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Spirulina vs. Amino Acids: What’s the Best Protein Powder?

Spirulina powder high in protein

Spirulina, a cyanobacteria (blue-green algae) is a complete plant-based protein source that’s easily digested for maximum nutrient absorption. This superfood has even been singled out as the most nutritious food on the planet gram-for-gram. But does that mean it’s your best option for boosting your protein intake with supplementation? This article takes a look at the spirulina vs. amino acids debate. Keep reading to see the winner.

Why Supplement with Spirulina or Amino Acids?

Protein makes up 17% of our body weight (second only to water which makes up 62% of body weight). It plays a role in virtually every cellular process, produces enzymes and hormones, and builds our tissues, bones, and muscles. As the building block of life, protein is arguably the most important macronutrient for survival.

Unfortunately, many of us don’t get enough of it. Whether that’s due to dietary restrictions, such as eating a plant-based diet and excluding animal proteins, or because, as we grow older, our muscles become less responsive to protein and need more of it, it’s always a good idea to supplement with an additional source.

There are many dietary supplements to choose from...whey protein, pea protein, soy protein, hemp protein, and spirulina powders! But these dietary protein powders are being outperformed by amino acid powders. 

It all has to do with the makeup of protein. Protein is a string of amino acids linked together in a specific order. There are tens of thousands of different types of protein. The type of protein and its role in the body are determined by the order of its amino acids. 

When we eat dietary protein, such as meat or eggs, or ingest a dietary protein powder like whey or spirulina, the protein breaks apart into its individual amino acids, which travel throughout the body performing their distinct functions. Before protein can be used, it has to be digested and broken down into amino acids.

This is where amino acids have spirulina and other dietary protein supplements beat.

An amino acid powder delivers free amino acids that don’t need to be digested. They are ready for work immediately upon intake! 

Amino acid powders can also be formulated with an ideal ratio of amino acids for unique health needs. For instance, if you are supplementing with protein to help stimulate muscle growth, then you’ll want a leucine-enriched essential amino acid supplement. And if you’re supplementing to speed recovery after an injury or surgery, you’ll want an amino acid powder that also contains creatine and slow-acting whey protein. 

Click here for our recommendation of amino acid powders.

To summarize: When you’re looking to supplement your diet with a protein powder, what you really want to do is to boost your intake of amino acids that make up protein. It’s far more effective to go straight to the source and supplement with an amino acid powder that does not need to be digested and is immediately bioavailable.

The Protein Content of Spirulina

As an additional source of protein, spirulina is a good choice. It’s considered a complete protein, which means it contains all nine of the essential amino acids the body cannot manufacture on its own. There aren’t many plant-based proteins that have this distinction.

Let’s take a look at the essential amino acid profile of 1 tablespoon (7 grams) of dried spirulina seaweed (for reference, most scoops of spirulina powder are 3 grams). That’s 4 grams of protein and the following milligrams of essential amino acids:

Amino Acid Mg %RDI
Histidine 76 mg 11%
Isoleucine 225 mg 16%
Leucine 346 mg 13%
Lysine 212 mg 10%
Methionine 80 mg 11%
Phenylalanine 194 mg 22%
Threonine           208 mg 20%
Tryptophan    65 mg 23%
Valine 246 mg 14%


You also get a good mix of nonessential amino acids, which the body can make on its own:

Nonessential amino acids
Alanine 316 mg
Arginine 290 mg 
Aspartic 406 mg
Cysteine 46 mg
Methionine 178 mg
Glutamic Acid 217 mg
Proline 167 mg
Serine 210 mg
Tyrosine 181 mg


Although spirulina has low levels of lysine, histidine, and methionine, it still contains a balanced amino acid composition for human nutrition. The problem is, you’d have to eat a ton of it to meet your essential amino acid requirements. 

Spirulina also gets a thumbs up for protein digestibility. A recent study published in the American Journal of Clinical Nutrition showed that the average digestibility of essential amino acids in spirulina protein was 85.2% (1). Compare that percentage to the protein digestibility of egg (97-98%), soy (95-98%), and quinoa (91-92%).

Biological value (BV) measures how much protein in a food is absorbed for use by proteins in the body. Because spirulina’s membrane is able to be dissolved easily by gastric acids, spirulina scores a BV of 68% (not bad!), while whey protein has a BV of 104 and soy 74.

Protein Content of Spirulina

Health Benefits of Spirulina

When it comes to spirulina vs. amino acids, amino acids are the clear winner for best protein powder.

But spirulina is more than just protein. This microalgae is also a good source of vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), and vitamin B9 (folate), as well as minerals including iron, copper, magnesium, potassium, calcium, and manganese. (It does not, as some other health sites mention, contain vitamin B12.) Vitamin A, vitamin D, vitamin E, and vitamin K also make an appearance in spirulina.

Spirulina has a noteworthy fatty acid profile, with a 1.5:1 ratio of omega-6 to omega-3, including alpha-linolenic acid and linoleic acid. It is also one of the few foods to contain the essential fatty acid gamma linolenic acid (GLA), which acts as an anti-inflammatory to reduce swelling and contributes to brain, skin, and metabolic health. The only other food sources of GLA are evening primrose oil, blackcurrant oil, borage oil, and breast milk. 

Spirulina fights back against inflammation and bolsters immune system health with an antioxidant called phycocyanin. Noted for its antioxidant properties, spirulina helps protect against oxidative damage from free radicals. Other antioxidants in spirulina include the carotenoid beta-carotene, as well as 1% chlorophyll, the photosynthesis pigment.

Like it’s cousin chlorella, spirulina supports heart health by lowering blood pressure and lipids such as triglycerides and LDL cholesterol, while raising heart-healthy HDL cholesterol levels.

It even gets props for being an anti-cancer agent. Research shows that spirulina can help protect against oral cancer, specifically a form of precancerous lesion of the mouth called OSMF. 

Spirulina powder and capsules are generally recognized as safe, but side effects such as nausea, headaches, and insomnia can occur. 

Forage for your spirulina wisely. Species include Spirulina maxima (Arthrospira maxima), Spirulina platensis (Arthrospira platensis), and Spirulina fusiformis (Arthrospira fusiformis). It is important to buy spirulina from a trusted source as heavy metal contamination in spirulina supplements and products has been reported. Heavy metals can exacerbate autoimmune conditions and lead to other health problems.

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