#uncat 

## Varieties
Hair, nails, and the outer layers of the skin are made of **keratin**, a *scleroprotein*, from the Greek skleros, meaning "hard".
Scleroproteins are impervious to digestive enzymes

The special proteins in muscle are **myosin**, **actin**, and **myoglobin**

The rubbery inner structure of bone marrow is protein-based

Red blood cells contain **hemoglobin** which carries oxygen.  Plasma contains [[Fat|fat]] and protein particles known as *lipoproteins*, which ferry [[Cholesterol|cholesterol]] around and out of the body


## Use
Every day, you reuse more proteins than you get from the food you eat, so you need a continuous supply to maintain your protein status. If your [[Diets|diet]] doesn't contain sufficient amoutns of proteins, you start digesting the proteins in your body.

## Conents
Humans require 22 [[Amino acids]]. 10 are considered [[Nutrients|essential]], others - non essential.
Arginine and histidine are essential only for children

| Essential amino acid     | Nonessential amino acid |
| ------------------------ | ----------------------- |
| Arginine (for children)  | Alanine                 |
| Histidine (for children) | Asparagine              |
| Isoleucine               | Aspartic acid           |
| Leucine                  | Citrulline              |
| Lysine                   | Cysteine                |
| Methionine               | Glutamic acid           |
| Phenylalanine            | Glycine                 |
| Threonine                | Norleucine              |
| Tryptophan               | Proline                 |
| Valine                   | Serine                  |
|                          | Taurine                 |
|                          | Tyrosine                |
## Evaluation
*High-quality proteins* come from animals, and thus are easier to absorb. The proteins from plants are called *low-quality proteins* cause they are harder to absorb EXCEPT the soybean, which contains enough (but there are some health complications with soybeans so yea)

The term used to describe the value of the proteins in any one food is *amino acid score*
In 1993, the FDA and WHO adopted the Protein Digestibility Corrected Amino Acid Score as the preferred method for determining protein quality.
![[Pasted image 20241213165301.png]]
(protein content incorrect!)

Another way to describe the quality of proteins: **complete proteins** contains ample amounts of all essential amino acids, an **incomplete protein** doesn't.
A protein low in one specific amino acid is called a **limiting protein** because it can build only as much tissue as the smallest amount of the necessary amino acid.
Solution: **complementarity** so in total you get somewhat enough
Examples:
rice and beans (rice low in lysine, beans low in methionine)
pasta and cheese (pasta low in lysine and isoleucine, milk products have a lot of these two)

![[Pasted image 20241213165919.png]]

## Calculating the correct amount
46 g/52 g per day for women/men respectively
Meet the quota by:
- up to 100 g of lean meat, fish,poultry
- up to 2 eggs (12 to 16 g), 2 slices of cheese (10 g), 4 slices of bread (3 g each), and 1 cup of yogurt (10 g)

Look up https://fdc.nal.usda.gov for food composition data

Signs of protein deficiency:
- weak muscles
- thin hair
- sore-covered skin
- low levels of *albumin*, a protein that helps maintain the body's fluid balance, keeping a proper amount of liquid in and around body cells
- anemia
- fluid retention (e.g. the big bely on a starving child)
- hair loss

DRI for pregnant or nursing women is 71 g/day.
If you are injured in any way you also need extra protein.

People with liver disease or kidney disesase either don't process protein efficiently into urea or don'te xcrete it efficiently through urine. The result may be uric acid kidney stones or uremic posioning. As well as **gout** (подагра) - a form of arthritis caused by uric acid crystals collecting in the space around joints