Presentation on theme: "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."— Presentation transcript:
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
Phospholipid Lecithin, 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 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