Chapter 5: Fats: Essential Energy-Supplying Nutrients

Chapter 5: Fats: Essential Energy-Supplying Nutrients

What Are Fats?

• Fats are a kind of lipid.

• Lipids are a varied group of natural substances that cannot dissolve in water.

• So, fats don't mix with water.

Types of Lipids

Triglycerides

• Triglycerides make up most of the fat we eat, about 95\% of our diet's fat.

• They are made of:

  • Three fatty acid parts.

    • Fatty acids: Long strings of carbon atoms with hydrogen atoms all around them.

  • One glycerol part.

    • Glycerol: A three-carbon alcohol that acts as the main structure (backbone) of a triglyceride.

Phospholipids

• They are made of:

  • A glycerol backbone.

  • Two fatty acids.

  • A phosphate group.

• Because of the phosphate group, they can dissolve in water.

• Our bodies make them, so we don't have to get them from our diet.

• They are very important parts of cell walls.

Sterols

• Sterols: Lipids that have many rings of carbon atoms.

• They are key parts of cell walls and help make many hormones.

• Our bodies make them, so we don't need to eat them.

• Cholesterol is the main sterol in humans.

How Fatty Acids in Triglycerides Are Different

Differences in Fatty Acids

Fatty acids can differ in:

• How long their carbon chain is:

  • Short-chain: Less than 6 carbons.

  • Medium-chain: 6-12 carbons.

  • Long-chain: More than 13 carbons.

• How saturated they are: This means how many hydrogen atoms are around each carbon atom.

• Their shape: This depends on whether they have double bonds and how these bonds are arranged.

Types of Saturation

• Saturated Fatty Acids:

  • Have hydrogen atoms on every part of their carbon chain.

  • Have no double bonds between carbon atoms.

  • They can fit closely together, so they are solid at room temperature (like coconut oil, animal fats, butter, lard).

• Monounsaturated Fatty Acids (MUFAs):

  • Are missing hydrogen atoms in one spot on their chain.

  • Have one double bond.

• Polyunsaturated Fatty Acids (PUFAs):

  • Are missing hydrogen atoms in many spots on their chain.

  • Have two or more double bonds.

  • Note: Every double bond means two hydrogen atoms are missing.

• Unsaturated fatty acids usually don't stack neatly, so they are liquid at room temperature (mostly found in plants, but coconut and palm kernel oil are exceptions).

How Unsaturated Fatty Acids Are Shaped

• The hydrogen atoms around the double bond can be arranged in different ways:

  • Cis: Hydrogen atoms are on the same side of the carbon chain at the double bond.

  • Trans: Hydrogen atoms are on opposite sides of the carbon chain at the double bond.

Hydrogenation

• Hydrogenation: is when hydrogen atoms are added to unsaturated fatty acids.

• This changes liquid fats (oils) into a thicker, more solid form.

• It's used to make things like margarine from plant oils.

• This process often creates trans fatty acids, which you'll see on food labels.