Lipids and Their Functions

Lipids (Fats & Oils)

• Fats are solid at room temperature.
• Oils are liquid at room temperature.
• The building blocks of lipids are triglycerides, a combination of one glycerol molecule and three fatty acid molecules.
• Lipids function as fuel, carrying essential fatty acids and fat-soluble vitamins (A, D, E, & K).
• Lipids provide insulation and protection for the body, acting as a protective layer for internal organs.
• They are essential components of cell membranes.
• Lipids contribute to satiety, adding flavor and texture to food.
• The USA does not have daily fat intake recommendations.
• Recommended daily fat intake:
  • Less than 30% of total daily calories.
  • 10% saturated fats.
  • 10% monounsaturated fats.
  • 10% polyunsaturated fats.

Polyunsaturated Fats

• Considered the best type of fat.
• Liquid at room temperature and stay liquid when chilled.
• Include Omega-6 and Omega-3 fatty acids.
• Omega-6 fatty acids are heart-friendly, lowering cholesterol levels.
• Examples of Omega-6 fatty acids:
  • Linoleum acid.
  • Sources: soybean and canola oil, nuts.
• Omega-3 fatty acids are heart-friendly, preventing blood clots and protecting artery walls from damage.
• Examples of Omega-3 fatty acids:
  • Linolentic acid
  • Sources: Cold-water fish, canola oil, soybeans, olive oil, nuts.

Monounsaturated Fats

• Considered good for you.
• Liquid at room temperature and thicken when chilled.
• Found in most nuts and olive, canola, and peanut oils.

Saturated Fats

• Considered bad for you.
• Solid at room temperature and harden when chilled.
• Found in animal foods and some plant foods like coconut oil and palm oil.
• Increase the risk of heart disease.

Cholesterol

• A fat-like substance found only in animal products.
• Not used for energy and has no calories.
• Plays a role in the production of estrogen and testosterone.
• Aids in the conversion of sunlight on the skin into vitamin D.
• A major component of nerves and the brain.
• Found in every cell.
• The body produces cholesterol if it isn't obtained through the diet.
• Two sources of cholesterol:
  • The body.
  • Animal fat.

Trans Fat (Artificial Fat)

• Artificially produced fats created through hydrogenation, a process that fills empty spots in polyunsaturated (vegetable oils).
• Found in many processed foods.
• Can be identified in ingredient lists as:
  • Hydrogenated fat.
  • Hydrogenated Oil.
  • Partially Hyderogenated fat.

Artificial Fat Examples

• Simplesse:
  • Low-calorie artificial fat made from milk protein and water.
  • Found in frozen desserts.
• Olestra (or Olean):
  • Non-digestible fat made from sugar and oil compounds.
  • Cannot be digested or absorbed by the body, so it provides no calories.

Lipid Digestion, Absorption, and Metabolism

• Digestion:
  • Begins in the stomach through mechanical digestion.
  • Gastric acid and enzymes, such as lipase, break down triglycerides into diglycerides.
  • Fat is water-insoluble and takes longer to leave the stomach (2-9 hours).
  • Continues in the small intestine where triglycerides and diglycerides are further broken down into fatty acids and glycerol with the help of bile.
  • Bile is produced in the liver, stored in the gallbladder, and released into the small intestine.
  • Bile emulsifies fat, breaking it down into smaller droplets to aid in digestion.
  • Pancreatic enzymes (lipase) are released into the small intestine to aid in digestion.
• Absorption:
  • Most absorbed through the small intestine.
• Metabolism:
  • Liver plays a key role.
  • Fats are used for energy or stored for later use.

Consequences of Fat Deficiency

• Intolerance to cold temperatures.
• Stunted growth in children.
• Skin deterioration.
• Women may experience menstrual irregularities and infertility.

Consequences of Excessive Fat Intake

• Obesity: Excessive accumulation of body fat.
• Heart disease: Leading cause of death in the USA and Canada.
• Cancer.

Vegetarian Diets

• Lacto-ovo Vegetarians: Avoid meat but consume dairy and eggs.
• Pescatarians: Consume fish.
• Pollo Vegetarians: Only eat chicken but avoid other meats.
• Vegans: Exclude all animal products.
• Plant-based diets can provide 100% of the protein your body needs.
• Plant-based diets are linked to lower risks of:
  • Heart disease.
  • Stroke.
  • High blood pressure.
  • Diabetes.
  • Obesity.
  • Chronic bronchitis.
  • Gallstones.
  • Kidney stones.
  • Colon cancer.
• Plant-based diets offer benefits:
  • Lower in saturated fat.
  • High in fiber.
  • Higher in vitamins, minerals, and phytochemicals.

Vitamins

• Folic acid is vital for preventing:
  • Heart disease.
  • Stroke.
  • Colon cancer.
  • Birth defects.
  • Breast cancer.
• B-12 deficiency signs:
  • Memory loss.
  • Mental confusion.
  • Blurred vision.
  • Tingling in the feet.
• Vitamin C is crucial for maintaining supple skin through collagen synthesis.
• Fat-soluble vitamins can be stored in the body:
  • Vitamin A:
    • Pre-formed sources:
      • Animal liver.
      • Supplements.
      • Can be toxic in high doses.
    • Beta-carotene sources:
      • Plants.
      • Not toxic.
  • Vitamin E: Acts as an antioxidant to prevent free radical damage.
  • Vitamin D: Essential for bone health.
  • Vitamin K: Crucial for blood clotting.
  • Sources: Leafy greens, cabbage, also produced by the body.

Groups Requiring Extra Vitamins

• Smokers: Need 66% more vitamin C. Depletion also linked to passive smoke.
• Vegetarians: May need vitamin D and B-12.
• Pregnant and breastfeeding women.
• Menopausal women:
  • Vitamin D.
  • Calcium.
• Individuals over 50:
  • B-12.

Maximizing Vitamin Intake

• At the grocery store:
  • Aim for 5 or more servings of fruits and vegetables daily.
  • Choose whole grain products.
  • Look for opaque containers to retain riboflavin in foods.

Vitamin Destroyers

• Water: Washing vegetables after chopping can reduce vitamin content.
• Heat: Cooking can destroy some vitamins.

Minerals

• Single atoms that cannot be created or destroyed.
• Bioavailability: The amount of a nutrient available for absorption and use by the body.
• Factors reducing bioavailability:
  • High fiber diets.
  • Individual mineral supplements.
• Factors increasing bioavailability:
  • Vitamins can enhance the absorption of minerals.
    • Vitamin D and calcium.
    • Vitamin C and iron.
• Beef is a good source of iron.
• Iron in the blood is crucial for:
  • Transportation of oxygen in arteries.
  • Transportation of carbon dioxide in veins.
• Symptoms of iron deficiency:
  • Short attention span.
  • Poor appetite.
  • Weakness and fatigue.
  • Increased risk of infections.
  • Pale skin.
  • Increased heart rate.
  • For infants and children: Mental retardation.
• Ways to increase iron intake:
  • Cook food in iron pans.
• Consuming tea with meals reduces iron absorption by 50%.

Electrolytes:

• Potassium: Dietary intake helps lower blood pressure.

Preventing High Blood Pressure

• Reduce sodium intake.
• Exercise regularly.
• Consume low-fat dairy products.
• Eat a diet rich in fruits and vegetables.

DASH Diet (Dietary Approaches to Stop Hypertension)

• Low in:
  • Total fat.
  • Saturated fat.
  • Cholesterol.
  • Sodium.
• Emphasizes:
  • Fruits.
  • Vegetables.
  • Fat-free or low-fat milk and dairy products.

Osteoporosis

• A painful and crippling bone disease where bones become thin and brittle, making them more susceptible to fractures.
• The "silent disease" because early stages often have no noticeable symptoms.
• Bone cycle:
  • Childhood: More bone is formed than removed.
  • After age 30: More bone is removed than formed.
• Causes:
  • Can begin at a young age:
    • Insufficient calcium and vitamin D intake leads to low bone mass.
  • Menopause:
    • Decreased estrogen production impacts calcium metabolism.
• Risk factors:
  • Uncontrollable:
    • Gender (women are more susceptible).
    • Family history.
    • Race (Caucasians are at higher risk).
  • Controllable:
    • Being underweight.
    • Smoking.
    • Heavy alcohol consumption.
    • Exercise less than 3 times a week.
    • Dietary intake of less than 2 servings of dairy or a diet low in vitamin D.

This quiz covers the properties and functions of lipids, including fats and oils. Learn about triglycerides, the role of lipids in nutrition, and the differences between saturated and unsaturated fats. Understand daily fat intake recommendations and the benefits of polyunsaturated fats such as Omega-3 and Omega-6.