FN 225: Nutrition
Teresa McFerran, M.S., R.D.
Health Professions Division
Lane Community College
Eugene, Oregon
EXAM during Week 5 (over both parts of chapter 4)

FORUM for Week 5:

     1.  Tina is an 19 y.o. soccer player who thinks all fat is bad for her health and therefore tries to avoid fat in food at all cost.  She has many forbidden foods.  She mostly eats plain bread, salad with no-fat dressing, chicken breasts, and low-fat snack foods.  What can you tell Tina about the disadvantages of avoiding fat?  Can you explain the different types of fat to Tina and how some fats are actually healthy for the heart?  What types of foods can you recommend that Tina focus on to get fat in her diet?

     2.  Frank is a 52 y.o. male who goes to school full-time and works part-time.  He does not have time to exercise and his diet mostly consists of fast food (burgers, fries, tacos, etc.).  His doctor recently diagnosed him with high blood cholesterol.  His doctor told him that his "bad" cholesterol is above normal, and his "good" cholesterol is below normal.   Can you explain to Frank what the doctor is referring to when he says "bad" and "good" cholesterol?  Frank wants to know what foods have good and and bad cholesterol.  What can you tell him?  What dietary advice would you give Frank to help improve his blood cholesterol levels?


LECTURE 5B: Chapter 5: The Lipids: Fats, Oils, Phospholipids and Sterols
First look through the major headings of this Lecture Outline in your packet:

Covered in Lecture 5A:
Now we're ready for:
 


IV  Digestion and Absorption  of Triglycerides
(As mentioned before, triglycerides are the major type of lipid in food and in the body.)

As the Lecture Outline says, after you've eaten a food, it quickly goes down to your stomach where the fats are separated from the rest of the food.  As you'll see in the rest of this section, fats are difficult to digest so the body keeps them separated & isolated in the stomach while other parts pass on to the small intestine.


Now watch the following Video Clip to continue filling out your lecture outline.


Video Clip: Digestion & Absorption of Triglycerides- Part 1
approximately 5 minutes

Digestion & Absorption of Triglycerides video part 1
/
Video Clip: Digestion & Absorption of Triglycerides- Part 2
approximately 12 minutes

Digestion & Absorption of Triglycerides video part 2
There is a "mis-speak" in the above Video Clip.  Beth should've said that enzymes are LIPASES, not lipids.  

Also, the Video Clip shows a line missing from the top of the drawing of glycerol. That's another mistake.  It was intended that glycerol be represented the way it is in your packet.



 A.    Value of Fats in the Body 
(another section will look at the value of fats in the diet)  
1.    FUNCTION of triglycerides and fatty acids in the human body  
  1. cushion  
  2. insulation layer 
     
  3. energy reserve  (Body's own oil well.) 
    You don't need fat in the diet for these first 3 functions (cushion, insulation, energy) because you can make that fat from eating extra foods with carbohydrate, or protein.
  4. specific fatty acids in those triglycerides

    Omega 6 EFA (linoleic, shown below) are used in production of cell membranes, including skin, nerve & brain cell membranes.


    The source of the slide photo above is unknown.  In pencil, the slide says that the child on the left had a deficiency of essential fatty acids.  

    Perhaps he (or she?) was mistakenly given a fat-free formula or     fat-free milk.

    Perhaps he had an intestinal disease preventing fat absorption.  

    The slide also says in pencil that it's the same child on the right, once he got essential fatty acids.

    05linoleic2


    Omega 3 EFA (linolenic, shown below) are used to make hormone-like compounds (called eicosanoids) that regulate blood pressure, blood clots and the immune response.  Notice the similarity between the structure of     linoleic acid and the structure of linolenic acid
    06linolenic2

    other important FAs like DHA & AA (they are NOT EFAs and they are shown below)- are involved in visual acuity & brain development in infants.

    DHA (docosahexaenoic acid) and AA (arachidonic acid; also called ARA)


    06epaaadha2
Similac Advance Baby formula: Nonfat milk, lactose, high-oleic safflower oil, soy oil, coconut oil, whey protein concentrate plus small amounts of C. and about 30 added vitamins and minerals     

This formula has many different kinds of oil in an attempt to match the various types of fatty acids in human milk.

2.    FUNCTION of cholesterol in human body
  1. used to make bile, which is an emulsifier (a substance that allows fat droplets to stay dispersed in water).
  2. used to make vitamin D (Later you'll see a comparison of the structure of cholesterol and the structure of vitamin D.)
  3. used to make reproductive hormones, like estrogen  
You don't need cholesterol in the diet for these 3 functions cholesterol in the body because your body can synthesize the cholesterol it needs. 

3.   FUNCTION  of phospholipids in human body. 

Phospholipids are part of the lipoproteins. They are EMULSIFIERS in cell membranes as well as in the blood      

What are the 3 places in the body where we've talked about emulsification taking place:    
  1. small intestine (bile)
  2. cell membrane (see just above)
  3. blood (see just above)

    As with  cholesterol, you don't need phospholipids in the diet for these functions of phospholipids in the body because your body can synthesize the phospholipids in needs .


When this Lecture listed functions of cholesterol, one of the listed functions was that cholesterol is used to make to make vitamin D.  The images below show how very similar cholesterol and vitamin D are in structure.


Cholesterol (below)
Vitamin D (below)
20structurecholesterol 21structurevitd



We've just looked at the value of fats in the body.  The next section looks at the value of fats in the diet.



 B.    Value of Fats in the Diet
  1. Fats & oils satisfy appetite (the desire to eat) because they satisfy our desire for flavor.  Many flavor compounds are fat soluble so when the fat is removed from a food, much of the flavor is lost.

    Consider fat-free cream cheese.      When the fat is removed from the cream, much of the flavor goes also.  As a result, many additives are used in an attempt to replace the lost flavor.

      
  2. Fats & oils satisfy
    hunger (the need to eat) because fats are slow to be digested and absorbed.  That means they may slow your need to eat again.

    Besides the effect of the macronutrients on hunger (as opposed to appetite), there are other factors that influence what signals your brain gives you about how full you are.  The following article, which some of you already chose to read, gives more information about that.
    An Australian study identifies the foods that will fill you up for the least amount of calories. 
  3. Fats & oils carry the fat soluble vitamins, which are

    vitamin A
    vitamin E
    vitamin K
    vitamin D

You need at least 10% of your calories coming from fat to get the fat soluble vitamins in your diet.  Vitamin E is very hard to get enough of with a low-fat diet since you find it in plant oils and products made with plant oils.  Good sources of vitamin E are nuts like almonds, seeds like sunflower seeds, also whole grains, and even salad dressing.



END OF LECTURE 5B