FN 225: Nutrition
Teresa McFerran, M.S., R.D.
Health Professions Division
Lane Community College
Eugene, Oregon

There is an EXAM this week (Week 5) on the material from Weeks 3 and 4.

FORUM for Week 5:

1. What did you learn in this chapter that makes you think more positively or more negatively about fats?

2.  Read "Nutrition myth or fact? Is Margarine More Healthful Than Butter?" What do YOU think, and WHY?


LECTURE 5A: Week 5: The Lipids: Fats, Oils, Phospholipids and Sterols

First look through the major headings of this Lecture Outline in your packet:


I  The THREE types of LIPIDS

A. Triglycerides (or fats)

B. Phospholipids (lecithin is the main one)

C. Sterols (an example is cholesterol)


Fill in your lecture outline while viewing the following:
A. Triglycerides (fats & oils)

As you can see in the Lecture Outline,
triglycerides (fats & oils) are
the MAJOR type of lipid in food and in humans.  Although you may think of eggs as having cholesterol, which they do, the
MAJOR type of lipid in an egg is still triglycerides.  If you look at the label of an egg, fats (or triglycerides) would be listed in terms of grams, and cholesterol would be listed in terms of milligrams (1000 mg = 1 g)


Now watch the Video Clip below to learn more about the structure of triglycerides.

Video Clip: Triglycerides
approximately 5 minutes

Next in your lecture outline it outlines the different types of fatty acids.  What I want you to know for each fatty acid is a little bit about its chemistry, what foods you predominately find these fatty acids in, and how they affect heart health.  Click on the following link to view a Powerpoint presentation to help you fill in the lecture outline on the different types of fatty acids.


The power point presentation had this image and said that the liquid oil would be polyunsaturated and the yellow fat would be monounsaturated.  That is not completely correct.  A highly mono or polyunsaturated fat would be liquid at room temperature.  For example olive or corn oil.  However a fat that is more saturated, but still contains high amounts of monounsaturated fatty acids (like chicken fat) would look like the yellow fat below.  And a fat that is highly saturated, like coconut oil would look like the white fat below.


Saturated Fatty Acids are a stable and compact way for a plant or an animal to store fat for later use as energy.  Animals in the wild don't have a chance to store very much fat since they constantly need an energy source to live.  On the other hand, animals that spend much of their time on feedlots, such as beef cattle, are inactive and therefore store a lot of saturated fat.  So while deer meat is a very small source of saturated fat, most beef purchased in a grocery store is high in it.  Foods that have mostly saturated fatty acids, like butter, are solid at room temperature and can raise risk of heart disease because they increase blood cholesterol, specifically the LDL or "bad" cholesterol.  (More on this later).  Food sources of saturated fatty acids include most animal fats, tropical oils (like coconut and palm oil), and partially or fully hydrogenated oils.

Unsaturated Fatty Acids - Cells in plants and animals may have the most use for unsaturated fatty acids. Fish and high-fat plant foods like nuts, seeds, avocados and wheat germ are good sources of unsaturated fatty acids.  Unsaturated fatty acids are not compact and are also unstable. When oxygen reacts with ("attacks") the double bonds in unsaturated fatty acids, it makes the fatty acids rancid.  These openings (double bonds) in the structure of unsaturated fatty acids are what keep them liquid at room temperature.   Both MUFAs and PUFAs can lower risk of of heart disease. Essential fatty acids (linoleic, alpha-linolenic) are unsaturated fatty acids that are called essential because we must get them from food since our body can't make them the way it makes other fatty acids.

Omega-6 Unsaturated Fatty Acids (PUFAS) - This is the type of fatty acid made by plants for storage.  People take in plenty of the essential linoleic acid (an omega 6) when they eat the oil of seeds, such as corn oil or soybean oil that we often find in margarines and salad dressings. 

Omega-3 Unsaturated Fatty Acids (PUFAS) - In the last decade, we have come to a much deeper understanding of this kind of unsaturated fatty acid.  An omega-3 fatty acid is even more unsaturated than other unsaturated fatty acids and has special functions in our body.

Some plant foods like flax seed have one type of beneficial essential omega-3 fatty acid called alpha-linolenic acid (ALA,) while some wild fish (like salmon) have another type of beneficial (not essential) omega-3 fatty acid, called EPA and DHA.

Most people associate omega-3 fatty acids with fish, but fish get them from green plants (specifically algae), who use them during photosynthesis. 

Research does NOT support that there is a beneficial ratio between omega-6 and omega-3 to support health.  Most people need to simply increase omega-3s in their diet because they already get plenty of omega-6s.


As you can see from the illustration below, there is a mixture of all fatty acids in fats, and oils, and therefore foods.  It can be confusing when we say that olive oil is a monounsaturated fat because that makes it seem like there are no saturated or polyunsaturated fatty acids present.  What would be more correct is to say that olive oil is predominately a monounsaturated fat, but it does contain other fatty acids as well as you can see from the illustration.

Looking at the illustration below, which dietary fat is the most saturated?

Click here to see answer.



As you can see from the label below 12g out of the total 14g of total fat (in 1Tbsp. of coconut oil) are saturated.  Notice that there is 0mg of cholesterol.  That is because only animal fats contain cholesterol, not plant fats.


The two essential fatty acids are linoleic acid and linolenic acid.  Below is linoleic acid, which is an omega-fatty acid.

Linoleic acid

Linoleic acid (above) is more common in the seeds of plants. The first double bond is after the 6th carbon starting on the left.  Below is another way of representing linoleic acid:

Below is the other essential fatty acid,
linolenic acid, which is an omega-3 fatty acid.

The fatty acids represented below are not officially considered essential because we can make them from the essential ones.  But new research supports a recommended intake of at least 250 mg per day of EPA+DHA. Having good levels of them in your DIET appears to decrease the risk of heart disease.

By no means is it important to know the names of all of the fatty acids in the following table.  This table was made to illustrate a little about the wide diversity of fatty acids in foods, and how those fatty acids affect blood cholesterol.

Chemical Names and Descriptions of some Common Fatty Acids and the Effect they have on Cholesterol

The first four fatty acids are saturated fatty acids.  Notice that the first three (Lauric, Myristic, and Palmitic) have a negative impact on blood cholesterol levels (increasing LDL levels), but they ALSO have a positive impact as well (increasing HDL levels).  Saturated fats get a bad reputation for being unhealthy, but recently there has been evidence that demonstrates that the link between saturated fat and heart disease may not be as strong as we once thought. 

In an article from Tufts University Health & Nutrition Letter (May 2010), Links Between Saturated Fat, Blood Cholesterol & Heart Disease Prove Complex,  a researcher from Children's Hospital Oakland Research Institute, Ronald M. Krauss, MD stated that, "Our meta-analysis showed that there is insufficient evidence from prospective epidemiological studies to conclude that dietary saturated fat is associated with an increased risk of cardiovascular disease (CVD)." 

Researchers state that one reason reducing saturated fat intake may not decrease CVD risk is because people tend to replace saturated fat with processed carbohydrates. 

"An overall eating pattern that emphasizes whole grains rather than refined carbs such as white flour, along with foods high in polyunsaturated fats, such as fish, seeds, nuts and vegetable oils, is of more value for reducing coronary heart disease risk than simply aiming to further reduce saturated fat," states Krauss. 

The message really is to displace saturated fat with unsaturated fat, and to eat a balanced diet with a variety of whole foods.


Trans Fatty Acids

Trans Fatty Acids are a bi-product of hydrogenation.  Hydrogenation of polyunsaturated fatty acids saturates the fatty acid with hydrogen (creating saturated fatty acids), but it does leave some of the double bonds as well, creating trans fatty acids.  As you can see from the image below trans fatty acids are actually a monounsaturated fatty acid, but they have the shape of a saturated fatty acid (they are not kinked like the naturally occurring monos in olive oil due to the configuration of the hydrogens at the double bond).  These partially hydrogenated and artificial fatty acids (trans fatty acids) now have an unusual shape that has an affect in the body similar to saturated fatty acids.


In about the 1990s, evidence began accumulating that trans fat are not healthy,  “Numerous studies have found that trans fats raise our risk of heart disease," says Cynthia Payne, a registered dietitian at the University of Maryland Medical Center. "They can also contribute to an increase in total cholesterol levels and a drop in the healthy HDL cholesterol.  These man-made fats are much worse for you than any other natural fat, even the saturated fats found in butter and beef.” 

Substitutes for trans fats- In 2006, the U.S. government began requiring trans fat information on the Nutrition Facts of food labels.  This has prompted the food industry to mostly eliminate the use of hydrogenated fat.  What they are sometimes using instead are the same palm oil and coconut oil (both of which contain saturated) that they removed from their products in the 1980s. 

Food Labels and Trans Fat:

As you might suspect labels can be tricky when it comes to trans fat.  A product can say Zero Trans Fat, and that does not necessarily mean the product is heart healthy as it may still be high in saturated fat, like the below label.

Also, if a product has 0.5g or less of trans fat the label can state 0g of trans fat. Therefore, you have to look at the ingredient list to really know if a product contains trans fat.  You want to look for partially hydrogenated oils in the ingredient list to determine if there is trans fat present. 


More About Hydrogenated Fats:

In an attempt to find an inexpensive substitute for butter, as far back as 1903, Britain was adding hydrogen gas to liquid (polyunsaturated) oils in a process called hydrogenation.  This hydrogen reacted with the double bonds in the structure of the unsaturated fatty acids of the corn oil.  Hydrogenation creates both saturated and trans fatty acids.  Not only did this make the oil solid at room temperature (so margarine and shortening were possible from oils like corn oil), it also preserved them by making the oil more stable and less likely to go rancid (so baked goods like cookies and chips would have a longer shelf life). 

Rancidity is when oxygen attacks double bonds.

So why is the above flaxseed meal especially prone to rancidity, leading to a distasteful smell for my colleague Roger Hecht?  
Flax seed contains a fatty acid that has 3 double bonds.  As said above, rancidity is when oxygen attacks double bonds.  With more double bonds, more rancidity happens.
Flaxseed meal is a wonderful food but it should be refrigerated to keep it from going rancid.

When concerns arose in about the 1970s and 1980s about the saturated fats in the palm and coconut oils used in baked goods and margarine (in part because they were cheaper than butter)  they were often replaced with these hydrogenated fats made from oils from corn and soybeans.  When used in cookies or potato chips instead using an oil like corn oil that contains polyunsaturated fats, the product had a longer shelf life.  And products like margarine made with corn oil were solid similar to butter. McDonald's and Kentucky Fried Chicken found the hydrogenated fats gave a wonderful crispness to their French fries and chicken that was difficult to replace.  Jif liked the smooth “mouth feel” small amounts of it added to their peanut butter.

Video Clip for the Lecture Outline about

Hydrogenation plus

B. Phospholipids
C. Sterols

approximately 7 minutes

Trans Fatty Acid video

As the Lecture Outline says, plants make sterols, but not cholesterol. An article in the journal Nutrition Today about pistachios said
"Among tree nuts, pistachios are the richest source of phytosterols, particularly beta-sitosterol and campesterol."
"Phytosterols are plant sterols, which compete with cholesterol in the intestinal lumen for uptake into the bloodstream, and phytosterols may reduce cholesterol levels."

"The Pistachio: A Surprising and Colorful Nut"
David Hever, MD, PhD
Susan Bowermanm MS, RD
Nutrition Today
Jan/Feb 2008

The article said that pistachios are botanically related to cashews and mangos (!).  
Although they are native to the high deserts of West Africa and the Middle East, our neighbor California now grows them.

So which fat is best to eat?
The best way to get fatty acids is in WHOLE foods, as you're also getting a variety of vitamins, minerals, phytochemicals and sometimes fiber and protein.  And consuming a lot of refined fats, whether it be in butter, olive oil or margarine can lead to an excess of a particular fatty acid and does not come packaged with other nutrition.

There are definitely times, though, when we may prefer something that is not whole, like when we have a nice slice of toast or we're wanting to stir-fry vegetables.

For bread and toast, what I prefer is butter, and the first reason for that is a personal preference for the taste of butter. Just a little bit goes a long way and I don't think a little bit of butter is going to raise my risk of heart disease, especially when there are also plenty of fruits, vegetables and whole grains in what I eat.

For saut
éing and other uses, I like to use canola oil.  It can be heated to a high temperature, plus it does not have any flavor so you can use it for baking.  It also contains Omega 3's which can help balance out the Omega 6's you find in soybean and corn oil that is the main oils used in a lot of processed foods.  For salads and other uses, olive oil is great and we always have it on hand.  I buy the less refined "Extra Virgin" olive oil that has a green color and a stronger flavor from the phytochemicals that are present.

Since margarine companies want to advertise their product as having no hydrogenated fat and no trans fat, they have been using other ways of making their margarine solid and spreadable.  What some companies are choosing to use are things like palm "oil", which is high in saturated fat.


These lectures have often said that WHOLE foods are usually the best way to get nutrients.  Just look at the nutrients in pistachios, listed in the previously mentioned article.

Serving size: 1 ounce (about 49 kernels)
Energy 165
Total fat 13 g
 Saturated fat 1.5 g
Polyunsaturated fat 4 g
Monounsaturated fat 7 g
Carbohydrate 9 g
Dietary Fiber 3 g
Protein 6 g
Cholesterol 0 mg
Sodium 190 mg
Potassium 310 mg
Vitamin A 4% DV
Vitamin C 2% DV
Calcium 4% DV
Iron 6% DV
Vitamin E 6% DV
Thiamin 15% DV
Vitamin B6 25% DV
Folate 4% DV
Phosphorus 15% DV
Magnesium 10% DV
Zinc 4% DV
Copper 20% DV
Manganese 15% DV
Using the "MAGIC DV", which nutrients would a serving of these pistachios be a good source of?

Our local filberts are just as nutrient dense as these pistachios are.

Click here for the remainder of LECTURE 5A.

INCORRECT.  Saturated fat is not one of the 3 types of lipids.
Click here to return to Lecture.

The most saturated fat is coconut oil.  Is this surprising?  Most people know animal fats are highly saturated, but don't realize tropical oils like coconut and palm oil are highly saturated as well.  Click here to return to lecture.











CORRECT.  Saturated fat is part of one of the 3 types of lipids.

Click here to return to Lecture.

CORRECT.  Cholesterol is one of the three types of lipids.
Click here to return to Lecture.

Click here to return to Lecture.