Lecture 5A: Lipids

As we just talked about and as the Lecture Outline says, the 3 types of LIPIDS are

triglycerides
phospholipids and
cholesterol

A. Triglycerides (in 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.

The 2 parts of a triglyceride are

one glycerol molecule in each triglyceride and
three fatty acid molecules in each triglyceride

How Fatty Acids Differ

Chain Length:

Fatty acids are even-numbered chains of 4-22 carbon atoms. Short chain fatty acids have from 4 to 10 carbon atoms in their chain.
Degree of Saturation.

To understand saturation, start with the rule of chemistry that carbon can form 4 bonds.

If a carbon atom has 4 elements bonded to it (as does the carbon atom on the far left of the fatty acid below, it is called saturated.

If the bond has an atom missing, as do the 6th & 7th carbon atoms from the left below, it is called unsaturated and that bond is called a double bond.

A fatty acid with no double bonds between carbon atoms is called a saturated fatty acid and something with mostly SaFAs is solid at room temperature.

A fatty acid with one double bonds between carbon atoms is called a monounsaturated fatty acid and something with mostly MUFAs is liquid at room temperature.

A fatty acid with two or more double bonds between carbon atoms is called a polyunsaturated fatty acid and something with mostly PUFAs is liquid at room temperature.

Now watch the Video Clip below. It will help you draw triglycerides and fatty acids.

Video Clip: Triglycerides
approximately 5 minutes

If an approximately 5-minute movie isn't showing up just above 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.

As mentioned in the Video Clip, there were a few mistakes in how fatty acids were drawn.

Look at the "silent movie" Video Clip below. Like the Charlie Chaplin movie classics, there is no sound, but please don't expect Charlie Chaplin-type entertainment.

"Silent Movie" Video Clip: Foods approximately 3 minutes If this 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.		As you're watching the "Silent Movie", you can use the page in the packet (Food Sources of Carbohydrates, Lipids, Proteins.... the LIPIDS part) and also the chart below:

The particular baby formula shown in this "Silent Movie" Video Clip has two fatty acids added to it to try to be more like breast milk. These fatty acids are DHA and ARA (also abbreviated AA). Later in this lecture, you'll find our a little more about DHA and ARA.		"The label below is the COCONUT "OIL" shown in the "Silent Movie" Video Clip above. It's contains many saturated fatty acids and it's very solid at room temperature. Coconut "Oil"

You still have some incomplete parts of the first part of page 73 in your packet, so let me repeat a little and fill in a little.

Lipids are very complicated and still not well understood. Your questions will help me as I continue to try to clarify them for myself as well as for you.

A. Triglycerides (in 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.

The 2 parts of a triglyceride are

one glycerol molecule in each triglyceride and
three fatty acid molecules in each triglyceride

How Fatty Acids Differ

Chain Length:

Fatty acids are even-numbered chains of 4-22 carbon atoms. Short chain fatty acids have from 4 to 10 carbon atoms in their chain.
Degree of Saturation.

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 sources 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 perhaps raise risk of heart disease.

A 1965 study looked at people in Crete who were eating a Mediterranean diet which is low in animal protein and low in animal fat. They found that their adipose tissue had a 11% lower concentration of saturated fat than the group they studied in a city in New York. ("Cardiovascular Benefits of the Mediterranean Diet", Caleb E. Pineo and John J.B. Anderson, Nutrition Today, May/June 2008.)

Unsaturated Fatty Acids- The cell membranes in plants and animals have the most use for unsaturated fatty acids in their day-to-day lives. Essential fatty acids are polyunsaturated fatty acids and they're called essential because we must get them from food since our body can't make them the way it makes other fatty acids.

High-fat plant foods like 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 perhaps lower risk of of heart disease.

When I was a graduate student in the early 70s, it was thought that the essential unsaturated fatty acids of a food like corn oil were sufficient. We now know that we need a large variety of unsaturated fatty acids from our food supply.

Omega-6 Unsaturated Fatty Acids - This is the type of fatty acid made in by plants for storage and is the most common unsaturated fatty acid we usually get when we eat the oil of certain seeds, such as corn oil or soybean oil. Michael Pollan, who wrote The Omnivore's Dilemma, says that omega-6s are involved in the rigidity of cell walls, clotting and the inflammation response.

Omega-3 Unsaturated Fatty Acids - 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 omega-3 fatty acid (shorter chain ones) while some wild fish (like salmon) have still another type of beneficial omega-3 fatty acid (long chain ones).

Most people associate omega-3 fatty acids with fish, but fish get them from green plants (specifically algae), who use them during photosynthesis. Pollan says they “appear to play an important role in neurological development and processing, the permeability of cell walls, the metabolism of glucose and the calming of inflammation.”

Since the two fatty acids compete with each other for attention in cells, the ratio in the diet between omega-3s and omega-6s may matter more than the absolute quantity of either fat. Thus too much omega-6 from oils like corn oil may be just as much a problem as too little omega-3.

Michael Pollan goes on to say in his book In Defense of Food,

"And that might well be a problem for people eating a Western diet. As the basis of our diet has shifted from leaves to seeds, the ratio of omega-6s to omega-3s in our bodies has changed too. The same is true for most of our food animals, which industrial agriculture has taken off their accustomed diet of green plants and put on a richer diet of seeds. The result has been a marked decline in the amount of omega-3s in modern meat, dairy products, and eggs, and an increase in the omega-6s. At the same time, modern food production practices have further diminished the omega-3s in our diet. Omega-3s, being less stable, than omega-6s, spoil more readily, so the food industry, focused on store food, has been strongly disposed against omega-3s long before we even knew what they were." (page 126)

In regard to food animals and their diet, Pollan says that butter from pastured cows eating green grass, actually has respectable amounts of omega-3s. (page 127)

The two essential fatty acids are linoleic acid and linolenic acid. Below is linoleic acid, which is an omega-6 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 considered essential because we can make them from the essential ones. But 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.

All of these fatty acids can do both good things and bad things for our health, so it's good to have neither too much nor too little of them in our diet and to have a balance of them.

Butyrate (also known in slightly as butyric acid) is the major energy source for colonic epithelial cells and plays an essential role in the maturation of colonic epithelium, regeneration of mucosa, induction of epithelial cell differentiation, and stimulation of their apoptosis.40 A reduced level of luminal SCFAs may play a role in the onset of IBD.

As discussed earlier, fatty acids vary by:

1. Chain length (# Carbon atoms ) and
2. Degree of Saturation (# Double Bonds)

The chart below shows these differences in both chain length and degree of saturation.

Chemical Names and Descriptions of some Common Fatty Acids


COMMON NAME (scientific name is different) * essential fatty acids	# Carbon atoms	# Double Bonds	Food Sources (Most of these are oils because that's what many of the charts I found had. But the cells of all parts of a plant or animal make fatty acids, even the cells of what we think of as a low-fat food, like spinach.)	A Few Roles & Benefits
Butyric acid	4	0	butterfat	major energy source for colon epithelial cells and plays an essential role in colonic health
Caproic Acid	6	0	butterfat
Caprylic Acid	8	0	coconut oil
Capric Acid	10	0	coconut oil
Lauric Acid	12	0	coconut oil
Myristic Acid	14	0	palm kernel oil
Palmitic Acid	16	0	palm oil
Palmitoleic Acid	16	1	animal fats, macademia nuts
Stearic Acid	18	0	animal fats
Oleic Acid	18	1	olive oil, almonds, peanuts, avocados
Vaccenic Acid	18	1	butterfat
*Linoleic Acid	18	2	many vegetable oils like corn oil, sunflower oil & safflower oil; almonds, walnuts, peanuts	involved in rigidity of cell walls, clotting and the inflammation response
Conjugated linoleic acid (CLA)			in the meat and dairy products of ruminants (Conjugated linoleic acid is a trans fat, though some researchers claim that it is not harmful in the same fashion as other trans fatty acids, but rather is beneficial. The trans fat is not counted as trans fat on food labels.)
*Alpha-Linolenic Acid (ALA) an omega-3 FA	18	3	flaxseed oil (linseed), walnuts, green leaves	plants- assoc. with photosynthesis; animals- neurological development and processing, the permeability of cell walls, the metabolism of glucose and the calming of inflammation
Gamma-Linolenic Acid (GLA)	18	3	borage oil
Arachidic Acid	20	0	peanut oil, fish oil
Gadoleic Acid	20	1	fish oil
Arachidonic Acid (ARA or AA)	20	4	liver fats
Eicosapentaenoic Acid (EPA)	20	5	cold water fish like salmon	cells release it from their membranes to communicate with each other
Behenic Acid	22	0	rapeseed (canola) oil
Erucic Acid	22	1	rapeseed (canola) oil
Docosahexaenoic Acid (DHA)	22	6	fish oil	animals make from ALA to think & see
Lignoceric Acid	24	0	small amounts in most fats

Your Lecture Outline on page 73 lists linoleic and linolenic as the essential fatty acids. It goes on to give other examples of omega-3 fatty acids such as EPA and DHA. Then thee are a few blanks:

(these are also _ _ FAs). What do you think goes there?

Hydrogenated Fatty Acids - 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. Most of the double bonds were now filled (saturated) with hydrogen. 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?

The above chart shows that one of the fatty acids in flax seed 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.

Trans Fatty Acids - Hydrogenation of polyunsaturated fatty acids saturates with hydrogen most of the double bonds but it does leave some of the double bonds. These partially hydrogenated and artificial fatty acids now have an unusual shape that has an effect in the body similar to saturated ones.

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, as far as I can tell, 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.

In a later chapter, we'll look at how genetic engineering is providing the food industry with a substitute soybean oil that has no trans fat. Although those soybeans have been engineered to have less of the fatty acid that needs to be hydrogenated, the beneficial omega-3 fatty acids in soybean oil are no longer present.

Video Clip for the Lecture Outline about

Hydrogenation plus

B. Phospholipids
C. Sterols
approximately 7 minutes

This will help you fill in other parts of page 73 in the packet.

Now that you have an understanding of fatty acids, I hope you can see why the food industry has been interested in finding ways to use inexpensive fats, like soybean oil, but to saturate them so they would be less likely to go rancid.

An interesting fact about phospholipids is that they make up about 25% of the dry weight of the brain.

Many of the fatty acids that are part of phospholipids in the brain are omega-3 fatty acids they can "preserve or enhance brain function".

("A Systemic Review of the Roles of n-3 Fatty Acids in Health & Disease,
ND Riediger et al, Journal of the American Dietetic Association, April 2009, p. 671)

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 Bowerman MS, RD
Nutrition Today
Jan/Feb 2008

The article said that pistachios are botanically related to cashews and mangoes (!).

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?

In my opinion, 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 that can be detrimental to health.

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.

A second reason I like it is that I can easily buy butter that comes from Oregon farmers.

For sautéing and other uses, I like to use a variety of fats and oils. One time we'll buy corn oil, the next time canola oil and the next time soybean oil. For salads and other uses, olive oil is great and we always have it on hand. There is a growing California olive industry so we can even buy it more regionally produced. We also keep some sesame oil on hand.

As this lecture has discussed, different oils have different fatty acids, and we're continuing to learn the benefits of individual fatty acids.

When I was on a study leave in Indonesia in 1990, I visited Akad Gizi (Academy of Nutrition) in Jakarta and talked to the researcher below who was investigating the effect of palm oil on the cholesterol level in rats.

I don't know what he found out, but a March, 2006, Chefs Collaborative Communiqué: A Slippery Slope: The search for sustainable fats and oils said that with new research, coconut oil is understood to be a very good source of medium-chain fatty acids (known as MCT- medium-chain triglycerides), "which aren't stored as readily in the body as oils composed of long-chain triglycerides (LCT)".

The above photo and the one below are at an is oil-palm plantation we visited on Malaysia.

This sign was at the Singapore Zoo.
Wikipedia has more information: http://en.wikipedia.org/wiki/Oil_palm

Here's putting it another way:

We continually search for an inexpensive and healthy fat, frequently changing course. The food industry wants one that has a long shelf life and won't go rancid easily.

mid 1800s	Demand for a less expensive replacement for butter. Oleomargarine made from beef.
1911	Proctor & Gamble Company introduces Crisco brand shortening made from partially hydrogenated oils. Under the influence of temperature, pressure, and catalysts, hydrogen gas is added to oil.
mid 1950s	Palm oil & coconut oil used in baked goods & margarine as less inexpensive, stable and solid.
1980s	Health authorities conclude that the saturated fats in products like lard and palm oil increase risk of LDL-cholesterol leading to increased risk of heart disease. Groups like the Center for Science in the Public Interest (CSPI) pressure the food industry to switch from palm & coconut oil to partially hydrogenated vegetable oils.
1990s	Research emerges indicating that the trans-fatty acids (TFA) formed during hydrogenation raise LDL-cholesterol. CSPI reverses its earlier supportive position and lobbies FDA to regulate TFAs.
about 2005	Products were reformulated with oil blends including palm oil. Research with "interestification" of stearic acid in a manufacturing process to synthesize fats with a high melting point useful for frying. It leads to positioning changes of FA on the glycerol backbone of the TG, changing the fat's digestion, absorption and health effects. Notice in the chart above in this lecture called Chemical Names and Descriptions of some Common Fatty Acids, stearic acid is a long chain fatty acid that is saturated. Through conventional plant breeding and genetic engineering, oilseeds are being bred to produce oils that are just as stable, solid and low in TFAs (more later). The fatty acid composition has been changed to “low-linolenic” and “high-oleic”. (Note from instructor: This decreases the content of beneficial omega-3 fatty acids, which both decreases the likelihood of it going rancid but also decrease possible health benefits.) Kris-Etherton PM, Grieal AE, Psota TL, Gebauer SK, Zhang J, Etherton TD. Dietary stearic acid and risk of cardiovascular disease: intake, sources, digestion, and absorption. Lipids. 2005;40:1193-1200.

On page 47 of your packet, I give my definition of'

WHOLE foods
PARTITIONED foods
REFINED foods

I am considering adding a fourth category called SYNTHESIZED foods.

These would be foods created in a laboratory using chemical reactions.

Examples would be the hydrogenated fats and interesterified fats described above.

Another example of a SYNTHESIZED food would be high fructose corn syrup, which was first developed in 1957 and it's made by enzymatic processing of corn syrup.

To me it seems like a waste of money to try to create something artificially when we'd be better off to limit fried foods and use small amounts of butter. (I've said before that I have a bias here as I love the taste of butter and I'm not tempted to overeat it.)

Also, it's large corporations like Archer Daniels Midlands who can afford to do the research and develop these products. They may feel a more critical commitment to profits for their executives and current shareholders rather than our long-term health.

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. As mentioned earlier, what some companies are choosing to use are things like palm "oil" (oil- palm trees are picture above), which is high in saturated fat. See the INGREDIENTS lists pictured above and below.

"Imports of palm oil from Malaysia to the United States have increased by 50,000 tons in the first 6 months of 2006 as compared with the same time in 2005."

("Reducing the Trans-Fatty Acid Content in Foods: Regulatory and Food Industry Approaches"; Peter A. Graf, Shawna Lemke and Maureen DiRienzo; Nutrition Today, March/April 2008.)

Count the number of ingredients in this spread.

I'm just reading Michael Pollan's new book called "In Defense of Food", a wonderful read. He has a whole section on margarine and other imitation foods.

As I've said before, my opinion is that butter is a better choice than any margarine but it's difficult to convincingly make that point when what Pollan calls the "nutritional industrial complex" has such a strong interest in persuading us otherwise. There is a lot of profit in the food industry being able to constantly re-engineer ingredients to respond to the latest fad.

In my opinion as well as Pollan's, all margarines are fake foods and they are most likely nutritionally inferior to a natural food. Pollan says "adulteration has been repositioned as food science."

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.