1. By Jennifer Turley and Joan Thompson
Lipids/Fats
By Jennifer Turley and Joan Thompson
© 2013 Cengage

2. Overview Categories, Chemistry, Functions & Foods of: Fat/Lipid
Triglycerides
Fatty Acids
Phospholipids
Sterols

3. Lipids - Fats Composition: Fats contain Carbon, Hydrogen, Oxygen
Lipids are organic compounds
Lipids are soluble in fat
Categories of Lipids:
1. Triglycerides
2. Phospholipids
3. Sterols

4. Triglycerides “Fats” Energy Yield: Fats provide 9 Calories/gram.
Fats are the only type of lipid that the body can convert to ATP or produce energy from.
Fats are the most Calorically Dense energy producing nutrient.

5. Triglycerides “Fats”
Caloric density: Refers to the Calories yielded per weight of the substance.
Triglycerides (dietary fats) provide 9 Calories per gram while protein and carbohydrate provide 4 Calories per gram and alcohol provides 7 Calories per gram.

6. 3 units of water are released
Triglyceride Model
Glycerol + =
3 Fatty Acids
A Triglyceride
3 units of water are released

7. Actual Triglyceride

8. Fatty Acids: Categories
Dietary fats are defined by the composition of the fatty acids in the triglyceride.
1. Saturated fat food sources are comprised of mostly saturated fatty acids (SFAs).
2. Monounsaturated fat food sources are comprised mostly of monounsaturated fatty acids (MUFAs).
3. Polyunsaturated fat food sources are comprised mostly of polyunsaturated fatty acids (PUFAs).

9. Fatty Acid: Examples SFA MUFA PUFA Stearic Acid Oleic Acid
Alpha-linolenic acid

10. Saturated Fatty Acids SFA Have 0 double bonds between the carbons.
Are found in animal products, hydrogenated vegetable fats, & tropical oils (palm & coconut oil).
Are solid at room temperature & unhealthy.
Chemistry of
Stearic Acid,
a SFA

11. Monounsaturated fatty acids
MUFA
Chemistry of
Oleic Acid,
a MUFA
Have 1 double bond in the carbon chain
Are healthy
High levels are in olive oil, canola oil, almonds, & avocado
Become semisolid when refrigerated
Are liquid at room temperature

12. Polyunsaturated fatty acids
PUFA
Chemistry of
Alpha-Linolenic Acid,
a PUFA
Have >1 double bond in the carbon chain.
Some are essential for the body.
Are found in plant oils like corn, cottonseed, safflower, and sunflower oil.
Are liquid at room temperature.
Too much can promote cancer.

13. Fat Food Sources
Oils, butter, cream, lard, margarine, dressings, cream cheese, olives, nuts & seeds are all examples of foods high in dietary fat.
Try to chose healthy fats from plant sources, like those shown on the right.

14. Fatty Acid Composition of Common Fats

15. Essential Fatty Acids
The body cannot make the essential fatty acids (EFAs).
Linoleic Acid & Alpha-Linolenic Acid.
These EFAs are found in plant oils & plant foods.
Deficiency characteristics develop when they are lacking in the diet.

16. Essential Fatty Acids
The AMDR level for adults that will optimize health are:
5-10% of Calories from Linoleic Acid
% of Calories from Alpha-linolenic Acid
Linoleic Acid is an omega 6 fatty acid.
Alpha-linolenic Acid is an omega 3 fatty acid. 3
COOH
CH3 1 2 4 5 6
Linoleic Acid
COOH
CH3 1 2 3
Alpha-Linolenic Acid

17. Essential Fatty Acids

18. Trans Fatty Acids
Created in food processing when PUFAs or MUFAs are partially hydrogenated.

19. Functions of Fat Increases satiety value of a meal.
Improves texture, flavor & aroma of food.
Required for fat soluble vitamin absorption.
Provides the body’s major energy stores.
Cushions vital organs.
Is an essential structural component of cell membranes.
Provides insulation.

20. Fat: Dietary Recommendations
20-35% of total dietary Calories should come from fat. This is the AMDR.
<7% should come from SFA. Limit trans fatty acids.
All excess Calories consumed whether from carbohydrates, proteins, or fats are converted to fat & stored in fat cells.
Fat is the storage form of energy in mammals.

21. Phospholipids (lecithin)
Non-Energy Yield: 0 Calories per gram. Phospholipids are non-caloric lipid substances.
Sources: Lecithin is found in egg yolk and soy products and is the most common phospholipid consumed in the diet.

22. Phospholipids (lecithin)
Functions:
1. Phospholipids like lecithin are emulsifiers that allow water soluble & fat soluble substances to mix (like oil & vinegar).
2. Lecithin provides choline which is a component of the neurochemical acetylcholine.
3. Phospholipids are used to make cell membranes.

23. Lecithin: A Phospholipid
Water
Soluble
Fat Soluble

24. Actual Structure of Lecithin

25. Cell Membrane lipid bilayer
Includes phospholipids, cholesterol, proteins.
lipid
bilayer

26. Sterols Cholesterol is the most popular dietary sterol
Non-Energy Yield: Noncaloric, 0 Calories/gram
Sources of Cholesterol:
1. Exogenous: From outside the body. Cholesterol is made by animals. It is only found in animal foods & byproducts.
2. Endogenous: Made inside the human body.

27. Exogenous Sources Egg yolk provides ~275 mg each.
Organ meats & crustaceans such as crab, shrimp & lobster provide ~190 mg per 3 ounces.
Much smaller amounts are in the fat portions of animal meats & products like milk.

28. Endogenous Sources
Cholesterol is a very important molecule in the body.
Cholesterol is made inside the human body, primarily in the liver, from SFA.
Usually about 1 gram (1,000 milligrams) of cholesterol per day is produced in the body.
It is a very waxy substance.

29. Cholesterol is used to make …

30. Cholesterol is used to make …
Myelin sheath that covers nerve cells.
Cell membranes.

31. Cholesterol Recommendation
Cholesterol can be deposited in the artery walls leading to plaque buildup & heart disease.
To maintain heart health, the dietary recommendation is to limit intake to < 300 mg/day.
To improve heart health, limit intake to < 200mg/day.

32. Summary Fat/Lipid is an organic compound.
Fat/Lipid is categorized as triglycerides, phospholipids, and sterols.
Triglycerides provide 9 Calories per gram.
Triglycerides contains fatty acids that are categorized as SFA, MUFA, & PUFA.
There are 2 EFAs that are PUFAs.
Triglycerides have many important functions.

33. Summary
Consume 20-35% of Calories from fat & limit SFA to <7% of Calories.
Phospholipids like lecithin, emulsify and help make up cell membranes and acetylcholine.
Cholesterol is found in animal foods. It is not essential and can be made in the liver. It has many important functions in the body but intake should be limited to less than 300 mg/day.
References for this presentation are the same as those for this topic found in module 1 of the textbook