Chapter 5 : Chapter 5 The Lipids: Fats, Oils, Phospholipids, and Sterols
Introducing the Lipids : Introducing the Lipids Lipids in foods and the human body fall into three classes:
Triglycerides
Phospholipids
Sterols
Usefulness of Fats in the Body : Usefulness of Fats in the Body When we say “fat,” we generally mean triglycerides
What are functions of fat in our bodies and in foods?
Usefulness of Fats in the Body and in Food : Usefulness of Fats in the Body and in Food
A Close Look at Lipids : A Close Look at Lipids Triglycerides (fat)
Phospholipids
Sterols
Triglycerides: Fatty Acids and Glycerol : Triglycerides: Fatty Acids and Glycerol 95 percent of dietary fat and stored fat
Triglyceride
Glycerol + 3 fatty acids
Saturated versus Unsaturated Fatty Acids : Saturated versus Unsaturated Fatty Acids
Saturated versus Unsaturated Fatty Acids : Saturated versus Unsaturated Fatty Acids Saturated fatty acid – filled to capacity with hydrogen atoms
Solid at room temperature
Unsaturated fatty acid – missing hydrogen
Liquid at room temperature
Monounsaturated – one point of unsaturation
Polyunsaturated – two or more points of unsaturation (PUFA)
Saturated versus Unsaturated Fatty Acids : Saturated versus Unsaturated Fatty Acids
Phospholipids and Sterols : Phospholipids and Sterols Phospholipid
Glycerol + two fatty acids + phosphorus
Phosphorus part makes it soluble in water
Fatty acids make it soluble in fat
Therefore can serve as an emulsifier
Key role is in cell membranes
Phospholipids and Sterols : Phospholipids and Sterols Sterols
Large molecules consisting of interconnected rings of carbon atoms with side chains of carbon, hydrogen, and oxygen attached
Cholesterol
is found in all animal cell membranes
is nonessential
forms plaques that cause atherosclerosis
Cholesterol serves as the raw material for
bile
vitamin D
steroid hormones including the sex hormones
Digestion and Absorption of Fats : Digestion and Absorption of Fats
Digestion and Absorption of Fats : Digestion and Absorption of Fats In the mouth, one enzyme plays a major role in digesting milk fat in infants but is of little importance to digestion in adults.
In the stomach, fat floats on the watery fluids.
In the small intestine, bile emulsifies fat.
Recommendations For Lipid Intakes : Recommendations For Lipid Intakes
Major Lipoproteins: VLDL, LDL, HDL : Major Lipoproteins: VLDL, LDL, HDL In addition to the chylomicron, the body uses three other types of lipoproteins to carry fats:
Very-low-density lipoproteins (VLDL), which carry triglycerides and other lipids made in the liver to the body cells for their use.
Low-density lipoproteins (LDL) transport cholesterol and other lipids to the tissues. LDL are made from VLDL after they have donated many of their triglycerides to body cells.
High-density lipoproteins (HDL), which are critical in the process of carrying cholesterol away from body cells to the liver for disposal.
Major Lipoproteins: VLDL, LDL, HDL : HDL and LDL play major roles with regard to heart health and are the focus of most recommendations made for reducing the risk of heart disease.
Which lipoprotein do you want to have more of? Major Lipoproteins: VLDL, LDL, HDL Answer: HDL
Major Lipoproteins: VLDL, LDL, HDL : Major Lipoproteins: VLDL, LDL, HDL
The LDL and HDL Difference : LDL – larger, lighter, and richer in cholesterol. Delivers cholesterol and triglycerides from the liver to the tissues.
LDL – Less healthy
HDL – smaller, denser, and packaged with more protein. HDL scavenge excess cholesterol and phospholipids from the tissues for disposal.
HDL - Healthy The LDL and HDL Difference
Slide19 : The more of these factors present in a person’s life, the more urgent the need for changes in diet and other controllable factors to reduce heart disease risk:
High blood LDL
Low blood HDL
High blood pressure
Type 2 diabetes
Obesity
Physical inactivity
Cigarette smoking
Atherogenic diet The Importance of LDL and HDL Cholesterol How many factors are in
your life?
What Does Food Cholesterol Have to Do With Blood Cholesterol? : What Does Food Cholesterol Have to Do With Blood Cholesterol? Saturated food fats (and trans fat) raise blood cholesterol more than food cholesterol does.
Dietary cholesterol makes a smaller but still significant contribution to elevated blood cholesterol.
A small percentage of people respond to a high cholesterol intake with greatly increased blood cholesterol.
Slide21 : The number one dietary determinant of LDL cholesterol is saturated fat. Fats to Avoid: Saturated Fats and Trans Fats
Recommendations Applied : Recommendations Applied To lower LDL
Reduce saturated fat
Reduce trans fat
Substitute monounsaturated or PUFA
Eat cholesterol in moderation
Slide23 :
Lowering LDL Cholesterol : Lowering LDL Cholesterol
Lowering LDL Cholesterol : Lowering LDL Cholesterol LDL is susceptible to oxidation which may trigger some of the damage to the arteries of the heart.
Adequate intakes of dietary antioxidants* may oppose LDL oxidation.
* Vitamin C, vitamin E, selenium, and some phytochemicals
Essential Polyunsaturated Fatty Acids : Essential Polyunsaturated Fatty Acids Linoleic acid and linolenic acid
Deficiencies of Essential Fatty Acids : Deficiencies of Essential Fatty Acids When the diet is deficient in all of the polyunsaturated fatty acids, symptoms include:
Reproductive failure
Skin abnormalities
Kidney and liver disorders
Growth and vision impairment in infants
The body stores EFA, so extreme deficiencies are rare.
Omega-6 And Omega-3 Fatty Acid Families : Omega-6 And Omega-3 Fatty Acid Families Linoleic acid is the “parent” member of the omega-6 fatty acid family
Abundant in vegetable oils
Linoleic acid can be converted to other members of this family, for example, arachidonic acid
Linolenic acid is the “parent” member of the omega-3 fatty acid family
Linolenic acid can be converted to other members of this family, for example, EPA and DHA
Omega-6 And Omega-3 Fatty Acid Families : EPA and DHA:
are made in limited amounts in the body
abundant in fish oils
lower blood pressure
prevent blood clot formation
protect against irregular heartbeats
may reduce inflammation
essential for normal infant growth and development
may support immune system
may inhibit cancers Omega-6 And Omega-3 Fatty Acid Families
Recommendations For Omega-3 Fatty Acid Intake : Recommendations For Omega-3 Fatty Acid Intake To obtain the health benefits from essential fatty acids requires obtaining the right balance between omega-3 and omega-6 fatty acids
Most Americans get mostly omega-6 from vegetable oils, salad dressings, and margarine and they need to balance this with more fish
Average U.S. intake of EPA and DHA is 150 mg/day
Recommended is 500 mg/day (about 2 fatty fish meals per week) to reduce CVD
Slide31 : Fats to Avoid: Saturated Fats and Trans Fats
Slide32 : The American Heart Association and other authorities recommend including two fatty fish servings a week in a heart-healthy diet.
Fish is the best source of EPA and DHA but is also a major source of mercury so vary your choices among fatty fish species. Fish: Benefits and Cautions
Eat Fish For Fish Oil : Eat Fish For Fish Oil Cardiovascular deaths occur less frequently in countries with higher intakes of EPA and DHA from seafood.
Other Food Sources of Omega-3 Fatty Acids : Other Food Sources of Omega-3 Fatty Acids Egg producers fortify certain brands of eggs by adding only fish meal to chicken food
The chickens lay DHA-enriched eggs
High-Fat Foods and Heart Health : High-Fat Foods and Heart Health Which of these high-fat foods rightly belong in a heart-healthy diet?
Avocados
Bacon
Walnuts
Potato chips
Mackerel
Answer: a, c, e
The Effects of Processing on Unsaturated Fats : The Effects of Processing on Unsaturated Fats Vegetable oils make up most of the added fat in the U.S. diet. Why?? Answer: Because fast food restaurants use them for frying, food manufacturers add them to processed foods, and consumers tend to choose margarine over butter
What Is “Hydrogenated Vegetable Oil,” And What’s It Doing in My Chocolate Chip Cookies? : What Is “Hydrogenated Vegetable Oil,” And What’s It Doing in My Chocolate Chip Cookies? Vegetable oils become more saturated when they are hydrogenated.
Points of unsaturation are vulnerable to attack by oxygen (oxidation).
When the unsaturated points in the oils of food are oxidized, the oils become rancid.
Hydrogenation forces hydrogen into the liquid oil, making the oil more saturated as it accepts the hydrogens.
What Is “Hydrogenated Vegetable Oil,” And What’s It Doing in My Chocolate Chip Cookies? : What Is “Hydrogenated Vegetable Oil,” And What’s It Doing in My Chocolate Chip Cookies?
What Is “Hydrogenated Vegetable Oil,” And What’s It Doing in My Chocolate Chip Cookies? : What Is “Hydrogenated Vegetable Oil,” And What’s It Doing in My Chocolate Chip Cookies? Hydrogenated fats:
Resist rancidity; more resistant to oxidation
Are firmer textured; more spreadable
Have a higher smoking point than unsaturated oils
Are unhealthy
Trans Fat In Foods : Trans Fat In Foods Largest contributor of trans fat to the U.S. diet has been commercially fried foods.
Newly formulated commercial oils and fats can now perform the same job as the old hydrogenated fats, but with fewer trans fatty acids.
Formation of Trans Fatty Acids : Formation of Trans Fatty Acids Trans fatty acids occur in small amounts in nature, mostly in dairy products
A lot of trans fatty acids formed during hydrogenation
Health Effects of Trans Fatty Acids : Health Effects of Trans Fatty Acids Consuming trans fat poses a risk to heart and arteries by:
Raising blood LDL cholesterol
Lowering blood HDL cholesterol
Increasing tissue inflammation, a key player in heart disease
Replacing heart-healthy oils
Are the New Fats Better For Health? : Are the New Fats Better For Health? One serving of these crackers presents no trans fat, but it contains almost a third of the saturated fat allowable for the day, with only small contributions of nutrients.
Fat In The Diet- Take Home Message : Fat In The Diet- Take Home Message Dietary Guidelines for Americans 2005 urge that, beyond a healthy minimum, people should:
Limit fat
Remember to check where your fat is coming from
More unsaturated- healthy fats
Limit saturated fat
Limit trans fat
Limit calories
Added Fats : Added Fats Fats added to foods during preparation or at the table are a major source of fat in the diet.
Majority of fats are hidden in fried foods, baked goods, sauces, and mixed dishes.
These fats provide about 5 grams of pure fat, providing 45 calories
1 tsp oil or shortening
1 ½ tsp mayonnaise, butter, or margarine
1 tbl regular salad dressing, cream cheese, or heavy cream
1 ½ tbl sour cream
Meat, Poultry, Fish, Dried Peas and Beans, Eggs, and Nuts : Meat, Poultry, Fish, Dried Peas and Beans, Eggs, and Nuts Most people consume meats in larger amounts than recommended
Milk, Yogurt, and Cheese : Milk, Yogurt, and Cheese
Grains : Grains
Food Feature: Defensive Dining : Food Feature: Defensive Dining Other tips to revise high-fat recipes
Grill, roast, bake, microwave, stir-fry, or poach foods
Choose larger portions of salad greens or vegetables and use dressings lightly
Reduce or eliminate “add-ons” such as butter, creamy sauces, cheese, bacon
Cut recipe amounts of meat in half; use only lean meats
Use defatted soups and gravies
Make prepared mixes, such as rice, without the fats called for on the label
Food Feature: Defensive Dining : Food Feature: Defensive Dining