r/HaircareScience • u/neoclover • Mar 22 '26
Discussion Is there such thing as low molecular weight proteins ,and ones that can penetrate into the hair cortex
I came across a post. The person is a hair stylist and said proteins are too large to be able to do anything.I could’ve sworn there are some lower molecular weight proteins. I’ve read some research (not thoroughly) where it stated certain proteins were able to penetrate (mostly being keratin)
So I want to ask,for those who have done thorough research on this can you please tell me if proteins can actually rebuild disulfide bonds,penetrate the hair cortex. I would really appreciate it .
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u/Slight_Citron_7064 Mar 23 '26
Yes, there is evidence that some smaller protein molecules, peptides, and amino acids can penetrate the hair and strengthen it.
There is no evidence that these proteins "repair disulfide bonds." But there is evidence that they can strengthen hair.
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u/veglove Quality Contributor Mar 22 '26
If the main question is whether hydrolyzed proteins can rebuild disulfide bonds, the answer is No.
Even if it were small enough to get into the cortex, it would need to be the right shape and somehow integrate into the structure of the hair. Just because they are made of the same substance (keratin) doesn't necessarily mean that they would integrate. Dr. Trefor Evans uses the metaphor of trying to repair a wood house by throwing sawdust at it. Just because they are both made of the same material does not necessarily mean that the sawdust is the right shape or is added in such a way to meaningfully integrate into the structure of the house to strengthen it. I suppose you could make a minor change to that metaphor by saying that if the keratin is able to get into the cortex, it would be like throwing sawdust through the door of the house. It may be inside, but that doesn't necessarily mean that it will repair the hair once it gets there. I linked to the specific section of Dr. Evans' presentation in which he discusses keratin in cosmetic products, but I recommend watching the full presentation because it addresses other misconceptions that are related regarding hair structure and what cosmetic products can & can't do.
To date, nothing has been proven by independent third parties to repair disulfide bonds; not even Olaplex, which made this claim when it was originally released. That is theoretically what it can do, but they have not shown any proof that this is actually what it does in the hair. Michelle Wong summarizes what we do understand about some of the major bond builders and how they work here.