); 
  3. Statistically, there were implausibly consistent between‐group changes;
  4. There were surprisingly small gains in strength and muscle mass in the placebo group;
  5. There were inconsistencies with the data collection procedures and recruitment that did not match the pre-registered protocols; and
  6. The same control group was used across multiple studies yet was reported differently in each [86-88].

However, this doesn’t mean that HMB is a useless compound. As I mentioned earlier, HMB has been shown to aid hypertrophy and body composition among untrained lifters as they experience high initial muscle damage from training. Additionally, in highly damaging training protocols (for example high-height drop jumps that produce eccentric overload) free-acid HMB has been shown to aid recovery [89]. However, if training is set up appropriately, after the initial months of training, levels of muscle damage should not be sufficient to warrant the use of HMB. Indeed, a 2018 meta-analysis found no effect of HMB on performance or body composition changes in trained individuals [90].

But what about…?

If you don’t see a supplement listed above, you can safely assume that it belongs in the “C-list”. While it would be nice to go through every single supplement that belongs to this list, I think it would be a waste of everyone’s time, and it’d certainly turn into a multi-volume behemoth of an article.

For even more details on this topic, check out this video:

As more research comes out, perhaps we will update this page with the latest and greatest. In order to help you process this information, I’ve created a downloadable PDF of this CrossFit supplement guide that you can print for your records. You can download it here:

Remember, when it comes to your overall performance, supplements are the least important part of your success as a CrossFit athlete. If you’ve taken care of everything else, then following this supplement guide may help you increase your performance in the gym, or even the competition floor.

If you’ve liked this detailed breakdown and would like to watch Andy and Ben discuss it further in a Q&A, check out this page.

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By Andy Morgan and Eric Helms

FREE access to our most popular Lecture - Supplements Q&A


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  • Very solid article gents re supplementation in Crossfit.

    Could you also give your thoughts on magnesium and zinc supplements, although given no comments maybe it’s already on the C-list.


    • Hi Ant, thanks for the question.

      Deficiencies can have a significant impact on health, performance, and potentially diet success if unchecked. A diet with good variety can cover these bases, but as calories and macronutrients get lower, it will be harder and harder to prevent micronutrient deficiencies.

      Zinc deficiencies specifically, can result in a downregulation of thyroid to the point where energy expenditure is substantially reduced.

      In one case study, one subject increased their resting metabolic rate (RMR) by 194 kcals after four months of supplementing with zinc, and the other subject increased RMR by a whopping 527 kcals after supplementing with zinc for two months. [Maxwell, C. and S.L. Volpe, Effect of zinc supplementation on thyroid hormone function. A case study of two college females. Ann Nutr Metab, 2007. 51(2): p. 188–94.]

      *If* there is a magnesium or zinc deficiency then it’s worth correcting, but there’s no benefit I know of to supplementing past your body’s needs.

  • I currently take a multi, fish oil and D3 regimen. What about taking a B12 or B-Complex? What’s your advice on that?

    • As for all micronutrients, if you have a deficiency, or are at risk of one, then it’s worth supplementing with.

      But if you eat a varied diet rich in fruits and vegetables, don’t purposfully exclude certain food groups, and take a multi, you’re probably fine.

      Those “at risk” in this case are vegans. I won’t try to use my own words on this as I’ll be accused of bias. This is from the website:

      “Vitamin B12, whether in supplements, fortified foods, or animal products, comes from micro-organisms. Most vegans consume enough B12 to avoid anemia and nervous system damage, but many do not get enough to minimize potential risk of heart disease or pregnancy complications.”

  • Do the B and C lists change at all (for BCAA’s or other supplements listed) hold true for the vegan lifter/crossfitter?

  • Is there a supplement that include all of the A-list properties out there? I am trying to find one to purchase before i start crossfit in may 2019

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