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The skinny on fats: clarifying the food industry's current understanding of nutritional implications of various forms of fat. (New Product Development).

The movie "Sleeper" opens with Woody Allen, a health-food store owner from the 1960s, awakening in the far-off future from a medical error-induced hibernation. The two future scientists (we can tell they are scientists because they are both wearing white lab coats) bringing him back to consciousness are trying to understand their slowly and comically reviving patient.

"Has he asked for anything?" asks Mr. Scientist.

"Yes, this morning for breakfast he requested something called wheat germ, organic honey and tiger's milk," answers a befuddled Ms. Scientist.

"Oh yes, those are the charmed substances that some years ago were felt to contain life-preserving properties," responds the nutritionally knowledgeable Mr. Scientist.

"You mean there was no deep fat, no steak or cream pies or . . . hot fudge?" queries incredulous Ms. Scientist.

"Those were thought to be unhealthy, precisely the opposite of what we now know to be true."

The future is looking up.

The only part of this classic food science vignette that is unbelievable is that it would take several hundred years for our industry's position on fat and nutrition to change that drastically. Only the Internet is fast enough to keep pace with the changes in the way we think about fat and fat's impact on nutrition. Eat fat, don't eat fat, eat margarine, don't eat margarine, don't eat butter, do eat butter, eat chocolate, don't eat chocolate (send it all to me). But it is possible to make sense of all this.

What is fat?

Fats and oils, as found complete in nature, are very complex mixtures of many components -- triglycerides, diglycerides, monoglycerides, free fatty acids, fat-soluble vitamins, phospholipids, plant sterols, oxidized breakdown products of the fatty acids.

Triglycerides make up the bulk of the fat. These compounds begin with a glycerol molecule that has three alcohol groups. The acid end of a fatty acid molecule attaches to this alcohol group on the glycerol. When three fatty acids are attached to the glycerol, you have a triglyceride. Think of the glycerol as the carrier with three hooks on it that fatty acids can attach to (and, of course, that the fatty acids can detach from when needed for metabolism).

Fatty acids have a carboxylic acid group at one end of the molecule, and a chain or skeleton of carbon atoms that extends from the carboxylic acid group. The exact structures of the fatty acids define the properties of the fat.

So what? Well, the exact set of fatty acids also defines the nutritional implications inherent in the specific fat. Therefore, the first step in understanding fats is to understand the underlying fatty acids. A great place to start is with the question: What are the two worst fats?

The answers are probably not what you expect:

* Too much fat in the diet. Especially too much of the "wrong" fats. Everybody has heard way too much about the "too much fat in the diet" part. The "wrong" fat part is the never-ending and frequently contradictory controversy that Woody Allen assures us will eventually be unequivocally ironed out.

* Too little fat in the diet. Especially too little of the "right" fats. Fear of fat has become so extreme that we have to a huge extent lost the nutritional importance of fat and the valuable, nutritionally functional ingredients that are a part of fat. Yes, just like you can damage yourself by eating too much of the wrong fats, you can also damage yourself by eating too little of the right fats. Yet how could there be such a thing as a "right" fat?

Essential fatty acids

Our mammalian metabolism requires fat to survive. Our bodies can make most of the fatty acids we require from the fats we eat if the particular fatty acid happens to not be present in our diet. But there are two fatty acids that our bodies cannot make, so it is essential to survival that our diet includes these two fatty acids: linoleic acid and aipha-linolenic acid.

Saturated? Hydrogenated? Cis? Trans?

"Saturated" and "hydrogenated" refer to the carbon atoms in the skeleton of the fatty acid and what the carbon atom is bonded to. A little organic chemistry follows: Each carbon atom has four available bonding potentials. When you look at the skeleton or chain of the carbon atoms that is attached to the acid group of the fatty acid, you have one carbon attached to the next carbon attached to the next, and so on until the end of the molecule.

This means that two of the carbon's bonding potentials are used up bonding to the carbon on either side of it; two bonding potentials are still available. If the molecule is fully saturated (hydrogenated), then the other two bonding potentials are used up by having attached hydrogen molecules. The carbon is therefore filled up with as many hydrogens as the carbon can hold.

But the carbon can also double-bond with the carbon next to it. This means that there are three bonds to carbons - one bond to the carbon atom on one side and two bonds to the carbon that it is double-bonded to on the other side. There is still one bonding potential left, and a hydrogen atom takes up that final spot. This is "unsaturated" because that carbon is not saturated with as many hydrogens as it could potentially hold.

When you look at this double-bonded set of carbons, the individual hydrogen atom attached to each of the two carbons can be either on the same side of the molecule or on opposite sides of the molecule.

Lay your fatty acid molecules across the page with the carboxylic acid group on the right side of the page and the carbon skeleton end on the left side of the page. Cis fatty acids have the two hydrogens on the same side of the molecule - either both on the top of the molecule or both on the bottom.

Trans fatty acids have the two hydrogens on the opposite sides of the molecule: one hydrogen on top of the molecule and the other hydrogen on the bottom of the molecule.

Some trans fats exist in nature, primarily in animal fats, although minimally from some plant sources. Most of the trans fats in our diet come from fats that have been purposely hydrogenated in order to create specific fats with specific properties useful in shelf life, manufacturing properties, mouthfeel properties, etc. This is a whole science in itself, and for purposes of this discussion we can just summarize these issues in the accompanying table.

Monounsaturated fatty acids?

Monounsaturated fatty acids are fatty acids that have one (mono) double bond. This term is most immediately associated with olive oil and the Mediterranean diet. The Mediterranean diet is rich in fish, colored vegetables and, unlike the modern U.S. diet, the use of olive oil, and low in the prevalence of saturated fats. The Mediterranean Diet is believed to be part of the reason for the lower incidence of heart and cardiovascular diseases in cultures that adhere to it.

Olive oil is predominantly oleic acid that is a monounsaturated fatty acid. There is much discussion concerning exactly what part of the diet causes the healthier CVD results. One argument centers on whether it is the positive benefits of consuming oleic fatty acids (the monounsaturated fat), or whether it is the result of eating less saturated fats. Both arguments probably have some merit, although much is being discovered about other factors of the diet and lifestyle that also contribute to the beneficial effects.

PUFA?

PUFAs, or polyunsaturated fatty acids, are fatty acids that have more than one double-bond in the carbon skeleton of the molecule. Long chain polyunsaturated fatty acids are particularly newsworthy at this time, and we'll cover these fatty acids in the next section. All fatty acids can be assigned to one of three categories based on size:

* Short chain fatty acids. These fatty acids have less than 10 carbon atoms in the carbon chain portion of the molecule.

* Medium chain fatty acids. These fatty acids have between 10 and 14 carbon atoms in the carbon chain portion of the molecule.

* Long chain fatty acids. These fatty acids have more than 14 carbon atoms in the carbon chain portion of the molecule.

"High in polyunsaturates" has been an ad claim for years, pretty much based on the issue that if you are eating polyunsaturated fats you should theoretically be eating less saturated fat. This has been changing lately as we've begun to see actual positive health benefits from eating certain specific polyunsaturated fats.

Omega-3 vs. Omega-6 fatty acids

"Omega" terms are all over the food industry at the professional, scientific and consumer levels, and there is an enormous misunderstanding of what this is all about. The omega number is merely an additional, very specific way of classifying a specific aspect of the chemical structure of a fatty acid molecule. The omega number tells you where the first double-bond in the specific fatty acid molecule occurs.

Once again, lay your fatty acid molecules across the page with the carboxylic acid group on the right side of the page and the carbon skeleton end on the left side of the page. Begin numbering carbon atoms from the left, and the number of the first carbon that has a double-bond is its omega number.

The omega fatty acids that we are hearing so much about in the food industry fall into two omega categories:

* Omega-3 fatty acids. The essential fatty acid alpha-linolenic acid (11:3n-3) is an omega-3 fatty acid. The omega-3 fatty acids are made only in plants and microalgae. If we don't eat omega-3 fats, our bodies do not get omega-3 fatty acids. Our mammalian bodies cannot make an omega-3 fatty acid out of a fatty acid that is not omega-3. For certain, at least with respect to fats, we are what we eat.

* Omega-6. The essential fatty acid linoleic (18:2n6) is an omega-6 fatty acid.

A simplified version of some of the human nutrition-related reasons that we are hearing so much about this are:

* Omega-3 fatty acids correlate with diets that are higher in fish and traditional vegetables -- what your mom wanted you to eat. The evidence for circulatory and cancer health-related advantages of this type of diet are by now generally accepted.

* Omega-6 fatty acids correlate with diets that are higher in meats and deep fat -- the "Sleeper" diet. One very interesting area of study is the relative proportion of omega-3/omega-6 fat in the diet and how this marker alone may be a significant predictor of a "healthiness quotient" for a particular diet.

* This omega-3/omega-6 ratio is part of the Cave Man Diet discussion. This discussion attempts to determine what the diet of the cave man was 5,000 to l0,000-plus years ago. The assumption is that this is the diet that our bodies evolved to require. By looking at how our diet now differs from that of the Cave Man Diet, deficiencies are theoretically pointed out. The ratio of omega-3/omega-6 fatty acids was very high in the Cave Man Diet and is very low in the current U.S. diet. There is much interesting work going on here, even an upcoming PBS-TV special.

* Docosahexanoic acid (22:6n-3), also known as DI-IA, has made the headlines because it has recently been approved as GRAS for use in baby formula. This is one of the two long chain, polyunsaturated omega-3 fatty acids that predominates in fish oil supplements. Eicosapentanoic acid (20:5n-3), also known as EPA, is the other. Our bodies can create both using alpha linolenic acid as the starring point. However, there is quite a bit of mounting evidence that this rate of manufacture is low, and direct consumption of DHA and EPA (fish, microalgae, fish oils, eggs with enhanced levels of DI-IA) may be of great benefit.

If this discussion has even come close to accomplishing its goal, then you should be able to go to a cocktail party and say something like "Long chain, polyunsaturated omega-3 fatty acid" and have a decent understanding of what this means in terms of the chemical structure of the fatty acid. As a refresher, think size of molecule, degree of saturation, where the first double-bond occurs. Remember, this means that instead of the carbon having a full complement of hydrogen atoms bonded to it, the carbon bonds twice -- double-bonds -- with the next carbon. This part of the molecule is unsaturated because it is not as saturated with hydrogen molecules as it could be. It is not as hydrogenated as it could be. This is a monounsaturate if this is the only double-bond in the molecule. ft is a polyunsaturated fatty acid if it has more than one double-bond. This molecule will be a trans fatty acid if the two hydrogens that are there are on opposite sides of the molecule. This molecule will be a cis fatty acid if the t wo hydrogens are on the same side of the molecule.

Finally, chocolate and deep fat!

I am not aware of any loudly proclaimed health and nutritional benefits of frying in deep fat. Yet. Deep-frying a turkey not only doesn't count, but comes awfully close to the nutrition version of going against the natural order of things. Please, no letters to the editor that the fat doesn't actually penetrate into the turkey (unless you deep-fry it in omega-3 fish oil, in which case the claim would be that the turkey absorbs all of it). Save it for the infomercial.

However, we have all seen the articles proclaiming the health benefits of the polyphenols in chocolate. Thank you, food science! More than a few copies of these articles have been framed and mounted on the wall right next to the family pictures. Forget about the fat -- bring on the polyphenols.
Property                        Effect on     Effect on
                               Melting Point  "Health"

Increased Chain Length           Increase     Negative
Increased Saturation             Increase     Negative
Increased Trans Configuration    Increase     Negative


John K. Ashby, Ph.D. is vice president, technical for the California operation of Mane Inc., an international flavor, fragrance and raw material company.
COPYRIGHT 2002 Putman Media, Inc.
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Comment:The skinny on fats: clarifying the food industry's current understanding of nutritional implications of various forms of fat. (New Product Development).
Author:Ashby, John K.
Publication:Food Processing
Article Type:Brief Article
Geographic Code:1USA
Date:Jul 1, 2002
Words:2352
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