1. Fats and Cholesterol Presented by Janice Hermann, PhD, RD/LD
OCES Adult and Older Adult Nutrition Specialist

2. Chemistry of Fatty Acids and Triglycerides
Like carbohydrates, fatty acids and triglycerides are composed of carbon (C), hydrogen (H) and oxygen (O).
These lipids have many more carbons and hydrogen’s in proportion to their oxygen’s; however, and so they supply more energy per gram.
Chemistry of Fatty Acids and Triglycerides
Like carbohydrates, fatty acids and triglycerides are composed of carbon (C), hydrogen (H) and oxygen (O). These lipids have many more carbons and hydrogen’s in proportion to their oxygen’s; however, and so they supply more energy per gram.

3. Fatty Acids
A fatty acid is an organic acid-a chain of carbon atoms with hydrogens attached, it has an acid group (COOH) at one end and a methyl group (CH3) at the other end.
There are over forty different fatty acids
Fatty acids
A fatty acid is an organic acid-a chain of carbon atoms with hydrogens attached, that has an acid group (COOH) at one end and a methyl group (CH3) at the other end. There are over forty different fatty acids.

4. Chain Length
Most fatty acids contain even numbers of carbons in the chains, up to 24 carbons in length.
Long-chain (12 to 24 carbons) fatty acids in meats, fish and vegetable oils are most common in the diet
Medium –chain (6 to 10 carbons) are less common
Short-chain (fewer than 6 carbons) fatty acids occur, mostly in dairy products
Chain length
Most naturally occurring fatty acids contain even numbers of carbons in the chains, up to 24 carbons in length. The long-chain (12 to 24 carbons) fatty acids of meats, fish and vegetable oils are most common in the diet. Smaller amounts of medium –chain (6 to 10 carbons) and short-chain (fewer than 6 carbons) fatty acids also occur, primarily in dairy products.

5. Degree of Saturation Fatty acids can be saturated or unsaturated.
A saturated fatty acids has all the carbons in the chain filled with hydrogen’s.
An unsaturated fatty acid is missing hydrogen’s, and as a result the carbons bond to each other twice, forming what is called a double bond.
One place in the fatty acid missing hydrogen’s the fatty acid is monounsaturated.
Two or more places in the fatty acid missing hydrogen’s the fatty acid is polyunsaturated.
Degree of Saturation
As mentioned, fatty acids are long chains of carbons with hydrogen’s attached. In addition, fatty acids can be saturated or unsaturated. A saturated fatty acid has all the carbons in the chain filled with hydrogen’s. Stearic acid is an 18 carbon saturated fatty acid with no double bonds. An unsaturated fatty acid is missing hydrogen’s, and as a result the carbons bond to each other twice, forming what is called a double bond. If there is one place in the fatty acid missing hydrogens (or one double bond) the fatty acid is monounsaturated. Oleic acid is an18 carbon monounsaturated fatty acid with one double bond. If there are two or more places in the fatty acid missing hydrogen’s (two or more double bonds) the fatty acid is polyunsaturated. Linoleic acid is an 18 carbon polyunsaturated fatty acid with two double bonds; whereas linolenic acid is an 18 carbon polyunsaturated fatty acid with three double bonds.

6. Monounsaturated Fatty Acid
Polyunsaturated Fatty Acid

7. Location of Double Bonds
Fatty acids are identified by the position of the double bond nearest the methyl (CH3) end.
A polyunsaturated fatty acid with its first double bone three carbons away fro the methyl end is an omega-3 fatty acid.
An omega-6 fatty acid is a polyunsaturated fatty acid with its first double bond six carbons away from the methyl end.
Location of Double Bonds
Fatty acids can differ not only in the length of their chains and the degree of saturation, but also in the location of the double bonds. Polyunsaturated fatty acids are identified by the position of the double bond nearest the methyl (CH3) end of the carbon chain, which is described by an omega number. A polyunsaturated fatty acid with its first double bone three carbons away fro the methyl end is an omega-3 fatty acid. An omega-6 fatty acid is a polyunsaturated fatty acid with its first double bond six carbons away from the methyl end.

9. Essential Fatty Acids
The body can make saturated fatty acids and the body can convert some saturated fatty acids into monounsaturated fatty acids.
The body cannot make two polyunsaturated fatty acids, linoleic acid (omega-6) and linolenic acid (omega-3), and therefore these are essential and must be provided from the diet.
Essential Fatty Acids
The body can make all but two fatty acids. The body can make saturated fatty acids, and the body can convert some saturated fatty acids into monounsaturated fatty acids if the body needs them. However, our body is not able to make two polyunsaturated fatty acids, linoleic acid (omega-6 fatty acid) and linolenic acid (omega-3 fatty acid). These two polyunsaturated fatty acids are therefore essential and must be provided from the diet. From these two polyunsaturated fatty acids the body can make the other fatty acids the body needs that are important in the maintaining the structure of cell membranes, make hormone like compounds that help regulate blood pressure, blood clotting, blood lipids, and immune response to injury and infection. 

10. Triglycerides
Fats in our body and in food are made up of fatty acids and glycerol called triglycerides.
Glycerol is a water soluble compound that can bind to three fatty acids.
Monoglyceride – one fatty acid on glycerol.
Diglyceride – two fatty acids on glycerol.
Triglyceride – three fatty acids on glycerol.
Triglycerides
Few fatty acids occur free in foods or in the body. Most often they are incorporated into triglycerides. Triglycerides are made up of two substances, fatty acids and glycerol. Glycerol is a water soluble compound that can bind to three fatty acids. To add a fatty acid to glycerol a condensation reaction occurs where a hydrogen atom (H) from the glycerol and a hydroxyl (OH) group from a fatty acid combines forming a molecule of water (H2O) and leaving a bond between the other two molecules. When one fatty acid is on the glycerol the compound is called a monoglyceride. When two fatty acids are on the glycerol the compound is called a diglyceride. And when there are three fats on the glycerol, the compound is called a triglyceride. Most fats in foods and in our bodies are in the form of triglycerides.

12. Solid or Liquid Fats
The relative amounts of different fatty acids effects whether a fat is solid or liquid.
Unsaturated fats tend to be liquid at room temperature and contain more unsaturated fatty acids.
Saturated fats tend to be solid at room temperature and contain more saturated fatty acids.
Exceptions are tropical oils, such as palm oil, palm kernel oil, cocoa butter and coconut oil. Even though these fats are liquid at room temperature they are very saturated.
Foods contain combinations of the three types of fatty acids. Completely saturated fats and completely polyunsaturated fats are very rare in nature. Whether a fat is solid or liquid depends of the relative amounts of the different types of fatty acids and the temperature. Unsaturated fats tend to be liquid at room temperature and contain more unsaturated fatty acids. Most saturated fats are solid at room temperature and contain more saturated fatty acids. Exceptions are tropical oils, such as palm oil, palm kernel oil, coco butter and coconut oil. These fats are from vegetable sources and are liquid at room temperature because of their short carbon chains (8 to 14 carbons) but their fatty acids are very saturated.

13. Fats in Food
Foods contain combinations of the three types of fatty acids.
Completely saturated fats and completely polyunsaturated fats are rare in nature.
The dominate fatty acid in a food determines whether the fat is refereed to as saturated or unsaturated.
The dominate fatty acid in the fat determines whether the fat is refereed to as saturated or unsaturated. The following table shows the fatty acids composition of some common fats, oils, and foods. Lard, for example, contains over one-third saturated fatty acids. Even though the other fatty acids are monounsaturated or polyunsaturated, it is refereed to as a saturated fat. Corn oil contains significant amounts of both saturated and monounsaturated fatty acid. However, since about half of the fatty acids in corn oil are polyunsaturated, it is refereed to as a polyunsaturated fat.

15. Modifying Fats In food processing polyunsaturated fats maybe modified.
Hydrogenation makes liquid polyunsaturated fats more solid and more saturated.
Saturated fats are less susceptible to oxidation and thus are more stable
Saturated fats are more solid and thus more pliable
Modifying fats
Saturation also influences stability. All fats can become rancid when exposed to oxygen. Oxidation of fats produces a variety of compounds that smell and taste rancid. Polyunsaturated fats are the must susceptible to oxidation because double bonds are unstable; monounsaturated fats are slightly less susceptible and saturated fats are the most resistant to oxidation and thus are least likely to become rancid. Manufactures can protect foods from oxidation in several ways. They can seal products in air-tight nonmetallic containers, protected from light and refrigerated, which is expensive and inconvenient. They can add antioxidants to compete for the oxygen and thus protect the oil, examples are the additives BHA and BHT and vitamin E. Or they may saturate some or all of the unsaturated sites by adding hydrogen molecules, a process known as hydrogenation.
Hydrogenation offers two advantages. First it protects against oxidation by making polyunsaturated fats more saturated. Second it alters the texture of foods by making liquid vegetable oils more solid. Margarine and shortening are examples of liquid polyunsaturated oil that are hydrogenated to become more solid.

16. Modifying Fats
In the process of hydrogenation not all unsaturated fatty acids are hydrogenated.
Hydrogenation changes some remaining unsaturated fats from a “cis” (same side) to a “trans” (opposite side)
Trans fatty acids function more like saturated fats and thus may increase the risk of heart disease.
In the process of hydrogenation not all polyunsaturated fatty acids are hydrogenation. Some of the polyunsaturated fatty acids that remain unsaturated after hydrogenation change shape from a cis to a trans configuration. In nature, most double bonds are cis, meaning that the hydrogens next to the double bonds are on the same side of the carbon chain. Only a few fatty acids, notably those found in milk and meat products are trans fatty acids, meaning the hydrogens next to the double bonds are on opposite sides of the carbon chain. These arrangements result in different configurations for the fatty acids, and this difference affects their function in the body. Trans fatty acids behave more like saturated fats than like unsaturated fats. Trans fats have been associated with higher risk of heart disease.

18. Chemistry of Phospholipids
Phospholipids have a glycerol backbone with fatty acids attached at two of the three sites and a phosphate group attached to the third site.
The phosphate group is a water-soluble group and the fatty acids are fat-soluble groups. This allows phospholipids to dissolve in both water and fat.
Chemistry of Phospholipids
Phospholipids have a glycerol backbone with fatty acids attached at two of the three sites and a phosphate group attached to the third site. Other compounds can then attach to the phosphate group. The phosphate group is a water-soluble group and the fatty acids are fat-soluble groups. This allows phospholipids to dissolve in both water and fat.

21. Phospholipids in the Body
Because phospholipids can dissolve in both fat and water they:
Are an important structural part of cell membranes.
Help fats and fat like compounds, such as fat soluble vitamins and hormones, to move across cell membranes.
Act like emulsifier and help keep fat and fat like compounds dispersed in the blood which is water based.
In the body phospholipids are an important structural part of cell membranes. Because phospholipids can dissolve in both fat and water they can help fats and fat like compounds, such as fat soluble vitamins and hormones, to move across cell membranes. Phospholipids act like emulsifier and help keep fat and fat like compounds dispersed in the blood which is water based.

22. Phospholipids in Food Lecithin is on the best known phospholipids
In foods lecithin keeps fat particles dispersed in water, such as salad dressings and mayonnaise.
Lecithin is an emulsifier found naturally in many foods; eggs, soybeans, and peanuts.
Lecithin is one of the best known phospholipids. Lecithin is used as an emulsifier in many food products to keep fat particles dispersed in water, such as salad dressings and mayonnaise. Lecithin also occurs naturally in many foods that have a high fat content such as eggs, soybeans, and peanuts. In the body phospholipids are an important structural part of cell membranes. Lecithin supplements are often touted because of the role of lecithin in cell wall integrity. However, the body can make all the lecithin it needs in the liver. In addition, most lecithin is broken down by digestive enzymes and little lecithin reaches the tissues intact.

23. Phospholipids in the Body
Phospholipids are important in the body.
Phospholipids are in cell membranes to help fats and fat like compounds such as fat soluble vitamins and hormones move across cell walls.
Phospholipids also help keep fat and fat like compounds dispersed in the blood which is water based.
The body can make lecithin in the liver.

24. Chemistry of Sterols Sterols are multiple- ring structures.
Cholesterol is one of the best known sterols.
Both plant and animal foods contain sterols, but only animal foods contain cholesterol.
Chemistry of Sterols
Sterols are compounds that have a multiple-ring structure. Cholesterol is one of the best known sterols. Both plant and animal foods contain sterols, but only animal foods contain cholesterol.

25. Cholesterol The body needs cholesterol every day.
Cholesterol serves as the starting material for many important body compounds.
Bile acids
Hormones
Vitamin D
Cell membranes
Myelin sheath around nerve fibers
Many vitally important body compounds are sterols, such as bile acids, sex hormones, adrenal hormones, and vitamin D, as well as cholesterol itself. Cholesterol in the body can serve as the starting material for the synthesis of these compounds. Cholesterol is also needed to form cell membranes and the myelin sheath around nerve fibers. 

26. Cholesterol The liver makes cholesterol
The liver makes 800 to 1500 mg of cholesterol every day, much more cholesterol than in food.
In healthy people the body makes less cholesterol if dietary intake is high, and it more cholesterol if dietary intake is low.
Dietary saturated fat intake effects cholesterol synthesis more than dietary cholesterol.
The liver makes about 800 to 1500 mg of cholesterol each day, much more that the cholesterol provided in the diet, out of fragments from fatty acids, proteins, and carbohydrates. Cholesterol is made in many cells, but liver cells make the majority of cholesterol. In a healthy body, if we eat more dietary cholesterol, the body makes less cholesterol. If we eat less dietary cholesterol, the body makes more cholesterol.

27. Digestion
Lipids are not water soluble and digestive are, this makes digestion of lipids more difficult.
Mouth
Little fat digestion occurs in the mouth
Solid fats melt when reach body temperature
An enzyme is released by salivary gland at base of tongue that has a major role in fat digestion for infants.
Digestion
Lipids tend to separate from water, whereas the digestive enzymes are soluble in water. This makes digestion of lipids more complicated.
Little digestion of lipids occurs in the mouth; however, hard fats do begin to melt in the mouth when they reach body temperature. A salivary gland at the base of the tongue releases an enzyme that plays a minor role in fat digestion in adults and an active role in infants.

28. Digestion
Stomach
The churning of the stomach helps disperse fat into smaller droplets which helps expose fat to attack by the gastric lipase enzyme, an enzyme that performs best in the acidic environment in the stomach.
Still, little fat digestion takes place in the stomach.
In the stomach the churning of the stomach helps disperse fat into smaller droplets which helps expose fat to attack by the gastric lipase enzyme, an enzyme that performs best in the acidic environment in the stomach. Still, little fat digestion takes place in the stomach.

29. Digestion Small intestine
Fat in the small intestine triggers the release of cholecystokinin which signals the gallbladder to release bile
Bile acts an emulsifier and disperses fat so pancreatic and intestine lipases can work
Lipases remove the fatty acids from triglycerides leaving monoglycerides, free fatty acids and glycerol.
Lipases remove fatty acids from phospholipids.
Sterols remain unchanged.
When fat enters the small intestine it triggers the release of cholecystokinin, which signals the gallbladder to release its stores of bile. The liver makes bile, which is stored in the gallbladder until needed. Bile contains bile acids, which are made in the liver from cholesterol and thus bile acids have a similar structure to cholesterol. Bile acids pair up with an amino acid. The amino acid end is attracted to water and the sterol end is attracted to fat. This structure improves bile’s ability to act as an emulsifier. Bile helps disperse fat into small particles in the watery fluids so that the intestinal fat digestive enzymes can work. Pancreatic and intestinal lipases (fat digestive enzymes) remove the fatty acids from triglycerides, leaving monoglycerides, free fatty acids and free glycerol. The fat digestive enzymes also remove the fatty acids from phospholipids. Most sterols are absorbed unchanged

30. Fat Digestion

31. Fat Digestion

32. Bile Two things can happen to bile after it has emulsified fat.
Most bile is reabsorbed from the intestine and recycled.
Some bile can be bound to fibers in the large intestine and excreted.
Because cholesterol is needed to make bile, excretion of bile effectively reduced blood cholesterol.
Two possible things can happen to bile after it has entered the small intestine and emulsified fat. Most of the bile is reabsorbed from the intestine and recycled. The other possibility is that some of the bile can be bound to fibers in the large intestine and carried out of the body in the feces. Because cholesterol is needed to make bile, the excretion of bile effectively reduced blood cholesterol.

33. Bile

34. Absorption
Lipid digestion products are absorbed by cells in the small intestine wall.
From the intestine, glycerol, short-chain fatty acids and medium chain fatty acids are released into the bloodstream.
The blood carries these lipids to the liver.
Absorption
The products of lipid digestion are absorbed by intestinal cells. From the intestine glycerol, short-chain fatty acids and medium chain fatty acids are released into the bloodstream and carried to the liver.

35. Absorption
In the intestine, larger monoglycerides and long-chain fatty acids reform triglycerides.
Phospholipids reform inside the intestine.
In the intestine, triglycerides, phospholipids and sterols (cholesterol) are packaged into a carrier called a chylomicron.
Chylomicrons are released into the lymph system which enters the bloodstream near the heart. The blood carries chylomicrons to body cells where lipids are removed.
Larger monoglycerides and long-chain fatty acids are not soluble in the water based blood, and once inside the intestinal wall they reform triglycerides. Phosholipids also reform inside the intestinal wall. Within the intestinal wall, the newly formed triglycerides, phospholipids and sterols are packaged into a lipid-protein carrier called a chylomicron. Chylomicrons are released into the lymph system which enters the bloodstream at the thoracic duct near the heart, thus bypassing the liver. Chylomicrons carry lipids from the intestine to body cells where lipids are removed.

36. Transport
Lipids are transported in the blood in lipid- protein carries called lipoproteins.
The lipids are packed in the center and surrounded by proteins which are water soluble and allow transport in the water based blood.
Transport
Lipids are transported in the blood in lipid-protein carries called lipoproteins. The lipids are packed in the center and surrounded by proteins which are water soluble and allow transport in the water based blood.

37. Chylomicrons Chylomicrons formed in the intestine
They carry lipids, mostly triglycerides, from the intestine to the body.
As cells remove triglycerides the chylomicrons get smaller. After most of the triglycerides have been removed and only protein, cholesterol and phospholipid remnants remain.
Special protein receptors on liver cell membranes recognize and remove the chylomicron remnants from the blood.
Chylomicrons
The chylomicrons are the largest and least dense of the lipoproteins. They carry lipids, mostly triglycerides, from the diet from the intestine to the rest of the body. Cells all over the body remove triglycerides from the chylomicrons as they pass by, so the chylomicrons get smaller and smaller. Within 14 hours after absorption, most of the triglycerides have been removed and only a few remnants of protein, cholesterol and phospholipids remain. Special protein receptors on the membranes of the liver cells recognize and remove the chylomicron remnants from the blood. After collecting the remnants, the liver cells first dismantle them and then either use or recycle the pieces.

38. VLDL
The liver is an active site of lipid synthesis. The liver uses glycerol and short-chain and medium-chain fatty acids from the blood; as well as carbohydrates, proteins and alcohol to make new triglycerides, cholesterol, phospholipids and other compounds.
Newly formed lipids are packaged into a carrier called VLDL (very low density lipoprotein) and released into the bloodstream.
Glycerol, short-chain fatty acids and medium chain fatty acids from lipid digestion are carried by the blood to the liver. The liver is the most active site of lipid synthesis. The liver cells use fatty acids arriving in the blood as well as carbohydrates, proteins or alcohols to make new triglycerides, cholesterol, and other compounds. In the liver newly formed lipids are packaged into a lipid-protein carrier called a very-low-density-lipoprotein (VLDL) and released into the bloodstream

39. VLDL VLDL has a high triglyceride and low cholesterol concentration.
As the VLDL is carried through the blood, body cells remove triglycerides, causing the VLDL to get smaller.
The VLDL picks up cholesterol from other lipoproteins, and the proportion of lipids shift to more cholesterol.
Eventually the VLDL becomes a low-density lipoprotein (LDL).
VLDL has a high triglyceride concentration and low cholesterol concentration. As the VLDL is carried through the blood body cells remove triglycerides, causing the VLDL to get smaller. The VLDL also picks up cholesterol from other lipoproteins, and the proportion of lipids shift to more cholesterol. Eventually the VLDL becomes a low-density lipoprotein (LDL).

40. LDL LDL has a high cholesterol content and low triglyceride content.
As the LDL is carried through the blood body cells remove cholesterol and phospholipids to build new membranes, make hormones or other compounds, or store them for later use.
LDL receptors on the liver help remove LDL from circulation.
LDL (Low-Density Lipoprotein)
LDL has a high cholesterol content and low triglyceride content. As the LDL is carried through the blood body cells remove cholesterol and phospholipids. The cells take triglycerides, cholesterol and phospholipids to build new membranes, make hormones or other compounds, or store them for later use. LDL receptors on the liver play an important role in removing LDL from circulation.

41. HDL The liver makes another carrier called HDL.
HDL is released from the liver and moves through the blood picking up cholesterol and phospholipids from body cells and returning them to the liver to be removed.
HDL (High-Density Lipoprotein)
The liver makes another carrier called high-density-lipoprotein (HDL). The HDL is released from the liver and circulates in the blood picking up cholesterol and phospholipids from body cells and returning them to the liver to be removed from the body.

42. Total, LDL, and HDL Cholesterol
Total blood cholesterol is a measure of cholesterol in both LDL and HDL.
Cholesterol in the LDL is going out into the body and increases risk of heart disease.
Cholesterol in the HDL is going back to the liver to be removed and decreases risk of heart disease.
The difference between LDL and HDL has implications for heart health. LDL carries cholesterol out to body cells and is associated with increased risk of heart disease. HDL carries cholesterol away from body cells back to the liver to be removed and is associated with decreased risk of heart disease.

43. Lipid Transport

44. Metabolism Storing triglycerides as triglycerides
Because fat provides twice the energy as carbohydrate and protein it is an efficient energy storage.
Unlike glycogen, the body can store an unlimited amount of fat. Unlike most body cells, which store only limited amounts of fat, adipose cells can readily take up and store fat.
Storing Triglycerides as Triglycerides
Fat serves as a storage form of energy. Fat provides more than twice the energy of carbohydrate and protein, making it an extremely efficient storage form of energy. Unlike the liver’s glycogen stores, the body’s fat stores have virtually unlimited capacity, thanks to the adipose tissue. Unlike most body cells, which can store only limited amounts of fat, the adipose tissue fat cells can readily take up and store fat.

45. Metabolism Energy stored as fat because fats are calorie dense
Half the weight of fat as carbohydrate is needed to provide the same amount of calories. Water is also stored with carbohydrates; further increasing weight.
The weight of stored energy is important in animals because they move around. Plants don't move around so weight of stored energy is not a problem.
The reason that we store energy as fat instead of carbohydrate is because fats are calorie dense. Almost half the weight of fat compared to carbohydrate is needed to provide the same amount of calories. In addition, water is also stored with carbohydrates; further increasing stored carbohydrate weight. This means the body has less weight to carry. Plants don't move around and so the weight of stored energy is not a problem. Plants can easily store energy as the bulkier carbohydrate.  Excess fat, carbohydrate and protein, beyond what our body needs are converted into fats and stored for later use. 
To convert food fats into body fat, the body simply absorbs the parts and puts them together gin in storage. This requires very little energy. An enzyme lipoprotein lipase (LPL) hydrolyzes triglycerides from lipoproteins producing glycerol, fatty acids and monoglycerides that enter the adipose cells. Inside the adipose cells, other enzymes reassemble the pieces into triglycerides again for storage.

46. Metabolism Using Triglycerides for Energy
When the body needs energy an enzyme, hormone-sensitive lipase, inside the adipose cells responds by dismantling stored triglycerides and releasing the glycerol and fatty acids into the blood.
Cells needing energy absorb these compounds and take them through a series of chemical reactions yielding energy, carbon dioxide and water.
Using Triglycerides for Energy
When the body needs energy an enzyme, hormone-sensitive lipase, inside the adipose cells responds by dismantling stored triglycerides and releasing the glycerol and fatty acids into the blood. Cells needing energy can capture these compounds and take them through a series of chemical reactions yielding energy, carbon dioxide and water.

47. Using Lipids for Energy

48. Functions of Fat Fats have many functions in our body.
Part of cell membranes and component of many body compounds.
Body fat protects internal organs and provides insulation from heat loss.
Source of fat-soluble vitamins and essential fatty acids.
Concentrated source of stored energy.
Lipid Functions
Dietary fats are necessary for a healthy body. Fats have many functions in our bodies. Fats along with protein are a basic part of cell membranes, and are components for many body compounds. Body fat cushions internal organs and protects them from being damaged. The fat layer below the skin insulates the body from heat loss. Fats also are important sources of the fat-soluble vitamins, A, D, E and K. Fats are a concentrated source of energy. One gram of fat provides 9 calories. Our bodies use this energy or store it as fat for later use.

49. Functions Essential Fatty Acids
From the essential fatty acids the body can make other polyunsaturated fatty acids that:
maintain the structure of cell membranes
make eicosanoids that regulate:
blood pressure
blood clotting
blood lipids
immune response to injury and infection
Linoleic acid and linolenic acid are essential fatty acids. These essential fatty acids are important in maintaining the structure of cell membranes. From these two polyunsaturated fatty acids the body can make other fatty acids the body needs and eicosanoids that help regulate blood pressure, blood clotting, and immune response to injury and infection. 

50. Health Effects of Lipids
Although fat is important, but too much fat increases the risk for chronic disease.
High saturated fat and trans fat intakes are associated with increasing blood cholesterol and heart disease.
High dietary cholesterol intake is also associated with increasing blood cholesterol and heart disease, although its effect is not as strong as saturated fat or trans fat.
Health Effects of Lipids
Some fat in the diet is essential for good health, but too much fat, especially saturated fat increases the risk for chronic disease. High saturated fat and trans fat intakes, are associated with increasing blood cholesterol and heart disease. High dietary cholesterol intake is also associated with increasing blood cholesterol and heart disease risk, although its effect is not as strong as that of saturated fat or trans fat.

51. Plaque Development

52. Health Effects of Lipids
Replacing saturated and trans fats with monounsaturated and polyunsaturated fats can help lower heart disease risk.
Consuming fish on a regular basis as a source of omega-3 polyunsaturated fatty acids may also lower the risk of heart disease by helping to prevent blood clots and protect against irregular heartbeats and lower blood pressure.
Replacing saturated and trans fats with monounsaturated and polyunsaturated fats can help lower the risk of heart disease. Consuming fish on a regular basis as a source of omega-3 polyunsaturated fatty acids may also lower the risk of heart disease by helping to prevent blood clots and protect against irregular heartbeats and lower blood pressure.

53. Health Effects of Lipids
High fat diets have also been associated with increased risk of certain types of cancers.
The relationship between fat intake and cancer is not clear, and may be more related to total calorie intake and obesity.
High fat diets have also been associated with increased risk of certain types of cancers. The relationship between fat intake and cancer is not clear, and may be more related to total calorie intake and obesity.

54. Health Effects of Lipids
Fat provide more than twice as many calories as carbohydrate or protein. As a result, people who consume high fat diets may exceed their calorie needs resulting in weight gain and obesity.
By increasing the risk of obesity, high fat diets may indirectly increase risk of diabetes and high blood pressure.
Fat contributes more than twice as many calories as carbohydrate or protein. As a result, people who consume high fat diets may exceed their calorie needs resulting in weight gain and obesity. By increasing the risk of obesity, high fat diets may indirectly increase risk of diabetes and high blood pressure.

55. Recommended Fat Intake
Defining the exact amount of fat, saturated fat or cholesterol that benefits health or begins to harm health, however, is not possible; for this reason, no RDA or upper limit has been set
Defining the exact amount of fat, saturated fat or cholesterol that benefits health or begins to harm health, however, is not possible; for this reason, no RDA or upper limit has been set.

56. DRI for Fat
DRI recommends a diet low in saturated fat, trans fat and cholesterol and provides 20 to 35% of the daily calories intake from fat.
The top end of this range is slightly higher than previous recommendations. This revision recognizes that diets with up to 35% of calories from fat can be compatible with good health if calorie intake is reasonable and saturated fat intake is low.
DRI recommendations suggest a diet that is low in saturated fat, trans fat and cholesterol and provides 20 to 35% of the daily calories intake from fat. The top end of this range is slightly higher than previous recommendations. This revision recognizes that diets with up to 35% of calories from fat can be compatible with good health if calorie intake is reasonable and saturated fat intake is low.

57. AI for Linoleic Acid The AI for linoleic acid is 5 to 10% of calories
Men: yr g/day
Men: yr g/day
Women: yr 12 g/day
Women: yr g/day
The AI for linoleic acid is:
5 to 10% of calories
Men: yr 17 g/day
51+ yr g/day
Women: yr 12 g/day
51+ yr g/day

58. AI for Linolenic Acid
The AI for linolenic acid is 0.6 to 1.2% of calories
Men: 1.6 g/day
Women: 1.1 g/day
The AI for linolenic acid is:
0.6 to 1.2% of calories
Men : g/day
Women: 1.1 g/day

59. Dietary Guidelines
Consume less than 10 percent of calories from saturated fatty acids and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible.
Keep total fat intake between 20 to 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.
The Dietary Guidelines for Americans recommendations regarding fat are:
Consume less than 10 percent of calories from saturated fatty acids and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible.
Keep total fat intake between 20 to 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.
When selecting and preparing meat, poultry, dry beans, and milk or dairy products, make choices that are lean, low-fat, or fat-free.
Limit intake of fats and oils high in saturated and/or trans fatty acids, and choose products low in such fats and oils.

60. Dietary Guidelines
When selecting and preparing meat, poultry, dry beans, and milk or dairy products, make choices that are lean, low- fat, or fat-free.
Limit intake of fats and oils high in saturated and/or trans fatty acids, and choose products low in such fats and oils.
The Dietary Guidelines for Americans recommendations regarding fat are:
Consume less than 10 percent of calories from saturated fatty acids and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible.
Keep total fat intake between 20 to 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.
When selecting and preparing meat, poultry, dry beans, and milk or dairy products, make choices that are lean, low-fat, or fat-free.
Limit intake of fats and oils high in saturated and/or trans fatty acids, and choose products low in such fats and oils.

61. Lowering Fat Intake
Lowering fat intake does not mean omitting meats and dairy foods
Lower fat intake by choosing lean meats and dairy foods, using low-fat preparation methods, limiting the use of added and hidden fats, and watching portion size.
Lowering Fat Intake
Lowering fat intake does not mean omitting meats and dairy foods
Lower fat intake by choosing lean meats and dairy foods, using low-fat preparation methods, limiting the use of added and hidden fats, and watching portion size.