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Lipids
The Good, the Bad and the Truly Ugly!
Lipids
• Organic molecules most of which do not dissolve in water.
• Fats & oils
• Types of lipids:– Fatty acids– Glycerides– Phospholipids– sterols
Fatty Acids
• Carbon chains
• Methyl, acid groups
• Degree of saturation
• Location of first double bond
Types of Fatty Acids
Glycerides
The major form of lipid in food and in the body
PhospholipidLecithin, a common food additive, is a phospholipid.
Embedded in cell membranes.
Sterols
• Cholesterol:– 90% is found in cell
membranes– Produced by the liver– Associated with
cardiovascular disease– Produced by animals
only. None found in plants.
Fats in the Diet
• Typically meats, dairy products, & other animal products are the main source of saturated fatty acids.
• Palm, coconut oils are high in saturated fats.
• Unsaturated fatty acids tend to come from plant oils: olive, canola, peanut , safflower, sunflower, corn; also fish, nuts
Fats in the Diet
Unsaturated Fats in the Diet
Omega-6- Omeg-3-
The Good!
Hydrogenated Fats
• Hydrogenation of vegetable oils converts some of unsaturated bonds to saturated, trans conformation.
• Trans fatty acids extend shelf life, improve margarine, shortening.
• Diet high in trans fatty acids risks heart disease, cancer.
Trans Fatty Acids
The Truly Awful!
Function of Lipids
• Immediate source of energy
• Stored form of energy (85% triglycerides)
• Protection and cushioning– Eye sockets, heart valves, kidneys, fatty
apron
• Insulation (temperature regulation)
Adipose Tissue
Fat stored in this cell
Fat Storage
Another view….
Fat Storage Area
When there is a bit much….
Before After
Abdominoplasty
Function continued
• Structural part of cell membranes (phospholipids, cholesterol)
• Regulation– Cell communication, neurotransmitter synthesis – Bile salts (from cholesterol),– Hormones (from cholesterol) – Prostaglandins, eicosanoids (from omega-3 & omega-
6 fatty acids)
Fat Packed on Heart
How you store fat….and then release it
Essential Fatty Acids
• Linoleic, alpha-linolenic acid are essential
• Deficiency– Rare because requirement is low– Symptoms: scaly, dry skin, liver abnormalities,
poor healing of wounds, growth failure, impaired vision and hearing
– Observed in infants, young children fed low-fat diets, adults consuming a weight-loss diet of only nonfat milk
Reduced Fat Foods
• Variety of reduced fat and free fat foods are available.
• Designed to mimic taste, texture of fat• Low fat may mean low fiber, vit., minerals• Low fat foods are not always low in kcal
– In many foods, fats are replaced with other energy-containing nutrients
– Regular brownie has 112 kcal; reduced fat brownie has 89 kcal
Low Fat Diet
• A diet low in fat & high in simple sugars increases blood triglyceride levels & may increase the risk of heart disease. May increase risk of diabetes.
• May not be a healthy diet.
• Snacks of fresh fruits instead of these would be much better.
Types of Artificial Fats• Carbohydrate-based fat substitutes
– Pectins, gums mimic texture of fat– Oatrim, Nutrim add soluble fiber
• Protein-based fat substitutes– Simplesse is fat substitute made from egg white, milk proteins– Used in frozen desserts, cheese foods; 1.3 cal/g
• Poorly absorbed fats as fat substitutes– Caprenin consists of glcerol with 3 poorly absorbed fatty acids
attached; 5kcal/g– Olestra has fatty acids attached to sucrose; cannot be digested; no
absorption
The Good!
The
Bad!
TheTrulyAwful!
The Consequences of Poor Choices!
The Ugly