i haven't read all of the responses. but to answer your question, i believe so. when i was relaxed and even now as a natural my hair was/is protein sensitive. anything with any type of protein, would break my hair off. once i started paying attention to ingredients, and making sure to only use protein-free products, my hair thrived. occasionally i would forget and buy something that was recommended on here, use it, and my hair would be back to breaking, and i would read the ingredients and sure enough, protein was the culprit. to make things worse, my hair strands are fine. i just had to make sure to protective style, not manipulate too much, and make sure to only use protein free products.