Protein is crucial to good health.

In fact, the name comes from the Greek wordproteos，意思是“主要”或“第一名”。

Proteins are made up of amino acids that join together to form long chains. You can think of a protein as a string of beads in which each bead is an amino acid.

There are 20 amino acids that help form the thousands of different proteins in your body.

蛋白质在细胞中大部分工作并从事各种工作。

这是您体内蛋白质的9个重要功能。

1. Growth and Maintenance

Your身体需要蛋白质for growth and maintenance of tissues.

Yet, your body’s proteins are in a constant state of turnover.

Under normal circumstances, your body breaks down the same amount of protein that it uses to build and repair tissues. Other times, it breaks down more protein than it can create, thus increasing your body’s needs.

This typically happens in periods of illness, during pregnancy and while breastfeeding ( 1 , 2 , 3 ）。

People recovering from an injury or surgery, older adults and athletes require more protein as well ( 4 , 5 , 6 ）。

Summary

蛋白质是组织生长和维持所必需的。您身体的蛋白质需求取决于您的健康和活动水平。

2.引起生化反应

Enzymes are proteins that aid the thousands of biochemical reactions that take place within and outside of your cells ( 7 ）。

酶的结构使它们与称为底物的细胞内部分子结合在一起，这催化了对您的代谢必不可少的反应（ 8 ）。

酶也可能在细胞外发挥作用，例如消化酶like lactase and sucrase, which help digest sugar.

Some enzymes require other molecules, such as vitamins or minerals, for a reaction to take place.

依赖酶的身体功能包括 9 ）：

  • 消化
  • 能源生产
  • Blood clotting
  • Muscle contraction

这些酶缺乏或不当功能会导致疾病（ 10 ）。

Summary

Enzymes are proteins that allow key chemical reactions to take place within your body.

3. Acts as a Messenger

Some proteins arehormones, which are chemical messengers that aid communication between your cells, tissues and organs.

They’re made and secreted by endocrine tissues or glands and then transported in your blood to their target tissues or organs where they bind to protein receptors on the cell surface.

激素可以分为三个主要类别（ 11 ）：

  • Protein and peptides:These are made from chains of amino acids, ranging from a few to several hundred.
  • Steroids:These are made from the fat cholesterol. The sex hormones, testosterone and estrogen, are steroid-based.
  • Amines:These are made from the individual amino acids tryptophan or tyrosine, which help make hormones related to sleep and metabolism.

Protein and polypeptides make up most of your body’s hormones.

Some examples include ( 12 ）：

  • Insulin:gluc吸收的信号ose or sugar into the cell.
  • Glucagon:Signals the breakdown of stored glucose in the liver.
  • HGH（人类生长激素）：Stimulates the growth of various tissues, including bone.
  • ADH (antidiuretic hormone):Signals the kidneys to reabsorb water.
  • ACTH (adrenocorticotropic hormone):Stimulates the release of cortisol, a key factor in metabolism.
Summary

各种长度的氨基酸链形成蛋白质和肽，它们构成了您人体的几种激素，并在细胞，组织和器官之间传递信息。

4. Provides Structure

一些蛋白质是纤维的，并为细胞和组织提供刚度和刚度。

These proteins include keratin,collagen和弹性蛋白，它们有助于形成体内某些结构的结缔组织（ 13 ）。

Keratin is a structural protein that is found in your skin, hair and nails.

Collagen is the most abundant protein in your body and is the structural protein of your bones, tendons, ligaments and skin ( 14 ）。

弹性蛋白比胶原蛋白灵活几百倍。它的高弹性使您体内的许多组织在拉伸或收缩后恢复其原始形状，例如子宫，肺和动脉（ 15 ）。

Summary

A class of proteins known as fibrous proteins provide various parts of your body with structure, strength and elasticity.

5. Maintains Proper pH

Protein plays a vital role in regulating the concentrations of acids and bases in your blood and other bodily fluids ( 16 , 17 ）。

The balance between acids and bases is measured using the pH scale. It ranges from 0 to 14, with 0 being the most acidic, 7 neutral and 14 the mostalkaline.

Examples of the pH value of common substances include (18）：

  • pH 2:胃酸
  • pH 4:番茄汁
  • pH 5:Black coffee
  • pH 7.4:Human blood
  • pH 10:Milk of magnesia
  • pH 12：Soapy water

各种缓冲系统允许你的身体fluids to maintain normal pH ranges.

A constant pH is necessary, as even a slight change in pH can be harmful or potentially deadly ( 19 , 20 ）。

One way your body regulates pH is with proteins. An example is hemoglobin, a protein that makes up red blood cells.

Hemoglobin binds small amounts of acid, helping to maintain the normal pH value of your blood.

您体内的其他缓冲系统包括磷酸盐和碳酸氢盐（ 16 ）。

Summary

Proteins act as a buffer system, helping your body maintain proper pH values of the blood and other bodily fluids.

6. Balances Fluids

蛋白质调节身体过程以维持液体平衡。

白蛋白和球蛋白是血液中的蛋白质，通过吸引和保留水来帮助维持身体的液体平衡（ 21 , 22 ）。

If you don’t eat enough protein, your levels of albumin and globulin eventually decrease.

Consequently, these proteins can no longer keep blood in your blood vessels, and the fluid is forced into the spaces between your cells.

As the fluid continues to build up in the spaces between your cells, swelling or edema occurs, particularly in the stomach region ( 23 ）。

这是一种严重的形式protein malnutrition当一个人消耗足够的卡路里但没有消耗足够的蛋白质时，称为kwashiorkor 24 ）。

Kwashiorkor is rare in developed regions of the world and occurs more often in areas of starvation.

Summary

Proteins in your blood maintain the fluid balance between your blood and the surrounding tissues.

7. Bolsters免疫健康

蛋白质有助于形成免疫球蛋白或抗体，以对抗感染（ 25 , 26 ）。

抗体是血液中的蛋白质，有助于保护您的身体免受细菌和病毒等有害入侵者的侵害。

当这些外国入侵者进入您的细胞时，您的身体会产生标记它们以消除的抗体（ 27 ）。

Without these antibodies, bacteria and viruses would be free to multiply and overwhelm your body with the disease they cause.

Once your body has produced antibodies against a particular bacteria or virus, your cells never forget how to make them.

这使抗体在下次特定疾病剂入侵您的身体时可以迅速反应（ 28 ）。

As a result, your body develops immunity against the diseases to which it is exposed ( 29 ）。

Summary

Proteins form antibodies to protect your body from foreign invaders, such as disease-causing bacteria and viruses.

8.运输和存储营养

Transport proteins carry substances throughout your bloodstream — into cells, out of cells or within cells.

这些蛋白质运输的物质包括nutrientslike vitamins or minerals, blood sugar, cholesterol and oxygen ( 30 , 31 , 32 ）。

例如，血红蛋白是一种蛋白质，可将氧气从肺部带到身体组织。葡萄糖转运蛋白（GLUT）将葡萄糖移至细胞，而脂蛋白将胆固醇和血液中的其他脂肪转移到您的细胞中。

蛋白质转运蛋白是特异性的，这意味着它们仅与特定物质结合。换句话说，移动葡萄糖的蛋白质转运蛋白不会移动胆固醇（ 33 , 34 ）。

Proteins also have storage roles. Ferritin is a storage protein that stores iron ( 35 ）。

Another storage protein iscasein，这是牛奶中的主要蛋白质，可以帮助婴儿生长。

Summary

Some proteins transport nutrients throughout your entire body, while others store them.

9.提供能量

Proteins can为您的身体提供能量.

Protein contains four calories per gram, the same amount of energy that carbs provide. Fats supply the most energy, at nine calories per gram.

However, the last thing your body wants to use for energy is protein since this valuable nutrient is widely used throughout your body.

Carbs and fats are much better suited for providing energy, as your body maintains reserves for use as fuel. Moreover, they’re metabolized more efficiently compared to protein ( 36 ）。

In fact, protein supplies your body with very little of its energy needs under normal circumstances.

However, in a state of fasting (18–48 hours of no food intake), your body breaks down skeletal muscle so that the amino acids can supply you with energy ( 37 , 38 ）。

如果碳水化合物储存较低，您的身体还使用破碎的骨骼肌中的氨基酸。这可能会在详尽的锻炼后发生，或者如果您通常不消耗足够的卡路里（ 39 ）。

Summary

蛋白质可以用作有价值的能源，但仅在禁食，详尽的运动或卡路里摄入量不足的情况下。

底线

Protein has many roles in your body.

它有助于修复和建立身体的组织，使代谢反应发生并辅助身体功能。

除了为身体提供结构框架外，蛋白质还保持适当的pH和流体平衡。

Finally, they keep your immune system strong, transport and store nutrients and can act as an energy source, if needed.

Collectively, these functions make protein one of the most important nutrients for your health.