Hair is also protein, why can’t we eat it?

I don't know since when,

hair

It has become a new era youth self-image management

One of the most important projects,

We have been committed to raising

A head of thick and beautiful hair,

Going further and further on the road of "How to prevent baldness",

But we ignore the deepest essence of hair——

It's protein.

Some people may be curious.

Hair as protein,

Why can’t you eat it?

Cats lick their fur every day.

Licking it into the stomach,

How can its fur be eaten?

Sometimes vomiting small balls of hair,

The stomach cannot digest hair.

Or is it that there is too much hair and the stomach cannot digest it all, so it has to be vomited out?

Don’t be impatient, we’ll talk about it slowly.

● Hair from macro to micro●

Let’s first introduce human hair from a macro perspective.

hair,

As the name suggests,

Refers to the hair that grows on the head.

Hair not only increases beauty,

Mainly used to protect the head.

(Copyrighted image from the gallery, no permission to reprint)

Soft and fluffy hair is elastic.

Can withstand minor collisions.

It can also help the evaporation of sweat on the head.

Of all the hair on the human body,

The longest hair can grow.

The growth rate is also the fastest.

Hair has no sense of pain or touch.

It is not a human organ and does not contain nerves or blood vessels.

The pain you feel from pulling your hair is due to irritation of the tactile nerves in your scalp.

Hair in biology is a general term.

In addition to the hair shaft exposed on the epidermis,

It also includes tissues such as hair follicles below the epidermis of the scalp.

At the base of the hair follicle,

Epidermal cells continue to divide and differentiate.

Grow out hair shaft.

The sebaceous glands secrete sebum.

Provides natural protection for hair.

Each hair is made of

It is composed of epidermis squamous layer, cortex layer and medulla layer.

The epidermal squama layer is the outermost layer of the hair.

Usually translucent or colorless,

So it allows the natural hair color to show through;

The cortex accounts for 80% of the hair.

Natural pigments are deposited here.

The natural hair color is due to it;

The medulla is located in the center.

(Copyrighted image from the gallery, no permission to reprint)

Hair is a fiber with a complex structure.

α-keratin is the main component of hair fibers.

The remaining ingredients include lipids, water, pigments and

Trace elements, etc.

Speaking of which,

There is another issue that still troubles the French. It is worth mentioning.

Because the arsenic content in Napoleon's hair exceeded normal values,

It is still unclear whether Napoleon died of poisoning.

Died of stomach cancer.

There is one more point worth pointing out here.

All vertebrates have hair made of

Composed of α-keratin,

Cat's hair is no exception.

The secret of why hair cannot be eaten lies in this magical keratin.

The so-called "eating hair" of cats

It’s not what we imagined.

● Microscopic process of protein digestion●

Before talking about keratin,

Let’s briefly review

The process by which the human body digests and absorbs protein.

We all know protein

As a large molecule, it is difficult to absorb without digestion.

Hydrolyzed food proteins

Amino acids and small peptides can be absorbed.

Since saliva does not contain enzymes that hydrolyze proteins,

So the digestion of food protein starts in the stomach.

Ends in the small intestine.

During this period,

Gastric acid, pepsin, trypsin and

Under the continuous action of intestinal proteases,

Protein macromolecules are broken down into small peptides.

Even amino acids,

Finally it is absorbed by the small intestinal mucosal cells.

The above is the traditional concept of protein digestion and absorption.

Main pathway.

With the deepening of scientific research,

Scholars have discovered more "special carrier transport channels" for small intestinal mucosal cells to directly absorb peptides.

Humans have a deeper understanding of protein absorption, but we will not discuss it here.

● The Secret of Keratin●

The above article introduces the ways in which the human body digests and absorbs protein.

It can be seen that protein wants to be digested by the human body.

First, the molecular structure of the protein needs to be destroyed.

Then it is broken down into small peptides or amino acids.

(Copyrighted image from the gallery, no permission to reprint)

α-keratin is the main protein that makes up hair.

It is a member of the fibrous structural protein family.

Because it contains more cystine,

Therefore, it plays a cross-linking role in protein peptide chains

The content of disulfide bonds is particularly high.

Therefore, the chemical properties of keratin are particularly stable.

It is extremely difficult to dissolve and digest in the human body environment.

This is why hair cannot be eaten.

Because keratin is difficult to

Destroyed and decomposed.

Cats also cannot digest the hair they lick into their stomachs.

Cat owners know that

Cats need to eat cat grass regularly

Or you can use hair removal cream to help remove the accumulated hair in the body.

Although it is called hair removal cream,

But it didn't have the effect of removing hair.

The main ingredient of most hair removal creams is oil.

Some cats will vomit and spit out hairballs after eating hairball paste.

It is mostly because the stomach is irritated by fat.

(Copyrighted image from the gallery, no permission to reprint)

It is worth mentioning that

Although all vertebrates have hair made of

Composed of α-keratin,

But some scholars have compared the hair of any different animals

Keratin comparison test with human hair,

It was found that there were significant differences in the components of the two.

It is reflected in the content of high-sulfur protein.

Although hair cannot be eaten,

However, animal feathers have been continuously studied and explored by scientists.

A variety of treatments have been developed.

Treated with high temperature, high pressure, acid, alkali or enzymes,

Keratin can be broken down into short peptides or free amino acids.

For food of livestock and poultry.

Feathers have now become a recognized

With high nutritional value and stable quality

Potential high-quality protein source used in feed and food industry,

Environmental protection, fertilizer, pharmaceuticals, etc.

Shining in many fields,

Scientists have never stopped exploring the treasure of keratin.

There must be more surprises ahead

Waiting for scientists to discover!

Creative team: China Science and Technology Museum New Media Team

Review expert: Han Hongwei, Director of Risk Communication Department, National Food Safety Risk Assessment Center, Researcher