Bioavailability of Plant-Based Proteins

Compared to animal-based proteins, plant proteins have reduced digestibility and bioavailability. But what does this really mean?

Even if the nutritional label shows that a product has a high amount of protein, it doesn’t mean we are able to digest and absorb all of it. But why is that? Aren‘t all proteins made of the same amino acids? Yes and no.

Plant-Based Proteins Have Different Amino Acid Sequences

Although all proteins are made of the same amino acids, their sequences and structure can be different. The structure of plant-based proteins is different from that of animal-based proteins. Plant-based proteins do not have a complete amino acid sequence like you would often find in animal-based proteins, but eating a range of different plant-based proteins across the day will provide a complete amino acid profile in your diet.

The different protein structures, along with antinutrient compounds, can actually decrease the amount of protein our digestive system absorbs from the food.² Although we cannot calculate exactly how many grams of protein we absorb per 100g of food, the best way to measure which protein sources are more nutritionally valuable is with the Protein Digestibility Corrected Amino Acid Score (PDCAAS).³

Best Plant-based Protein Sources

While vegan-vegetarian cuisine has improved greatly in look and taste in recent years, we should not forget that the protein yield of some of these meals is rather low.

That is not to say plant proteins are not valuable; it just means that soy, pea, peanut and seed proteins have very different protein profiles and should not be put in the same box. Legumes, especially soy, are the best plant sources of protein in terms of quantity, amino acid profile and bioavailability.

Plant-Based Protein Supplements Are Better Digested?

Soy protein isolates or other legume protein supplements actually have an improved digestibility that is very close to that of animal proteins. This is because these protein isolates receive a heat treatment that inactivates 80% of the compound, which decreases their digestion, making it just as bioavailable as casein (cow’s milk protein).³

So, for those who might need a higher protein intake, plant-based protein isolates would be viable supplements to consider.

Who should consider protein supplements?

1. The elderly are known to reduce their protein intake due to decreased appetite for these kinds of foods. This, accompanied by a decreased rate of muscle synthesis, puts them at risk of sarcopenia or muscle loss.⁴
2. Athletes who undergo strenuous physical exercise need a surplus of protein to repair muscle tissue.⁵ Plant-based proteins have a lower leucine content (which stimulates protein synthesis and inhibits protein degradation), so if you are an athlete on a plant-based diet, you should boost your protein intake to guarantee safe muscle recovery.

It’s important to remember that plant-based foods vary greatly in their protein value and digestibility. While some sources provide high quantities of readily available protein, you could be overestimating your daily protein intake if all you do is snack on some nuts and seeds here and there.

If you follow a plant-based diet and need more protein, you should focus on getting high-quality protein and even consider supplementation.