The amino acid profile of any protein source will vary based on the sample use.
The table below is pulled from this study where researchers looked at 44 strains of soybeans throughout Arkansas. It shows the range of each essential amino acid, alongside the amino acid profiles of egg and milk protein.
In some cases the ranges are quite large, showing that there can be significant variation between beans grown in different places.
Is Soy a Complete Protein?
Let’s look at how the essential amino acids in soy stack up against the ideal distribution of a complete protein (from Wikipedia). Since the units above are in mg/g of protein, we can just divide by 10 to convert it to a percent.
|Complete Protein (min %)||Soy protein (%)|
Soy stacks up really well, it’s a balanced protein source.
There are some strains might be relatively low in certain essential amino acids. However, soy protein is still considered a complete protein since it has a sufficient amount of all essential amino acids.
Soybeans are one of the most nutritionally packed legumes there is. See my bean nutrition comparison for more detail.