When to Use Amino Acids vs. Protein Powders, According to Dietitians

So, what's the difference between amino acids vs. protein supplements? We’ve spoken with two registered dietitians to help you understand what amino acid supplements are, their touted benefits, if they might be right for you, and if they should substitute your go-to protein powder.

What are amino acid supplements?

Amino acids are the building blocks of protein in the body. There are 20 amino acids in total and these are generally broken down into non-essential and essential amino acids. Non-essential amino acids can be created in the body whereas essential amino acids cannot, and thus, must be consumed.

The 11 non-essential amino acids include:

• Alanine
• Arginine
• Asparagine
• Aspartic acid
• Cysteine
• Glutamic acid
• Glutamine
• Glycine
• Proline
• Serine
• Tyrosine

The nine essential amino acids are:

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

“Amino acid supplements can either be individual amino acids, specific combinations, such as branched-chain amino acids (BCAAs), which include leucine, isoleucine, and valine, or a blend of several types like the essential amino acids,” says Sam Schleiger, RDN, functional dietitian, women's health specialist, and owner of Simply Nourished Functional Nutrition. Because of this, there are several amino acid supplement varieties available for purchase, each with a different intended purpose.

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When to use amino acids vs. protein powders

One of the major differences between amino acids vs. protein powders is how they’re digested and metabolized. “Amino acid supplements are usually free-form, meaning they don't need to be broken down by digestion before absorption, so they can enter the bloodstream quickly,” says Schleiger. Protein powders generally contain whole protein, i.e. long chains of amino acids that need to be digested and broken down into individual amino acids before absorption. This is an area where amino acid supplements can have a leg up, depending on the intended health benefits.

“Amino acids are also different from protein powders in that they can be more customized and targeted to specifically aid desired health results (more on this below),” says Lena Bakovic, RDN, registered dietitian at Top Nutrition Coaching. Certain amino acid supplements may be aimed at improving specific physiological functions, like gut health, for example. “Protein powders, on the other hand, are often used to add total protein to one’s diet, provide additional calories if weight management is a goal, or support athletic performance,” Bakovic adds.

However, there are instances where the two supplement varieties are intended for similar goals. For example, some amino acid supplements (like BCAAs) are aimed at supporting muscle growth, recovery, and overall health, just like many protein powders.

Benefits of amino acid supplements

Given that there are 20 different amino acids, it may not be surprising to discover that there are a range of health benefits associated with different amino acid-based supplements. Here are some areas of health these up-and-coming products can benefit the most (depending on formulation):

1. Immune function

When it comes to supporting the immune system, several amino acids can play a positive role. “Methionine and cysteine are sulfur-containing amino acids are involved in the production of glutathione, a powerful antioxidant that helps protect cells from oxidative stress and reduces inflammation,” says Schleiger, “taurine has anti-inflammatory properties¹ and supports the antioxidant defense system, protecting tissues from damage,” she adds. Glutamine can support immune cells² while arginine enhances nitric oxide production³, which promotes immune function through optimized blood flow.

2. Gut health

“Glutamine is also an amino acid which works to help strengthen, heal, and maintain the gut,” says Bakovic. This is accomplished through the amino acid’s ability to help maintain intestinal lining integrity and suppress pro-inflammatory signaling pathways⁴ in the gut. “Glycine plays a role in the synthesis of bile acids⁵, which are essential for fat digestion and overall digestive health,” Schleigher adds.

3. Heart health

Arginine’s ability to positively influence blood flow through nitric oxide production, not only aids in the immune response, but it can also help to lower blood pressure, a common risk factor for hypertension and certain heart diseases. “Citrulline works similarly to arginine by increasing nitric oxide levels⁶ and improving blood flow, which supports heart health,” Schleigher also shares.

4. Physical performance and muscle maintenance

“BCAAs are often utilized in sports nutrition, due to their important role in protein synthesis and athletic performance,” says Bakovic. This amino acid blend has also been linked to reduced muscle soreness⁷ and improved muscle recovery. Schleiger explains that glutamine⁸ can, too, support muscle recovery through preventing muscle breakdown during intense training⁹ or stress while also replenishing muscle glycogen stores. Meanwhile, “isolated leucine is an essential amino acid that plays a key role in muscle protein synthesis¹⁰, which can benefit the aging population,” Schleigher adds.

BCAA supplements or products featuring glutamine or leucine are often the amino acids supplements people are most likely to swap protein powder out for, if they use protein powder for performance and muscle health.

5. Skin, hair, and nail health

Collagen peptides are a buzzworthy amino acid-based supplement that is frequently turned to for skin, hair, and nail support¹¹ (as well as joint health¹²). However, Schleiger explains that cysteine is also involved in the production of keratin¹³, a protein that makes up hair, skin, and nails.

6. Mental health and sleep

“Phenylalanine and tyrosine aid in dopamine production, potentially resulting in positive effects on depression and mood,” says Bakovic. Whereas tryptophan is a precursor to serotonin¹⁴ which can help improve mood, enhance sleep quality, and reduce symptoms of depression. “Tyrosine can also help improve mental performance, especially in stressful situations or during prolonged periods of cognitive effort while glycine acts as an inhibitory neurotransmitter in the central nervous system, promoting relaxation and reducing symptoms of anxiety,” Schleiger adds.

7. Energy production

Finally, BCAAs, glutamine, and alanine can aid in energy production throughout the body. “BCAAs can be used directly by muscles for energy during prolonged exercise and are metabolized in muscle tissue, providing an immediate energy source, particularly when glycogen stores are low,” says Schleiger. Meanwhile, glutamine can support gluconeogenesis¹⁵ which releases glucose into the bloodstream, sustaining energy levels. Alanine can be taken up by the liver where it can then regenerate glucose¹⁶, contributing to our energy supply as well.

Taking amino acid supplements

Given the multitude of benefits amino acids can offer, several different types of people with varying goals could be interested in a specific amino acid supplement or blend for their needs. These could be athletes, aging individuals looking to maintain muscle mass, or those who want to support their digestive, immune, heart, mental, or skin health.

Amino acid supplements can be taken per product instructions, however, when you take them can be important depending on your goals. For example, if you’re taking an amino acid supplement to boost energy for exercise, you want to take it before your workout. Whereas if you’re looking for muscle recovery support after your workout, you’d take the supplement after you’ve finished. If you take tryptophan for sleep, ideally you’d take it before bedtime, while an essential amino acid blend or one aimed at improving gut or immune health can usually be taken in the morning with your other supplements.

However, your body naturally produces most of the amino acids that you need and ideally you’re consuming nine essentials through whole foods. If you take specific amino acid supplements above and beyond this, especially in high doses, it can potentially result in negative side effects for the immune system and other body systems according to a 2022 study¹⁷ published in Physiological Research.

It's also worth noting that while there’s plenty of evidence pointing to the exact physiologic processes of certain amino acids in the body, you’ll be hard-pressed to find any large-scale, peer reviewed research on the efficacy of specific amino acid-based supplements. Some brands do conduct independent studies of their products, but this doesn’t hold the same level of clinical significance.

To avoid taking a supplement you don’t need or an accidental excessive dose, speak with your healthcare provider prior to starting a new regimen. If that regimen is okayed by your doctor, choose a product that is verified by a third party like the U.S. Pharmacopeia or National Science Foundation as the Food and Drug Administration doesn’t regulate dietary supplements for purity, safety, or effectiveness.

The bottom line on amino acids vs. protein powder

Amino acids boast an impressive array of health benefits throughout the body. Many of these benefits can translate to high-quality amino acid supplements when taken appropriately. And while some of these perks can serve as a logical substitute for protein powder, the two products are generally not interchangeable. This is especially true given that there are several amino acid supplements of different formulations available. If you think you may benefit from taking an amino acid supplement, it’s crucial to first consult your healthcare provider or a registered dietitian, and then choose a product from a reputable, third-party verified brand.