L6 Lipids and Fatty Acids Quiz

Lipids

• Lipids are a class of nutrients also known as fats
• Lipid classification includes triglycerides, phospholipids, and sterols
• Triglycerides are the predominant type in food and the body
• Triglycerides consist of one glycerol molecule attached to three fatty acids
• The identity of the fatty acids determines the physical properties, like hardness, of the triglyceride.
• Lipids are stored in the body as adipose tissue

Types of Fatty Acids

• Fatty acids are categorized as saturated, monounsaturated, and polyunsaturated
  • Saturated fatty acids: found in meat, dairy, eggs, and coconut oil
  • Monounsaturated fatty acids (MUFA): one double bond, found in olive oil, peanut oil, and canola oil
  • Polyunsaturated fatty acids (PUFA): at least two double bonds, essential fatty acids, including omega-3 (e.g., linolenic acid) and omega-6 (e.g., linoleic acid)

Saturated and Unsaturated Fatty Acids

• Saturated fatty acids are heavy and dense, solid at room temperature, and primarily from animal sources
• Unsaturated fatty acids are less dense and less heavy than saturated fatty acids
• Unsaturated fats are liquid at room temperature

Types of Fats

• The slides display several types of fats like coconut oil, butter, beef tallow, palm oil, lard, chicken fat, olive oil, canola oil, peanut oil, safflower oil, sunflower oil, corn oil, soybean oil, walnut oil, cottonseed oil, flaxseed oil, and fish oil (salmon)
• These demonstrate variation in saturated, monounsaturated, and polyunsaturated fatty acid content

Phospholipids

• Structurally similar to triglycerides, but contain phosphate and choline instead of one fatty acid, attached to a glycerol molecule
• Lecithins are a type of phospholipid, serving as emulsifiers in food additives, found in egg yolks, soybeans, liver, and peanuts
• Phospholipids help fat-soluble substances (like vitamins) pass in and out of cells and keep fats suspended in the blood and body fluids

Sterols

• Plant sterols are called phytosterols
• Animal sterols are called zoosterols
• Sterols play roles in membrane fluidity and cellular signaling
• Cholesterol is a significant zoosterol
• It's found in animal products like eggs, meat, poultry, seafood, and dairy

Zoosterol

• Cholesterol is the most significant zoosterol
• Cholesterol is found in foods of animal origin

Plant Sterols

• Plant sterols (other than cholesterol) are naturally found in plants
• Phytosterols are structurally similar to steroid hormones
• They block the absorption of dietary cholesterol, potentially reducing blood cholesterol
• FDA approved claims that they promote healthy cholesterol
• Long-term safety is still under investigation

Digestion of Fats

• Lipase enzymes hydrolyze lipids
• Lingual lipase is found in the tongue
• Gastric lipase is found in the stomach
• Pancreatic lipase is found in the pancreas
• The goal of fat digestion is to break down triglycerides into smaller components like monoglycerides, fatty acids, and glycerol
• These molecules can then be absorbed by the body

Absorption of Dietary Lipids

• Triglycerides are insoluble in water, and thus require processing
• Bile emulsifies fats into smaller globules in the small intestine
• Pancreatic lipase hydrolyzes triglycerides into monoglycerides and free fatty acids
• These components combine with bile to form micelles (water-soluble structures) and diffuse through the intestinal cells
• Chylomicrons are formed in the intestinal cells, combining triglycerides, cholesterol, phospholipids, and proteins, to transport these components into the bloodstream and lymphatic vessels

Functions of Fat in the Body

• Energy source (9 kcal/g)
• Essential fatty acid source
• Component of cell membranes
• Skin and hair health support
• Body insulation
• Satiety regulation
• Transport of fat-soluble vitamins
• Nerve impulse transmission

Functions of Cholesterol in the Body

• Regulates cell membrane fluidity
• Aids communication between cells and the environment
• Limits leakage of electrolytes (Na and K) across cell membranes
• Assists in the synthesis of bile acids (crucial for fat absorption)
• Involved in hormone synthesis (including sex hormones and vitamin D)

Health Issues in Lipids

• Excessive fat intake leads to excess calorie storage, increasing risk of obesity, diabetes, heart disease, and high blood pressure
• High levels of saturated fat and cholesterol can promote atherosclerosis, raising the risk of heart attacks and strokes

Where's the Saturated Fat in Foods?

• Specific examples like beef, lamb, poultry (especially skin), lard, cream, certain cheeses, ice cream, coconut oil, and palm oil are high in saturated fat

Lowering Blood Cholesterol Levels

• Reduce consumption of saturated and trans fats
• Limit processed foods
• Increase fish consumption
• Enhance intake of plant foods
• Leverage antioxidant and phytochemical-rich foods
• Engage in regular exercise

Dietary Recommendations of Fat in the Diet

• Total fat: 20-35% of daily calorie intake
• Polyunsaturated fats: 5-10% of daily calories (omega-6) and 0.6-1.2% of daily calories (omega-3)
• Saturated fat: less than 10% of total daily fat intake
• Cholesterol: less than 300 mg daily
• Avoid trans fat

Food Label Evaluation

• Examples of how to evaluate nutrition labels, specifically for fat content

International Recommendations for Fat Content in Food Products

• Specific ranges for total fat and saturated fat in different food categories (solid, liquid)

Test your knowledge about lipids and their classifications, including triglycerides, phospholipids, and sterols. Explore the different types of fatty acids, such as saturated, monounsaturated, and polyunsaturated. Understand the roles of these nutrients in the body and their physical properties.