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Fat makes up a larger caloric portion of the American diet than any other foodstuff. The average American’s food intake is 40% fat. He eats animal foods rich in fat; he tosses his salads in fat; and he spreads his bread with fat. When he eats out, he patronizes fast food restaurants that deep-fry and grill-fry most of their food in fat.

Fat makes up a larger caloric portion of the American diet than any other foodstuff. The average American’s food intake is 40% fat. He eats animal foods rich in fat; he tosses his salads in fat; and he spreads his bread with fat. When he eats out, he patronizes fast food restaurants that deep-fry and grill-fry most of their food in fat.

He lives off the “fat of the land” and “high on the hog,” and he suffers from some of the most serious health problems in the world. His arteries become clogged with choles- terol, his breathing becomes short and he dies in what should be his prime years.

He lives off the “fat of the land” and “high on the hog,” and he suffers from some of the most serious health problems in the world. His arteries become clogged with cholesterol, his breathing becomes short and he dies in what should be his prime years.

Fat is not the only culprit in the American diet, and indeed fat is not “bad,” just as proteins and carbohydrates are neither good nor bad. Fat is needed in the diet. It is pre- sent in every food we eat—even cucumbers, watermelons and apples have fat.

Fat is not the only culprit in the American diet, and indeed fat is not “bad,” just as proteins and carbohydrates are neither good nor bad. Fat is needed in the diet. It is present in every food we eat—even cucumbers, watermelons and apples have fat.

It is the particular sources from which people get their fat and the way in which fat is utilized in the diet that is “bad,” or at least unhealthy.

It is the particular sources from which people get their fat and the way in which fat is utilized in the diet that is “bad,” or at least unhealthy.

What you will learn in this lesson is what fats are, how the body uses them, how they are digested and how they should be obtained in the diet. This is the type of understand- ing we need to evaluate intelligently the role of fats in the human diet.

What you will learn in this lesson is what fats are, how the body uses them, how they are digested and how they should be obtained in the diet. This is the type of understanding we need to evaluate intelligently the role of fats in the human diet.

== What Are Fats? ==

== What Are Fats? ==

Fats, or hydrocarbons, are one of three food categories, the other two being proteins and carbohydrates.

Fats, or hydrocarbons, are one of three food categories, the other two being proteins and carbohydrates.

Fats are composed of the same three elements as carbohydrates—carbon, oxygen and hydrogen. However, they are much poorer in oxygen and richer in carbon and hy- drogen than are carbohydrates. Because of this higher carbon and hydrogen content, fats have a greater heat or energy equivalent than carbohydrates.

Fats are composed of the same three elements as carbohydrates—carbon, oxygen and hydrogen. However, they are much poorer in oxygen and richer in carbon and hydrogen than are carbohydrates. Because of this higher carbon and hydrogen content, fats have a greater heat or energy equivalent than carbohydrates.

The fats found in plants are manufactured from water and carbon dioxide with the aid of chlorophyll, much in the same manner that the carbohydrates in a plant are pro- duced. The fats found in humans and animals come from two sources: 1) from the fats in the diet and 2) from the metabolism of excess carbohydrates into fat. The greatest amount of fat in the body usually comes from carbohydrate metabolism.

The fats found in plants are manufactured from water and carbon dioxide with the aid of chlorophyll, much in the same manner that the carbohydrates in a plant are produced. The fats found in humans and animals come from two sources: 1) from the fats in the diet and 2) from the metabolism of excess carbohydrates into fat. The greatest amount of fat in the body usually comes from carbohydrate metabolism.

As far as the human digestive process is concerned, fats are composed of two com- ponents: 1) glycerin (or glycerol) and 2) fatty acids.

As far as the human digestive process is concerned, fats are composed of two components:  

 

# glycerin(or glycerol)

# fatty acids.

Glycerin is the energy source of fats and is metabolized much in the same manner as are the carbohydrates. The glycerin is broken down into sugars which may be used by the body for fuel.

Glycerin is the energy source of fats and is metabolized much in the same manner as are the carbohydrates. The glycerin is broken down into sugars which may be used by the body for fuel.

Fat that is unsaturated is composed of fatty acids in which one or more of the carbon atoms in the chain do not have all of their accompanying hydrogen atoms. In other words, unsaturated fatty acids have open available links in their chains.

Fat that is unsaturated is composed of fatty acids in which one or more of the carbon atoms in the chain do not have all of their accompanying hydrogen atoms. In other words, unsaturated fatty acids have open available links in their chains.

These open links in fatty acid chains are important. The body is able to combine var- ious nutrients with the fatty acid chains through these open links. This combination of nutrients and fatty acids allows both of them to be transported through the body where they can be used in building cell structure.

These open links in fatty acid chains are important. The body is able to combine various nutrients with the fatty acid chains through these open links. This combination of nutrients and fatty acids allows both of them to be transported through the body where they can be used in building cell structure.

Animal fats contain very little unsaturated fats. The chief sources of unsaturated fatty acids are nuts and seeds. Almost all vegetable fats in their natural state have a high pro- portion of unsaturated fatty acids.

Animal fats contain very little unsaturated fats. The chief sources of unsaturated fatty acids are nuts and seeds. Almost all vegetable fats in their natural state have a high proportion of unsaturated fatty acids.

The term polyunsaturated means that there is a large number of fatty acids which have two or more open links in their chains. These vegetable polyunsaturated fats are used in making margarine and shortening. This is done by the process of hydrogenation.

The term polyunsaturated means that there is a large number of fatty acids which have two or more open links in their chains. These vegetable polyunsaturated fats are used in making margarine and shortening. This is done by the process of hydrogenation.

Hydrogenation causes liquid fats to become solidified by introducing hydrogen atoms into the open links of the fatty acid chains. If a fat becomes completely hydro- genated, it is rock-hard. The process is controlled, however, so that varying consisten- cies of hydrogenated fats can be produced.

Hydrogenation causes liquid fats to become solidified by introducing hydrogen atoms into the open links of the fatty acid chains. If a fat becomes completely hydrogenated, it is rock-hard. The process is controlled, however, so that varying consistencies of hydrogenated fats can be produced.

The hydrogenation process consists of heating the fats and oils to a temperature of 212 to 400 degrees. Hydrogen is then mixed in, along with Some catalytic agents, such as nickel or platinum. The fatty acids then take on the hydrogen atoms and begin to so- lidify.

The hydrogenation process consists of heating the fats and oils to a temperature of 212 to 400 degrees. Hydrogen is then mixed in, along with Some catalytic agents, such as nickel or platinum. The fatty acids then take on the hydrogen atoms and begin to solidify.

The heating of the oils during this process destroys any vitamins that might be pre- sent. The addition of the hydrogen atoms fills the open links in the fatty acid chains and thus prevents nutrients from binding with the acids. As a result, hydrogenated fats can supply only empty calories and no nutritive value.

The heating of the oils during this process destroys any vitamins that might be present. The addition of the hydrogen atoms fills the open links in the fatty acid chains and thus prevents nutrients from binding with the acids. As a result, hydrogenated fats can supply only empty calories and no nutritive value.

Since hydrogenated fats cannot become rancid (nor can they support life), they are manufactured extensively. Margarine, cooking fats, processed cheeses, lard and peanut butter are but a few products subjected to hydrogenation.

Since hydrogenated fats cannot become rancid (nor can they support life), they are manufactured extensively. Margarine, cooking fats, processed cheeses, lard and peanut butter are but a few products subjected to hydrogenation.

The saturated fats are found chiefly in animal fats. Saturated fats are solid at room temperature, unlike the liquid unsaturated fats. Saturated fats are found in animal flesh, dairy products, eggs and coconuts. It should be noted that the saturated fats in coconuts have a different chemical structure.

The saturated fats are found chiefly in animal fats. Saturated fats are solid at room temperature, unlike the liquid unsaturated fats. Saturated fats are found in animal flesh, dairy products, eggs and coconuts. It should be noted that the saturated fats in coconuts have a different chemical structure.

Like hydrogenated fats, the saturated fats cannot enter into a nutrient bonding within the body. Consequently, they cannot be used effectively by the body in cellular compo- sition than the saturated animal fats metabolism. The saturated fats are usually empty calories that contribute to a fat build-up within the body. They serve no useful function.

Like hydrogenated fats, the saturated fats cannot enter into a nutrient bonding within the body. Consequently, they cannot be used effectively by the body in cellular composition than the saturated animal fats metabolism. The saturated fats are usually empty calories that contribute to a fat build-up within the body. They serve no useful function.

=== Cholesterol: Villain or Hero? ===

=== Cholesterol: Villain or Hero? ===

Cholesterol is not a harmful substance as such. The body uses it in all of its tissues. It occurs in the brain, spinal column and skin. Cholesterol is part of the raw materials from which bile salts, sex and adrenal hormones and vitamin D are made. It combines with proteins to enable fats to be carried to the cells.

Cholesterol is not a harmful substance as such. The body uses it in all of its tissues. It occurs in the brain, spinal column and skin. Cholesterol is part of the raw materials from which bile salts, sex and adrenal hormones and vitamin D are made. It combines with proteins to enable fats to be carried to the cells.

The liver produces all the cholesterol the body needs for its functions. In an average adult, about 3,000 milligrams of cholesterol are produced each day, regardless if choles- terol is present in the foods eaten or not.

The liver produces all the cholesterol the body needs for its functions. In an average adult, about 3,000 milligrams of cholesterol are produced each day, regardless if cholesterol is present in the foods eaten or not.

When additional cholesterol enters the body through diet, an excess occurs. Typi- cally, a person consuming animal products ingests about 800 milligrams of cholesterol a day. This extra cholesterol is deposited along the walls of the arteries throughout the body.

When additional cholesterol enters the body through diet, an excess occurs. Typically, a person consuming animal products ingests about 800 milligrams of cholesterol a day. This extra cholesterol is deposited along the walls of the arteries throughout the body.

As these deposits grow, a condition known as atherosclerosis or “hardening of the arteries” occurs. The arteries become constricted and circulation is seriously impaired. This impaired circulation contributes to a wide variety of problems, including loss of hearing, baldness, shortness of breath, dizziness and heart attacks. All tissues the body are harmed since a reduced amount of oxygen and nutrients reach the cells.

As these deposits grow, a condition known as atherosclerosis or “hardening of the arteries” occurs. The arteries become constricted and circulation is seriously impaired. This impaired circulation contributes to a wide variety of problems, including loss of hearing, baldness, shortness of breath, dizziness and heart attacks. All tissues the body are harmed since a reduced amount of oxygen and nutrients reach the cells.

Atheroschlerosis now affects a majority of Americans, regardless of age. Autopsies of infants less than one year old, many of them fed commercially prepared baby formu- las, revealed large amounts of cholesterol already deposited within their arteries.

Atherosclerosis now affects a majority of Americans, regardless of age. Autopsies of infants less than one year old, many of them fed commercially prepared baby formulas, revealed large amounts of cholesterol already deposited within their arteries.

There is absolutely no need for saturated fats or cholesterol in the diet. The body manufactures all of its cholesterol needs. The consumption of additional amounts in the form of saturated animal fats destroys the health of the body at the cellular level.

There is absolutely no need for saturated fats or cholesterol in the diet. The body manufactures all of its cholesterol needs. The consumption of additional amounts in the form of saturated animal fats destroys the health of the body at the cellular level.

== Fat Digestion ==

== Fat Digestion ==

Fat digestion takes much longer than the digestion of carbohydrates and somewhat longer than the digestion of proteins. A raw salad consisting of nonstarchy vegetables can be digested within two to three hours. When free fats such as corn, sesame, peanut or other oils are added to the salad, digestion is delayed for another two or three hours.

Fat digestion takes much longer than the digestion of carbohydrates and somewhat longer than the digestion of proteins. A raw salad consisting of non-starchy vegetables can be digested within two to three hours. When free fats such as corn, sesame, peanut or other oils are added to the salad, digestion is delayed for another two or three hours.

Coating our food with free oils inhibits the natural digestive processes by preventing digestive juices access to these foods until the oils are digested. Consequently, by the time the oils or fats surrounding the other food particles are digested, the elementary car- bohydrates or proteins in the vegetables have begun to ferment (carbohydrates) or putre- fy (proteins) in the stomach.

Coating our food with free oils inhibits the natural digestive processes by preventing digestive juices access to these foods until the oils are digested. Consequently, by the time the oils or fats surrounding the other food particles are digested, the elementary carbohydrates or proteins in the vegetables have begun to ferment (carbohydrates) or putrefy (proteins) in the stomach.

=== Fats Require Special Digestion ===

=== Fats Require Special Digestion ===

The emulsified fats are then split by enzymes into fatty acids and glycerol. At this point, the fats can be absorbed through the intestinal mucosa. During absorption, the fatty acids and glycerol recombine with a small amount of protein to form microscopic particles of fat called chylomicrons.

The emulsified fats are then split by enzymes into fatty acids and glycerol. At this point, the fats can be absorbed through the intestinal mucosa. During absorption, the fatty acids and glycerol recombine with a small amount of protein to form microscopic particles of fat called chylomicrons.

The fats in the form of chylomicrons are now soluble enough to enter lymph circu- lation. The fatty acids are converted to the liver to acetate or ketone bodies as an energy source for the cells.

The fats in the form of chylomicrons are now soluble enough to enter lymph circulation. The fatty acids are converted to the liver to acetate or ketone bodies as an energy source for the cells.

The fat which is not used immediately for the body’s energy needs is stored primarily in adipose tissue. Adipose tissue is a special kind of tissue (found mainly around the stomach, thighs and buttocks) which contains the necessary enzymes to continually pro- duce and release new fat to meet the body’s needs.

The fat which is not used immediately for the body’s energy needs is stored primarily in adipose tissue. Adipose tissue is a special kind of tissue (found mainly around the stomach, thighs and buttocks) which contains the necessary enzymes to continually produce and release new fat to meet the body’s needs.

== How The Body Uses Fat ==

== How The Body Uses Fat ==

==== Fat is used in the body in four main ways: ====

==== Fat is used in the body in four main ways: ====

# As a source of heat and energy;

# As a source of heat and energy.

# As padding and insulation for the organs and nerves;

# As padding and insulation for the organs and nerves.

# As a regulator for the fat soluble vitamins (A, D, E and K); and

# As a regulator for the fat soluble vitamins (A, D, E and K).

# As a source of the essential fatty acids.

# As a source of the essential fatty acids.

=== Fats Supply Heat and Energy ===

=== Fats Supply Heat and Energy ===

Each gram of fat supplies nine calories. This is more than twice the amount of energy supplied by a gram of carbohydrates. The body uses fat in much the same way as it uses carbohydrates. That is, fat is used mainly as an energy food.  Fats are converted to energy by being split into fatty acids and glycerol. Glycerol is then converted to either glucose or glycogen. At this point, the usual processes of carbo- hydrate metabolism take over to produce needed energy from the glucose and glycogen.  While fats may supply twice the caloric energy of carbohydrates, we find that they must undergo a longer digestive process before they are ready for an essentially carbo- hydrate metabolism. In general, carbohydrates do a more efficient job of providing the body with readily usable fuel. Fats are valuable in that they may provide a form of stored energy, but strictly speaking, they are not a necessity in the diet as far as a fuel source goes. Fats, however, are usually more extensively stored within the body than are carbohy- drates and may be converted into fuel when the body’s carbohydrate reserves are deplet- ed. In fact, this is exactly what occurs when a person goes on a diet, fasts, or is exposed to extremely cold weather. As the stored carbohydrate reserves in the liver are exhaust- ed, the body’s fat reserves are metabolized for a new supply.  It should be understood that these fat reserves in the body do not simply come from the fat that is eaten in the diet. When an excess of carbohydrates is eaten, it is converted by the body into fat and stored.  In this way, the body can store and use fat without having a large amount of fat in the diet. The fat deposits could be viewed as a carbohydrate bank, where deposits and withdrawals are made as necessary.

Each gram of fat supplies nine calories. This is more than twice the amount of energy supplied by a gram of carbohydrates. The body uses fat in much the same way as it uses carbohydrates. That is, fat is used mainly as an energy food.   

 

Fats are converted to energy by being split into fatty acids and glycerol. Glycerol is then converted to either glucose or glycogen. At this point, the usual processes of carbo- hydrate metabolism take over to produce needed energy from the glucose and glycogen.   

 

While fats may supply twice the caloric energy of carbohydrates, we find that they must undergo a longer digestive process before they are ready for an essentially carbo- hydrate metabolism. In general, carbohydrates do a more efficient job of providing the body with readily usable fuel. Fats are valuable in that they may provide a form of stored energy, but strictly speaking, they are not a necessity in the diet as far as a fuel source goes.

 

Fats, however, are usually more extensively stored within the body than are carbohydrates and may be converted into fuel when the body’s carbohydrate reserves are depleted. In fact, this is exactly what occurs when a person goes on a diet, fasts, or is exposed to extremely cold weather. As the stored carbohydrate reserves in the liver are exhaust- ed, the body’s fat reserves are metabolized for a new supply.  It should be understood that these fat reserves in the body do not simply come from the fat that is eaten in the diet. When an excess of carbohydrates is eaten, it is converted by the body into fat and stored.  In this way, the body can store and use fat without having a large amount of fat in the diet. The fat deposits could be viewed as a carbohydrate bank, where deposits and withdrawals are made as necessary.

We can see that fat within the body is an important energy and heat source, but strict- ly speaking, fat in the diet is not an essential outside source for this fuel.

We can see that fat within the body is an important energy and heat source, but strictly speaking, fat in the diet is not an essential outside source for this fuel.

=== Fats Provide Padding and Insulation ===

=== Fats Provide Padding and Insulation ===

Some of the vitamins are termed “fat-soluble.” This means that fatty compounds must be present in the intestines for these vitamins to be absorbed. The fat soluble vita- mins are A, D, E and K. The other vitamins (B, C, etc.) are termed “water-soluble.”

Some of the vitamins are termed “fat-soluble.” This means that fatty compounds must be present in the intestines for these vitamins to be absorbed. The fat soluble vita- mins are A, D, E and K. The other vitamins (B, C, etc.) are termed “water-soluble.”

If these fat-soluble vitamins are obtained from the foods in which they naturally oc- cur and eaten in an unprocessed state, they will be readily absorbed by the body. The wholesome foods which contain these vitamins also contain the necessary fatty com- pounds for their absorption.

If these fat-soluble vitamins are obtained from the foods in which they naturally occur and eaten in an unprocessed state, they will be readily absorbed by the body. The wholesome foods which contain these vitamins also contain the necessary fatty com- pounds for their absorption.

If these vitamins, however, are extracted (as in supplements) or occur in foods which have been fragmented, processed or subjected to heat, then their absorption will be im- paired. Heating fatty foods, for example, renders almost all of the fat-soluble vitamins useless.

If these vitamins, however, are extracted (as in supplements) or occur in foods which have been fragmented, processed or subjected to heat, then their absorption will be impaired. Heating fatty foods, for example, renders almost all of the fat-soluble vitamins useless.

=== Fats Are Sources of the Essential Fatty Acids: Vitamin F ===

=== Fats Are Sources of the Essential Fatty Acids: Vitamin F ===

Even if no fat is eaten, the body can manufacture most of its fatty acids from fruit and vegetable sugars. There are three fatty acids, however, that the body is said to be unable to synthesize. These are called the essential fatty acids.

Even if no fat is eaten, the body can manufacture most of its fatty acids from fruit and vegetable sugars. There are three fatty acids, however, that the body is said to be unable to synthesize. These are called the essential fatty acids.

The three essential fatty acids are linoleic acid, arachidonic acid and linolenic acid. The linoleic acid is generally thought to be the most important and has been termed ab- solutely essential to life by some nutritional researchers. The arachidonic acid can act as a fairly good substitute for linoleic acid. The third acid, linolenic, is said to be only a partially satisfactory substitute for linoleic acid in that it can support growth but cannot aid in the other functions that linoleic acid performs.

The three essential fatty acids are linoleic acid, arachidonic acid and linolenic acid. The linoleic acid is generally thought to be the most important and has been termed absolutely essential to life by some nutritional researchers. The arachidonic acid can act as a fairly good substitute for linoleic acid. The third acid, linolenic, is said to be only a partially satisfactory substitute for linoleic acid in that it can support growth but cannot aid in the other functions that linoleic acid performs.

=== Functions ===

=== Functions ===

Collectively, these essential fatty acids are sometimes referred to as vitamin F. The fatty acids or vitamin F are considered necessary for normal glandular activity, especial- ly the adrenal glands. The adrenal and sex hormones seem to require the presence of these fatty acids for their manufacture.

Collectively, these essential fatty acids are sometimes referred to as vitamin F. The fatty acids or vitamin F are considered necessary for normal glandular activity, especially the adrenal glands. The adrenal and sex hormones seem to require the presence of these fatty acids for their manufacture.

The essential fatty acids are thought to be involved in many of the body’s metabolic processes. They promote the availability of calcium and phosphorous to the cells and help form the fat-containing portion of every cell’s structure. They are also considered a factor in growth and in reproduction.

The essential fatty acids are thought to be involved in many of the body’s metabolic processes. They promote the availability of calcium and phosphorous to the cells and help form the fat-containing portion of every cell’s structure. They are also considered a factor in growth and in reproduction.

=== Requirement ===

=== Requirement ===

No minimum requirement for vitamin F or the essential fatty acids has been estab- lished. The National Research Council has stated that about 1% of the total daily calo- ries of about 2200-2800 per day should consist of unsaturated fats to provide a margin of safety for the intake of essential fatty acids.

No minimum requirement for vitamin F or the essential fatty acids has been established. The National Research Council has stated that about 1% of the total daily calories of about 2200-2800 per day should consist of unsaturated fats to provide a margin of safety for the intake of essential fatty acids.

The following wholesome foods contain the shown percentages of linoleic acid, the major fatty acid. In general, if the intake of linoleic acid in the diet is adequate, then all other fatty acid needs are also well satisfied.

The following wholesome foods contain the shown percentages of linoleic acid, the major fatty acid. In general, if the intake of linoleic acid in the diet is adequate, then all other fatty acid needs are also well satisfied.