nutrition / proteins and food chemistry

A step-by-step explanation of the role proteins play in human nutrition.
What is a protein? What are the many different types of proteins? How proteins are digested? How proteins function in the body? What are the benefits of a protein-rich diet?

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The main topics covered in this video-tutorial are the following:

What is protein?

Categorization of proteins and amino acids

Role that protein serves within the body

Protein-rich diet and benefits

Proteins are macromolecules composed of amino acids.

Proteins (and amino acids) contain the elements carbon, hydrogen, oxygen (just as other macronutrients). However, proteins are the only macronutrient that contain nitrogen.
Each amino acid consists of a central carbon atom connected to a side chain R (alkyl or hydrogen), a nitrogen containing amino group, a carboxylic acid group—hence the name “amino acid.”
Amino acids differ from each other by which specific side chain is bonded to the carbon center. There are 20 different amino acids .
Because of the variety of side chains (R in the Figure ) that occur when these amino acids are linked together, the different proteins may have different chemical properties
ii) What are the different types of proteins?
Thousands of different type of proteins are known. Scientists estimate that greater than one-hundrend thousand different proteins exist within the human body.

Proteins (from the Greek word “of primary importance”) are essential nutrients since they serve as structural components and regulate a large variety of bodily functions (proteins make up approx. 20% of the human body:
The nutritional value of a protein is dependent on what amino acids it contains and in what quantities.

Amino acids are classified based on nutritional aspects. There are twenty different amino acids and they can be categorized as:

Essential amino acids: Amino acids that are not made by humans and must be obtained from the diet. There are nine essential amino acids (see table below)

Nonessential amino acids: Amino acids that are made in the human body. There are eleven nonessential amino acids (see table below)
iii) What is the role that proteins serve within the body?

Proteins regulate a large variety of bodily functions:

Structure and motion: More than one hundred of structural proteins are known. Collagen, elastin and keratin are the most important. The contractile parts of muscles are the proteins actin and myosin

Enzymes: Enzymes are proteins that act as catalysts and facilitate specific chemical reactions. The liver alone contains hundreds of enzymes

Hormones: Hormones are proteins that regulate several functions of the body (i.e. insulin)
iii) What is the role that proteins serve within the body?

Protection: Antibodies are proteins which are secreted by the white blood cells and survey the entire circulatory system looking for intruders – viruses and bacteria – to surround and destroy

Transport: Hemoglobin and albumin are transport proteins. Albumin chemically binds to hormones, fatty acids, vitamins and drugs and transports them throughout the circulatory system. Hemoglobin binds oxygen in the lungs and transports it to all the tissues in the body
iv) What are the benefits of a rich-protein diet?
Increased metabolic rate: Proteins require 30% of the energy they provide in order to be metabolized by the organism. In comparison carbohydrates require 6-8% and fats 2-3 %. This means greater fat loss when dieting.

Increased Glucagon: Glucagon is responsible for the reduction of effects of insulin in adipose cells leading to greater fat mobilization. This means greater fat loss when dieting.

Reduction in cardiovascular risks
Increased protein turnover
Increased IGF-1: Proteins and amino acids have shown to increase IGF-1 which is an anabolic hormone that increases muscle growth

Increased protein availability: More protein is available in the body for muscle growth.

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