FATS-LIPIDS-AND-OILS

Personal Nutrition

• Module 3: The Lipids: Fats and Oils

• Authors: Marie A. Boyle, Sara Long, 8e Future Nurses 2022

True or False Questions

• 1. The body can store fat in virtually unlimited amounts. (True)

• 2. Dietary cholesterol is found only in animal foods. (True)

• 3. A person’s blood level of cholesterol is a predictor of that person’s risk of having a heart attack. (True)

• 4. For the health of your heart, the fat you should avoid eating, most of all, is cholesterol. (False: should avoid saturated and trans fats)

• 5. The more monounsaturated fats you consume, the better it is for your health. (True)

• 6. Fruits are essentially fat-free. (False: some fruits contain fats)

• 7. In general, the softest margarines are the most polyunsaturated. (True)

• 8. Polyunsaturated fat has the same number of calories as saturated fat. (True)

• 9. All the foods you eat should contain less than 10% of calories from saturated fat. (True)

• 10. No one is free of atherosclerosis. (True)

A Primer on Fats

• Lipids: family of compounds including:

  • Triglycerides (fats and oils)

  • Phospholipids (e.g., lecithin)

  • Sterols (e.g., cholesterol)

• Sources of fat:

  • Obvious: oil, butter, margarine, shortening.

  • Other sources: meat, nuts, mayonnaise, salad dressings, eggs, bacon, gravy, cheese, ice cream, and whole milk.

Functions of Fat

• Important source of energy and essential fatty acids.

• Aids in absorption of fat-soluble vitamins (A, D, E, K).

• Insulates body temperature and helps in brain and cell development.

• Building blocks for hormones.

Types of Fat

• Trans fat: found in commercially baked and fried foods made with partially hydrogenated oils.

• High-content sources:

  • Unsaturated fat: nuts, seeds, vegetable oils, avocados, and various fish (e.g., tuna, mackerel).

  • Saturated fat: full-fat dairy, red meat, processed meat, and eggs.

• Infancy Nutrition: breast milk provides almost 50% energy as fat.

  • Solids cooked in oil can be introduced after one year in limited amounts.

  • Recommendations: reduce fried foods and limit trans fat intake.

Types of Lipids

• Fats: solid at room temperature.

• Oils: liquid at room temperature.

Functions of Fats in the Body

• Provide a concentrated energy source to fuel body work.

• Chief energy reserve, major components of cell membranes.

• Nourish skin and hair, insulate the body from temperature extremes.

• Cushion vital organs and supply raw materials for various compounds (bile and vitamin D).

Fat Storage

• Body stores fat as energy reserve; unlimited capacity.

• Excess carbohydrates and proteins can convert to fat, but fat cannot be converted back to them.

• 1 pound of body fat = 3,500 calories.

• Lipid stored in fat cells can enlarge to accommodate more fat.

Satiety

• Satiety: feeling of fullness after meals.

• Fats slow stomach emptying, leading to prolonged feelings of fullness.

Fatty Acids

• Basic units of fat, consisting of carbon chains with an acid group at one end.

• Major dietary lipids include triglycerides, composed of three fatty acids and one glycerol.

Triglycerides

• About 95% of lipids in foods and human body are triglycerides.

• Glycerol: organic compound and backbone of triglycerides.

Other Lipids

• Phospholipid: lipid containing phosphorus (e.g., lecithin).

  • Major constituent of cell membranes.

  • Used as emulsifiers in foods.

• Sterols: lipids with structures similar to cholesterol.

  • Cholesterol: synthesized in the body, necessary for various functions but can contribute to diseases when accumulated in arteries.

Fatty Acid Characteristics

• Differ in chain length: short-chain, medium-chain, long-chain; affects solubility.

• Differ in saturation:

  • Saturated: maximum hydrogen atoms, typically solid.

  • Unsaturated: hold empty spots, typically liquid.

Saturated vs. Unsaturated Fats

• Saturated Fatty Acids: maximum hydrogen, found in animal sources, solid at room temperature.

• Unsaturated Fatty Acids: one (monounsaturated) or more (polyunsaturated) points of unsaturation, found in plant and fish sources.

Essential Fatty Acids

• Omega-3 and Omega-6: essential for human health, cannot be synthesized in sufficient quantities by the body.

Health Benefits of Omega-3 Fatty Acids

• Found in fish oils; linked to lower heart disease rates.

• Reduces blood clot formation, lowers triglycerides, improves artery health.

Dietary Recommendations

• Reduce solid fats and trans fats in the diet.

• Consume fish at least two times per week.

Digestion of Fat

• Begins in the mouth, continues in the stomach and emulsified by bile in the small intestine.

• The pancreas secretes lipase to break down triglycerides.

• Final products are fatty acids, glycerol, and monoglycerides, which are absorbed into the bloodstream.

Role of Bile

• Bile emulsifies lipids, preparing them for digestion.

• Lipids are transported via lymph containing lipoproteins.

Lipoproteins

• Types include:

  • Chylomicron: transport newly digested fats from intestine.

  • VLDL: transports fats from the liver.

  • LDL: carries cholesterol to cells; high levels indicate heart disease risk.

  • HDL: carries cholesterol back to the liver.

Good vs. Bad Cholesterol

• Atherosclerosis: process where LDL penetrates artery walls and gets oxidized, forming plaque.

• Foam cells: scavenger cells accumulate oxidized LDL, leading to more plaque buildup.

Dietary Sources of Fat

• Saturated Fat: animal meats, tropical oils, dairy products.

• Polyunsaturated Fat: Fish, nuts, seeds; beneficial if replace saturated fats.

• Monounsaturated Fat: found in olive oils and avocados; beneficial for heart health.

Recommendations for Fat Intake

• Total fat: 20 to 35% of total calories. Limit saturated fats to less than 10%, cholesterol to 300 mg/day, and trans fats as low as possible.

• Consider cooking methods that reduce fat intake, e.g., grilling, baking.

Conclusion

• To promote heart health, balance your intake of different fats while minimizing saturated and trans fats, focusing instead on unsaturated fats from plants and fish.