There are a lot of blog posts, and even AI tools, that claim protein is bad for low porosity hair. But here's the truth: there’s no scientific evidence to support that idea. In fact, the concept of "protein overload" in general isn’t supported by peer-reviewed research either.

In this post, I’ll walk you through what the science actually says about how low porosity hair interacts with protein. Every claim I make is backed by either peer-reviewed research or by cosmetic scientists.

What is Low Porosity Hair?

From a scientific perspective, low porosity hair refers to undamaged, healthy hair, so called "virgin" hair. This kind of hair has a full set of protective features, including a hydrophobic lipid layer and hair cuticle, made up of overlapping shingles, that help it resist moisture movement in and out of the strand ^[24].

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 damaged. The protective fatty layer can erode, and cuticle scales can lift, crack, or chip away. If your hair is long, the ends are almost certainly more porous than the roots ^[25].

When scientists study high porosity hair, they usually aren’t talking about hair damaged slightly by everyday combing and washing, they’re studying extremely damaged hair. This can mean hair that’s been bleached, relaxed, permed, dyed...or sometimes all of the above. In these cases, the cuticle may be partially or fully missing, exposing the inner layers of the strand. This makes the hair feel rough, frizz more easily, and become much more prone to breakage.

That context matters a lot. When you see a study comparing high and low porosity hair, the "high porosity" sample is often severely damaged. And the product testing in those studies? It’s usually done with protein concentrations far higher than what’s found in everyday products, applied under conditions that don't reflect real-world uses like extended soaking times, elevated heat, or chemical cuticle lifting.

This makes applying those findings directly to your everyday routine... tricky.

As cosmetic chemist Lab Muffin Beauty Science discusses in her video on cosmetic research quality, many published studies suffer from biased funding, poor design, or come from journals with questionable standards ^[26].

What Is Protein and Why Do We Use It in Haircare Products?

Proteins are the building blocks of life and you can extract them from everything from cows to wheat to fungi. Your hair is made of protein too! Specifically, it’s made of keratin, a tough, fibrous protein that gives hair its structure and strength. Technically, proteins are polymers made up of long chains of amino acids held together by peptide bonds ^[27]. I’m not just throwing science terms around for fun, this part will be important later. Just think of proteins as being big things (relatively) made up of small things.

Saying “protein is bad” for hair is kind of like saying “food is bad.” There are many types of proteins, and they behave very differently depending on their size, structure, and how they’re processed.

Proteins have been used in hair care products for a very long time. Early DIY treatments used things like egg, rice water, gelatin, or milk. But these proteins, in their natural state, are large and not especially effective at interacting with hair. They’re too big to penetrate the hair (absorb) and often too large to even form a good coating on the surface hair shaft (adsorb).

That changed with the invention of hydrolyzation, a process developed in the 1800s to break down proteins into smaller fragments like peptides and individual amino acids. These smaller molecules have a lower molecular weight, which means they’re more likely to bind to hair (adsorb), and possibly even enter the strand (absorb), though that’s still debated ^{[27] [28]}.

From there, cosmetic scientists developed new ways to make proteins stick to hair even better, a quality known as substantivity (how well something stays on the hair through 1+ washes). This is achieved by chemically modifying proteins—for example, by:

• Quaternization, which adds a positive charge so the protein binds more easily to negatively charged hair
• Combining proteins with other functional ingredients, like silicones
• Purifying individual amino acids for specific effects

Each of these modifications results in different properties, so saying “protein causes buildup” or “protein is too heavy” doesn’t make sense without knowing which protein, how much, and in what product.

So why go through all this trouble?

The Many Uses of Protein in Hair Products

Protein serves multiple useful roles in haircare:

• Acts as a humectant, an ingredient type that attracts and holds on to moisture (moisture retention)
• Forms films on the hair that improve shine, softness, and volume
• May strengthen or repair the hair surface by bonding to damaged areas or penetrating inside the hair to strengthen it from the inside out ^[27]

That last point, strengthening hair from the inside, is controversial. Some researchers believe hydrolyzed proteins may penetrate hair and improve internal structure, but others argue the effect is minimal or only happens under extreme conditions (like during chemical treatments that lift the cuticle). ^[29]

Some Examples of Proteins Used in Hair Products

Even one ingredient, like “hydrolyzed collagen”, can behave completely differently depending on how it’s processed. Here are a few examples that illustrate how much protein effects can vary and some sizes (in da, a unit of molecular weight called Daltons):

• Hydrolyzed Collagen (5000–15,000 Da): A film-forming humectant that adds shine, body, and manageability^[27]
• Hydrolyzed Collagen (2000 Da): Targets damaged areas to improve elasticity and strength ^[27]
• Hydrolyzed Elastin (2000–5000 Da): Less humectant than collagen—better in humid climates ^[27]
• Keratin: The same protein hair is made of; very large molecule (125,000+ Da) ^[27]
• Wheat Amino Acids: Very small; more likely to be substantive; used for moisture and softness ^[27]
• Taurine: A negatively charged amino acid that can enhance the function of other ingredients ^[27]
• Hydrolyzed Vegetable Protein PG-Propyl Silanetriol: Wheat protein fused with a silicone molecule, makes it both water-soluble and good at strengthening and conditioning ^[30]
• Hydrolyzed Milk Protein: Increases hydration and improves elasticity to reduce breakage ^[31]
• Hydrolyzed Tremella Fuciformis Polysaccharide: Sourced from mushrooms; huge molecule (1 million Da!); works as a strong humectant and film-former ^[30]

Is Protein Overload Real? What Scientific Experts Say

Yes... and no.

If you search for “protein overload” in scientific databases, you won’t find anything. It’s not a recognized term in peer-reviewed research. But we do know that some proteins can be substantive, meaning they can cling to the hair surface. And like any substantive ingredient (silicones, polyquats, conditioning agents) there’s always some risk of buildup over time.

There aren’t controlled studies on protein buildup in real-world use, but a few cosmetic chemists have spoken about it.

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 ^[32]. 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.

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” product. He also emphasizes how difficult it is to get these proteins to actually stick to hair rather than wash off.

Experiments have shown that protein binds more readily to high porosity or damaged hair ^[29]. In low porosity hair, the cuticle is smoother and more tightly packed, so proteins likely don’t stick well and rinse off more easily. If protein really caused stiffness or brittleness, it would logically affect high porosity hair more, not low porosity. But even that depends on the type of protein.

In Principles of Polymer Science and Technology in Cosmetics and Personal Care, cosmetic chemists Alessandro Teglia and Gianfranco Secchi note that the real concern with proteins is the potential for buildup. Like other conditioning agents, proteins can accumulate on the surface after repeated use ^[29]. This could lead to heaviness, rough texture, or stiffness. They recommend formulators use the lowest possible concentrations and test their products under real-world conditions.

So "protein overload" isn't a real concept, but protein product build-up is.

Is Protein Moisture Balance Real?

Here’s a weird twist: some researchers have found that hair feels better when it contains less water ^[33] . When hair holds more moisture, it can actually feel rougher or less manageable. Since protein is also a humectant, maybe it isn’t protein buildup causing the problem, it’s the extra moisture the protein attracts.

The “moisture-protein balance” idea floating around curly communities might be oversimplified. After all, protein often is moisture. But it's worth noting that many scientists believe products can only influence moisture content slightly, since hair tends to equilibrate with the surrounding air.

You may have seen blog posts claiming that protein creates a barrier that “blocks moisture” from entering the hair. But from a scientific standpoint, there is no evidence that any ingredient forms a true waterproof seal on hair.

More likely, if you’re experiencing roughness after using protein, you're dealing with a cracked or poorly formed protein film. This might feel dry or stiff, but it does not block water from entering the strand.

Negative charges repel each other, positive charges do too

Another potential factor is that some protein ingreedients are polar, meaning they have both positively and negatively charged parts. Hair is negatively charged, so when you coat it in polar molecules, strands may begin to repel each other slightly.

Some companies actually promote this as a benefit, saying it increases volume ^[34]. But depending on your hair type, it could also contribute to that unwanted “poofy” look.

The Bottom Line: There's No Evidence that Protein Is Worse for Low Porosity than High Porosity hair

There are so many different types of proteins, formulations, and concentrations that saying “protein is bad for low porosity hair” simply isn’t supported by science. There’s no study that shows protein harms low porosity hair more than high porosity hair. In fact, most research suggests proteins act primarily on the hair surface, regardless of porosity.

That said, if you’ve experienced dryness or roughness and want to minimize potential buildup or stiffness, here are some tips to experiment with your haircare routine more confidently:

✅ Tips for Avoiding Protein Buildup

• Avoid the most substantive protein types, especially those with added chemical modifications that help them stick to the hair. These ingredients often are more wordy than simpler protein ingredients like "hydrolyzed silk protein" or "hydrolyzed wheat protein":
  • Lauryldimonium hydroxypropyl hydrolyzed collagen
  • Cocodimonium hydroxypropyl hydrolyzed keratin
  • Hydroxypropyltrimonium hydrolyzed collagen
• Avoid protein in leave-in products (like leave-in conditioners, gels, mousses, or creams), where the protein stays on your hair instead of being rinsed out
• Try alternative proteins such as oat, soy, or pea, which tend to be more lightweight and less stiffening than wheat or collagen
• Use a stronger or clarifying shampoo occasionally if you suspect buildup
• Avoid high-percentage protein treatments (typically 2% and above) or deep-conditioning masks

Final Thoughts

Protein is a complex, nuanced topic. It can absolutely benefit low porosity hair, when used correctly and in the right context. I personally have low porosity hair and have had both great and not-so-great results from different protein products. It’s not about porosity alone, it’s about the type of protein, the product formula, and how it fits into your routine.

🧪 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