Dietary Supplements to Gain Muscle and Strength

Do dietary supplements make you big and strong?

No, they don’t. No legal supplement will make you bigger or stronger by itself. You can’t pop a pill and expect to have it build muscle for you. 

However, combined with strength training, a select few can help you build muscle and grow stronger. Which ones are we talking about? Which ones can you leave on the supplement store shelf? Those questions, and many more, will be answered in this article.

For every supplement, we’ll go through any effects they have, both proven effects and speculative effects.

The Magic Pill

There are few absolute truths when it comes to strength training. Something we can probably all agree on is the fact that it takes a long time to get big and strong. Too long, many would argue. Even if you have spectacular genetics, there are only so many corners you can cut. Most likely, we are talking years of training, combined with a proper dietary plan, before you reach your goal if you ever do. If a legal and safe addition to your regular training and diet could lend a helping hand, chances are you’d be willing to spend a fair amount of money on such a product, right?

That’s why it’s hardly surprising that the supplement industry is a multi-billion dollar business, growing year by year. For many years, the dietary supplement industry has seen yearly growth of nearly 10%, and nothing indicates that the future looks any different.

If you are one of those willing to use a dietary supplement that might help you reach your training goals, you are not alone. 

Up to 90% of all athletes reportedly use some kind of dietary supplement, anything from vitamins and minerals to protein supplements and free-form amino acids to synthetic caffeine and energy drinks. Even amongst people who have never set foot in a gym or ran a single lap on a track, supplement use is quite common. More than half of the general population regularly uses some kind of dietary supplement to boost their health, performance, and well-being.

A Recent Compilation of Research

Let’s get into it! This article is about dietary supplements that might help you get bigger and stronger. Which ones work, and which are the equivalent of flushing your money down the drain? Is there any scientific evidence supporting more or less outrageous claims from supplement companies?

To our help, we have a recent review summarizing and analyzing the available research on the topic, Supplements with purported effects on muscle mass and strength.1 It grades supplements touted as beneficial for building muscle and gaining strength according to support from scientific evidence.

Read on for a detailed analysis of said analysis. It’s written in a way that is hopefully easy to understand. We’ll go through everything you need to know about 20 of the most popular dietary supplements for anyone looking to get bigger and stronger. You’ll find out which are or might be worth your money, which don’t live up to their promise, and which you shouldn’t touch with a six-foot pole.

Evidence Level A, B, C, and D

Grading supplements by placing them into one of four categories depending on how robust the scientific evidence supporting them helps you decide if they are worth your money. These categories are as follows:

  • Evidence Level A – these are the dietary supplements supported by overwhelming scientific evidence. Randomized controlled trials and meta-analyses demonstrate their efficacy and safety. These supplements are recommended if you are looking to add something to your training and dietary plan that improve your results and help you get bigger and stronger.
  • Evidence Level B – this is the category where you find supplements supported by some scientific evidence, but not at the level of those in evidence level A. The available studies might have come to conflicting conclusions. Some might show a positive effect, while others might find the supplement no more effective than a placebo. There could even be some safety concerns. In other words, these supplements lack convincing scientific evidence, and you might not get your money’s worth.
  • Evidence Level C – these are the supplements lacking enough evidence to support any claims regarding their efficacy or safety. There might not be any controlled studies available in the scientific literature at all, only less reliable research, like observational studies, studies lacking control groups or non-randomized studies. Don’t expect solid evidence for anything that’ll help you build muscle and strength from supplements in this category.
  • Evidence Level D – the bottom of the barrel, where you find supplements without evidence to reach level A, B, or C. Any claims for strength and muscle gains by using one of these supplements are taken straight out of thin air.

Keep in mind that we’re only talking about strength and muscle growth here. Some of the lower tier supplements might shoot up in the rankings in other respects, but that’s out of the scope of this article.

Level A Dietary Supplements

These are the top-tier supplements you can’t go wrong with when you’re looking for a helping hand getting bigger and stronger.

Caffeine

Caffeine is the most widely consumed drug in the world. It is a performance booster both in endurance sports and in sports that require short bursts of intense effort. Recent research proves that caffeine helps you perform better in strength sports and regular strength training in the gym. The fact that caffeine used to be on WADA’s list of prohibited substances and banned from Olympic competitions speaks for its effect.

Coffee and other sources of caffeine boost performance by stimulating your central nervous system, elevating your levels of endorphins, and by making intense training feel less painful.

Also, caffeine offers several benefits that might not be associated with immediate gains in performance, but that could still help you gain muscle and strength.

Caffeine boosts glycogen synthesis. This means that you store carbohydrates in your muscles more effectively with the help of caffeine. More glycogen in your muscles improves recovery and makes you look fuller and perform better.

Caffeine might increase your testosterone levels following a workout. While your cortisol levels get a boost as well, the ratio between the two hormones improves.

The most common way to improve performance through caffeine intake is, of course, by partaking of regular coffee. Early research suggests that coffee is a poor choice if you want the performance-enhancing effects of caffeine. Several studies could not replicate the documented effects of pure caffeine. More recent research wiped those doubts away, and today, scientific consensus tells us that you get the same performance boost regardless of the source of caffeine. A cup or three of coffee, energy drinks containing caffeine, caffeine pills, or even caffeinated chewing gum all work just fine.

According to the International Olympic Committee, supported by decades of research, 3 to 6 mg of caffeine per kilogram of body weight, one hour before exercise, maximizes performance with low to no risk of unwanted side-effects. Higher doses might boost performance even more, but also increase the risk of side-effects like nausea and dizziness.

Six mg of caffeine per kilogram of body weight is also the dose where you can expect max benefit in the bench press. You’ll be able to lift a higher total and do more reps with a certain weight if you are caffeinated as you lie down on the bench and grip the bar. If you can handle heavier weights, you will likely get stronger and stimulate muscle growth in the long run. That’s why we can safely conclude that caffeine is a great supplement for anyone looking to gain strength and size. Also, the fact that the recommended dose of 3 to 6 mg per kilogram of body weight is considered safe makes caffeine an even safer bet.

Further reading: Caffeine: Effects, Benefits, and Safety

Creatine

Creatine is a molecule your body produces from the amino acids methionine, glycine, and arginine. You can also find creatine in the food you eat. Creatine is produced in your pancreas, your liver, and your kidneys. You store creatine in your muscles as creatine phosphate. Creatine phosphate creates adenosine triphosphate, or ATP, which is vital for energy production during all kinds of physical work.

A physically active person uses more than 100 kilograms of ATP each day. No, you didn’t misread. Your production of ATP is that monumental. However, you can’t store ATP for future use. You synthesize new ATP at the rate you use it. By increasing your levels of creatine phosphate, meaning supplementing with creatine, your body can create ATP faster and more efficiently. In gym terms, that means you’ll be able to grind out a few extra reps with a certain weight before reaching failure.

Creatine supplements do not stimulate muscle protein synthesis, but they still help you gain muscle mass and strength. By increasing ATP production, you can lift heavier and do more reps. Training intensity and training volume are two of the most important things for strength training results.

Also, creatine might increase the number of satellite cells inside your muscles. Satellite cells contribute to your gains by splitting and adding new muscle protein when you subject them to load-bearing activities like lifting weights. If you quit training or take a lay-off, these satellite cells help you regain your muscle mass once you start lifting again. They don’t disappear, just go dormant. Once you start training again, they wake up and activates, ready to help you gain your lost muscle mass back. 

Decades of research and a large number of studies demonstrate that creatine is effective for gaining muscle mass and strength. The evidence is so strong that you rarely find new studies on creatine and strength and/or building muscle anymore. There simply is nothing left to prove. Studies on creatine now focus on other things, like preventing loss of muscle mass during periods of immobilization and potentially positive effects on brain function. These studies often reveal the benefits of creatine supplementation in these fields as well, and never find any negative effects.

The best and cheapest form of creatine is ordinary creatine monohydrate. No other types of creatine are more effective. If you see claims to the contrary, it’s a sales pitch without scientific evidence. Some other types of creatine, like creatine ethyl ester, are quite a bit less effective than the cheaper monohydrate.

As a bonus, creatine has no negative side-effects. The only side-effect is a larger and heavier body. While this might be detrimental in certain sports with weight classes and where your body weight directly influences performance, it’s a boon for anyone looking to gain strength and muscle mass. Early speculation about renal issues following creatine supplementation has been proven to be unfounded.

In summary, creatine is recommended for anyone looking to perform better, gain strength, or build muscle. About 20–25% of the population don’t get any effect from creatine supplements. They are so-called non-responders. However, the reason for this might be something positive for those affected. It’s probably because they already have high enough levels of creatine in their muscles. Ingesting more doesn’t do anything. So, if you are one of those 20–25%, don’t feel too bad.

Further reading: Creatine: Effects, Benefits and Safety

Protein

Protein supplements simply work. They are just regular food proteins in powder form. You get no more and no less “effect” from protein supplements than you would get from adding the same amount of protein from eggs, meat, beans, dairy, or whatever complete protein you can think of. 

More protein equals more muscle mass, at least up to a certain point. Let’s say you increase your protein intake from, say, 0.8 grams of protein per kilogram of body weight and day, as recommended for the general population, to 1.6 grams per kilogram of body weight and day. You will gain more muscle mass, everything else being equal, as long as you combine that increase with strength training. A larger muscle is also, in general, a stronger muscle.

This article is about supplements, though, not regular food. Good thing there are a substantial number of well-controlled studies and meta-analyses on the subject. They show that protein supplements increase muscle mass in adolescents, adults, and the elderly. A few studies with elderly participants stand out in that they do not find any effect from protein supplements. This is likely because of the dosage. When you get old, your muscles become less responsive to protein-rich meals. This phenomenon is called amino acid resistance. It means that you have to double the amount of protein you eat in a sitting to get the same anabolic response as you got when you were young. Most of the studies suggesting a lack of effect from protein supplementation have not considered this.

What it comes down to is your total daily protein intake. Timing and distribution of said protein are not irrelevant, but the importance of those factors pales in comparison. Evidence suggests that 1.6 to 2.2 grams of protein per kilogram of body weight and day maximize your potential for gaining muscle. Adding even more protein won’t do any harm, but neither will it make you build muscle any faster.

Speaking of your total protein intake, it makes no difference if you get it solely from regular food or if you use protein supplements to boost it. You’ll build muscle just as well in both cases. You don’t need protein supplements under any circumstances if you prefer to get your protein from regular foods. At the same time, there is nothing wrong with having part of your everyday protein intake come from supplements. Protein supplements are cheap, or at least they can be if you look around for deals, and very convenient. Most people find it easier to drink a post-workout protein shake than opening a can of tuna in the locker room.

Are Different Types of Protein Supplements Better Than Others? 

That remains to be seen, but probably not. Not as long as you get what you pay for. Some manufacturers dilute their product to save money. 

Animal proteins are complete proteins, meaning they provide enough of all the amino acids you need to build muscle. Vegetable proteins don’t, with one or two exceptions. In general, vegetable protein has less essential amino acids, the amino acids you have to supply through your diet, not only to build muscle but to live. If you don’t eat animal protein or only a little of it, you can simply eat more vegetable protein to make up for it. That way, you’ll get the same amount of essential amino acids. Also, the body is smart. It can combine amino acids from different food sources to make a complete protein from two or more incomplete ones.

Some studies show greater gains by supplementing with dairy proteins, like whey and casein proteins, compared to soy isolate protein. At the same time, several studies find no difference, as long as you match the total protein intake.

Most likely, you can use a protein supplement from vegetable or animal sources and see comparable results. They are both good choices to increase your total daily protein intake and help you gain muscle and strength, as long as you don’t already get more than enough.

Protein supplements have no detrimental effects on your health. They simply add to your daily protein intake, nothing more, nothing less. Studies have not found any harmful effects from high protein intakes, up to 3 grams per kilogram of body weight and day, over prolonged periods. This does not mean that a protein intake higher than that is harmful, just that no long-term studies have used that high an amount.

Speculations about kidney and liver damage from protein supplements have no scientific support as long as you are healthy. If you already have some kind of medical condition where high protein intakes are contraindicated, you should, of course, follow the advice of your doctor and not exceed those recommendations. However, you won’t develop such conditions by eating protein or by using protein supplements.

Further reading: Protein for Strength Athletes and Bodybuilders – How Much, How Often, and What Kind

Nitrate

Nitrate is a substance found in abundance in vegetables like spinach and beets. When you eat those, your body converts the nitrate into nitric oxide. Nitric oxide, or NO, is a molecule regulating your glucose metabolism and helps your muscles to contract. It also plays a role in regulating key steps in the muscle repair process, like following acute or chronic injury.

Nitrate supplements, most often in the form of beet juice, help you perform better in endurance sports by enhancing the function of your mitochondria. Limited strength training research suggests that you can do more work, meaning reps, before reaching failure with a nitrate supplement. If that means you end up with a higher total training volume, it could lead to greater gains in the long run.

Athletes eating enough of a regular mixed diet already get a fair amount of nitrate. One study found the average person gets slightly more than 100 mg per day from a mixed diet. You will, however, see a performance benefit by increasing that amount to 300–600 mg per day. That requires a supplement unless you base your diet on beets and spinach.

The most common nitrate supplement is beet juice concentrate. A supplement providing the amount of nitrate you’d get from drinking half a liter of beet juice a couple of hours before a workout gives you enough for a performance-enhancing effect. Most people would cringe at the thought of drinking half a liter of beet juice in one go, but a corresponding amount from a beet juice supplement lands somewhere around 70 ml. Much easier to get down.

If you love beet juice, you could use the real thing, of course, and drink half a liter or more before training. That might also have the added benefit of turning your urine blood red for a while.

The authors of the review this article is based on have placed nitrate at the highest level of evidence. Since it’s about strength and building muscle, I’m not sure I’d agree with them. I don’t think there is enough evidence, even though the number of studies showing support for nitrate supplements in strength sports is growing. Currently, I think I’d place it a step lower on the evidence ladder, though.

Since nitrate likely offers several health benefits, and many studies demonstrate a performance-enhancing effect, a beet juice supplement doesn’t sound like a bad idea, regardless.

Polyunsaturated Fatty Acids (Omega-3 and Omega-6)

Your body can synthesize most of the fatty acids you need when you need them. This is not the case with several of the polyunsaturated fatty acids omega-3 and omega-6. You have to provide them through your diet or supplements.

Omega-3 fatty acids have anti-inflammatory properties, while omega-6 can be pro-inflammatory. The latter might sound bad, but there is no evidence that omega-6 increases the risk of inflammation in a real-life scenario.

Recent research shows an association between omega-3 fatty acids and gaining muscle mass. In one study, subjects received 1.86 and 1.5 grams of the omega-3 fatty acids EPA and DHA. Muscle protein synthesis and anabolic signaling increased in both young and old participants. 

Long-term studies show actual muscle growth and strength gains in elderly men and women supplementing with omega-3 fatty acids over the course of 6 months, not just acute increases in muscle protein synthesis. Also, one particular study didn’t even include weight training, just omega-3.

Those results notwithstanding, I believe the evidence is too limited to place polyunsaturated fatty acids in the A category of evidence for strength and muscle mass. You only have the support of individual studies, no meta-analyses. That shouldn’t be enough to qualify a supplement for inclusion in the highest tier of evidence. At best, omega-3 and omega-6 fatty acids are promising supplements for building muscle, but I wouldn’t call the effects confirmed beyond any doubt. 

However, considering that there might be health benefits to be had from supplementing with these fatty acids, especially if your diet does not provide you with a lot, it might not be a bad idea for other reasons.

After the publication of the review this article is based upon, another review article concluded that omega-3 fatty acid supplements do not seem to have any anabolic properties in untrained subjects and that the effects on trained individuals are uncertain at best.2

Further reading: Omega-3 Fatty Acids: Effects, Benefits, and Safety

Level B Dietary Supplements

Here we have the second-tier supplements. They are supported by some scientific evidence, but it’s inconclusive.

Branched-Chain Amino Acids (BCAA)

BCAA are the three essential amino acids with a branched structure: leucine, isoleucine, and valine. 

Essential amino acids are the ones your body can’t synthesize on its own. You have to provide them with your diet. The essential amino acids are also the ones you need to eat or drink to stimulate muscle protein synthesis. Of the essential amino acids, three have a side chain of one carbon atom and three hydrogen atoms. This makes their molecular structure look like little trees. They are the Branched Chain Amino Acids or BCAAs. They, leucine in particular, “turn on” muscle protein synthesis and start the signaling mechanisms that tell your body to build new muscle.

BCAA supplements stimulate muscle protein synthesis both at rest and following a workout. However, a supplement containing all essential amino acids, not just the BCAAs, has a more powerful anabolic effect. In other words: protein powder or a regular protein-rich meal. A recent study demonstrated that BCAAs in supplement form stimulate muscle protein synthesis about 20 % more than placebo.3 Not a heck of a lot.

Unfortunately, the authors of the review this article is based upon have either failed to read or ignored the last few years of research. The current consensus is that BCAAs in supplement form don’t help you build muscle if you get enough protein. And even if you don’t, boosting your amino acid/protein intake through food or protein supplements instead of BCAAs is better and more effective.

If you want to use an amino acid supplement, get one with all the essential amino acids, not just BCAAs.

Also, while the authors point out the lack of convincing evidence for BCAA supplements, they still make it sound like BCAA supplements have powerful anabolic effects, something current research does not support.

BCAAs stimulate muscle protein synthesis. This does not translate into actual gains in muscle protein unless you have enough of the other essential amino acids as well. And all complete proteins already provide enough of all amino acids, leaving BCAAs the lesser choice in all situations.

One thing of note is that leucine can “rescue” a protein intake too small to properly stimulate muscle protein synthesis. If you add leucine to a small serving of protein, you get the same anabolic effect as from a larger serving. However, you need pure leucine without the other two BCAAs. If you add leucine in the form of a BCAA supplement, the valine and isoleucine compete with the leucine for intestinal uptake, resulting in not much at all happening.

If you already get 10 grams of essential amino acids from a meal, adding more amino acids in the form of a supplement, be it leucine, BCAAs or all EAAs, is just a waste of money.

Branched-chain amino acids in supplement form have one documented effect that could be of potential benefit. They reduce DOMS, muscle soreness, and might speed up muscle recovery compared to placebo. 

BCAAs seem safe enough in recommended doses, but if you take them for building muscle mass and gaining strength, you are probably hoping for too much. There is little doubt that you will gain more, both literally and figuratively, by adding the same amount of BCAAs from a regular source of complete protein.

Further reading: BCAA Supplements: Beneficial or a Waste of Money?

Adenosine Triphosphate (ATP)

If you read the creatine chapter earlier in the article, you might remember that adenosine triphosphate is the main energy source of your cells. It can also boost your performance when you take it as a supplement. High ATP levels improve your muscles’ ability to contract and the glucose uptake in your muscle cells. It also increases blood flow to your muscles when needed.

Adenosine triphosphate in high doses (more than 225 mg per day) increased both maximal strength and the number of reps to failure in one study. Four hundred mg a day improves both muscular power and leads to greater muscle growth and strength gains compared to placebo, according to another study.

Sounds great, right? Sure, there are a couple of studies that support the use of adenosine triphosphate supplementation to increase muscle mass and strength. Those studies are very few, though. Also, no meta-analyses have meta-analyzed them. Simply put, there is not enough evidence to recommend ATP supplements without reservation. Several studies suggest limited or very poor uptake and bioavailability from oral supplements.

Supplementing with adenosine triphosphate seems safe, without any reported side effects even with high doses and long-term usage. If you have more money than you know what to do with, you could experiment with ATP. More than likely, you could find better and more effective supplements to spend your cash on.

L-Citrulline

L-citrulline is a non-essential amino acid, one of those you don’t have to get from your food, as it can be synthesized by your body. Your kidneys convert citrulline into arginine and nitric oxide. Check out the nitrate section above for more about nitric oxide. 

Even though your body can make l-citrulline on its own, you can help things along by using an l-citrulline supplement. This increases the levels of several amino acids in your body above normal.

A few studies associate arginine with anabolic properties. Scientists have speculated whether or not citrulline might also have muscle-building properties. Unfortunately, no studies have followed up on these speculations. Also, arginine hasn’t lived up to the theoretical promises either, failing to deliver any additional muscle growth in real-world settings.

L-citrulline does not seem to increase growth hormone release or stimulate muscle protein synthesis. If it has any muscle-building properties, those are likely indirect through other mechanisms.

Combining l-citrulline with malate can increase both your max strength and the number of reps you can do before reaching failure. There is also some evidence that supplementing with citrulline reduces muscle soreness. However, other studies have failed to replicate any of these results. Also, strength training subjects consistently fail to increase muscle mass compared to placebo in controlled trials.

Some studies show performance benefits from l-citrulline, while others suggest little to no effect beyond that of placebo. Unfortunately, there are no meta-analyses, and the available evidence at times point this way, and at other times that way.

At the moment, this means that l-citrulline ends up in the “maybe”-category. There is no convincing evidence that citrulline supplements will help you get bigger and stronger. Future studies might change that.

L-citrulline is safe, but it does have side-effects. Not dangerous ones, but possibly unpleasant, as it can play havoc with your stomach if you are sensitive to it. Those issues go away if you stop taking citrulline, though.

HMB

ß-Hydroxy ß-Methylbutyrate, better known as HMB, is a metabolite of the essential and branched-chain amino acid l-leucine. About 5% of the leucine in the protein you eat is metabolized into HMB. HMB has both anabolic and anti-catabolic properties, although the anti-catabolic effects are much more substantial. While HMB activates muscle protein synthesis (which is not the same thing as actually building muscle), it reduces protein breakdown to a larger degree.

Plenty of research examines the potential effects of HMB on strength and muscle mass, both with and without strength training. These studies are, mildly put, of varying quality. Fortunately, we have several meta-analyses at our disposal, indicating which way the scientific winds blow.

Studies show that HMB help retains muscle mass in untrained, elderly subjects. It is a much less promising supplement for young and trained individuals.

A recent meta-analysis found no effect of HMB supplements on strength or body composition in trained individuals.4 Compared to placebo, total body mass, fat-free mass, body fat, leg press strength, and bench press strength didn’t improve any more in the HMB groups compared to the placebo groups in a number of controlled trials.

Now, we should mention a 2014 study that stands out from the rest. The subjects in that one gained strength and muscle mass, a lot of it. They gained as much strength and muscle as if they had taken 600 mg of testosterone per week instead of HMB. The reasons behind those results are unclear, but something is wrong with it. It is purposefully excluded from new meta-analyses on HMB.

HMB is considered safe. In the elderly, it is a promising supplement to combat catabolic states like inactivity and illness to maintain and preserve muscle mass. However, if you are young and/or trained, chances are HMB supplements won’t help your efforts in the gym one bit.

Minerals

The amount of minerals you need every day is very small. This minuscule amount supports a myriad of functions in your body, making minerals essential nutrients. Many of their effects relate to muscle functions and growth. Because of this, speculations abound that various minerals might help you build muscle and strength. There is quite a bit of research available.

Magnesium

Magnesium is a multi-faceted mineral, affecting your body in a lot of different ways, from muscular to cardiovascular. A regular mixed diet normally provides all the magnesium you need, but if you engage in a lot of physical exercise, you might need more. Both the amount of magnesium in your diet and the amount in your blood is associated with strength and muscle mass. However, it is unclear whether or not supplementing with magnesium improves your gains.

A few studies suggest greater strength gains with a magnesium supplement compared to placebo following seven weeks of strength training. Another study demonstrated larger 1RM increases in the bench press with magnesium. 

Meta-analyses do not support these isolated results. This means a lack of scientific support for claims that magnesium improves muscle growth or strength unless you actually have a magnesium deficit and simply restore normal levels by supplementing.

Zinc

You need zinc for protein synthesis and your hormone production to work properly. Zinc is associated with both higher testosterone levels and a larger muscle mass. In children with growth disorders, zinc supplements increase levels of anabolic hormones and enhance natural growth. Individuals suffering from zinc deficiency leading to abnormally low testosterone levels can improve their situation with a supplement.

In athletes, zinc enhances testosterone release following a training session. However, no studies reliably demonstrate greater muscle growth or strength gains in non-deficient athletes. If you have some kind of disorder where zinc plays a central role, your gains might benefit from a zinc supplement. If you don’t, then probably not.

Chromium

Chromium helps your body control blood glucose and insulin turnover. Insulin is a hormone with powerful anabolic properties and crucial in order to open up your cells to receive nutrients. In theory, the effects of chromium on insulin action could increase strength and muscle mass through these indirect effects. In theory. You see, no study has ever demonstrated these results from chromium supplementation.

A number of both short-term and long-term studies featuring subjects engaging in strength training showed no effect on strength, power, or body composition from chromium supplements.

Minerals: Summary

In summary, scientific evidence tells us that mineral supplements have no significant effects on your strength or muscle mass unless you are deficient. High doses of one or more minerals probably have no positive effects without a clinical deficiency. Supplementing randomly can do more harm than good in the long run. For example, a very high intake of zinc is associated with markers indicating an increased risk of heart disease. Most of the side effects associated with high-dose mineral intakes are acute and unpleasant rather than harmful. A lot of magnesium can give you an acute case of explosive diarrhea, for example.

Vitamins

Most vitamins are important or even essential for gaining muscle mass and strength. They are part of the processes regulating neuromuscular health and function in one or more ways.

However, this is a case where more is not always better. Unless you are deficient or get too little of a vitamin, you rarely or never benefit from supplements, and neither does your wallet.


Vitamin D

Vitamin D is a fat-soluble vitamin and often the exception to the above. Getting too little vitamin D is common. True vitamin D deficiency is not common, but lower than optimal levels is. Since you can make vitamin D through exposure to sunlight, the risk of low levels of vitamin D is extra high if you live in the northern hemisphere where the sun is absent or weak for large parts of the year.

Low levels of vitamin D are associated with bone metabolism disturbances, mood, and weakened immune function. If you don’t get enough through the combination of food and sunlight, a vitamin D supplement is a good idea.

More on topic, can you expect better gains from your efforts in the gym by supplementing with vitamin D, even if you don’t suffer from particularly low levels? According to research, you should probably keep your expectations in check. While vitamin D is important for optimal muscle function, unless your levels are lower than normal, adding more through supplementation likely will do nothing for your muscle mass or strength.

Vitamin D is safe, as long as you stay at or below the established safe upper limit of 100 micrograms or 4,000 International Units (IU) per day. If you want to ensure you get enough vitamin D, feel free to use a supplement even if you don’t have any signs of deficiency, for other reasons than gains.

Vitamin C and E

Both vitamin C and E have antioxidative properties. Even though antioxidants are important for your cell health, most people already get enough of these vitamins. Large doses of antioxidants seem to block anabolic mechanisms and can hamper your gains, not help them.

Vitamins: Summary

Regardless of which ones we’re talking about, the same goes for vitamins as for minerals: as long as you’re not deficient, don’t expect any noticeable effects from supplements. You won’t gain any muscle or strength from using them. In some cases, if you take very large doses, they can prevent your gains instead.

Phosphatidic Acid

Phosphatidic acid is a so-called anionic phospholipid. It’s a compound naturally found in your body, used to build and maintain the membranes of your cells. Also, phosphatidic acid is a part of the mechanisms starting muscle protein synthesis.

Several studies show greater gains in muscle mass and strength by supplementing with phosphatidic acid compared to placebo. At the same time, other controlled studies show zero effect from using the same amount of phosphatidic acid.

There are no meta-analyses on phosphatidic acid and strength training, leaving the research results ambiguous. Most likely, phosphatidic acid has anabolic properties, but whether or not these properties translate into bigger muscles and greater gains has not been proven.

There are no known negative health effects of phosphatidic acid. Then again, there are no controlled long-term studies that confirm the safety either. At least the participants in the phosphatidic acid studies did not report any issues.

One thing of note is that the effect of phosphatidic acid seems to be age-dependent. In young people, a few studies demonstrate anabolic effects by supplementing with phosphatidic acid, but in the elderly, it might be the opposite. One study found that phosphatidic acid shuts down muscle protein synthesis signaling rather than enhance it.

L-Arginine

L-arginine is an amino acid used in supplement form by athletes for many years. It increases nitric oxide production, the blood flow to your muscles, and boosts growth hormone release.

Speaking of growth hormone, arginine increases growth hormone release at rest. If you take arginine before or after a strength training session, your growth hormone response to the workout diminishes compared to training without arginine. Long-term, a daily arginine supplement increases your growth hormone levels somewhat, in both men and women. However, it is highly unlikely that the amount of growth hormone release you can expect from arginine has any effect on your muscle mass whatsoever, even if one study saw an increase in fat-free mass after one month of arginine supplementation.

When it comes to performance, quality research is lacking. Arginine studies where the physical performance of the subjects increased did not follow up on the cause of those improvements. This makes it hard to say if it was the arginine or something else boosting performance. Most likely, evidence level B is the right place for l-arginine. Might l-arginine contribute to mechanisms regulating muscle mass and strength? Sure. Is there evidence that supplementing with l-arginine leads to increased strength and muscle mass in practice? No, there is not.

Anecdotal evidence shows that pre-workout l-arginine increases the feeling of pump in your muscles while training. If that’s the effect you’re after, experiment with arginine to your heart’s content. Some theories suggest that pump itself might contribute to muscle growth, through cell swelling, increased blood flow, and nutrient transport to the muscle cells. Again, no scientific evidence backs these speculations up.

L-arginine in recommended doses is safe, although you might end up on the toilet if you take doses above your individual tolerance.

Level C Dietary Supplements

Now we are approaching the bottom of the barrel. We are not quite there yet, though, as level C supplements might have some benefits for someone, even if there is no solid evidence for using them.

CLA (Conjugated Linoleic Acid)

CLA is a fatty acid most often marketed as a fat-burning supplement because of its effects on receptors controlling fat metabolism, inflammations, and blood glucose action. Human research is both ambiguous and often low-quality.

When it comes to the effects of CLA on strength and building muscle, we find a handful of studies of varying quality. One study found that strength-training subjects supplementing with CLA increased both their strength and muscle mass compared to a group performing the same training program but with no CLA. Another study came to the same conclusion but with elderly participants. In that study, the CLA supplement was combined with creatine, a provenly effective supplement. That makes it impossible to say how much of the effect the CLA contributed. If it contributed at all.

In summary, while some studies suggest positive effects from CLA supplementation, others show no effect at all. All in all, CLA does not currently look like a promising supplement to help you gain strength and muscle mass.

L-Glutamine

L-glutamine is the most abundant of all the amino acids, both in the food you eat and in your muscle. During most conditions, glutamine is a non-essential amino acid, one you don’t have to get from your diet, although you will get it whatever you eat. Your body can make glutamine just fine on its own. However, there are times when you can make use of extra glutamine, like during severely catabolic situations like sepsis, some diseases, and extensive burns. Your body goes through glutamine like crazy during situations like that. It can’t keep up with the elevated requirements. However, despite what manufacturers of dietary supplements would like you to think, a workout does not put you into such a catabolic state.

During periods of severe illness and, for example, abdominal surgery, intravenous glutamine prevents the decline of protein synthesis. Oral glutamine intake does not have the same preventative effects. In regards to strength training, glutamine is an extensively researched supplement. It does not help you gain muscle mass or strength compared to a placebo. Meta-analyses conclude that glutamine has no effect on immune function, body composition, or performance in strength-trained individuals. 

The one positive thing about glutamine supplements is that there are no negative health effects from using them.

Resveratrol

Resveratrol is a natural phenol produced by plants, which have been marketed and hyped to a noteworthy degree in the last decade or so. It’s been touted as having a number of effects potentially beneficial to your health. In nature, you find resveratrol in, for example, the peel of grapes and in peanuts. The most well-known source is probably red wine. Resveratrol has antioxidative, anti-inflammatory, and tumor-inhibiting properties.

In animal trials, resveratrol enhances muscle growth after prolonged inactivity. While this has garnered interest for any potential effects on human muscle mass, very few studies have been published to date. One of those few studies demonstrated improved muscle function and increased muscle cross-sectional area in elderly who combined training with a resveratrol supplement.

In another study, “strength training” rats ended up with negative effects after being given a resveratrol supplement. They did not respond as well to mechanical overload, and the satellite cell content in their muscles diminished.

In addition to that, resveratrol as a supplement is problematic. Your liver breaks it down almost entirely before it is absorbed into the body where it could potentially be of any use. You could get it from red wine, but drinking enough wine on a daily basis to provide sufficient amounts of resveratrol would probably hamper your gains for other reasons.

Ursolic Acid

Ursolic acid is a molecule found in many fruits, herbs, and other plants, including apples, oregano, and cranberries. It is anti-inflammatory, antioxidative, and even has anabolic properties, at least if you are a rat.

Animal studies reveal several anabolic effects of supplementing with ursolic acid. Not only does it stimulate the release of anabolic hormones like growth hormone and IGF-1, but it also increases the number of satellite cells in the muscles, and stimulates muscle protein synthesis.

Human trials are not, sadly, as positive, or at least not unambiguous. One study showed greater increases in strength and IGF-1-levels with ursolic acid compared to placebo. Several other studies have failed to see either short-term anabolic effects or long-term changes in body composition and strength.

Ursolic acid is great if you are a rodent bodybuilder. For us humans, while ursolic acid looks promising on paper, there is currently not enough evidence to recommend it to anyone looking to gain mass and strength.

Tribulus Terrestris

The herb tribulus terrestris has been used in Asia for centuries. In the last few decades, it’s become popular amongst bodybuilders and strength athletes due to claims that it increases testosterone levels.

Unfortunately, no controlled studies support these claims. Several long-term studies with young, healthy participants could not find any effects on anabolic hormones, including testosterone, IGF-1, and dihydrotestosterone.

Several other strength training-related studies examine the effects of tribulus terrestris on body composition and strength. Again, they consistently find no difference between tribulus terrestris and placebo.

There is one exception: the elderly with age-related testosterone deficiency. Studies show increased levels of both total and free testosterone following three months of tribulus terrestris supplementation. It is possible that tribulus terrestris has anabolic properties if you are old and your testosterone levels are below normal. However, this is very unlikely to translate into muscle growth if you are young and/or healthy.

Level D Dietary Supplements

These are the supplements that you can bet on to empty your wallet without you getting anything out of it. No evidence, no effect.

Alpha-Ketoglutarate (AKG)

AKG is a precursor to glutamine and arginine. In test tubes, it stimulates protein synthesis in cells. AKG is sometimes given to malnourished patients along with the amino acid ornithine, which reduces protein breakdown.

In healthy human individuals, there is little to no evidence that AKG has any effect whatsoever on muscle mass, strength, or performance. One study did show a greater increase in bench press 1RM in subjects consuming AKG in combination with arginine, but those results have never been replicated.

Ornithine

If you read bodybuilding magazines back in the early 1990s, you might remember ads hailing the amino acid ornithine as something of a miracle cure for growth hormone release.

There is a tiny bit of truth to those old ads, as ornithine stimulates a certain amount of growth hormone release, both in untrained individuals and bodybuilders, at least if the dose is high enough. Nothing suggests that this growth hormone pulse could influence strength and muscle mass in any way.

Conclusion

In summary, this is how the authors classified the various supplements:

Evidence Level A:

  • Caffeine
  • Creatine
  • Protein
  • Nitrate
  • Polyunsaturated Fatty Acids (Omega-3 and Omega-6)

Evidence Level B:

  • BCAA
  • Adenosine triphosphate (ATP)
  • L-Citrulline
  • HMB
  • Minerals
  • Vitamins
  • Phosphatidic Acid
  • Arginine

Evidence Level C:

  • CLA
  • L-Glutamine
  • Resveratrol
  • Ursolic Acid
  • Tribulus Terrestris

Evidence Level D:

  • Alpha-Ketoglutarate (AKG)
  • Ornithine

As I said earlier in the article, I feel the authors misplaced nitrate and polyunsaturated fatty acids. I don’t think they have the anabolic properties or the required evidence backing them up for them to be called A-level supplements. Not if we’re talking about gaining muscle mass and strength.

For example, no meta-analysis supports the use of omega-3 or omega-6 for greater gains in the gym. The authors themselves proposed meta-analyses or overwhelming evidence from randomized controlled trials as requirements for evidence level A. Polyunsaturated fatty acids are not backed by either of those. I would move both polyunsaturated fatty acids and nitrate down one level.

All in all, it’s a comprehensive and well-researched review. It is common for supplement companies and resellers to tout their products as being something they aren’t, or with properties taken out of context and irrelevant to healthy humans. The fact that a rat in a lab gained 4 grams of muscle instead of 3 grams does not make a supplement worth the money for you.

The authors conclude that there aren’t many so-called muscle-building dietary supplements out there backed by scientific evidence. There is no arguing with that conclusion. The more exotic or fantastic something looks or sounds, the less likely it lives up to that promise.

If we are talking about immediate effects, only caffeine and nitrate are worth mentioning. Those are safe bets and allow you to perform better in the gym, use heavier weights, or handle a greater training volume. Those are all factors that could improve your results in the long run, too. The anabolic effects of these supplements are indirect, not direct. They help you perform better but don’t build muscle.

Regarding long-term effects, the authors give thumbs up to fatty acids, protein, and creatine. You can get all three from your food, but only the first two in sufficient amounts to benefit your training. Protein supplements in particular are just powdered food. They have the same effect as the same amount of protein from regular food. No more and no less. That doesn’t mean that protein powder is a waste of money. On the contrary, they are quite effective, if we are talking about ease of use and price per gram of protein.

Most other supplements, even those without any of the purported effects, are fairly harmless if you want to experiment with them. Even if they aren’t backed by science, you can try them out if money is of no consequence. Placebo and “works for me” doesn’t have to be a bad thing, but if you want evidence-based supplements, your options are limited, for better or worse.

Back to basics is often the best choice.

References

  1. European Journal of Nutrition volume 58, pages 2983–3008 (2019). Supplements with purported effects on muscle mass and strength.
  2. Clinical Nutrition, Volume 39, Issue 1, January 2020, Pages 23-32. Is there sufficient evidence to supplement omega-3 fatty acids to increase muscle mass and strength in young and older adults?
  3. Front. Physiol., 07 June 2017. Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans.
  4. J Sci Med Sport. 2018 Jul;21(7):727-735. Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials.

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