Lipids

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