Lipids (Fats and Oils) • Non-polar long chains of carbon atoms • Fatty Acids have carboxylic acid functional group and methyl group at other end - most often even number of C atoms • Saturated fats - contain only single covalent bonds, no double bonds • Unsaturated fats - contain one or more double covalent bonds
Basic Categories of Lipids • Fatty Acids fatty acids and glycerol • Triglycerides (Glycerol + 3 FA’s) … mono-, di-, tri- • Phospholipids (Glycerol + 2 FA’s + P group) amphiphilic (polar and non-polar) • Steroids (Derivatives of Cholesterol) complex and important!
Functions of Lipids in Body • Energy Storage • Energy Source • Insulation/Protection • Cell Membrane Structure • Transport of Fat Soluble Vitamins • Hormones and Signal Molecules • Vitamin D, Bile, Sex Hormones, Prostaglandins • Regulators of Appetite and Satiety
Lots of Lipids to Choose from in Your Diet
Fatty Acids – are one of the fundamental building blocks of nutritional lipids! General Formula of Fatty Acids: CH3(CH2)n COOH n = any even # from 2 to 24 Carbon chain contains no double bonds Carbon chain contains one or more double bonds
Fatty Acids: A chain of C and H atoms with a carboxyl group At alpha end and a methyl group at omega end. • FAs attached to OH groups, gives off H2O • Bonds between FA and glycerol = ester bond • Attach a FA to glycerol = esterification • Remove FA from glycerol = deesterification
20 different Fatty Acids, vary by: • Degree of Saturation • Length of the C chain • Shape Fatty Acids classified by number of C atoms as: • Short-chain fatty acids (SCFAs): Less than 8 C’s • Medium-chain fatty acids (MCFAs): 8 to 14 C’s • Long-chain fatty acids (LCFAs): 16 or more C’s • Very-long-chain fatty acids (VLCFAs): More than 22 C’s
Saturation and Length of the C chain Saturated Fatty Acids Monounsaturated Fatty Acid (MUFA) Has one double bond Polyunsaturated Fatty Acid (PUFA) Has two or more double bonds
Saturated Fatty Acids in Diet Lauric acid- CH3 (CH2)10 COOH coconut oil, breast milk. Myristic acid CH3 (CH2)12 COOH - coconut, palm kernel oil, butter, cheese, whale blubber. Palmitic acid CH3 (CH2)14 COOH - poultry, beef, game meats. Stearic acid CH3 (CH2)16 COOH - cocoa butter, beef tallow, lard, butter, beef, pork, lamb.
Stability of Fatty Acids Rancidity: Spoiling of fats through oxidation • Double bonds lessstable than single bonds. • Foods with unsaturatedfats become rancid fasterthan saturated fats. • Need to Add antioxidants • Limit Oxygen, Heat, Light • Hydrogenation of Oils
Essential Fatty Acids (EFA) - unsaturated, essential to human health, cannot be manufactured in the body. 1, 2 or 3 EFAs: • Linoleic Acid* - only from diet! • α-Linolenic Acid • Arachnoidic Acid - from linoleic acid! • *When linoleic acid is obtained in the diet, it can be converted to both arachnoidic and linolenic acid.
Omega-3 Fats Plant Based: Alpha-Linolenic Acid (ALA) is essential: chia (64%), kiwi fruit (62%), flaxseed oil (53%), Hemp (20%) walnuts (9%), and canola oil (10%), soybean oil (7%). Plus, red meat; dairy products. Animal Based: Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acids (DHA) fish, shellfishand krill. DHA needed for brain and retina; EPA its precursor. You can make some EPA and DHA from short-chain ALA, but does so inefficiently. Omega-6 Fats Linoleic Acid (LA) is essential, which is the most prevalent PUFA in the Western diet, is abundant meat,poultry,eggs,hempand nut-based oils – Plus corn, sunflower, soybean and canola oil. All to be avoided! Arachidonic Acid (AA), important (membranes, regulate inflammation, promote blood clotting, communication). Made by EFA’s
Essential Fatty Acids Manufacture Eicosanoids and Cell Membranes • Linoleic Acid • Converted to Arachidonic Acid • Alpha-Linolenic Acid (ALA) • Converted to Eicosapentanoic acid (EPA) • Elongated to Docosahexanoic acid (DHA) • EPA and Arachidonic Acid (AA) make Eicosanoids. Hormone-like substances regulating blood clotting, immune system, inflammation, blood pressure cell membranes in nerve tissue and retina.
Eicosanoids • Prostaglandin- hormone-like compounds. Various actions include: uterine contraction, sleep cycles, body temp regulation, vasoactive effects. • Prostacyclin- made by blood vessel walls, potent anticoagulent (thins the blood). • Thromboxane- stimulant of blood clotting. • Leukotrine- chemical signal regarding state of inflammation. Involved with hypersensitivity reactions, and asthma (contracts bronchioles). • Lipoxin- made by WBCs, involved in immune and allergic responses.
Dietary Deficiency of Fatty Acids Not enough FAs in diet causes: • Flaky skin • Depression; lower alertness • Compromised immune system • Infections • Slowed wound healing • Anemia • Diarrhea
Triglycerides 1 3 2 Esterification Process Note the different configuration of the ‘tails’
Formation of Triglycerides The Functions of Triglycerides in the Body 1 – Energy Storage and Energy Source Lipids are energy rich (9kcal/g vs 4kcal/g). The process to use lipids as a fuel source is complex and secondary to glucose in most diets. • Fats as Fuel • Preferred by the heart, liver, and resting muscle • Spares glucose for use by nervous system and RBCs • Provides a backup source of energy between meals • Glucose is needed to metabolize fat. • Glycerol portion of fat can make small amounts of glucose
The Functions of Triglycerides in the Body 2 – Insulation and Protection Triglycerides are stored in adipose tissue inside adipocytes (fat cells). Subcutaneous fat is the adipose under the skin, it insulates your Tb Visceral fat surrounds internal organs, protects and cushions. 3 – Nutrition The fat-soluble vitamins, A, D, E, and K all require lipids in the body to absorb them. Vitamins E, D, and K are also stored in the fat tissue.
Note: The fatty acids in a triglyceride molecule are usually comprised of all saturated or unsaturated.
Phospholipids Like a Triglyceride – with 1 FA replaced with alcohol/sugar phosphate group both Hydrophobic and Hydrophilic
Phospholipid Structure Phospholipid Bilayer of all Cell Membranes
Average Cell membrane contains 50% lipids 75% Phospholipids; 20% Cholesterol; 5% Glycolipids
Lecithin aka phosphatidylcholine – is a type of phospholipid. • Synthesized by the liver • Functions • Used as an emulsifier in foods (e.g., salad dressing) • A major phospholipid in the cell membrane micelle
Sterols! Sterols contain the steroid of four fused carbon rings.
The Liver Uses Cholesterol as starting Material for Vitamin D3 Sex Hormones (Estrogen and Testosterone) Bile Acid Cortisol Structural elements of cells Highest content in liver, brain, heart, and kidney
Please note: The information presented is incorrect (wrong!) –and on a Time Magazine cover in 2014 even they admit this. Time Magazine cover story in 2014. Scientists were wrong about saturated fats. They don’t cause heart disease after all. Time Magazine Cover from 1984 blaming cholesterol and saturated fats as a cause of heart disease.
All Fats are Not Equal! Omega-3- and 6-Fatty Acids Cholesterol (LDL’s and HDL’s) Just Say No! Hydrogenated Vegetable Oils Trans Fats and Acrylamide *Dr. Ancel Keys (1958) Ischemic Heart Disease
Cholesterol Vitamin D Cortisone Glucocorticoids Mineralcorticoids Steroid Hormones (testosterone, estrogen, progesterone) Bile Salts
Acetyl CoA Hydroxymethyl Glutaric Acid (HMG-CoA) Statin = HMG-CoA reductase inhibitors Mevolaonate Mevolaonate Pyrophosphate Isopentenyl Pyrophosphate Geranyl Pyrophosphate *Without these 3 end products you age prematurely Famesyl Pyrophosphate Squalene *Dolichol *Ubiquinone (CoQ10) *Cholesterol Biochem Cell Biol. 1992 Jun;70(6):422-8
Decreased Levels of Dolichol result in: Dolichol in Brain • decrease in energy • compromised immune system • hormone imbalance or deficiency • low sperm count • cell damage or cell death • poor brain function • nervous disorders • depression Ubiquinone (CoQ10) The heart, liver and kidney have highest CoQ10 concentrations CoQ10 is Protectant!
Unsaturated Oils vs. Saturated Fats Polyunsaturated Fats – e.g., canola, soybean, safflower, corn - easily become rancid when exposed to oxygen and produce free radicals in the body. Just Say No! *Olive oil – Still good; best if not heated! Why is it that every processed food has the same basic 5 ingredients in them? The Farm Bill
Say- Yes Please! Virgin Coconut Oil- a saturated fat with medium chain Fatty Acids (MCFA) - extremely heat stable and very beneficial for human physiology. Saint-Onge and Jones (2003) * Coconut Oil does not elevate cholesterol or cause heart disease. * Reduces weight gain. * 50% Lauric Acid – same lipid in breast milk. Protective properties.
Eating fat makes you fat and increases your risk of cardiovascular disease - Right?
One of the best foods to eat to control blood glucose is Fats - the right fats! Yes - like Coconut Oil!
Triglyceride Digestion Begins in Mouthand Stomach • The digestion of fat begins in the mouth with chewing. • Food mixes with saliva and lingual lipase. • Lingual lipase hydrolyzes the medium-chain fatty acids. • The bolus of food travels through the esophagus into the stomach. • Gastrin is released from the gastric pits lining the stomach and stimulates the release of gastric juices, rich in gastric lipase. • Gastric lipase hydrolyzes one fatty acid from the triglyceride, which produces a free fatty acid and a diglyceride.
Most Triglycerides Digested and Components Absorbed in the Small Intestine • Fat globules in chyme tend to cluster together. • In the intestine, bileemulsifies larger fat droplets into smaller fat droplets. • Allows pancreatic lipase to digest the lipids easily. The resulting lipid complex is a micelle –thesetransport the lipid complex across the small intestinal wall. • Cholecystokinin (CCK) is the hormone that stimulates the gallbladder to release bile. • CCK triggered to release when cells of the duodenum detect the presence of lipids.
Phospholipids • Emulsified by bile during digestion • Dismantled into 2 free FA’s phospholipid remnant • Packaged as micelles & transported through intestinal wall • Sterols • Not digested • Carried and absorbed intact by micelles • Bile emulsifies sterols. • Undigested/non absorbed lipids: • Bind with fiber • Are eliminated in the feces
Chylomicrons Facilitate Lipid Absorption Glycerol and short- to medium-chain fatty acids are absorbed directly into the bloodstream. Long-chain fatty acids combine with phospholipids and cholesterol to form Chylomicrons.
Chylomicrons Facilitate Lipid Absorption Chylomicrons are too large to be absorbed directly into the bloodstream. • Travel through lymphatic system first • Exit the lymph and enter bloodstream via thoracic duct next to the heart • Lipoprotein lipase (LPL) hydrolyzes triglycerides in the chylomicrons as they travel to liver via the bloodstream.
Fat Absorption • Bile and lecithin emulsify and break down fats into triglycerides • Lipases in small intestine break down triglycerides in food into FAs and monoglycerides • Monoglycerides and FAs absorbed through villi into intestinal cells • The reassembled into triglycerides • Triglycerides collect and combine with protein, cholesterol, and phospholipids to form chylomicrons
Nutrients ultimately end up in your Blood Blood has 2 parts:Plasma (fluid) and Cells! Plasma is 92% Water and we know that Lipids are hydrophobic, so they require special mechanism for transport through the blood to the tissues. Lipoproteins