Soy Protein Amino Acid Profile

The following graph shows a typical soy protein amino acid profile. There’s a little asterisk next to the names of essential amino acids.

(Data Source)

This graph was made with our amino acid profile comparison tool.

It might be easier to read in table form. Essential amino acids are again marked with an asterisk (*).

  % of total amino acids
Alanine 4.5
Arginine 6.1
Aspartic Acid 13.1
Cystine 1.9
Glutamic Acid 18.6
Glycine 4.5
Histidine* 4.7
Isoleucine* 2.8
Leucine* 6.8
Lysine* 8.7
Methionine* 2.6
Phenylalanine* 4.5
Proline 4.2
Serine 6.8
Threonine* 2.3
Tryptophan* 0.2
Tyrosine 4.7
Valine* 3

Overall Summary of Soy Protein’s Amino Acid Profile

There are a few points of note in the data above.

First, soy has very low levels of tryptophan, which is an essential amino acid. That’s why you wouldn’t want a 100% soy diet. But as long as you have other protein sources, it’s not a big deal. For example, pea protein's amino acid profile is relatively high in tryptophan.

Secondly, soy has relatively high levels of a different essential acid - histidine. It has a relatively higher percentage than even whey does.

Overall, soy is a complete protein source with a well balanced amino acid profile.