There are a lot of blog posts, and now even AI tools, that claim protein is bad for low porosity hair.

There is no scientific evidence this is true.

If you avoid every product with protein in it, you will skip a lot of formulas that work REALLY well on low porosity hair. Saying “protein is bad for hair” is kind of like saying “food is bad.” There are many different proteins, and they behave very differently depending on their size, structure, and how they are processed and modified.

A lot of the internet panic comes from some ideas that sound scientific but really are not:

• “Protein overload”: the claim that using too much protein leads to stiffness, dryness, or breakage
• “Protein vs moisture balance”: the belief that protein and moisture fight each other and must be kept in perfect proportion

Neither of these shows up in actual peer-reviewed science.

In this post, I will walk through what the research and cosmetic chemists actually say about protein, porosity, and buildup. Every claim I make is backed by either peer-reviewed research or by cosmetic scientists.

Are you low porosity? Find out with our porosity quiz.

TLDR: Protein is not bad for low porosity hair, but it is not a magic nutrient you “need” either

There are thousands of different protein ingredients used in hair products and they do not all behave the same way. Treating them as one big “bad for low porosity” category guarantees you will miss out on products that might work very well for you.

Here is the short version:

• Low porosity hair does not benefit from protein treatments formulated for damaged hair, because by definition it is not highly damaged
• Some types of protein can build up on hair and this is often mistaken for "protein overload", this is most common in products that claim to add body to the hair.
• Your head probably is not 100 percent low porosity from root to tip, especially if your hair is long, so you might benefit from protein treatments on just the ends (though honestly bond repair products are probably a better option)

Bottom line: don't avoid products just because they have protein! There are lots of types of proteins and they all do different things!

What does “protein” in hair products actually mean?

“Protein” in hair products is confusing, because it's not like the protein in milk or protein powder.

What it usually means is protein derivatives: ^{[1] [2]}

• Hydrolyzed proteins The original protein (wheat, soy, collagen, keratin, etc.) is chopped into smaller fragments
• Peptides Short chains of amino acids from that original protein
• Amino acids The smallest building blocks

Your hair itself is made of keratin, a big, tough protein held together by peptide bonds ^[1]. So of course there is nothing inherently “toxic” about protein touching hair. The details matter: which protein, how small it has been chopped, how it is modified, and how much is in the formula.

People who say “protein is bad for low porosity hair” are usually talking about penetration. It is true that low porosity hair does not absorb ingredients into the hair shaft as easily as damaged high porosity hair. That includes proteins.

But protein has more than one job in haircare. Getting inside the hair is only one possible function.

What proteins actually do in hair products

Depending on their size and chemistry, protein derivatives can ^{[1] [3]}:

• Attract and hold water (they are humectants) for hydration
• Form thin films on the surface of the hair that change shine, slip, frizz, and volume
• Stick to damaged areas and help smooth or reinforce the surface
• Possibly add elasticity to damaged (high porosity) hair by penetrating the hair strand

To make them better at sticking to hair, cosmetic chemists also chemically modify proteins. For example: Quaternization, which is adding a positive charge so the protein is attracted to negatively charged hair and stays on the surface longer

This property is called substantivity: how well an ingredient hangs on through washes.

So when people say “protein causes buildup,” what they are really noticing is that some of these more substantive protein derivatives can form films that feel stiff or coated on certain hair types.

That is not about porosity or protein alone. It is about the specific ingredient and formula.

Perry Romanowski, also a cosmetic chemist and the Beauty Brains podcast co-host, points out that in most commercial products, proteins are used in very low concentrations. He mentions formulating with as little as 0.1 percent hydrolyzed protein in a VO5 "Extra Body" shampoo. He also emphasizes how difficult it is to get these proteins to actually stick to hair rather than wash off.

What is low porosity hair, really?

From a scientific perspective, low porosity hair usually means relatively undamaged, healthy hair.It still has all its built-in protective features:

• A hydrophobic lipid layer (a fatty coating) on the outside
• A hair cuticle made of overlapping shingles that lie fairly flat

Together, these help the fiber resist water moving in and out of the strand ^[4].

SEM (Scanning Electron Microscopy) image of a low porosity hair with tight cuticle scales (left) and a high porosity hair with loose cuticle scales (right)

As hair grows out and is exposed to everyday life (combing, brushing, sun, pollution), it gets more damaged. The fatty layer can erode. Cuticle scales can lift, crack, or chip away. If your hair is long, the ends are almost certainly more porous than the roots ^[5].

So even if your roots test as low porosity, you probably have a mix of porosities along the strand. I call this mixed porosity.

There is also the possibility that your hair is not low porosity at all. The symptoms of "protein overload" overlap with the characteristics of damaged (high porosity) hair.

High porosity hair is damaged hair. Common sources of damage include chemical treatments (perms, bleaching, etc.), heat styling, and environmental damage (pollution, UV exposure, etc.).

If you are not sure about your porosity you can take our quiz, or even better, get an analysis from a professional like Strandprint.

Why do people think protein is bad for low porosity hair?

Short answer: because a lot of people assume protein’s only job is to soak into hair and repair it from the inside.

If you start with that assumption, then the logic goes:

1. Low porosity hair does not absorb ingredients easily
2. Protein is only useful if it absorbs
3. Therefore, protein is “useless” at best and “buildup” at worst on low porosity hair

The problem is that this picture leaves out:

• Proteins that act mainly as surface conditioners or film formers
• The reality that many formulas use very low protein levels

On top of that, social media has turned “protein overload” into the catch-all explanation for every problem: frizz, tangles, dryness, breakage, you name it. If your hair looks weird, someone will yell “overload” in the comments.

In the actual scientific literature, there is no such diagnosis. What we do see are:

• Proteins binding more to damaged, high porosity hair than to low porosity hair ^[3]
• Some modified proteins with positive charges building up on hair surface over repeated use, like other conditioning polymers ^[6]

That is buildup, not a mysterious imbalance.

If you want the deep dive on this, I have a separate post on “protein overload” as a myth.

Does low porosity hair “need” protein?

So, is protein bad for low porosity hair? No.

Does low porosity hair need protein as some kind of essential nutrient? Also no.

Remember:

• Low porosity hair is, by definition, less damaged
• It still has its own natural barrier and structure
• That means it usually does not need heavy “repair” treatments to function

On the other hand, high porosity hair (bleached, relaxed, permed, repeatedly dyed, etc.) is missing more of its natural defenses. It loses internal protein more easily because it is damaged ^[3]. Some of these fibers can benefit from proteins that stick to damaged areas or help reinforce the structure.

Even then, there is no rule that says “you must use protein to fix this.” It is one tool among many. For example bond building products

If your hair is long, you probably have mixed porosity hair.

So you may end up liking some protein in products that live on your ends, while your roots are fine with very little.

This is why strict rules like “never use protein on low porosity hair” fall apart in real life.

Do you need to “balance” protein and moisture?

No. The whole “protein vs moisture balance” thing sounds scientific, but once you look at how these ingredients behave, it does not really make sense.

Here is why:

• Many protein derivatives also behave like humectants
• Humectants attract and hold water
• So protein often is a source of “moisture” ^[1]

You cannot really set protein on one side of a scale and “moisture” on the other when both are influencing how water moves in and out of the hair.

What does make sense is:

• Some hair needs more conditioning
• Some hair needs less conditioning

Low porosity hair already has built-in conditioning from its natural lipid layer. It is easier to over-condition. That does not mean protein is uniquely dangerous. It means any film-forming conditioning ingredient can build up if you overdo it.

That includes:

• Cationic surfactants
• Polyquaterniums
• Silicones
• Some modified proteins

There is a study on quaternized (positively charged) proteins that shows they can build up on hair over time, just like other conditioning polymers ^[6]. This is the closest thing in the literature to “protein overload.”

So when people describe:

• Hair feeling coated
• Stiff curls
• Styles that fall flat or feel rough

They are probably dealing with buildup from one or more conditioning ingredients, not a mystical protein-moisture see-saw. Again, I break this down more in my protein overload investigation.

Once you see protein as just one category of conditioners among many, it becomes much easier to predict what will work for you.

The worst protein products for low porosity hair

The main protein products you want to avoid if you have low porosity hair are protein repair treatments and deep conditioning masks that make big “repair” or “rebuild” claims and are meant for heavily damaged (high porosity) hair.

And you might be cautious about protein-heavy products that claim to add body because they can sometimes form stiff films, but not always. Again, it depends on the type of the protein and the formulation.

For example, Valerie George, on the Beauty Brains podcast, explains that some proteins, like wheat protein, can leave a stiff film on hair, especially on curly hair types. Others, like pea or soy proteins, are more flexible and tend to cause fewer issues ^[6]. She also warns that some protein treatments contain very high concentrations (like 5 percent), and says she would not recommend using something that strong if you're concerned about brittleness.

The best protein products for low porosity hair

In my opinion, what makes a protein product “good” or “bad” is not porosity alone. Strand thickness and curl pattern matter more.

For my own fine, wavy, low porosity hair, I like:

• Light, flexible protein systems that add a bit of structure without making my hair brittle or weighed down
• Formulas where protein is not the star, just one part of the conditioning system

For example, I tend to get along with:

• Silk protein like in water-based products like MopTop custard (one of my fav gels)
• Hydrolyzed Vegetable Protein PG-Propyl Silanetriol, a wheat-based protein fused with a silicone that is water-soluble and designed to reinforce the hair while still conditioning ^[7]

MopTop Curling Custard

This lightweight gel has silk protein and my low porosity hair loves it

CGM Approved

Sulfate FreeSilicone Free

Buy on Amazon

These give me a bit of extra “structure” without product buildup.

Also many "protein" products just don't have that much protein. One of my favorite leave-in conditioners is Pantene 10 in 1 Multitasking Leave in Conditioner Spray. It has keratin in it, but it's way down the ingredient and I doubt it has much impact on my hair.

Pantene Miracle Rescue 10 in 1 Multitasking Leave in Conditioner Spray

This product may have keratin in it and be formulated for high porosity hair, but it's light enough that it works great for my low porosity hair.

Buy on AmazonBuy on AmazonBuy at Kroger

This is why I focus less on porosity fear and more on “what does my hair actually do when I use this product?”

If you want help checking your products for protein types, you can always plug them into the CurlsBot Ingredient Analyzer.

Conclusion

There is no scientific evidence that protein is uniquely bad for low porosity hair.

What we do know:

• Low porosity hair is usually less damaged and does not need aggressive “repair” routines
• High porosity hair binds more protein and loses internal protein more readily, so it is the one more likely to respond to strong protein treatments ^[3]
• Some modified proteins can build up on the hair surface over time, just like other conditioning polymers, which can be a problem for low porosity hair ^[6]
• Most normal products use quite low levels of protein, often as part of a general conditioning system

So if you have low porosity hair:

• You do not need to avoid every product that mentions protein
• You probably can skip intense protein masks and treatments unless your hair is actually very damaged
• If you do end up with stiff buildup, clarifying is the solution and the top suspects would be products that claim to add "body"

Don't discount a product just because it has protein!

🧪 Want to explore further?

• 🧬 Try the CurlsBot Ingredient Analyzer to see if your product contains protein and what kind
• 🧴 Browse our Best Protein Products for Low Porosity Hair
• 🚫 Prefer to go protein-free? Check out our Best Protein-Free Products for Low Porosity Hair
• 📚 Or dig deeper in our Ingredient Listings for Proteins

Myths about protein and low porosity hair

About the Author

Melissa McEwen is the creator of CurlsBot. She is a software developer with training in science writing and a B.S. in Agricultural Science. Her writing has appeared in publications such as NPR and Quartz.