Fats Getting from to How are fats digested, utilized, and stored?

Fats Cholesterol Omega-3 Trans Fats LDL HDL Fatty Acids Sterols
So far we’ve called fats oils or fats. We’ve referred to cholesterol, unsaturated fats, monounsaturated fats, polyunsaturated fats, saturated fats, and trans fats. You may have heard of HDL, or the ‘good cholesterol’ and LDL, or the ‘bad cholesterol’ and you may have heard of the health benefits of Omega-3. We’re going to introduce terms like lipids, fatty acids, and sterols. Fat is a necessary constituent of the human diet, but not all fats are created equal. Some fats are better than others. Lipids Triglycerides Oils What are they?

Fats Where do they come from?
Fats are mostly found in oils, milk, and meats. Fats are predominantly animal source, but there are some plant sources of oils. Where do they come from?

Where are Carbohydrates found on the Food Pyramid?
Fats Animal fats are found in oils, milk, and meats & beans. Plant oils are found in some fruits and vegetables. Generally plant oils are better for you than animal fats. Any food cooked in fat will absorb some fat. P P P P P GRAINS VEGETABLES FRUITS OILS MILK MEAT & BEANS Where are Carbohydrates found on the Food Pyramid?

Functions of Fats in the Diet
Provide Energy Provide Essential Fatty Acids Provide Fat Soluble Vitamins Provide Flavor and Satisfaction (satiety) Fat provides 9 kcal/g versus 4 kcal/g for carbohydrates. This is a more effective way to store energy, and this energy can be stored for indefinite periods of time. Food fats supply the body with essential fatty acids and carry fat-soluble vitamins. Fats add flavor to foods. Because fats stay in the stomach much longer than carbohydrates, and even proteins, fats provide satiety. Satiety can be described as the feeling of satisfaction, the feeling of fullness, or the loss of hunger. Why do we need them?

Provide Energy Provide Essential Fatty Acids Provide Fat Soluble Vitamins Provide Flavor and Satisfaction (satiety) Each gram of fat provides 9 Calories of fuel. A body needs a constant energy supply. As glycogen levels are depleted, fats are broken down to be used as energy. Remember that some tissues require fat rather than glucose for energy. Muscles use a mixture of both glucose and fat for energy. The heart, which is a muscle, uses predominantly fatty acids for energy. Still, the predominant use of fat is not immediate energy but long term storage of energy. Why do we need them?

Provide Energy Provide Essential Fatty Acids Provide Fat Soluble Vitamins Provide Flavor and Satisfaction (satiety) An essential nutrient is one that must be be supplied by the diet because the body cannot manufacture it. Even though glucose is essential to health and life, glucose is not considered to be an essential nutrient because the body can convert fructose and galactose to glucose. This is not the case with all fatty acids. We’ll talk more about fatty acids soon. Why do we need them?

Provide Energy Provide Essential Fatty Acids Provide Fat Soluble Vitamins Provide Flavor and Satisfaction (satiety) Some vitamins are water soluble and others are fat soluble. B complex vitamins and Vitamin C are water soluble. Vitamins A, D, E, and K are fat soluble vitamins. Fats are needed to transport the fat soluble vitamins into cells. Remember, all metabolism takes place at the cellular level and no metabolism can take place except within the cell. Why do we need them?

Provide Energy Provide Essential Fatty Acids Provide Fat Soluble Vitamins Provide Flavor and Satisfaction (satiety) Because fat delays stomach emptying time, the person feels ‘full’ longer. Why do we need them?

Functions of Fats in the Body
Adipose Tissue - Protects Organs - Regulates Temperature Cell Membrane Structure - Forms part of cell membrane - Helps transport nutrients across cell membranes It is important to have some fat in the body. Body fat is called adipose tissue. Adipose tissue protects organs from damage. Without adipose tissue, any jarring or bumping might injure or rupture our liver, stomach, intestines, gall bladder, kidneys, or any other abdominal organ. Adipose also helps the body to conserve heat, or keep the body warm. People with markedly decreased adipose tissue cannot maintain a normal body temperature and feel cold. Fats also help to form the membrane structure of cell membranes. Fats also help to transport nutrients across cell membranes. Blood is water soluble. Many body components are fat soluble. Like oil and water, these materials don’t often mix well. Some fats have properties of both water and fat. They act as mediators or buffers in transporting pure fats though a water soluble environment. Why do we need them?

Glycerol and Fatty Acids What are the Building Blocks?
Fats Glycerol and Fatty Acids Every fat molecule is composed of a glycerol molecule and at least one fatty acid. What are the Building Blocks?

What are the Building Blocks?
Fats Monoglyceride A fatty acid is also called a glyceride. If there is just one fatty acid chain attached to the glycerol, then that fat is a Monoglyceride. Glycerol 1 Fatty Acid What are the Building Blocks?

Fats Diglyceride If there are two fatty acid chains attached to the glycerol, then that fat is a Diglyceride. In actuality, monoglycerides and diglycerides make up less than 1% of all the fat we eat. The other 99% is in the form of triglycerides. Glycerol 2 Fatty Acids What are the Building Blocks?

Fats Triglyceride And 3 fatty acids attached to one glycerol is a triglyceride. Excess triglycerides make up adipose tissue. Triglycerides are also associated with the build up of plaque in our arteries causing high blood pressure, stroke, and heart attack. Triglycerides are found in both plants and animals. Glycerol 3 Fatty Acids What are the Building Blocks?

Glyceride Structure Determines Type Saturated – MUFA – PUFA - Trans
Fats Glyceride Structure Determines Type You’ve heard of triglycerides. Now you even know why they’re called triglycerides. But what about those other terms: saturated, unsaturated, monounsaturated, polyunsaturated, trans fats? What’s that all about? To better understand saturation, you need to look at the structure of the fatty acid chains. Let’s review a little bit of chemistry. Saturated – MUFA – PUFA - Trans

Fats Atoms and Covalency 4 2 1 How many bonds?
Each element has a certain valency, or the number of bonds it must make with another element when it forms a molecule. Carbon must make four bonds. Hydrogen must make one bond. Oxygen must make two bonds. Double bonds can be made, but the total of bonds from each atom must equal each element’s valency. You don’t need to be a chemist. Just try to understand the concept. How many bonds?

How many hydrogens are attached to each carbon link?
Fats The Glyceride Chain Saturated fats are composed of a strand of carbon molecules with two specific ends. The first carbon uses one bond to attach itself to the chain, a double bond to attach itself to an oxygen molecule and the fourth bond to attach to an oxygen molecule. It is this oxygen that then attaches to glycerol. The first end is a carbon attached to 3 hydrogen atoms and the fourth available bond is attached to another carbon. Because hydrogen atoms can only make one bond, they can’t attach any further. The chain continues until it reaches the end. The last carbon’s first bond is to the prior carbon, and the three bonds left over are attached to hydrogen atoms. The end carbons aren’t all that important. How many hydrogens are attached to each carbon link?

How many hydrogens are attached to each carbon link?
Fats Saturated Fat It’s the chain of carbons that are important. When each chained carbon has a single bond with its neighboring carbon and the other two bonds connected to a two hydrogen atoms, then the fat is saturated. Saturated means all available spots are filled (saturated) with hydrogen. Saturated fats are generally solids at room temperature. Most animal fats are saturated fats. Saturated fats are known to contribute to cardiovascular disease and cardiac disease. How many hydrogens are attached to each carbon link?

Fats Monounsaturated Fat – MUFA
When there exists one double bond between two carbons, two hydrogens have no place to attach. If it only happens in one connection, that fat is called a monounsaturated fat. More recently, a monounsaturated fat has been referred to as MUFA. Olive oil is a monounsaturated fat and has been found to have a positive effect on cholesterol levels when used in place of a saturated fat. How many hydrogens are attached to each carbon link?

Hydrogenation – Adding Hydrogens
Fats Hydrogenation – Adding Hydrogens Hydrogenation is the process of breaking those double bonds . . Why would anyone turn a healthy unsaturated fat to an unhealthy saturated fat?

Fats Hydrogenation – Adding Hydrogens Leaving empty bonds . . . Why would anyone turn a healthy unsaturated fat to an unhealthy saturated fat?

Fats Hydrogenation – Adding Hydrogens And filling those empty bonds with hydrogen. The result? A hydrogenated saturated fat. Do you know that soft margerine is better for you than hard or stick margerine. Now YOU know why. Why would anyone turn a healthy unsaturated fat to an unhealthy saturated fat?

Actual peanut butter container circa 1930
Fats But WHY would people deliberate harm our food? Sometimes it was done so that lesser saturated fats would more resemble the saturated fats. The most common example is margerine. Margerine is mostly unsaturated fats, that’s why it’s soft, even when refrigerated. Hydrogenated margerine, unlike tub or soft margerine, resembles butter in that it can be formed into solid sticks and maintain that shape when refrigerated. The main reason unsaturated fats are hydrogenated, though, is to lengthen the shelf life. Hydrogenation acts as a preservative. Hydrogenated fats don’t spoil as quickly as unsaturated oils. In the 1930’s, hydrogenation was thought to be a good thing. Now we know better. Actual peanut butter container circa 1930

Why are they called ‘Trans Fats’?
What about those trans fats? In most cases, hydrogenation isn’t full. Not every double bond is broken, some double bonds remain. In this instance, the term is partially hydrogenated. But, in the process of hydrogenation, the chemical structure is slightly altered. Why are they called ‘Trans Fats’?

Notice that the hydrogen atoms attached to the double bonded carbons are on the same side. This is called ‘cis’. You don’t need to know this term. Just listen and watch and see what happens. Why are they called ‘Trans Fats’?

One of the double bonds is broken and two hydrogen atoms are added. Why are they called ‘Trans Fats’?

But in the process, at least one pair of hydrogen atoms of a doubled bonded carbon pair change from the ‘cis’ position to the ‘trans’ position. Research has now demonstrated that trans fats, those partially hydrogenated fats that alter the position of hydrogens, are even more detrimental to health than naturally saturated fats. Trans fats from trans fatty acids in the body and these trans fatty acids actually contribute to higher production of lipids in the body. The evidence is so compelling that the amount of trans fats must be included on the food labels. In response to the growing health concern of trans fats, the food industry has developed ‘trans free’ solid and soft tub margarines and cooking fats. Why are they called ‘Trans Fats’?

Listing Trans Fats on the Food Label
The food label, by FDA mandate, must tell you the trans fat amounts. The food label from the left is from natural popcorn with no preservatives and no added fats for a ‘buttery’ taste. The popcorn on the right has a ‘buttery’ taste and will last on the shelf longer, but at what cost? The 3 g of trans fat comes directly from the hydrogenation process of the soybean oil. Just another example of trying to ‘outdo’ Mother Nature and paying the consequences. Listing Trans Fats on the Food Label

Fats (Lipids) The Mouth Mechanical – Mastication
Let’s talk about the digestion of fats. There are no enzymes in the mouth that will break down fats. Chewing (mastication) does cause some mechanical digestion in breaking the fat into smaller chunks.

Fats (Lipids) The Stomach Mechanical – Churning
Chemical– Hydrochloric Acid The food is swallowed and peristalsis, the churning action of the stomach, and hydrochloric acid helps to further break down fat chunks. No fat enzymes are released into the stomach.

Fats (Lipids) The Small Intestine Emulsifier – Bile
Enzyme – Pancreatic Lipase Enzyme – Intestinal Lipase Lipogenesis – Rebuilding the Triglycerides Absorption – via the villi into the blood stream Once the fat reaches the small intestine, bile is released. Bile is produced in the liver and stored in the gall bladder. When fats are eaten, the gall bladder releases the stored bile into the small intestine. Bile emulsifies the fat. Emulsification breaks the larger fat globules into smaller particles, giving the lipase more surface area to act upon.

Fats (Lipids) The Small Intestine Emulsifier – Bile
Enzyme – Pancreatic Lipase Enzyme – Intestinal Lipase Lipogenesis – Rebuilding the Triglycerides Absorption – via the villi into the blood stream Lipase is the enzyme that breaks down lipids to glycerides and fatty acids. Lipase is secreted by both the pancreas (pancreatic lipase) and the small intestine (intestinal lipase). Regardless of the source, the enzymes do their work in the small intestine. Glycerol, fatty acids are then recombined to form triglycerides. This is called lipogenesis. These triglycerides are covered with special proteins called lipoproteins (containing both fat and protein properties) and move into the blood stream. Proteins are water soluble. Fats are not. This is why fats need to be wrapped with lipoproteins before they can be transported to the blood system.

Fat Storage Adipose Tissue Adipose Tissue – Long Term Storage
Triglycerides are then stored as adipose tissue The triglycerides are then stored as adipose tissue. Adipose Tissue – Long Term Storage

Burning Fats for Energy
Fats are not meant to be metabolized for quick energy. That is the function of carbohydrates. There are two conditions when the body will turn to fats for quick energy. The first is when the body is in starvation mode. During prolonged periods of fasting, the glucose circulating in the blood will be depleted. As the glucose is being used up, the glucagon acts upon glycogen to break down those molecules to the simple glucose molecules. Remember that only about 24 hours worth of glycogen is stored. Once the glycogen supply is exhausted (or near exhaustion), the body will turn to adipose tissue as its primary source of energy.

Burning Fats for Energy
Diabetics who don’t have enough insulin are unable to use the circulating glucose because insulin is needed to transport the glucose inside the cells. When insulin levels are low, blood glucose levels can be very high, yet the body is unable to use the glucose. The body will then burn fat, or adipose tissue, for quick energy. This also results in high levels of ketones causing the body to turn to a state of acidosis. Ketones can sometimes be detected on the breath, which is usually described as sweet and fruity. Left untreated, this state of metabolic acidosis can be fateful.

Provide Energy Provide Essential Fatty Acids Provide Fat Soluble Vitamins Provide Flavor and Satisfaction (satiety) Let’s go back to the Functions of Fats. The body needs fatty acids to prevent diseases. Some fatty acids can be ‘refashioned’ from other fatty acids by restructuring the glyceride chain. This is similar to the body restructuring fructose and maltose to make glucose. Essential fatty acids are those fatty acids that are necessary for a healthy body, but cannot be manufactured by the body. Essential fatty acids must be obtained via the diet. Why do we need them?

Must be obtained in the diet.
Essential Fatty Acids Linoleic Acid (Omega-6) Linolenic Acid (Omega-3) Let’s go back to the Functions of Fats. The body needs fatty acids to prevent diseases. Some fatty acids can be ‘refashioned’ from other fatty acids by restructuring the glyceride chain. This is similar to the body restructuring fructose and maltose to make glucose. Essential fatty acids are those fatty acids that are necessary for a healthy body, but cannot be manufactured by the body. Essential fatty acids must be obtained via the diet. Linoleic Acid is more commonly known as Omega-6 and Linolenic Acid is more commonly known as Omega-3. They are both polyunsaturated fatty acids. Must be obtained in the diet.

Food Sources of Omega-3 and Omega-6
Essential Fatty Acids Linoleic (Omega-3) and Linolenic (Omega-6) acids are founds in fish, fish oils, eggs, dairy products, and nuts. Food Sources of Omega-3 and Omega-6

Health Benefits of Omega-3 and Omega-6
Tissue strength Cholesterol metabolism Muscle tone Blood clotting Heart action Some of the known health benefits of Omega-3 and Omega-6 are tissue strength, cholesterol metabolism, muscle tone, blood clotting, and heart action.

Lipoproteins Lipoproteins wrap themselves around fat molecules so fat can travel in the blood stream. The blood then carries these packages of fat to and from cells to supply necessary nutrients.

Lipoproteins and Density
High Density [High Protein Load] Low Density [Low Protein Load] The ratio of protein to fat determines the density of the lipoprotein. A high density lipoprotein has a higher ratio of protein, thus not as much fat. A low density lipoprotein has a lower ratio of protein, thus more fat.

HDL’s and LDL’s HDL  [Hint: H = Healthy] LDL  [Hint: L = Lethal]
We group these lipoproteins into two classes – HDL’s and LDL’s. High density lipoproteins are higher in protein than in fat. LDL’s are lower in protein than fat. Healthy people have a higher level of HDL’s than LDL’s.

What about Cholesterol?
Sterol – a subgroup of steroids Occurs naturally in animal foods Not present in plant foods Cholesterol is not a fat, but is contained in animal fats. Cholesterol is actually a sterol, which is a subgroup of steroids. Sterols provide cell structure and also play an important role in sending signals from cell to cell. The body can actually produce all the cholesterol it needs. High blood levels of cholesterol have been linked to high blood pressure and coronary heart disease.

Cholesterol and Atherosclerosis
Your Fundamentals book also states that LDL’s transport cholesterol to body cells. Increased levels of LDL’s cause fatty deposits on the walls of arteries and veins. This condition is known as atherosclerosis. The buildup of these fatty deposits cause narrowing of the arteries leading to coronary artery disease and possibly a heart attack. As a result, LDL is often referred to as “bad cholesterol.” HDL’s remove cholesterol from the bloodstream, bringing the cholesterol back to the liver where it can be used to produce bile. Because HDL’s remove cholesterol from the bloodstream, a high level of HDL’s protect against heart disease. HDL’s are known as “good cholesterol.” Keep in mind, though, that “bad cholesterol” and “good cholesterol” are misnomers because these lipoproteins transport cholesterol, they aren’t the cholesterol itself. Monounsaturated fats (MUFA’s) and poly unsaturated fats (PUFA’s) have been shown to lower LDL’s and raise HDL’s. Saturated fats raise HDL’s but also raise LDL’s. Trans fats have raise LDL’s, but have no real effect on HDL’s.

What “Good” is Cholesterol?
Form Cell structure Form Vitamin D Form Estrogen Form Testosterone Cholesterol is needed to stabilize and support cell membranes. Cholesterol is also needed to form Vitamin D and some hormones, including the sex hormones.

Types of Fat Monounsaturated Polyunsaturated Saturated Trans Fats
Olives, Olive Oil Canola Oil Peanut Oil Cashews, Almonds, Nuts Avocados Corn Soybean Safflower Cottonseed Oils Fish Saturated Trans Fats Here are some examples of MUFA’s, PUFA’s, saturated fats, and trans fats. Many products that used to be high in trans fats are no longer. Many companies advertise “Trans Fat Free” or “No Trans Fats.” To be healthy, look for anything on the label that specifically states Trans Fats or contains some type of wording like ‘hydrogenated’ or ‘partially hydrogenated.’ As you look at this list, ask yourself, which foods contain ‘Visible Fats’ and which contain ‘Invisible Fats?’ Whole Milk, Ice Cream Butter, Cheese Red Meat Chocolate, Coconuts Margarine ‘Partially hydrogenated’ products and oils Deep fried foods ‘Fast Foods’

Phospholipids Phospholipids are a triglyceride in which the 3rd glyceride chain has been replaced with a phospherous group. Like lipoproteins, phospholipids also allow transport of fats through the blood stream. Phospholipids are also a key building block of cell membranes.

Fats / Lipds – Wrapping It Up
Triglycerides (Fatty Acids) Unsaturated / Saturated / Trans fats Lipoproteins (HDL’s and LDL’s) Cholesterol (not truly a lipid) To review Fats are also known as lipids. Dietary fats are molecules with a fatty acid chains These chains are called glycerides. Most fats are triglycerides. The most important function of fats is energy. Fats are stored as adipose tissue. Bile and lipase are important agents in the digestion of fats. Unsaturated fats have at least one double carbon bond. Polyunsaturated fats have 2 or more double carbon bonds. Monounsaturated fats have only 1 double carbon bonds. In general, unsaturated fats are better for you than saturated fats. Also, in general, unsaturated fats are softer, even liquid, at room temperature. Unsaturated fats can have more hydrogen atoms added to break the carbon bonds, thus turning an unsaturated fat into a saturated fat. This process is called hydrogenation. Hydrogenation sometimes cause a twisting of the molecule to form trans fats. Trans fats have been determined to be harmful to the heart and cardiovascular system. Lipoproteins are fats wrapped in protein. This allows the fat molecules to travel freely throughout the blood system. HDL’s are higher in protein, lower in fat. HDL’s (remember healthy) are good for you. LDL’s are lower in protein, higher in fat. LDL’s (remember lethal) are bad for you. Cholesterol is not a fat, but is found in animal fats. The body can produce all the cholesterol it needs. High blood levels of cholesterol, like triglycerides and LDL’s, are associated with high blood pressure and coronary artery disease.

Fats Dietary Requirements
Carbohydrates 50% Proteins 40% Fats 10% How many fats should a person consume each day? The Food and Nutrition Board of the National Research Council recommends Total fat intake should not exceed 20% to 35% Less than 10% total fat intake should come from saturated and trans fats combined Fats higher in Omega-3 and Omega-6 are preferred over other fats Polyunsaturated fats and monounsaturated fats may help to raise HDL levels while lowering LDL levels.

Fats Getting from to So what are you thinking of now? Let me guess . . .

Fats All of this is important, because if you don’t understand that
burning fats for quick energy causes ketones as a waste product and that these ketones will cause the potentially fatal state of metabolic acidosis, then how will you understand diabetic coma in Med Surg and Pharmacology? And if you don’t understand that fats play an important role in cellular metabolism but some fats are better than others Cholesterol, Triglyceride, LDL, and HDL levels can all be influenced by diet Essential fatty acid deficiencies can lead to hair loss, blood clotting problems, impaired vision, impaired mental states and memory, learning problems and growth problems in children, Then how will you progress to a good understanding of Diet Therapy in Term II? And how will you promote your own, your loved ones, and your patients’ healthy dietary choices?

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