Final answer:
Protein conditioners partially aid hair growth by strengthening hair and minimizing breakage, but they do not directly cause hair to grow.
Step-by-step explanation:
Protein conditioners can partially help with hair growth by improving hair strength and reducing breakage. The lack of protein in a diet can lead to weakened hair structure, because the body conserves available protein for critical functions, potentially leading to hair loss. Furthermore, protein deficiency can reduce the immune system's effectiveness and lead to energy loss, both of which can negatively impact hair health and growth. While protein conditioners may not directly cause hair to grow, they can provide the necessary building blocks that help maintain strong, healthy hair, which may reduce breakage and loss.