How Digestible is Pea Protein?

Pea protein isolate is an increasingly common protein supplement due to its purported ease of digestion and high quality.

But how digestible is pea protein really?

Clinical Nutritionist & Researcher Cliff Harvey breaks down the science to explain.

Protein digestion and why it’s important

Digestion refers to the process of breaking down substances (from food) to forms that can be absorbed into the body for use. It is now commonly accepted that differences in protein sources are relatively minor and that the most important consideration is to consume (and absorb!) enough protein for optimal health and performance.

What can affect digestibility?

Antinutrients

Phytic acid

Phytic acid stores phosphorus in grains and legumes. Because humans lack the phytase enzyme to break this compound down, we cannot absorb the phosphorus from phytic acid¹. While phytic acid might aid some health conditions², it is also an antinutrient because it binds to proteins and essential minerals, inhibiting them from being absorbed.

Phytic acid can be reduced or eliminated by cooking, sprouting, and soaking³. As outlined below in Table 1, pea protein isolate is practically free-from phytic acid.

Saponins

Saponins are chemicals found in a wide variety of plants such as soybeans, chickpeas, peanuts and spinach⁴. Some saponins can also promote benefits to health^5–8, but they can act as antinutrients – affecting the digestion of protein and reducing the uptake of minerals from the gut⁷. Saponins are also effectively removed by cooking, processing⁵ and the isolation process of pea protein isolate.

Lectins

Lectins are a type of protein found in both animals and plants, as well as in many foods. They can have a range of health effects, both positive and negative^9–10, and the actions of some plant lectins can be toxic and act as antinutrients, reducing the ability of the body to properly absorb protein, carbohydrate and essential minerals. Plant lectins have been linked to anaemia, digestive issues, and protein and carbohydrate malabsorption and allergies^11–14. Lectins are also reduced or removed by cooking, sprouting, or isolation processes^12–13.

Table 1. Anti-nutrients in Pea Protein Isolate

Anti-nutritional Factors	Pea protein isolate	Pea (seed)	Soybean	Soy protein isolate
Trypsin inhibitor (TIA/g protein)	2.5	8.1	101	73.6
Lectins (HU/mg protein)	Approx. 0.2	37.1	3.2	0
Tannins (mg cat eq/g protein)	None detected	0.96	0.8	0.25
Phytic acid (mg/g protein)	1.2	101.1	89.6	62.7
Saponins (mg/100g)	1	2.5	6	9.04

Allergens and irritants

Common allergens include wheat, soy and dairy. Most commercial protein supplements are made from dairy proteins and these can cause digestive issues for some people.

The incidence of dairy allergies appears to be rising¹⁵, and while most people can tolerate dairy (and it can even be beneficial for health), it is an inflammatory food for those with underlying allergies to dairy proteins¹⁶, thus reducing dairy intake has been associated with improved outcomes for people with inflammatory conditions like asthma and inflammatory bowel diseases^17–19.

How digestible is pea protein isolate?

The digestion rate of pea protein isolate has been studied in comparison to a range of other protein. In one study, the in vitro digestion of pea protein isolate was shown to be around 90%, which is a similar digestion rate to whey protein (~89.8%)²⁰. In other studies, pea protein has also been shown to have absorption rates of over 89%²¹.

Pisane^®, the pea protein isolate used in Nuzest Clean Lean Protein, however, has been tested in comparative in vivolaboratory studies, and has been shown to have a 98% digestibility rating. Making it easier to digest than various milk proteins and fish, such as tuna.

Functional outcomes

The most important factor in choosing a protein is whether you can tolerate it AND whether it gets the job done. As discussed earlier, pea protein is both well digested and absorbed, and is also very well tolerated. It also performs equally well for muscle growth and retention. In an evaluation of pea protein isolate vs. whey protein, both protein types elicited nearly identical increases in muscle thickness when compared with placebo²².

Conclusion

Pea protein isolate is digested and absorbed easily and offers the benefits of being extremely low in antinutrients, allergens, and irritants while being at least as effective as other protein supplements for supporting the growth and repair of tissue and for the other benefits of protein such as satiety and reduced hunger.

It is for these reasons that Nuzest utilises pea protein isolate in their Clean Lean Protein range. Not only is pea protein isolate the superior protein choice in terms of its efficacy and allergen and antinutrient content, but it is also a sustainable protein choice which is why it is loved so much by people all around the world!