Lecture 5B: Lipids

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

FORUM for Week 5:

Take a look at the chart on page 64 of your packet called "Food Sources of Carbohydrates, Lipids, Proteins". Now look at the food sources listed on that table of fatty acids, including SaFAs, MUFAs, omega 6 PUFAs, short chain omega 3 PUFAs and long chain omega 3 PUFAs. What is ONE food you eat that is on any of those lists of food sources of fatty acids and which list (or lists) is it on?

(The chart on page 64 in your packet doesn't make this clear, but all foods with fat have a MIXTURE of fatty acids. So even though olive oil has MOSTLY MUFAs, olive oil also has SaFAs, omega 3 PUFAs as well as omega 6 PUFAs.)
On pages 74 and 75 of your packet, read about some recommended key words regarding lipids and health.

Consider Lou, who had triple bypass surgery at age 51.

Based on what you've learned this week, which of those recommendations do you think would be most important for Lou?
Do you have any other questions regarding the lectures or the study questions for week 5?

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:

I The THREE types (kinds) of LIPIDS

II Where do lipids come from?
III Lipoproteins
IV Recommendations regarding lipids & heart health

Now we're ready for:

V Digestion and Absorption

VI Usefulness of Fats

Before continuing with this Lecture (and while you're waiting for the Video Clips to buffer, go to the end of the Lecture Outline in your packet (page 77) and answer those questions called "REVIEW. QUARTET OF TRIOS" (with a fifth questions). I suspect you'll spend the most time on #4 and I'll start a FORUM about it.

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

As the Lecture Outline in your packet 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.

(You can click on the following image to see an enlarged version.)

Now watch the following Video Clip to continue with page 75 in your packet.

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

If the Part 1 movie isn't showing up just above on your computer and the Part 2 movie isn't showing up just below on your computer, you may not have the latest version of QuickTime on your computer. Click here to download the newest version of Quick Time.

Video Clip: Digestion & Absorption of Triglycerides- Part 2
approximately 12 minutes

There is a "mis-speak" in the above Video Clip. I 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.

Now go to the Foods and Digestion page in packet (page 66).

Notice that the Milk (which is whole milk) has triglycerides. Which of the other foods on that page do you think have triglycerides? For help, flip back to page 64 in your packet.

The foods on page 64 that have triglycerides include:

Butter
Soybean oil
Meat

(like chicken, fish & beef, although some have less fat than others so they have fewer triglycerides)

Eggs

So you can write triglycerides in the first column with blanks (the column headed my MACRONUTRIENT THAT NEEDS TO BE ENZYMATICALLY DIGESTED).

Then in the column headed by WHAT IS ABSORBED INTO VILLI, for the foods with triglycerides, you can write "fatty acids & glycerol".

Now return to page 76 in your packet.

VI Usefulness of Fats

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 human body

cushion
insulation layer
energy reserve (Body's own oil well.)
You don't you need fat in the diet for these first 3 functions (cushion, insulation, energy) of fat in the body because you can make that fat from eating extra foods with carbohydrate, protein or fat.
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 with my writing, 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.

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

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

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

Similac Advance Baby formula: Nonfat milk, lactose, high-oleic safflower oil, soy oil, coconut oil, whey protein concentrate plus small amounts of C. cohnii oil, M. alpina oil 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

used to make bile,which is an emulsifier (a substance that allows fat droplets to stay dispersed in water.
used to make vitamin D (Later you'll see a comparison of the structure of cholesterol and the structure of vitamin D.)
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 make 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:

small intestine (bile)
cell membrane(see just above)
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 make the phospholipids in needs .

B. Value of Fats in the Diet

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.
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.

For Exams, be certain you're clear on the difference between appetite and hunger, as they're defined here.
Fats & oils carry the fat soluble vitamins, which are

vitamin A
vitamin E
vitamin K
vitamin D

As stated at the beginning of this Lecture, you should try to answer the questions below QUARTET OF TRIOS on page 77 in your packet. The fourth question will be discussed in the FORUM this week.

Cholesterol (below)	Vitamin D (below)