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Summary
For 50 years, you've been told to combine rice and lentils to get complete proteins; I think I've heard that hundreds of times in 34 years of plant-based eating. This rule, born from a scientific error in 1971, completely ignores algae – true complete plant proteins. Discover why spirulina and chlorella make this chore obsolete.
If you are vegetarian, vegan, or simply concerned about your protein intake, you have certainly heard this advice a thousand times: "Don't forget to combine rice and lentils!" This injunction, repeated by dietitians for decades, is based on a persistent myth. Modern science has long demonstrated its futility, and more importantly, it completely overlooks a much simpler solution: microalgae.
Spirulina contains 60 to 70% complete proteins with the 8 essential amino acids, a digestibility of 83 to 90%, and zero antinutrients (Soni and others, 2017). Why has no one told you about it? This is what we will explore together.
The myth of rice-lentil complementation finally deconstructed
Frances Moore Lappé's mistake in 1971
The history of protein complementation begins with a well-intentioned book. In 1971, Frances Moore Lappé published Diet for a Small Planet, a book that would become a global bestseller with over 3 million copies sold (Lappé, 1971). Its goal was noble: to demonstrate that humanity could feed itself without heavily relying on livestock farming, which is responsible for a considerable waste of resources.
Lappé, a sociologist by training and not a nutritionist, argued that plant proteins were "incomplete" and that it was imperative to combine them in the same meal to obtain all the essential amino acids. She offered complex charts indicating the exact proportions of grains and legumes to combine.
The problem? This theory was not based on any solid scientific data.
What science really says about essential amino acids
Ten years later, in the anniversary edition of her book in 1981, Frances Moore Lappé herself publicly retracted:
"In 1971, I emphasized the complementarity of proteins because I assumed that the only way to get enough protein was to create a protein as usable by the body as animal protein. In fighting the myth that meat is the only way to obtain high-quality protein, I reinforced another myth.". I gave the impression that one must be very careful in choosing foods to get enough protein without meat. In reality, it's much easier than I thought. "(Lappé, 1981)"
The research by Vernon Young and Peter Pellett, published in the 1990s, definitively debunked this myth (Young & Pellett, 1994). Their work demonstrates that 24-hour complementation is more than sufficient: our body stores amino acids and uses them as needed. No urgent need to ingest them simultaneously.
The Academy of Nutrition and Dietetics (formerly the American Dietetic Association) officially confirmed this position in 2016: " Plant proteins can meet protein needs when a variety of plant foods are consumed throughout the day. It is not necessary to combine specific foods at the same meal. " (Melina and others, 2016)
Why does this myth persist even today?
Despite these retractions and scientific evidence, the myth of mandatory complementation at the same meal persists. Why ?
First, nutritional recommendations evolve slowly. Health professionals trained in the 1970s-1990s often retain this outdated information. Then, the food industry has no interest in simplifying the message: worried consumers buy more enriched products. Finally, repeating a mistake a hundred times does not turn it into truth, but gives it the appearance of truth.
The good news? Not only is complementing at the same meal unnecessary, but there are naturally complete plant-based sources that make this issue completely obsolete.
Comparison: Algae Dominate the Realm of Plant-Based Proteins
Spirulina: 60-70% complete proteins
SpirulinaArthrospira platensis) is a cyanobacterium often called "blue-green algae" that fascinates scientists around the world. And for good reason: with 60 to 70% protein on a dry matter basis, it far surpasses all other plant sources (Soni and others, 2017).
What makes it exceptional is the quality of these proteins. The study by Tessier and collaborators (2021) measured a PDCAAS score (Protein Digestibility Corrected Amino Acid Score) of 84% for spirulina, with a chemical score of 0.98 and a nitrogen digestibility of 90%. In comparison, lentils have a PDCAAS of about 50-60% and rice around 75% – but with only 7% protein.
The FAO (Food and Agriculture Organization of the United Nations) describes spirulina as a "highly digestible protein product," and UNESCO considers it "the food of the future" (FAO, 2008). NASA uses it as a dietary supplement for its astronauts due to its exceptional nutritional density (Momin). and others, 2023).
Authorized health claim (Regulation EU 1924/2006) : Proteins contribute to the maintenance of muscle mass and the maintenance of normal bone structure.
Chlorella: 55% protein + unique growth factor
ChlorellaChlorella vulgaris) is a green microalga that contains 50 to 60% protein and also includes all essential amino acids (Becker, 2007). Its distinctive advantage lies in its "growth factor" (CGF – Chlorella Growth Factor), a complex of nucleotides, peptides, and polysaccharides.
Wang et al. (2020) demonstrated that cell wall-lysed chlorella (mechanically opened) reaches a PDCAAS from 77 to 81%, compared to 63-64% for untreated chlorella. That is why at Biovie, we exclusively offer Organic chlorella with lysed cell wall : the mechanical opening of the walls allows for optimal assimilation of proteins and nutrients.
Authorized health claim Proteins help increase muscle mass.
Nori, dulse, wakame: the trio of seaweeds
Edible seaweeds complete this overview of complete plant proteins. Although their protein content is lower than that of microalgae (15-35% depending on the species), they provide all essential amino acids as well as a remarkable mineral profile (Holdt & Kraan, 2011).
Nutritional characteristics of seaweed:
- Nori : 30-35% protein, rich in iodine and vitamin B12
- Dulse : 20-25% protein, exceptional source of iron
- Wakame : 15-20% protein, rich in fucoxanthin and calcium
To discover all the nutritional benefits of seaweed, check out our comprehensive guide. Seaweed and microalgae: benefits, nutrients, recipes, and uses.
Legumes vs. Algae: The Amino Acid Matchup
Comparison of plant-based protein sources (scientific data) with the true scientific digestibility scores PDCAAS: Protein Digestibility Corrected Amino Acid Score:
- Spirulina : 60-70% protein, 8/8 essential amino acids ✓, PDCAAS 84% (Tessier and others, 2021), digestibility 83-90%, no antinutrient
- Lysed chlorella (Lysée: the one we propose, of course): 55-60% protein, 8/8 essential amino acids ✓, PDCAAS 77-81% (Wang and others, 2020), digestibility 75-85%, no antinutrient
- Lentils : 25% protein, 7/8 amino acids (deficient in methionine), PDCAAS 50-60%, digestibility 50-60%, high antinutrients
- Chickpeas : 19% protein, 7/8 amino acids (deficient in methionine), PDCAAS 52%, digestibility 55-65%, high antinutrients
- Rice : 7% protein, 6/8 amino acids (deficient in lysine), PDCAAS 56%, digestibility 75%, moderate antinutrients
- Beef (reference) : 26% protein, 8/8 essential amino acids ✓, PDCAAS 92%, digestibility 94%, no antinutrients
Sources: FAO/WHO (1991), USDA, Tessier et al. (2021), Wang et al. (2020)
The conclusion is clear: microalgae are at the top of the list of plant-based protein sources, both in terms of quantity and quality.
List of complete plant proteins (without combination)
Microalgae: Spirulina and Chlorella
Microalgae represent the top category of complete plant proteins. Their amino acid profile is naturally balanced, requiring no combination.
Spirulina is distinguished by:
- 60-70% highly digestible proteins
- All 8 essential amino acids present
- Absence of a cellulose wall (unlike plants), facilitating digestion (Lafarga and others, 2020)
- Rich in phycocyanin, a powerful antioxidant
Chlorella provides in addition:
- 55-60% complete proteins
- The unique growth factor CGF
- Support for the body's natural elimination functions, as demonstrated by the studies of Ryu and collaborators (2014)
For an optimal plant protein regimen, discover our Ecocert certified organic spirulina.
Edible seaweeds
Seaweeds (nori, dulse, wakame, kombu, sea lettuce) are complete plant proteins, although less concentrated than microalgae. Their advantage lies in their culinary versatility and their richness in marine minerals (Holdt & Kraan, 2011).
Other complete sources: quinoa, buckwheat, soy
Apart from algae, a few terrestrial plants have a complete profile of essential amino acids:
- Quinoa : 14-16% protein, PDCAAS of 89% (FAO/WHO, 1991)
- Buckwheat : 13-15% protein, balanced profile
- Soybean : 36-38% protein, high PDCAAS but presence of antinutrients
These sources nevertheless remain well below microalgae in terms of protein concentration and bioavailability.
Comparative Digestibility: The Decisive Advantage of Algae
Digestibility is the criterion often overlooked in the evaluation of proteins. A poorly digested protein, even if complete, does not contribute much to the body.
Spirulina has a major structural advantage: its cell wall is made up of mucopolysaccharides that are easily degradable by our digestive enzymes, unlike the cellulose of typical plant cell walls (Lafarga). and others, The study by Devi and collaborators (2018) measured an average amino acid digestibility of spirulina at 85.2%.
For chlorella, the treatment by cell wall lysis (mechanical grinding) significantly increases digestibility: from 35% to over 70% according to studies (Van De Walle). and others, 2025). This is why the transformation of chlorella is crucial to fully reap its benefits.
Antinutrients: The Hidden Problem of Legumes
Phytic acid and lectins: impact on protein absorption
Legumes are often presented as excellent sources of plant-based proteins. What is generally omitted is that they contain compounds called Antinutrients which significantly reduce the absorption of nutrients.
Thephytic acid (or phytate) is the main antinutrient found in legumes, cereals, and seeds. The study by Shi and collaborators (2018) measured phytic acid contents ranging from 8.55 to 22.85 mg/g in Canadian legumes. This compound chelates (traps) essential minerals such as iron, zinc, calcium, and magnesium, making them unavailable for intestinal absorption (Schlemmer). and others, 2009).
The Lectins are proteins found in legumes that can interfere with nutrient absorption and cause digestive issues in some sensitive individuals (Peumans & Van Damme, 1995). Soybeans contain the highest levels (692.8 HU/mg), followed by beans (87-88 HU/mg) according to the study by Shi. and others (2018).
The impact on protein absorption is measurable: legumes have a protein digestibility of only 50-60%, partly due to these antinutrients (Gilani). and others, 2012).
Germination and soaking: partial solutions
Traditional techniques allow for the reduction of antinutrients in legumes:
- Soaking : reduces lectins by 0.11 to 5.18% and oxalates by 17 to 52%, but has no impact on phytic acid (Shi and others, 2018)
- Cooking : more effective at degrading lectins and trypsin inhibitors
- Germination : can reduce phytic acid by 50 to 75%
- Fermentation : combined with other methods, can reduce phytates by up to 98% (Samtiya and others, 2020)
These techniques are useful but partial. They require time, preparation, and never completely eliminate antinutrients.
Why don't algae have this problem?
Microalgae such as spirulina and chlorella simply do not contain these antinutrients (Soni and others, 2017). Here is why:
- Absence of phytic acid : algae do not need to store phosphorus in this form, unlike terrestrial seeds
- No problematic lectins : their different metabolism does not produce these defense proteins
- No trypsin inhibitors : their enzymatic system is compatible with our digestion
This absence of antinutrients partly explains the superior digestibility of algae proteins compared to legumes.
To understand the principles of an optimized diet, consult our article. What is a bioactive diet ?
How to incorporate seaweed into your diet
Recommended dosages (3 to 5 g/day)
The integration of microalgae into daily nutrition is simple and gradual. Scientific recommendations suggest (Jung and others, 2019):
- Spirulina : 3 to 5 g per day for an adult, which is about 1 teaspoon
- Chlorella : 2 to 3 g per day, with a gradual increase
- Seaweed : regular culinary use (a few grams per dish), start with the ready-to-eat seaweed tartare that you can then produce yourself at home by 3 kilos as I have been doing for 25 years, and it is very economical.
To start, begin with 1 g for a week, then gradually increase to the optimal dosage. This approach allows your body to adapt.
Authorized health claim Proteins contribute to the maintenance of muscle mass.
Simple recipes: smoothies, salads, pesto
Morning protein smoothie :
- 1 banana
- 200 ml of plant-based milk
- 1 teaspoon of spirulina
- 1 tablespoon of hemp seeds
- Option: 1 spoonful of almond butter
Seaweed pesto :
- 50 g of fresh basil
- 30 g of pine nuts
- 1 teaspoon of spirulina or dulse flakes
- 3 tablespoons of olive oil
- 1 clove of garlic
- Salt, pepper
For more creative ideas, check out our guide. How to consume spirulina: 6 uses.
Which algae to choose according to your goals
Recommendations by objective:
- Increase protein intake : Spirulina, 5 g/day
- Support the body's elimination functions : Chlorella, 3 g/day
- Iron intake : Spirulina + Dulse, 3 g + culinary use
- Iodine intake : Wakame or Kombu, moderate culinary use
- Overall well-being : Alternating spirulina/chlorella, 3 g/day each
If the taste of seaweed concerns you, our French fresh spirulina with a neutral taste offers an ideal solution for sensitive palates.
FAQ – Complete Plant Proteins
What are complete plant proteins ?
Complete plant proteins containing the 8 essential amino acids are: spirulina (60-70% protein), chlorella (55%), quinoa, buckwheat, and soy. Unlike legumes and cereals, these sources do not require any combination. Spirulina remains the champion with a PDCAAS of 84% and a digestibility of 83-90% (Tessier). and others, 2021).
Is it really necessary to combine rice and lentils ?
No, this rule is obsolete. It comes from the book. Diet for a Small Planet from 1971, which the author retracted in 1981 (Lappé, 1981). Modern studies confirm that 24-hour complementation is more than sufficient (Young & Pellett, 1994), and that algae like spirulina make this question irrelevant since they already contain all the essential amino acids.
Is spirulina a complete protein ?
Yes, spirulina is a complete plant protein. It contains all 8 essential amino acids in balanced proportions, with 60-70% protein and an exceptional digestibility of 83-90% (Soni). and others, 2017; Tessier and others, 2021). This is why it is considered a superfood by the FAO and UNESCO.
What is the best source of plant-based protein ?
Spirulina is objectively the best source of plant-based proteins: 60-70% complete proteins, all essential amino acids, 83-90% digestibility, and no antinutrients (Soni). and others, 2017). The Chlorella arrives in second place with 55% protein and unique properties.
Why are legumes not complete proteins ?
Legumes (lentils, chickpeas, beans) lack methionine, an essential amino acid. Additionally, they contain antinutrients (phytic acid, lectins) that reduce protein absorption by 30 to 50% (Shi and others, 2018; Gilani and others, 2012). Algae do not have these disadvantages.
Conclusion: Simplify your protein intake
For 50 years, the myth of protein complementation has unnecessarily complicated plant-based diets. Modern science frees us from this constraint: not only is complementation at the same meal unnecessary, but microalgae offer a naturally complete, concentrated solution without antinutrients.
With 1 spoonful of spirulina per day (5 g), you get about 3.5 g of highly digestible complete proteins – the protein equivalent of 15 g of red meat, but with an incomparably lower environmental footprint.
? Ready to simplify your protein intake ?
Discover our entire range of organic microalgae : spirulina, chlorella, and much more. Complete proteins, zero combination, 100% natural.
And to delve deeper into the world of seaweed, our award-winning book at the Gourmand World Cookbook Awards 2025, Algae in Everyday Life, offers you 40 recipes with 13 varieties of seaweed to incorporate these superfoods into your daily cooking.
A varied and balanced diet and a healthy lifestyle are important. Dietary supplements do not replace a varied and balanced diet.
Scientific bibliography
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- Devi, A., Suhaila, M., Lai, O.M., et al. (2018). Nutritional profile of Spirulina and its role in health management. Asian Journal of Clinical Nutrition, 10(1), 1-11.
- FAO (Food and Agriculture Organization of the United Nations). (2008). A review on culture, production and use of Spirulina as food for humans and feeds for domestic animals and fish. FAO Fisheries and Aquaculture Circular No. 1034. Rome: FAO.
- FAO/WHO. (1991). Protein quality evaluation: Report of the joint FAO/WHO expert consultation. FAO Food and Nutrition Paper, 51. Rome: Food and Agriculture Organization. https://www.fao.org/3/t0501e/t0501e00.htm
- Gilani, G.S., Xiao, C.W., & Cockell, K.A. (2012). Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality. British Journal of Nutrition, 108(S2), S315-S332. https://doi.org/10.1017/S0007114512002371
- Holdt, S.L., & Kraan, S. (2011). Bioactive compounds in seaweed: functional food applications and legislation. Journal of Applied Phycology, 23(3), 543-597. https://doi.org/10.1007/s10811-010-9632-5
- Jung, F., Krüger-Genge, A., Waldeck, P., & Küpper, J.H. (2019). Spirulina platensis, a super food? Journal of Cellular Biotechnology, 5(1), 43-54. https://doi.org/10.3233/JCB-189012
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- Lappé, F.M. (1971). Diet for a Small Planet. New York: Ballantine Books. ISBN: 978-0345321206.
- Lappé, F.M. (1981). Diet for a Small Planet (10th Anniversary Edition). New York: Ballantine Books. https://www.amazon.com/Diet-Small-Planet-Revised-Updated/dp/0593357779
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- Momin, A., Intikhab, A., Syed, H.H., & Abbas, K. (2023). Spirulina, an FDA-Approved Functional Food: Worth the Hype? Cell Biochemistry and Function, 41(3), 299-315. https://doi.org/10.1002/cbf.3792
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- Ryu, N.H., Lim, Y., Park, J.E., Kim, J., Kim, J.Y., Kwon, S.W., & Kwon, O. (2014). Impact of daily Chlorella consumption on serum lipid and carotenoid profiles in mildly hypercholesterolemic adults. Nutrition Journal, 13, 57. https://doi.org/10.1186/1475-2891-13-57
- Samtiya, M., Aluko, R.E., & Dhewa, T. (2020). Plant food anti-nutritional factors and their reduction strategies: an overview. Food Production, Processing and Nutrition, 2, 6. https://doi.org/10.1186/s43014-020-0020-5
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