NUTR 1030 1st Edition Lecture 9 Outline of Last Lecture I. Explain the basic structure of triglyceridesII. Describe the functions of lipidsIII. Identify food sources of lipidsIV. Identify and explain essential fatty acidsOutline of Current Lecture I. Identify phospholipidsII. Identify sterolsIII. Understand the functions of cholesterolIV. Identify key components of the Mediterranean dietV. Understand and explain the digestion/absorption of lipidsCurrent LecturePhospholipids:- Hydrophobic and hydrophilic ends- Built on a glycerol backbone- Have at least one fatty acid replaced with phosphorus containing compoundFunctions:- Components of cell membranes- Emulsifiers (ex: bile)Sources:- Synthesized by the body- Food: egg yolks, wheat germ and peanutsSterols:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Carbons arranged in rings- Waxy substance- Do NOT have a glycerol backbone- Most well-known sterol is cholesterolSources:- Synthesized by body- Foods of animal origin (cholesterol)- And plants (plant sterols)Cholesterol functions:Steroid hormones- Active vitamin D- Estrogen- TestosteroneBileCell membrane componentLipoprotein shell (ex: chylomicrons)Recommended Fat Intake:- No RDA- AMDR: 20-35%- Dietary guidelines 2010: limit saturated and trans fat- AHA recommendations for those at risk for heart disease:I. Limit saturated fats to 7% of total caloriesII. Limit cholesterol intake to less than 200 mg/dayIII. Limit trans-fat to less than 1% of total caloriesThe Mediterranean Diet:- Up to 40% kcal from fat can be heart healthy if mostly MUFA and part of healthy overall lifestyle- Traditional diet features:I. Olive oil as main fatII. Abundant fruits and vegetables, whole grains, beans, nuts and seedsIII. Daily intake of small amounts of cheese and yogurtIV. Weekly fish intake: limited use of eggs and red meatV. Regular exercise and restVI. Moderate wine intakeThe Mediterranean diet emphasizes:- Eating primarily plant-based foods- Replacing butter with healthy fats, such as olive oil- Using herbs and spices instead of salt- Limiting red meat to no more than a few times a month- Eating fish and poultry at least twice a week- Drinking red wine in moderation (optional)Fat Intake:- North American fat intake has doubled in the last century- Omega 6 intakes are plentiful - Omega 3 intakes are usually lowI. Food sourcesII. SupplementsIII. CautionsDigestion of Lipids:In the mouth and stomach:- Mouth- minimal breakdown of triglycerides by lingual lipase- Stomach- gastric lipase works only in an acidic environment- Gastric lipase acts on triglycerides containing short and medium chain fatty acids- Longer fatty acid chain is not affected in the stomachIn the small intestine:- Primary site of fat digestion- CCK stimulates the release of bile to help emulsify fat- CCK stimulates pancreas to release pancreatic lipase- Pancreatic colipase is released to help facilitate lipase enzyme action- Fat is broken down to monoglycerides and fatty acids- ~95% of fat consumed is absorbedFat Absorption:- Short and medium chain FA- portal vein- Long chain FA re-esterified back to TG- packaged into chylomicrons- lymphatic system- Bile- recycled by enterohepatic circulation Transportation of Fats:- As lipoproteins (chylomicrons, VLDL, LDL)I. Lipid core, protein/phospholipids/cholesterol shell- At cellular levelI. Lipoprotein lipase breakdown triglycerides from the chylomicrons, fatty acids are absorbed by cellsII. Takes 2-10 hours to clear