Back to the Basics: An Overview Of Amino Acids

Amino acids are the foundation of life. Here is an overview of basic information about amino acids and how and why they are perfectly suited for, and in fact “essential” to, the dietary goals of people committed to health and their own well-being.

Amino acids are the foundation of life. They are involved in everything from muscle growth and the maintenance of connective tissues to making the chemicals necessary for our brain and vital organs to function. Beyond serving as the building blocks for all-important proteins, amino acids are in and of themselves important signaling factors and intermediaries in many metabolic pathways.

The average human body is 60-70% water while protein constitutes two-thirds of the non-water component of the body. We can all appreciate how important it is to drink plenty of fluids in order to balance the water lost through sweat, urine, and respiration. But we also lose protein on a daily basis as muscles and tissues degrade and amino acids are oxidized. Just as it’s important to rehydrate with water, a significant dietary input of amino acids is required to maintain this body pool at an optimal level. These requirements are even greater under conditions that affect our overall diet quality and subject us to a variety of physiological stresses.

Here is an overview of basic information about amino acids and how and why they are perfectly suited for, and in fact essential to, the dietary goals of people committed to health and their own well-being.

What Are Amino Acids?

Amino acids (20 in total for biological purposes) are important organic compounds that exist in all protein-containing food sources. They are the building blocks of proteins.

In chemical terms, an amino acid is an organic compound containing amine (-NH2) and carboxylic acid (-COOH) functional groups. In addition, each amino acid contains a unique side chain (R group) that features an element or chemical structure that imparts a specific characteristic or function to that amino acid.

Basic information on how Amino Acids is essential to your health.

While at least 500 naturally occurring amino acids have been identified, in this article we will concern ourselves only with those that are referred to as “proteinogenic,” which means they are used in the making of all biological proteins. You may already be familiar with some of these amino acids since an increasing number are available as nutritional supplements (for example, the ever-popular branched-chain amino acids).

Currently, there is a great deal of interest in identifying functional benefits of different amino acids beyond their role as constituents of muscle protein. As we discuss each amino acid, keep in mind that these functions occur in an environment in which all amino acids are present and maintained in a specific balance and physiological concentration.

Eleven of the standard amino acids found in the human genetic code are considered dispensable or nonessential, meaning the body has the ability to make or synthesize these amino acids, and so it is not necessary to get them from the diet.

Nine amino acids must be obtained from food sources or supplements since humans do not have the ability to make them, and these are deemed indispensable or essential. There is a recommended dietary allowance (RDA) for the essential amino acids, while there is no required dietary intake defined for the nonessentials.

There are also some conditionally essential amino acids. In healthy people, these amino acids can be synthesized, but in certain disease states, some amino acids must be obtained from diet since the amount produced by the body is inadequate to meet demands. This occurs, for instance, when the liver functions less than optimally. Liver damage impairs the conversion of some essential amino acids to nonessential amino acids, and these nonessentials then become classified as conditionally essential amino acids. Overall good nutrition is important as well, since sub-optimal vitamin and mineral status can interfere with the synthesis of nonessential amino acids by impairing enzymes or other cofactors involved in the reaction.

Essential vs. Nonessential Amino Acids

The essential amino acids include:

  1. Histidine
  2. Isoleucine
  3. Leucine
  4. Lysine
  5. Methionine
  6. Phenylalanine
  7. Threonine
  8. Tryptophan
  9. Valine

Histidine was thought to be nonessential for adults since it appeared that only infants could not synthesize it, but more extensive studies suggest that adults, too, rely upon dietary sources of this amino acid.

The nonessential amino acids include:

  1. Alanine
  2. Arginine
  3. Asparagine
  4. Aspartic Acid
  5. Cysteine
  6. Glutamic Acid
  7. Glutamine
  8. Glycine
  9. Proline
  10. Serine
  11. Tyrosine

While in theory, we could function perfectly well without any dietary intake of nonessential amino acids, we are actually much more metabolically efficient if we have some percentage of these common amino acids supplied by the diet. In the absence of a dietary source, the body has to divert energy and resources to making the particular amino acid that is in short supply. Depending upon the circumstances and the desired outcome, this may or may not be a good thing.

For example, with an illness or a catabolic disease, having an abundance of all amino acids facilitates immune system function by ensuring all the amino acid components are available and energy does not need to be devoted to synthesizing nonessential amino acids.

On the other hand, efforts to lose weight for health can be helped along by the added calorie cost of processing protein and making nonessential amino acids. Bodybuilders who eat very high-protein diets or individuals who need to reduce urea production (for example dialysis patients or people with kidney impairments), can benefit from supplementing with essential amino acids, which effectively reduces the breakdown of nonessential amino acids (and the consequent release of nitrogen). On average, a high-quality dietary protein contains a ratio of essential to nonessential amino acids of approximately 55:45 which is similar to the makeup of human muscle.

Amino Acids in Balance: The Whole Is Greater Than the Sum of the Parts

Every amino acid can serve as a structural component of protein, skeletal muscle being the main reservoir in the human body. Individual amino acids have unique functions, such as L-arginine’s role in the production of nitric oxide, L-leucine’s ability to initiate the process of protein synthesis, or L-lysine’s beneficial effect on blood sugar regulation. However, it is an oversimplification to expect a specific outcome in response to taking a single amino acid supplement.

When a specific action is attributed to an amino acid, it is in the context of all the chemical reactions occurring throughout the human body, which involve all the amino acids working together. For example, it seems reasonable to consume arginine to stimulate nitric oxide production since that is what arginine does in the body. Yet arginine supplements do not cause a large increase in arginine concentrations in the blood and tissues because much of the orally ingested arginine is taken up and metabolized in the liver. It is more effective to take a citrulline supplement which is converted to arginine in the kidneys, thus making arginine available to circulate to endothelial cells and other tissues.

Just like the way in which many vitamins function, taking more of a single amino acid does not necessarily create more of an effect, and often it is only with a deficiency of the nutrient that a problem arises. Isolated amino acid deficiencies are very rare and usually attributable to metabolic defects.

Amino acids function as a team in a physiological system with many other compounds and factors that affect how it operates. To keep amino acids in balance, eat a varied protein- and antioxidant-rich diet and take a well-formulated essential amino acid supplement as needed.

Basic information on how Amino Acids is essential to your health.

5 Proven Health Benefits of Amino Acids

Amino acid supplements are popular in the bodybuilding world. But amino acids, while key muscle makers, perform many more health-enhancing feats. They can help improve mood, keep stress at bay, and even strengthen the immune system. Let’s take a look at 5 of the most celebrated benefits of amino acids.

Amino acids, fittingly nicknamed the building blocks of proteins, not only make up the protein you eat, but also join together to form proteins in your body. These proteins are the very foundation of your hair, nails, bones, muscles, cartilage, connective tissues, and skin. They are the proteins your body uses to build and repair tissues and to synthesize hormones and enzymes. When you eat dietary protein, your body breaks amino acids into their individual parts, and then uses these amino acids to build the protein your body requires. Given that amino acids are so integrated into the makeup of the human body, it’s hardly surprising that researchers have uncovered a plethora of health benefits of amino acids.

Amino acids play a key role in muscle health, and, for this reason, amino acid supplements are popular in the bodybuilding world. But amino acids, while key muscle makers, perform many more health-enhancing feats. While they undoubtedly play vital roles in processes such as muscle growth and muscle recovery, they also contribute to brain function. Research indicates that increasing your amino acid intake from food sources or by taking supplements can help improve mood and keep stress at bay. Plus, they can strengthen the immune system. Before diving deep into five scientifically validated health benefits of amino acids, let’s take a moment to go over some amino acid basics.

The Basics of Amino Acids

In scientific terms, amino acids can be defined as organic compounds composed of nitrogen, carbon, hydrogen, and oxygen, along with a variable side chain group. Scientists have identified 20 different amino acids that the human body requires in order to properly develop and maintain itself. Though all 20 make essential contributions to your overall health, 9 of those amino acids have been categorized as essential amino acids (EAAs):

  1. Histidine
  2. Isoleucine
  3. Leucine
  4. Lysine
  5. Methionine
  6. Phenylalanine
  7. Threonine
  8. Tryptophan
  9. Valine

The reason scientists deemed those nine amino acids essential is that your body cannot independently produce them, making it essential that you obtain them from the food you eat or supplements you take.

Three of the nine essential amino acids exist in their own subcategory: the branched-chain amino acids (BCAAs). Those amino acids are:

  1. Isoleucine
  2. Leucine
  3. Valine

While many have touted the benefits of BCAA supplements, based on the impressive effects of those three specific amino acids, the truth is that to benefit from an increased supply of one amino acid, your body must have a balanced amount of all the essential amino acids.

The 11 amino acids necessary for human health that the body can produce on its own are called nonessential amino acids (NEAAs), because it’s not essential that you consume them.

However, the dividing line between essential amino acids and nonessential amino acids has more wiggle room than their names might initially lead you to believe. Enter the conditionally essential amino acids. Of the 11 nonessential amino acids, 7 have been identified as conditionally essential:

  1. Arginine
  2. Cysteine
  3. Glutamine
  4. Glycine
  5. Proline
  6. Serine
  7. Tyrosine

While your body has the ability to generate these amino acids, that ability becomes compromised under certain conditions, like if you become ill or are dealing with chronic stress. To illustrate this idea, let’s look at how this plays out with one specific conditionally essential amino acid: arginine. Researchers have found that your body cannot produce enough arginine on its own while fighting diseases such as cancer. Under those conditions, it becomes essential to augment your body’s supply of naturally produced arginine with supplemental arginine.

Now that you have a working understanding of the different types of amino acids relevant to human health, we can discuss some of the most exciting, research-backed health benefits associated with individual amino acids.

5 Proven Benefits of Amino Acids for Your Body and Mind

We rely on amino acids to perform a multitude of roles. An adequate intake of amino acids helps us build muscle, maintain mental focus, maximize exercise performance, and more. Amino acids contribute to crucial bodily functions such as:

  • Protein synthesis
  • Tissue growth and repair
  • Energy production
  • Immune defenses
  • Wound healing
  • Nutrient absorption

Individual amino acids have been shown to prevent muscle loss, increase energy, boost endurance and stamina, improve mood, decrease body fat percentage, speed recovery time, enhance immune health, optimize sleep quality, and more.

The essential amino acids, which your body cannot generate, can be found in high-quality sources of dietary protein. While eating a vegetarian or vegan diet may necessitate that you pay closer attention to your amino acid intake, it’s certainly possible to meet your body’s needs using only plant-based proteins. Furthermore, it can be beneficial to take concentrated doses in supplemental forms regardless of how healthy and balanced a diet you eat.

Essential amino acids are the only macronutrients required for survival. A normal diet containing high-quality proteins should deliver adequate amounts of essential amino acids to meet minimal requirements. However, amino acid supplements can provide benefits not achievable with even high-quality protein food sources.

Amino Acid Benefit #1: Muscle Protector

Muscle tissue consists mainly of proteins, and protein is made of amino acids. It stands to reason that amino acids would have a pronounced effect on muscle growth. As you may be aware, increasing your amino acid intake can boost muscle mass, strength, and function by stimulating muscle protein synthesis, or the building of new muscle tissue.

Did you know, however, that amino acids also help prevent muscle breakdown during exercise or between meals? In other words, they not only encourage muscle growth, but they also protect the gains you’ve worked so hard to build.

When you exercise, your body uses glucose, fats, and protein as fuel sources. If the body is low in fuel, it will start pulling protein from muscles, chipping away at your overall muscle mass. For instance, endurance activities quickly drain your stores of branched-chain amino acids (BCAAs). To avoid muscle loss, it’s important to supply your body with more essential amino acids, either by eating dietary protein or supplementing with amino acids. This ensures amino acid levels in your bloodstream stay stable and keeps your muscles protected.

Amino Acid Benefit #2: Energy Generator

As I touched on above, your body requires fuel to carry out tasks such as contracting your muscles. However, the body stores very little energy. The energy stored in your muscle takes the form of creatine phosphate.

Three amino acids—arginine, methionine, and glycine—join together to form creatine. The process of breaking down creatine phosphate releases energy that can provide an immediate source of fuel for muscle contraction. It gives us the energy boost we need for activities like sprinting or lifting heavy weights.

Because only a small quantity of creatine phosphate can be stored in our muscles at any given time, we depend on a different kind of cellular energy called adenosine triphosphate (typically abbreviated to ATP) for more sustained exercise activities. As with creatine phosphate, the breakdown of ATP provides energy that can fuel muscle contraction. When ATP is broken down, it forms adenosine diphosphate (ADP). Your body then regenerates ATP from ADP and phosphate in small organelles in the muscle called mitochondria.

There are a number of proteins in the mitochondria that enable the production of ATP from the oxidation of glucose, fatty acids, and amino acids. These specialized proteins are called enzymes. The more mitochondrial enzymes you have, the more ATP can be produced and the more energy is available to fuel muscle function. The number of mitochondrial enzymes depend on the number of mitochondria and the number of oxidative enzymes in each mitochondria.

Amino acids play a crucial role in increasing both the number of mitochondria available to generate ATP as well as the number of enzymes within each mitochondria. Both the formation of new mitochondria and the enzymes they contain result from protein synthesis.

A proportionately blended amino acid supplement stimulates the production of new mitochondria and increases the number of enzymes in the mitochondria by stimulating mitochondrial protein synthesis. Thus, an ample availability of dietary amino acids is an indispensable part of producing the energy our bodies need to keep functioning and to perform at their best.

Amino Acid Benefit #3: Endurance Enhancer

In addition to increasing your body’s ability to produce physical energy to fuel exercise performance, amino acids can help improve mental energy during a long workout.

Your mental energy depends on the balance between the inhibitory neurotransmitter serotonin (which brings on feelings of calm) and the excitatory neurotransmitter dopamine (which stimulates feelings of excitement). These neurotransmitters are made inside the brain from amino acids circulating in your bloodstream. The amino acid tryptophan serves as a precursor to serotonin production and tyrosine fulfills the same role for dopamine.

During long, grueling workouts, the balance between tryptophan uptake and tyrosine uptake can be disrupted. The brain begins to let in more tryptophan, and as production of serotonin outstrips production of dopamine, you end up feeling mental fatigue. You have plenty of physical energy to keep going, but not the cognitive drive you need.

Taking an amino acid supplement with a balance of essential amino acids can counter the increased uptake of tryptophan by the brain, helping you work out for longer by reducing serotonin production and thus delaying the mental perception of fatigue.

It is important to use an appropriately balanced amino acid mixture that also increases dopamine production, as it is the balance between serotonin and dopamine that determines your mental energy level.

As I briefly mentioned earlier when introducing the concept of branched-chain amino acids, taking an imbalanced mixture of amino acids will not yield the results you hope for. While taking a BCAA supplement can reduce the uptake of tryptophan by the brain, it will also reduce the amount of tyrosine taken up by the brain.

In order to boost mental energy so you can sustain focus during a workout, an amino acid supplement must decrease the ratio of serotonin to dopamine in the brain. Decreasing the amount of serotonin will have minimal effect on brain focus and energy if the amount of dopamine is also reduced. It is, therefore, important that you use a balanced amino acid supplement that not only decreases brain tryptophan uptake, but also increases the dopamine precursor tyrosine.

Amino Acid Benefit #4: Mood Stabilizer

As we just discussed, too much serotonin can cause fatigue during workouts. Too little serotonin, however, has been linked to depression, anxiety, insomnia, and overall moodiness. While tryptophan, and subsequently serotonin production, is ideally down-regulated during exercise, it can have a palliative effect when it is increased in individuals battling mood disorders.

Low tryptophan can be especially problematic when you are dieting. Dieting generally calls for eating fewer calories, which typically entails eating less protein, even if you’re on a so-called high protein diet. So, it is especially important to consume sufficient tryptophan if you’re on a diet.

There are two other standout amino acids for promoting balanced moods. The first, which I introduced in the preceding section, is tyrosine. This amino acid functions as a precursor not only for dopamine, but also for the equally influential brain chemicals epinephrine and norepinephrine. Increasing your intake of tyrosine has been shown to significantly amplify energy, strengthen motivation, elevate sexual function, and heighten concentration, thereby benefiting mood. The best route to increasing tyrosine levels, however, is not to up your intake of tyrosine itself but rather to focus on the essential amino acid phenylalanine, which the body then converts into tyrosine.

The third amino acid that’s particularly important when it comes to promoting balanced moods is glutamate. This nonessential amino acid can act as a neurotransmitter itself, but is probably more relevant as a mood enhancer due to its role as the precursor of gamma-aminobutyric acid, better known as GABA. As the main inhibitory neurotransmitter in the brain, GABA helps us feel calm and relaxed and prevents overstimulation of nerve cells. Glutamate is produced from glutamine, so both glutamine and glutamate have similar effects on GABA production.

It’s also worth noting that theanine, a non-dietary amino acid, mimics some of the properties of glutamate and GABA. Green tea is one of the few natural source of theanine, and probably responsible for green tea’s reputation as a mood enhancer.

Amino Acids Benefit #5: Immune Strengthener

Nutritional deficiencies, stress, and environmental toxins can take a toll on our immune systems. Amino acid support can help keep our immune systems strong.

People with compromised immune systems tend to have low levels of the amino acid cysteine, which is a precursor of the master antioxidant glutathione. To efficiently and effectively increase your stores of this vital amino acid, select a balanced essential amino acid supplement that contains cysteine in the form of N-Acetyl-L-Cysteine (NAC).

Research consistently demonstrates that an increased intake of cysteine can fortify the immune system. According to one study published in The European Respiratory Journal, supplementing with cysteine significantly decreased flu symptoms in elderly patients.

Since cysteine is produced from the essential amino acid methionine, it’s also possible to use methionine supplementation to achieve similar effects while promoting the production of proteins involved in the immune response.

Lysine is another amino acid noted for its antiviral and immune-boosting properties. It is traditionally recommended as a preventative nutraceutical for flare-ups of the herpes virus and shingles.

If only one piece of information from this article stays with you, I hope that it is this: in order to benefit from the properties of any individual amino acid, it is vital that you supply your body with an appropriate quantity of all the essential amino acids. That’s why research consistently shows that the most reliable way to access the health benefits of amino acids is by taking a carefully formulated essential amino acid supplement.

Can Amino Acids Cause Weight Gain?

Is it possible that amino acids cause weight gain? Let’s explore this question and see if we can find the answers you seek.

When you ingest amino acids—the building blocks of protein—your body uses them to make both enzymes and proteins as demands require. Any leftover amino acids then follow various metabolic pathways. Some are converted into glucose and used as energy. Others become glycogen and are stored in the liver and muscle tissue for future energy use. And still others are turned into fat and stored in fat cells. But is it possible that amino acids cause weight gain? Let’s explore this question and see if we can find the answers you seek.

Amino Acids Are Low in Calories

Amino acids contribute 4 calories for every gram of protein you consume. Which means if you take 4 grams of an amino acid supplement, you’re consuming only 16 calories. Moreover, beneficial effects of essential amino acid supplements have been demonstrated with doses less than 4 grams. So if you’re worried about the number of calories in your diet, you can choose to supplement with a simple 4-gram, 16-calorie dose.

You also get amino acids from the dietary protein you eat. However, the calorie load from dietary protein intake is significantly higher. For example, let’s say you choose to get your 4 grams of essential amino acids from a high-quality whole food source such as pasture-raised meat. In this case, you’ll be getting an extra 100 calories a day compared with the 16 calories you would be getting from the amino acid supplement.

However, when it comes to weight gain, it’s important to monitor the number of calories you’re ingesting and compare that to what your body needs. To determine how many calories you should eat each day based on your sex, height, and activity level, you can use this online calculator, which is based on the Mifflin-St Jeor equation for estimating calorie requirements.

Amino Acids for Fat Loss

Far from causing weight gain, amino acids can actually help boost the production of hormones that burn fat and promote weight loss. One such hormone is the growth hormone somatotropin (STH). STH activates protein synthesis—and therefore muscle building—as well as fat burning.

Studies show that obese and overweight individuals tend to have low concentrations of STH. However, certain amino acids have been shown to increase levels of STH, most notably arginine, methionine, and glutamine.

Moreover, a 2011 study published in The Journal of Nutrition that focused on middle-aged adults from East Asian and Western countries showed that individuals with a higher intake of branched-chain amino acids (BCAAs) have a lower prevalence of obesity and are not as overweight.

Researchers attributed this effect to the BCAA leucine—which can increase energy expenditure and thereby decrease both body weight and body fat—as well as the ability of BCAAs to lessen the effects of insulin resistance and improve glucose tolerance (the measure of how well your body processes blood sugar).

So Do Amino Acids Cause Weight Gain?

After examining the evidence, my answer to this question would have to be no. I don’t think amino acids will cause you to gain weight unless you eat too much protein—such as excessive amounts of animal protein or whey protein powders, protein shakes, or other types of protein supplements, which can be high in calories—and don’t burn off the excess amino acids.

However, I do think amino acids will help you maintain and even build muscle tissue. And this may cause moderate weight gain because muscle weighs more than fat. But that would still leave you with a better body composition, improved body mass index (BMI), and leaner, more toned figure. And who’s going to argue with that?

I don’t think amino acids cause weight gain, unless you are eating an ultra-high-protein diet and not burning off the excess amino acids. I do think amino acids are helping you maintain and build muscles, which may cause moderate weight gain, but a better body mass index (BMI) and leaner, more toned figure.

Dietary Protein or Amino Acid Supplements: Which Is Better?

Dietary proteins are the source of new amino acids for the body. The nutritional actions of dietary protein are in fact the actions of the absorbed amino acids. The question is, which is better—dietary protein or amino acid supplements? There are a number of factors to consider when answering this question.

Dietary proteins are the source of new amino acids for the body. The nutritional actions of dietary protein are in fact the actions of the absorbed amino acids.

The quality of a dietary protein, as scored by the system of the World Health Organization, is determined by the profile of amino acids in the protein and the extent to which those amino acids are absorbed.

When an amino acid supplement is consumed, digestion is not required. Rather, there is complete absorption of the ingested amino acids. The question is, which is better—dietary protein or amino acid supplements? There are a number of factors to consider when answering this question.

Dietary Proteins—the “Natural” Way to Obtain Amino Acids

There is a school of thought in the nutrition community that natural food sources are always better than supplements. However, the scientific basis for this perception is unclear. For example, individuals who have had large portions of their intestines removed surgically can live for many years on entirely artificial nutrition given intravenously.

The water is particularly muddied in the case of dietary protein vs. amino acid supplements. Amino acids are not only natural components of the diet (albeit in the form of protein), but essential amino acids (the nine amino acids that cannot be produced in the body), are the only macronutrients required for survival.

The nutritional purpose of dietary protein is to deliver amino acids to the body. Is there really a difference in how natural it is to ingest amino acids directly or in the context of dietary protein, even if it is as a “supplement”?

A further complication in distinguishing between the advantages of dietary protein or amino acid supplements arises when considering specific dietary supplements of protein, such as whey protein. Is whey protein a natural protein food source? While whey protein occurs in the same form as it does in nature, it is still a byproduct of milk, the original protein food source.

Clearly, when it comes to distinguishing between “natural” protein food sources and amino acid supplements, there is a lot of room for interpretation. Rather than worry if a nutritional supplement is natural, it is more relevant to consider whether there is a difference between the nutritional benefits of protein that occurs as part of a normal diet and the nutritional benefits of amino acids supplements.

Why Consume a Protein or Amino Acid Supplement?

Protein is a fundamental part of our diets, and optimal amino acid and protein nutrition starts with the protein component of our meals. However, in many circumstances the amount of protein in the regular diet is insufficient to obtain maximal benefit of amino acid intake. In some cases, this is due to limitations in the ability to consume adequate high-quality proteins in the diet.

It may be that living circumstances limit the availability of high-quality protein. College students living in dorms would be a good example of this. Maybe the taste of protein food sources isn’t pleasing, or you have difficulty chewing meat, two common problems in aging. Adherence to a vegetarian or vegan diet commonly results in insufficient intake of high-quality protein as well.

There are also circumstances that increase the optimal amount of dietary protein intake. Participation in a competitive sport is one example, and the natural aging process is another. Recovery from a serious injury/illness and wound repair are also circumstances that may increase the amount of dietary protein you should consume.

A mismatch between the optimal amount of dietary intake and the amount actually eaten can be addressed by taking a protein or amino acid supplement. A protein supplement may come as relatively pure preparations of protein. Whey protein isolate is a good example. Alternatively, protein may be a component of a more complete food product that also contains carbohydrates and fat. Protein bars or meal replacement beverages are examples of these sources of dietary protein that are meant to be supplements to the normal diet. Amino acid supplements may also come as part of a complete nutritional supplement containing fat and carbohydrate, but more commonly amino acid supplements are in pure form consumed either as a beverage or in capsules.

Nutritional Benefits of Protein and Amino Acid Supplements

Amino acids absorbed from a protein supplement perform a wide range of functions, including production of key chemicals that regulate a variety of physiological functions including immune function, regulation of blood flow, and production of brain neurotransmitters. However, the predominant role of amino acids is to stimulate the production of new proteins in the body, particularly in muscle. The value of protein supplements has therefore traditionally been evaluated in terms of the ability to stimulate the production of new muscle protein.

The extent to which a protein supplement can stimulate the production of new muscle protein is highly dependent on the specific protein and how much is consumed. Intact proteins are composed of essential amino acids (EAAs) and nonessential amino acids (NEAAs). High-quality proteins such as whey protein have close to 50% EAAs, while collagen protein has about 10% EAAs. The EAAs are the active components of dietary proteins. The NEAAs in protein have no impact on the production of new muscle protein. Consequently, the amount of EAAs in protein determines how well the protein stimulates muscle protein synthesis. Further, all the EAAs are required for a sustained stimulation of muscle protein production. Incomplete proteins, meaning proteins that have only some of the EAAs, are not effective.

What Protein Supplement Is Most Effective?

Whey protein has been shown to be the most effective protein supplement in terms of stimulating the production of new muscle protein. In general, plant-based proteins like pea protein are ineffective. Soy protein is the exception—it is the only plant-based protein classified as a high-quality protein. Nonetheless, whey protein is more effective than soy protein.

The response to whey protein is dose dependent to an extent, but progressively larger doses get less and less effective. Doses greater than 30 grams have little added benefit compared to lower doses.

Whey protein isolate in pure form has greater effectiveness than when it is contained in a meal replacement. In fact, meal replacement protein supplements often have little to no beneficial effect. The problem may be the added non-protein calories in the form of carbohydrates and fats, but it is more likely that low-quality proteins have been added to the whey protein in the formulation. Labels are required to list total protein content in a serving of the product but are not required to list how much of each protein of a mixture is contained in that serving. It is particularly common to add collagen, a very low-quality protein that is appealing because of its low cost and ease of mixing into an overall formulation. If you are going to use a protein supplement, be sure to check that it is composed of only whey protein if muscle protein synthesis is your goal. If it is a combination of proteins, be sure that they are all high-quality proteins.

Amino Acid Supplements

Amino acid supplements have many benefits. The profile of amino acids in the supplements is completely controlled, so only the active amino acids are included. Amino acid supplements are also fully and rapidly absorbed. The peak concentrations of EAAs reach a high level more quickly than when a similar amount of protein is consumed. As a result, a blend of EAAs may stimulate muscle protein synthesis three times as much or more than a similar amount of whey protein. A very small amount of EAAs (less than 4 grams) can effectively stimulate muscle protein synthesis.

While amino acid supplements, particularly those made with all the EAAs, have many advantages over protein supplements, there are a few disadvantages to amino acid supplements that do not also include a dietary protein component such as whey. Peak concentrations of amino acids are reached much quicker than when whey protein is consumed. The concentrations also drop away much quicker. Thus, the response to an amino acid supplement is not as sustained as the response that might occur with whey protein. Also, amino acids may be somewhat difficult to make into a palatable production, while proteins such as whey protein tend to be tastier.

Your Best Bet: Amino Acid/Protein Supplements

It is clear from the above discussion that both EAAs and protein supplements, particularly whey protein isolate, have benefits. But one is not necessarily better than the other, especially when they can be combined for maximum benefit.

The rapid, intense response to EAAs can be merged with whey protein to achieve a more sustained response in a flavorful product. There are some circumstances, such as before exercise, that the rapid absorption of the amino acids make aminos a preferable choice. But in other cases, such as after exercise, a combination of EAAs and whey protein capitalizes on the benefits of each.

In summary, both amino acids as well as high-quality proteins like whey protein can be helpful dietary supplements. A mixture of EAAs has many important advantages, but the rather short period of stimulation is a limitation in some circumstances that can be prolonged by the ingestion of whey protein isolate at the same time.

Should I Take Amino Acids Pre-Workout?

The before, during, or after debate on amino acids for working out can leave you utterly confused as to when you should take your amino acid supplement. I’ll cover the details, but the quick and easy answer to the question should I take amino acids pre-workout is yes!

The before, during, or after debate on amino acids for working out can leave you utterly confused as to when you should take your amino acid supplement. I’ll cover the details, but the quick and easy answer to the question should I take amino acids pre-workout is yes! An amino acid pre-workout powder can help support muscle building, reduce the breakdown of muscle, increase blood flow to the muscle during your workout, and help prevent fatigue and boost performance.

Why Amino Acids Make Ideal Pre-Workout Supplements

You’re taking your sports nutrition goals seriously. You load your plate with whole foods and make sure to prioritize quality protein at every meal. Maybe you’re even incorporating protein powder or other dietary supplements into your regimen. You commit to each training session. You should be seeing major muscle growth gains and yet, you seem to be stuck.

The problem may be that you’re ignoring just how essential a role the fittingly named essential amino acids play when it comes to increasing your muscle mass. No matter how much time you put into weight training, if you fail to provide your muscles with the raw materials they need to grow, you won’t see the results you’re craving.

Key Facts About Amino Acids

You may have heard amino acids described as the building blocks of protein. That’s not a bad description, but it doesn’t entirely do justice to the importance of amino acids.

Not only do amino acids provide structural integrity to protein, but they’re also vital to the synthesis and metabolism of proteins, enzymes, hormones, and neurotransmitters. They regulate the activity of numerous metabolic pathways. They contribute to cognitive function. In short, amino acids are involved in just about everything that occurs inside the human body.

There are 20 amino acids present in the human body. Nine of those are called essential amino acids because unlike the others, your body cannot synthesize them de novo—in plain English, they can’t be made from scratch. Instead, it’s essential that you supply your body with these amino acids via the food you eat or supplements you take.

Researchers have categorized six of the other amino acids as conditionally essential. Under most circumstances, your body can produce these amino acids, but when you’re under extreme duress, that ability becomes compromised.

The remaining four amino acids get grouped together as nonessential. In some instances, you’ll see people refer to 11 nonessential amino acids—when they do so, they’re simply lumping in the 7 conditionally essential amino acids listed above. Your body absolutely needs the nonessential amino acids, but it also has the ability to synthesize them, so it’s nonessential that you get them from your diet.

The easy answer to the question should I take amino acids pre-workout is yes! An amino acid pre-workout powder can help support muscle building and boost performance.

When it comes to using amino acid supplements to facilitate muscle growth and muscle recovery, all the key players can be found on that list of the nine essential amino acids. Here are some key facts about what each of these amino acids does inside your body.


The analgesic (pain-killing) and antidepressant properties of this amino acid typically spark the most excitement. It’s also a precursor to norepinephrine and dopamine, two of the feel-good brain chemicals. When it comes to sports nutrition, the primary benefit of phenylalanine is that due to its ability to raise norepinephrine and dopamine levels in your brain, it may lower your rate of perceived exertion during exercise, helping you stay in a positive headspace through even the most grueling endurance exercise workouts. Our bodies also need phenylalanine to produce metabolism-regulating thyroid hormones.


A true power player when it comes to muscle synthesis, valine is both an essential amino acid and a branched-chain amino acid (BCAA)—more on these later. One of valine’s main functions is preventing muscle breakdown. That means if you take valine prior to or during an exercise session, it can help decrease muscle damage, allowing you to recover faster. Valine also stimulates your central nervous systems and regulates blood sugar levels.


This amino acid helps keep your connective tissues and muscles strong and elastic, in part because it’s a precursor for two other amino acids: serine and glycine. The benefits of glycine have received a lot of attention from researchers lately. Studies show it can encourage muscle growth as well as decrease muscle loss, among other desirable effects. Threonine can also shorten the time it takes your body to heal wounds and recover from injuries. Plus, it supports healthy fat metabolism and stops fat from building up in the liver.


Another amino acid that serves as a precursor for a feel-good brain chemical—in this case, serotonin, which can help quell physical sensations of pain. That means boosting your tryptophan can increase your tolerance for pain during challenging workouts. The human body also needs tryptophan to manufacture vitamin B3, which ensures your blood sugar levels stay balanced, forestalls free radical damage, and stymies the accumulation of cholesterol.


Like valine, isoleucine is both an essential amino acid and a branched-chain amino acid. It’s a crucial component of hemoglobin, the protein in your red blood cells that transports oxygen. Our bodies also use isoleucine for muscle repair, which means upping your isoleucine levels lets you bounce back faster from taxing workout sessions.


The principal task of this amino acid is to assist your body with metabolizing fat. Plus, it provides your body with the sulfur it needs to produce glutathione, its most abundant antioxidant compound, as well as cysteine and taurine, two other amino acids that contain sulfur. Thanks to its lipotropic properties, methionine can safeguard your liver function by preventing the buildup of fats.


This amino acid, which has some antioxidant properties itself, is a precursor to histamine and helps your body synthesize carnosine. This can directly impact your physical performance because histamine can flush the potentially damaging free radicals generated during exercise from your system, while caronsine keeps lactic acid from accumulating in your muscles.


Along with valine and isoleucine, leucine is both an essential amino acid and a branched-chain amino acid. It’s the most abundant amino acid found in human muscle tissue. In addition to enhancing stamina and endurance as well as promoting muscle recovery, leucine initiates the process of protein synthesis and helps to maintain your body’s nitrogen balance and energy supplies.


Research indicates that lysine can simulate the release of growth hormone, meaning it can offer vital support to your muscle-building efforts. Lysine also ensures you body properly absorbs calcium. Plus, it demonstrates significant antiviral properties and encourages the production of antibodies, making it a phenomenal immune system booster.

Understanding Branched-Chain Amino Acids

Scientific analysis shows that 35% of your muscle protein is composed of three essential amino acids: valine, isoleucine, and leucine. These are, as you may have noticed if you’ve been paying close attention, the infamous branched-chain amino acids (BCAAs). These amino acids get their name from their molecular structures, which have distinctive, branch-like shapes.

The popularity of BCAA supplements with athletes skyrocketed based on studies indicating that they can help to reduce physical fatigue, sharpen mental focus, decrease muscle breakdown, preserve muscle glycogen stores, stimulate muscle protein synthesis, prevent muscle soreness, and more.

Leucine, found in high concentrations in whey protein, is arguably the most important BCAA. But as I mentioned earlier, simply increasing your intake of dietary protein or even adding a whey protein supplement is not the most effective way to benefit from leucine or other amino acids. When taken in supplement form, amino acids can be digested and absorbed more quickly, which maximizes their impact.

As I’ve discussed in previous articles, taking BCAA supplements is also not the most effective way to increase muscle concentrations of these beneficial compounds. There’s no question that BCAAs facilitate muscle growth and optimize athletic performance, but when you take them on their own, they have a minimal impact.

That’s because in order for your body to build complete proteins, it requires all the essential amino acids—and in their appropriate concentrations. Taking a supplement that contains only BCAAs throws off your amino acid balance. Taking an essential amino acid (EAA) supplement that contains the appropriate ratios of all the amino acids needed for protein synthesis is a far better way to amplify your muscle-building results.

When Should I Take My Amino Acids?

Now that you have an increased understanding of how amino acids prevent protein breakdown, facilitate healthy weight loss, improve recovery, and increase energy levels, among other benefits pertinent to those engaged in various physical pursuits, let’s discuss the optimal timing for taking an amino acid supplement.

One of the main reasons to take amino acids for fitness is to build muscle. When you exercise, muscle breaks down in order to release amino acids for the energy the muscles need to contract. Some of the released amino acids are used to rebuild the lost muscle protein. But many of the amino acids are oxidized and cannot be used for muscle protein synthesis. That’s where taking amino acids pre-workout comes in. They help replace the amino acids that are oxidized when your muscle protein breaks down as you exercise.

Taking an amino acid pre-workout powder before resistance exercise is especially important to maintaining and building muscle mass. During resistance exercise blood flows to the muscles at an increased rate. When you ingest amino acids pre-workout, there are more essential amino acids available to strengthen and build muscle.

Taking amino acids before a cardiovascular workout, such as a high-intensity interval training (HIIT class), can help reduce fatigue by balancing the uptake of amino acids that are responsible for the production of the neurotransmitters serotonin and dopamine in the brain.

That said, taking amino acids after a workout (within an hour after exercise) gives your body a boost when it comes to replacing damaged muscle fibers with new muscle protein. Essential amino acids are also important for reducing inflammation, thereby accelerating workout recovery.

To maximize all the beneficial effects of amino acids, it’s best to take a high-quality essential amino acid blend both before and after exercise. If you’re carrying out a resistance-training regimen, you may also see benefits from taking amino acids during your training sessions. This approach to amino acid supplementation is optimal for improving muscle strength as well as accelerating recovery.

Amino Acids for Heart Failure

Heart failure occurs when the heart muscle is not able to handle its workload. As the condition progresses, the heart just can’t pump enough blood through to meet the body’s blood and oxygen requirements. There is some evidence that shows amino acids for heart failure may help improve heart function, exercise tolerance, and possibly quality of life.

Heart failure isn’t the complete failure of the heart, although, as the name suggests, the heart is moving in that direction.

Essential Amino Acids for Heart Failure

There is strong evidence that people with heart failure lose mobility not only because the heart is not working as it should, but also because of a decline in muscle strength and function. Essential amino acid supplements have been shown to help improve muscle strength and function. The heart is a muscle, so it logically follows that an amino acid supplement formulated to promote muscle strength would also support heart muscle as well as skeletal muscle.

We know that essential amino acids may help offset hypercatabolic states like chronic heart failure. We also know that amino acid supplies are limited in heart failure patients, which leads to abnormalities in heart and skeletal muscle metabolism and eventual loss in heart function and quality of life.

Two studies come to mind in support of amino acid supplementation for heart failure.

The first is a pilot study published in the Mediterranean Journal of Nutrition and Metabolism in 2010 designed to see if an essential amino acid supplement improved quality of life, cardiac function, and exercise tolerance in 27 male patients with stable chronic heart failure. Patients took an amino acid supplement made up of the following amino acids (as well as t4 and vitamins B1 and B6) two times a day for three months.

  •      Leucine
  •      Lysine
  •      Isoleucine
  •      Valine
  •      Threonine
  •      Cysteine
  •      Histidine
  •      Phenylalanine
  •      Methionine
  •      Tryptophan

Researchers concluded: After 3 months, essential amino acid supplementation significantly improves cardiac function, quality of life, and exercise tolerance in stable chronic heart failure patients.

A separate study published in 2014 in Clinical Medical Insights: Cardiology investigated the effects of amino acid supplementation for three months in 13 male stable chronic heart failure patients. Researchers measured exercise tolerance with a cardiopulmonary stress test and six-minute walking test and evaluated quality of life with the Minnesota Living with Heart Failure Questionnaire. As with the aforementioned study, supplementation was safe and well tolerated with no adverse side effects. After three months of amino acid supplementation exercise tolerance improved. There was, however, no statistically significant gains in quality of life reported by patients.

As you can see, essential amino acid supplements show promise as a safe and natural way to help counteract and quite possibly prevent heart failure.

Heart failure occurs when the heart muscle is not able to handle its workload. As the condition progresses, the heart just can’t pump enough blood through to meet the body’s blood and oxygen requirements. There is some evidence that shows amino acids for heart failure may help improve heart function, exercise tolerance, and possibly quality of life.

Should You Take an Ornithine Supplement for Muscle Building?

Visit any bodybuilding forum on the web and you’ll see mention of ornithine and its athletic performance-enhancing and muscle-building benefits. But is an ornithine supplement the best amino acid supplement for muscle building?

Visit any bodybuilding forum on the web and you’ll see mention of ornithine and its athletic performance-enhancing and muscle-building benefits. This amino acid (also called: L-Ornithine, L-Ornithine HCl, L-Ornithine Hydrochloride, L-5-aminorvaline, L-2,5-diaminovaleric acid, and Ornithine HCl) is frequently promoted as a dietary supplement for stimulating muscle growth. But is an ornithine supplement the best amino acid supplement for muscle building?

5 Top Uses for Ornithine Supplements

While much of the excitement about ornithine has to do with its impact on muscle mass and athletic performance, scientists have found that this potent amino acid can affect your health in other ways as well.

Here’s further information on five of the top reasons people try ornithine supplementation:

  1. Anti-fatigue effects: Some evidence indicates that ornithine helps flush fatigue-inducing metabolites from your muscles and can relieve fatigue related to excess ammonia in the blood (common with chronic stress).
  2. Increased muscle mass: Studies show that ornithine supplementation can positively influence factors that stimulate the growth of muscle tissue, like testosterone and growth hormone levels.
  3. Boosted athletic performance: Because of its role in the urea cycle, ornithine can increase your capacity for physical exertion, allowing you to push yourself harder, for longer.
  4. Enhanced wound healing: Research shows that ornithine supplementation can substantially improve wound healing, largely due to the way ornithine influences collagen synthesis.
  5. Strengthened immune function: At least one study (which looked specifically at the use of ornithine alpha-ketoglutarate) has found that ornithine can improve your immune function.

How the Body Uses Ornithine

In order to understand the mechanics of L-ornithine supplementation, it’s important to have a grasp on the basics of how your body uses amino acids.

Amino acids, in technical terms, are simple organic compounds that link together to form protein. Our bodies need an adequate supply of amino acids to build muscle tissue and perform other vital functions. Because amino acids—including L-ornithine—are so essential to our overall health and well-being, they’ve earned the moniker: the building blocks of life.

A quick note about why you’ll sometimes see amino acids like ornithine referred to interchangeably as “L-ornithine” and “ornithine.” Amino acids can be in either a D configuration (like D-aspartic acid) or L configuration (like L-aspartate). However, since there really isn’t a “D-ornithine” in supplements, it’s common to see both terms used synonymously.

When we talk about amino acids, we tend to focus on the role they play in protein metabolism. But certain amino acids carry out different functions that are not directly linked to the synthesis or production of protein. These acids are categorized as non-proteinogenic amino acids or NPAAs.

Neither the proteins we eat nor the proteins our bodies make contain ornithine. Rather, ornithine functions in the liver as part of the urea cycle. In fact, the urea cycle is often called the ornithine cycle because ornithine is such an important component.

Understanding the Urea Cycle

The urea cycle is a biochemical reaction that converts ammonia to urea that the body can then excrete. This is an absolutely crucial detoxification process since excess ammonia, a waste product generated from cellular metabolism, can be toxic when blood concentration levels rise too high.

The urea cycle has four phases: 1) your liver produces urea, 2) your liver releases the urea into your bloodstream, 3) the urea travels to your kidneys, 4) your kidneys excrete the urea in your urine.

As part of the urea cycle, ornithine combines with ammonia to form the amino acid L-citrulline, or more simply, citrulline. Citrulline then combines with another ammonia molecule to form the amino acid L-arginine, which is more commonly referred to as (you guessed it) just plain arginine. From here, arginine is converted to ornithine, with urea as a byproduct—and we’re back to where the cycle started. Ornithine to citrulline to arginine to ornithine, and so on.

So, the urea cycle converts ammonia to nontoxic urea for excretion by the kidneys without disrupting amounts of the essential components: arginine, ornithine, and citrulline. In almost all circumstances other than liver failure, the cycle functions adequately to produce urea and prevent excess ammonia from entering the bloodstream. None of the amino acids involved in the urea cycle are essential amino acids, which must be taken in from the food you eat or from dietary supplements. Under normal conditions, the body produces sufficient amounts of these nonessential amino acids to effectively keep plasma ammonia levels in check and produce urea for elimination.

Why You Should Care About Your Nitric Oxide Levels

The idea behind ornithine supplementation (and prior to that, arginine supplementation), is that it can increase blood levels of nitric oxide, a desirable outcome for several reasons.

During the urea cycle, a small percent of arginine is not converted to ornithine but rather is converted to citrulline. Nitric oxide (NO) is the byproduct of this arginine to citrulline conversion. Testing has revealed that nitric oxide helps to regulate how much blood can pass through your blood vessels. When nitric oxide levels increase, the diameter of your blood vessels expands, a process known as vasodilation. Maximizing vasodilation during exercise can be highly beneficial since you want as much blood flowing to your muscle tissue as possible in order to bring in oxygen and nutrients and clear out waste products.

Nitric oxide also supports healthy sexual function in men.

Methods for Increasing Nitric Oxide Levels

As scientists began to appreciate the physiological importance of nitric oxide, they devised different approaches to promote its production.

1. Arginine Supplementation

One of the first methods they tried was arginine supplements, which have been used since the 1950s. In the early days, arginine supplements were considered to have nutraceutical properties, as they seemed to have more potent effects than would have been expected, but the precise mechanisms were not understood.

Subsequent studies showed that the benefit of arginine supplementation was due at least in part to the increased production of NO. Arginine was also found to have a direct stimulatory effect on muscle protein production by activating a key molecular factor inside the cell (mTOR). Finally, in large doses arginine was discovered to stimulate the release of growth hormone.

There are, however, two considerable problems with arginine supplementation. The first has to do with the cellular metabolism of arginine. After L-arginine is absorbed from the intestine it must pass through the liver before reaching the blood in the rest of the body. However, your liver cells very effectively take up and metabolize orally ingested arginine. As a result, consuming oral L-arginine has only a small effect on blood levels of arginine.

The second problem, which is related to the first, is that in order to elevate blood levels of arginine to the desired extent, you have to take doses that are so high they cause digestive distress in most people. Studies show that doses of arginine at 10 grams and higher can cause diarrhea as well as other unpleasant side effects.

2. Ornithine Supplementation

Given the problems with using dietary supplements of arginine, scientists started to explore alternate options for raising arginine levels in the blood with the ultimate goal of increasing nitric oxide production.

We’ve already seen how ornithine, citrulline, and arginine convert from one to the other via the urea cycle. Both amino acids are possible alternative approaches to arginine supplementation. The idea behind ornithine supplementation is to increase arginine by conversion in the urea cycle.

Research indicates that oral L-ornithine supplementation can have an anti-fatigue effect while improving measures of athletic performance including speed, strength, and power.

A study published in the Journal of Sports Medicine and Physical Fitness found that ornithine supplementation increased lean muscle mass as well as power output for weight lifters.

Separate findings from a study done with bodybuilders demonstrated that ornithine can increase growth hormone levels. Low-dose ornithine supplementation had no effect, but the highest dose (170 milligrams of ornithine hydrochloride) increased growth hormone concentrations to 318% above baseline. As with arginine, high doses of ornithine frequently cause digestive side effects.

The effects of ornithine on growth hormone appear to be short-lived. The desirable effects of raising growth hormone levels, such as increased lean muscle mass gains and fat loss, occur when you sustain elevated levels. This makes ornithine supplementation an ineffective method for pursuing those goals.

3. Citrulline Supplementation

Another reason taking an ornithine supplement may not be the most logical route to achieving goals like improved endurance and increased muscle mass is that the ornithine you take is converted to citrulline, which is then converted to arginine. So, ornithine is two metabolic steps away from arginine.

Keep in mind too that if your primary reason for trying arginine supplementation or ornithine supplementation is to build muscle and maximize your athletic performance, you need to increase nitric oxide production and stimulate muscle protein synthesis and muscle growth.

Citrulline is the optimal nutritional supplement to achieve this. Unlike arginine, the liver lets most of the absorbed citrulline pass through. Citrulline is largely converted to arginine in the kidneys, which release the arginine into the blood for circulation to the rest of the body, including muscle tissue. This explains the surprising fact that the blood level of arginine increases much more after consumption of citrulline than after the same amount of arginine.

The second aspect of citrulline that makes it a great way to increase arginine concentration is that citrulline consumption rarely causes gastric distress.

All in all, it appears that supplementing with citrulline is the most effective way to increase blood levels of arginine as well as ornithine, elevate production of nitric oxide, and reap the benefits.

The Truth About Complementary Proteins

Combine two incomplete proteins together and you have a complementary protein that contains a sufficient amount of essential amino acids. Or does it? Just because two proteins are complementary doesn’t necessarily mean that the combination becomes a high-quality protein.

First, let’s get some protein terminology under our belts.

Proteins are made up of amino acids. There are 20 dietary amino acids that may be components of protein. Each protein has a distinct number of amino acids and a specific sequence in which they are linked together. Nine of these aminos your body cannot make on its own. These are called essential amino acids, and you need to get them from the protein you eat or the essential amino acid supplement you take.

A normal diet includes a variety of protein food sources. Some protein foods are considered complete proteins, which contain all the essential amino acids the body needs…and other protein foods are considered incomplete proteins, which have low amounts of just some of the essential amino acids.

amino acid nutrition

Combine two incomplete proteins together and you have a complementary protein that contains a sufficient amount of essential amino acids. Or does it?

There are many websites that provide “examples” of complementary proteins:

  • Legumes with grains, nuts, seeds, or dairy
  • Beans and rice
  • Peanut butter sandwich
  • Yogurt with nuts

However, a big cautionary note about complementary plant-based protein foods is warranted. Let’s take the example of red beans and rice, which is often cited as a good example of complementary proteins. While neither is a high-quality protein food source, together they provide a balanced mixture of essential amino acids, in theory. Beans are deficient in methionine. Grains generally are relatively high in methionine, so the combination of beans and rice provide at least some of all the essential amino acids. However, just because two proteins are complementary doesn’t necessarily mean that the combination becomes a high-quality protein.

The Incomplete Nature of Complementary Proteins

The notion that the combination of a grain and a legume provide a complete protein is widely promoted on vegetarian websites. Take the example of the peanut butter sandwich. Technically a peanut butter sandwich provides a complete mixture of all the essential amino acids, because the combo of peanut and wheat protein provide at least some of all the essential aminos. However, the quality of peanut protein is low, and the quality of wheat protein is even lower. A peanut butter sandwich also has low protein density, which means the protein calories are fewer than the non-protein calories. The caloric intake required to consume sufficient peanut butter to meet all of your essential amino requirements exceeds the total caloric requirement for the day. The bottom line is that although peanut and wheat proteins are technically complementary proteins, a peanut butter sandwich is still a very low-quality protein food source.

Complementary proteins must have truly complementary profiles of essential amino acids. Unfortunately, the quality of most plant-based proteins is limited by the availability of lysine. Therefore, it is unlikely that two plant-based proteins will be complementary. This can become a real challenge to vegetarian diets and vegan diets that don’t allow for dairy. In contrast to the difficulty of finding complementary plant-based proteins that result in a high-quality protein source of essential amino acids, a typical omnivore diet that combines animal protein and plant-based protein foods can be quite effective. Most plant-based proteins are limited by lysine and animal-based proteins are generally high in lysine. The abundant lysine in the animal protein can improve the quality of the plant-based protein.

A practical alternative to combining animal and plant-based proteins to enhance protein quality is to incorporate essential amino acid supplements into the diet. Amino acid supplements can address any imbalance in the essential amino acid profiles of dietary protein. Furthermore, since an essential amino acid supplement has minimal non-protein components, the protein density of the meal will be greatly increased by consuming essential amino acids with dietary proteins. Adding an essential amino acid supplement to vegetarian and vegan diets is particularly appealing, as it will greatly improve the ratio of essential amino acids to nonessential amino acids in the diet without contributing much to the total caloric intake. And you won’t need to put as much thought into matching the “right” protein foods to make high-quality complementary proteins!