noun
protein source; source of protein
Refers to foods or ingredients that provide protein.
大豆は優れたタンパク源です。
Soybeans are an excellent source of protein.
肉や魚以外のタンパク源を探している。
I'm looking for protein sources other than meat and fish.
タンパク質 means 'protein' as a substance, while タンパク源 means 'protein source'.
Compound of タンパク (protein) and 源 (source).