'protein-rich' is a compound adjective formed from 'protein' and 'rich'. 'Protein' originates from the Greek word 'prōteios', meaning 'primary' or 'of first importance'.

'Protein' was first coined in the early 19th century by the Dutch chemist Gerardus Johannes Mulder and the Swedish chemist Jöns Jacob Berzelius.

Initially, 'protein' referred to a class of nitrogenous organic compounds, and it still retains this meaning today.