FN 225: Nutrition
Rathakette, Ph.D.
Health Professions Division
Lane Community College
Eugene, Oregon

EXAM 3 next week (Week 7).  Online Review Quiz this week (Week 6)


FORUM for Week 6:

  1. One of the Video Clips this week discusses some environmental problems of raising lots of protein-rich foods. So what's a person to eat if you're a meat-eater, and vegan (no animal food) is not your choice? 
  2. What types of meat alternative dishes do you prepare?  How do you make them tasty?
  3. Look at your Diet Analysis printouts.  Did you meet or exceed your protein recommendation?  How could you improve your protein intake? 

LECTURE 6A: Protein
First skim through the Lecture Outline:
I  Introduction
II  The Structure of Amino Acids & Protein
III    FUNCTIONS of Protein
IV  Protein in the Diet- Quality
V  Problems with Protein Quantity
VI     Digestion of Protein
VII    Using Amino Acids




Watch the following two Video Clips to help with filling out the following sections of your lecture outline.

I  Introduction
 II  The Structure of Amino Acids & Protein
III    FUNCTIONS of Protein
 


Video Clip: Amino Acids & Proteins
approximately 11 minutes


In you lecture outline it mentions that the protein coils and folds based on how the amino acids in the strand attract and repel one another.  Here is an illustration of that:

 

An important concept with proteins is that SHAPE determines FUNCTION.  When the wrong amino acids are bonded together when synthesizing proteins, the result is a different shaped protein, that does not function like it should.  An example of this is Sickle Cell Anemia (which is a genetic disorder).  Below is a picture of hemoglobin, which is globular in shape and when packed in red blood cells to deliver oxygen, it gives red blood cells a donut shape.

 

With Sickle Cell Anemia, DNA gives cells the incorrect message when bonding amino acids together to make hemoglobin.

 

 

The result is a crescent shaped red blood cell, that is sticky and does not transport oxygen like the non-sickle red blood cells.

This is the result of a different shaped protein!
 

Video Clip: Proteins
approximately 16 minutes

Towards the beginning of the video the following question is answered, "What process in the body break up the uncoiled protein into amino acids?" but there was no audio, it was just text.  If you didn't get this answer post a question in the forum.  But here is a hint: It is the same process that needs to happen to starch and disaccharides in order for absorption to occur.

The above Video Clip doesn't mention the following parts of your Lecture Outline.

Additional functions of proteins include:

5.    Antibodies.  

Antibodies are proteins, so a person needs protein in the diet in order to supply amino acids to build antibodies.  Antibodies fight infection.

6.    Energy.
We usually use glucose & fat for energy before using protein.
 
The important way the muscles help provide energy for the brain is by having their amino acids rearranged to become glucose for the brain.  Our brain cannot use fat for energy, at least not in any significant amount.



IV  Protein in the Diet- Quality

Measures of Protein Quality in a food include digestibility and how well the amino acid pattern of the protein supports growth.

A.    Digestibility.  Animal protein is more digestible than plant protein.  I'm not sure why this is, I have not been able to find a good answer.  Let me know if you know why.

B.    Amino Acid Pattern     
1.    Complete protein       
This is a protein in food that has all the ESSENTIAL amino acids (in the needed proportions) for building protein in the cells of the body.   Food sources for complete protein are listed in the document, "Food Sources and Health Benefits of the Macronutrients" which is posted in moodle.  Typically these are foods of animal origin, with the exception of soy.  One food not listed there is quinoa.  Quinoa along with soy are both examples of plant proteins that have all the essential amino acids. A chicken puts protein in its eggs for the same reason we need to eat protein- to provide amino acids to build proteins.  In other words, the developing chick will get amino acids out of that yolk and white, then uses those amino acids to build the proteins it needs for muscles, bones, enzymes, hormones, etc.

2.    Incomplete protein       
This is a protein in food that is missing enough of one or more of the essential amino acids needed for the building of protein in the body's cells.  Typically these are plant proteins.

 


Video Clip: Complete & Incomplete Proteins
approximately 16 minutes
This Video Clip will help you answer the Study Question about why kidney beans have more protein than green beans.


3.    Mutual Supplementation Proteins-

2 incomplete proteins that when combined form complete protein (legume + grain)


 

In the illustration above the orange squares represent what essential amino acids legumes and grains are high in, and the white squares represent what essential amino acids they are limited in.  If you were to simply eat grains and no other foods, you would develop a protein deficiency, since your body would not have all the essential amino acids needed to build body proteins.  However, if you were to combine grains with legumes, you would be getting all the essential amino acids you need.   We call this mutual supplementation. 
 

A good example of Mutual Supplementation would be a bean burrito.  The tortilla would be a grain source and the beans would be the legume.

Another example of Mutual Supplementation would be split pea soup & cornbread, as split peas are legumes.

 
Green beans with a dinner roll would be a poor example of Mutual Supplementation because the green beans haven't had much time to manufacture protein the way a kidney bean would, as explained in a previous Video Clip.  Grean beans are more similar to a vegetable than they are a legume, and vegetables are not as rich in protein as are legumes.

The oatmeal & milk would be a fine way to get protein, but they are NOT an example of Mutual Supplementation because the milk has complete protein and Mutual Supplementation involves 2 incomplete proteins.


V  Problems with Protein Quantity

A.     Problems with high protein levels in your diet:     
1.    Amine group (the N part) of extra amino acids:
Below is aspartic acid, an amino acid we looked at earlier when we said all amino acids have 4 parts.  One part is the amine group and the other 3 parts have carbon (1- Central C & H, 2-acid groups (COOH) & 3- side chains). First the amine group.

Aspartic Acid

     
The amine group (NH2) is pulled off by the liver & excreted by the kidney, which can be hard on the liver and kidney.  
     
2.    Central C & H, acid groups (COOH) & side chains (mostly C, H, O)

are used for energy if you need it OR if the calories are extra, it is changed into fat.
     
3.    High protein diets may accelerate adult bone loss by causing calcium loss.  The following is a link to a recent article I read in Nutrition Action Healthletter, "Bad for Bones?: The latest on food and fractures."  Very interesting information.

4.  A high protein diet is often not good for the heart, because it is high in both saturated fat and cholesterol.  I had a student keep food records for his diet analysis project when he was doing the Atkins diet, and he was eating 45% of his total Calories from fat, 20% of those Calories from saturated fat, and almost 1,500 mg of cholesterol.  If you remember from the lipid chapter last week, these numbers are well above the recommendations for a heart healthy diet.

 

Video Clip: Environmental problems
of raising lots of protein-rich foods

approximately 6 minutes


(The above Video Clip says there is not a supplier of pasture-raised chickens.  That has changed, which you'll find out about in Lecture 7B next week.)
h.    So what's a person to eat if vegan (no animal food) is not your choice? 
(Discussed in the FORUM for Week 6.)

B.  Protein Deficiency: Global Hunger

Since the first cells to suffer from protein deficiency are those that are replaced most often, including red blood cells, plasma proteins as well as inner and outer skin cells (epithelial tissue), you would expect early symptoms to be problems affecting

blood
the digestive tract since it's inner "skin"
outer skin

Protein deficiency usually happens when someone isn't getting enough food, so that means they ALSO aren't getting enough calories and they have something called PEM or Protein Energy Malnutrition (it's also known as PCM or Protein Calorie Malnutrition).  There are two forms of PCM.
The protein deficiency part is called kwashiorkor, a beautiful word from Ghana in Africa  that means "the evil disease that strikes the first child when the second child is born.  In other words, weaning.  It is possible to nurse 2 children, but it takes a well-nourished mother to do it.

When the child is weaned a mother who is very poor can probably manage just a thin cereal to feed her first child.  The child may get barely enough calories, but not enough protein.  That's the situation below for the child below who has kwashiorkor.  Notice the edema (fluid buildup) at the ankles and wrists as well as the skin problems.  I'll explain the edema in one of the Video Clips.  On the right is the same child once protein was added to his diet.
01kwashiorkor
Sometimes a person gets enough protein, but not enough calories.  That person has marasmus, shown below with the girl with anorexia nervosa.
02marasmus

The mother and child shown below have BOTH a deficiency of calories and a deficiency of protein, so they both have PCM (PEM).  Notice the abdominal edema (called ascites) in the child.
03pcmsudanmotherson

Click here for Part 2 of LECTURE 6A.