Protein Nutrition; Its Role in Infection

Protein

Came from the Greek word “proteios” meaning of the first rank

Are large, complex molecules that basically contain carbon, hydrogen, oxygen and nitrogen atoms arranged into amino acids

The most plentiful substance in the body, next to water

Classification of Proteins• Simple Proteins – yields only amino acids on

hydrolysis, examples are globulins found in legumes such as beans and peas.

• Conjugated Proteins – are compounds formed by attachment of a protein molecule such as globin to a nonprotein molecule or prosthetic group such as heme.

• Derived Proteins – are products resulting from the hydrolysis of proteins such as proteose and cooked egg albumin.

Protein Structure and Metabolism

Proteins are necessary for building the structural components of the human body, such as muscles and organs

You also need proteins to keep your immune system healthy, synthesize neurotransmitters, create and signal hormones

Meats, eggs, and dairy products are significant sources of protein, but you can also get protein from a variety of grains, legumes, nuts, and seeds.

Just a Tiny Bit of Protein Chemistry

Proteins tend to be large molecules made up of several building blocks called amino acids.

The general structure of any amino acid molecule includes a carboxyl group of atoms, an amine group and a side chain.

The carboxyl group contains one carbon, two oxygen, and one hydrogen atom.

The amine group contains one nitrogen atom with two hydrogen atoms attached to it.

All 20 amino acids have different side chains, which vary in shape including straight chains of atoms, branched chains of atoms and rings of atoms.

The side chains may include carbon, hydrogen, sulfur, nitrogen and oxygen atoms.

There are 20 different amino acids.

Amino acids are linked together to form peptides, which are small chains of amino acids.

The peptides are then linked together to form larger proteins.

There are thousands of different proteins that carry out a large number of jobs in the human body.

Even though so many different proteins are at work in your body, you don't have to worry about consuming each individual protein from the foods you eat. Your body will make those

proteins

Make sure your body has a healthy supply of all 20 of the different amino acid "building blocks.“

Having enough of those amino acids is easy because your body can make 11 of them from other compounds already in your body. That leaves 9 amino acids that you must get from your diet.

Those nine amino acids are called "essential amino acids."

Non Essential and Essential Amino Acids

The 11 non-essential amino acids are not called "non-essential" because they are not important.

They are important and your body requires them to perform several functions. These amino acids are called "non-essential" because you don't need to get them from your diet.

Your body can build those 12 amino acids from chemicals already present in your body. The non-essential amino acids include:

Alanine Arginine

Asparagine Aspartic Acid

Cysteine Glutamic Acid

Glutamine Glycine

Proline Serine

Tyrosine

The nine essential amino acids are called "essential" because you can't manufacture them, you have to eat proteins that contain those amino acids. Those essential amino acids include:

• Histidine • Isoleucine • Leucine • Lysine • Methionine • Phenylalanine • Threonine • Tryptophan • Valine

Do you really need to worry about essential amino acids when you plan your daily meals?

Not really. Animal sources of protein such as meat, eggs, and dairy products are "complete proteins." That means that each protein found in an animal product contains each of the nine essential amino acids

Vegetarians and vegans may need to pay a little more attention to the dietary proteins. Plant proteins are called "incomplete proteins."

Each plant protein is missing at least one of the nine essential amino acids

Every amino acid is found in some type of plant, so you can combine different plant proteins to get all of the amino acids you need

Protein Functions in the Body

There are many different proteins in your body, and they perform different functions.

Proteins functions include: • Contributing to enzyme activity that promotes

chemical reactions in the body

• Signaling cells what to do and when to do it

• Transporting substances around the body

• Keeping fluids and pH balanced in the body

• Serving as building blocks for hormone production

• Helping blood clot

• Promoting antibody activity that controls immune and allergy functions

• Serving as structural components that give our body parts their shapes

• Protein Digestion and Metabolism

The digestion of protein begins in the mouth with chewing. Chewing not only makes food easier to swallow, it also helps with digestion by chopping food up into smaller bits.

Remember that it really is important to chew your food thoroughly; don't gulp your food down in huge bites.

Protein digestion continues in the stomach with the release of hydrochloric acid and pepsinogen.

Hydrochloric acid converts pepsinogen into pepsin, which begins to break down the bonds between the amino acids.

This process takes place while the muscles surrounding the stomach squeeze and squish the foods and stomach fluids together.

The next step occurs in the small intestine where the hydrochloric acid is neutralized with bicarbonates released from the pancreas.

The pancreas also releases an enzyme called trypsin. Trypsin continues to break apart the amino acids, which are then absorbed into the blood stream.

Once in the bloodstream, the amino acids are carried to the cells in various parts of your body.

Your body uses the individual amino acids that were broken down during digestion to build the proteins needed for the various functions

You may not think of protein as an energy source, but proteins do contribute calories to you diet.

Each gram of protein you eat has four calories

15% to 20% of your daily calorie intake should come from protein

It isn't difficult to get enough protein in your diet.

One chicken leg alone will provide you with about 30 grams of protein

One salmon fillet has about 40 grams of protein

A cup of oatmeal has six grams of protein

A cup of asparagus even has two grams of protein

Since most people get enough protein from their diet, protein deficiency is rare in developed countries.

In underdeveloped countries, protein deficiency is more common. Severe protein deficiency is called kwashiorkor. Children with kwashiorkor tend to have very thin arms and legs and large, distended bellies.

Lack of protein can cause growth failure, loss of muscle mass, a depressed immune system, lung problems, heart problems, and death.

Marasmus

• Weight for age < 60% expected

• No edema

• Often stunted

• Hungry, relatively easier to feed

Kwashiorkor(Edematous Malnutrition)

• Underweight with edema

• Irritable, difficult to feed

• Electrolyte abnormalities

• Highest mortality – 50 to 60%

Marasmus

• < 1year• Weight loss• Low protein• Boarder line Hgb• Energy deficiency• No edema

Kwashiorkor

• >18 months• No weight loss• High extracellular water• Low Hgb• Protein deficiency• With edema