Types of Fats and Structures

Overview

This lecture explains the four major types of fats, their sources, molecular structures, health impacts, and dietary recommendations.

There are two main types of fats: saturated and unsaturated.
Unsaturated fats are sub-divided into trans fats, monounsaturated fats, and polyunsaturated fats.
The main form of fat in foods is triglycerides, made of glycerol and three fatty acid chains.
Saturated fats have no double bonds between carbon atoms; they are linear and solid at room temperature.
Unsaturated fats have at least one double bond, which may be in cis (bent) or trans (linear) formation.

High in foods like pork, beef, cheese, whole milk, eggs, coconut oil, palm oil, and butter.
Raise both LDL ("bad") and HDL ("good") cholesterol levels and increase LDL particle size.
Recommended limit is 5-6% of daily calories, about 13g/day for a 2,000-calorie diet.
Research is mixed on their link to heart disease; moderation is advised.

Trans fats are solid at room temperature and have high melting points.
Natural trans fats are found in dairy and meat and are not considered harmful in moderate amounts.
Artificial trans fats, made by hydrogenating oils, are found in processed foods like margarine, baked goods, and fried foods.
Artificial trans fats are linked to higher LDL, lower HDL, heart disease, and blood vessel damage.
Health agencies advise eliminating artificial trans fats from the diet.

Feature a single cis double bond, creating a kinked structure.
Found in olive oil, canola oil, peanut oil, avocados, nuts, and seeds.
Liquid at room temperature; generally considered healthy when replacing saturated or trans fats.

Have multiple cis double bonds and are liquid at room temperature.
Classified by Omega number based on first double bond position (Omega-3, 6, 7, 9).
Omega-3 and Omega-6 are essential fatty acids; body cannot produce them.
Omega-6 sources: vegetable oils, salad dressings, fried foods, grain-fed beef.
Omega-3 sources: flax seeds, walnuts, fatty fish (salmon, tuna).
Balance is key: a 4:1 (Omega-6:Omega-3) ratio or lower is healthiest; typical Western diets are higher in Omega-6.

Triglyceride — main form of dietary fat, consisting of glycerol and three fatty acids.
Saturated fat — fat with no double bonds between carbons; solid at room temperature.
Unsaturated fat — fat with at least one double bond; generally liquid at room temperature.
Trans fat — unsaturated fat with hydrogens on opposite sides of the double bond; increases LDL, lowers HDL.
Monounsaturated fat — has one double bond in cis configuration; usually plant-based and healthy.
Polyunsaturated fat — has multiple double bonds; includes Omega-3 and Omega-6.
Hydrogenation — process converting liquid oils into solid fats by adding hydrogen.