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Fat in In the Body: Table 5-1 p.150 (9 things)
1. Energy Storage (fat is chief form of stored energy in body) 2. Muscle Fuel --fats provide most of the energy to fuel muscular work 3. Emergency Reserve (in times of illness/famine) 4. Cushions (protects organs) 5. Insulation (through temperature extremes) 6. Phospholipids form cell membranes 7. Raw materials (converted to hormones, bile, Vitamin D) 8. Cholesterol Necessary for Brain function 9. (Breathing and heart beating burns fat)
In Food: Table 5-1 p.150 (8 things)
1. Nutrient - fats provide essential fatty acids
2. Calories - Concentrated energy source
3. Transport - Fat soluble vitamins A,D,E,K along with some phytochemicals + aid in absorption
4. Raw Materials- for making needed products
5. Sensory appeal (taste,aroma)
6. Stimulate appetite (probably due to satiety)
7. Satiety (contribute to feelings of fullness)
8. Texture (tender)

Triglycerides class
three fatty acids attached to a glycerol. Triglycerides are the body’s storage form of fat. Can differ in chain length and degree of saturation. Fatty acid types vary.
Phospholipids class
two fatty acids and a phosphate group attached to a glycerol. With the phosphate group attached, phospholipids are soluble in water, and the fatty acids are soluble in fat. This helps keep fat dispersed in water. Serves as an emulsifier. They also bind together to form cell membranes. Have both hydrophobic and hydrophilic (polar and non-polar) characteristics that help transport fats across these membranes. Generate signals inside cells in response to hormones (i.e. insulin) to help regulate body functions
Sterols class
interconnected rings of carbon atoms with side chains of C, H and O attached. Serves as raw material for making emulsifiers in bile, which is important in fat digestion. Also play roles in vitamin D, sex hormones, and other important compounds. Also important for the structure of cell membranes.
Triglycerides structure
(fatty-acids and oils) are the main form of fat in the body, making up 95% of the lipids in the body. They consist of one glycerol molecule and three fatty acid chains. Generally, the more unsaturated the fatty acids, the more liquid the fat is at room temperature, and the more saturated the fatty acids, the firmer the fat.
omega-6 fatty acid or Linoleic acid structure
(triglyceride) a polyunsaturated fatty acid with its endmost double bond six carbons from the end (omega end) of the carbon chain. More blood clotting, higher blood pressure and inflammation. Lowers all cholesterol--good and bad. (ex: in vegetable oils, mayo, seeds, nuts, poultry fat) To check saturation, put oil in a clear container and put it in the fridge. Watch for cloudiness. The least saturated oils remain clear. Found in vegetable oils, margarine, and salad dressings. Omega-6 includes linoleic acid and arachidonic acid.
omega-3 fatty acid or Linolenic acid structure
(triglyceride) is a polyunsaturated fatty acid with its endmost double bond 3 carbons from the omega end of the carbon chain. Prevents blood clotting, lowers blood pressure (keeps vessels pliable), protects against irregular heartbeats, reduces inflammation, and is essential for infant growth and development. Also lowers LDL. Excess of omega 3 increases risk of hemorrhage and stroke. (ex: canola oil, flaxseed oil, soybean oil, nuts and seeds, fatty fish) . Omega-3 includes linolenic acid, EPA and DHA.
EPA, DHA structure
(triglyceride) in fish, seafood, human milk. DHA and EPA (contained in fish oils) in fish tissue are important for unclotting blood, lowering blood pressure, and is an essential fatty-acid. Very important in infant growth and development
Phospholipids structure
consist of one glycerol molecule, 2 fatty acids, and a molecule containing phosphorus (phosphate--water soluble/polar end). (ex lecithin) acts as an emulsifier--aids in breakdown of fats, holds water to fat (ex: eggs contain lecithin, and are used in baking to hold polar and non-polar ingredients together). make up cell membranes because they are water-loving (hydrophilic) and fat-loving (hydrophobic)
Sterols structure
consist of interconnecting rings of carbon atoms with side chains of carbon, hydrogen, and oxygen attached. (Most commonly found in animal products) (ex: cholesterol, which aids in creation of Vit. D and makes the emulsifiers in bile, and sex hormones). Sterols other than cholesterol exist in plants. Plant sterols resemble cholesterol in structure and can inhibit cholesterol absorption in the human digestive tract, thus lowering blood cholesterol levels. Not only can plant sterols (phytosterol) inhibit cholesterol absorption, they also may block absorption of other important nutrients as well. Cholesterol is important in cell membrane structure. It can be made by the body, so it’s not an essential nutrient.
Lipid Digestion (3 things)
• Mouth: In infants, saliva is the first part of digestion (contains enzyme (lingual lipase) that helps break down milk fat)
Lipid Absorption
• Free fatty acids, phospholipids and monoglycerides cling together in balls surrounded by bile emulsifiers. Bile shuttles lipids across water mucus layer to waiting cells of intestinal villi, then the cells extract the lipids. The bile may also be absorbed and reused or be excreted by feces. The body is very efficient at digesting lipids, up to 98% of fats consumed are absorbed! Very little fat is excreted by a healthy system. Fat makes digestion take longer, so the more fat in a meal the longer the digestion system action becomes. pg. 158 diagram
Lipid Transportation (3 things)
• Glycerol and shorter chains can pass directly through the cells of the intestinal lining into the blood stream, where they travel UNASSISTED to the liver. The larger ones must be reconverted back into triglycerides and combine them with protein, which forms lipoproteins (chylomicrons). fart. This must occur before they can be released into the lymph in vessels that lead to the blood stream. Fats need special transport vehicles-the lipoproteins-to carry them in watery body fluids. • Lipoproteins: Assembled packages of lipid and protein molecules, which serve as transport vehicles for lipids in blood and lymph. Larger lipids fragments such as • monoglycerides and long chain fatty acids are re-formed into triglycerides and clustered together with proteins and phospholipids in small intestine cells to form chylomicrons (one type of lipoprotein) before they can be released into the lymph in vessels that lead to the blood. Shorter chain fatty acids and glycerol can pass directly through the cells of the intestinal lining where they can travel unassisted to the liver.
Types of Lipoproteins (distinguished by density, more buoyant = more fat content)
- Chylomicrons and other lipoproteins are clusters of protein and phospholipids that are emulsifiers. They enable their large lipid passengers to travel dispersed in the watery body fluids. Body tissues can extract whatever fat they need from chylomicrons passing by in bloodstream. Remnants are then picked up by liver, which dismantles them and reuses their parts.
(mostly fat, neutral for risk of CVD)- formed when lipids from a meal are combined with carrier proteins and phospholipids in the cells of the GI tract. They transport food fats through the watery body fluids to the liver and other tissues a. made in GI tract b. Deliver fat
Three types of lipoproteins to carry fats besides chylomicrons
(very low density lipoprotein) carry triglycerides and other lipids made in the liver to body cells for use. Neutral for CVD risk a. made in liver
(bad) (low density lipoprotein, VLDL with less fat) transport cholesterol and other lipids to tissues a. Made from VLDL after VLDL have donated many of their triglycerides to body cells b. drops off cholesterol- raises blood cholesterol level c. increased risk of CVD d. carry lipids that trigger inflammation: leads to heart disease (CVD) e. larger, lighter and richer in cholesterol (more lipid, less protein) f. can be easily damaged by oxidation, which contributes to the damage to the arteries of the heart and inflammation LDL rises with intakes of saturated and trans fats.
(good) (high-density lipoproteins) “garbage trucks of circulation” - return cholesterol from tissues to liver for dismantling and disposal
Heart and Artery Disease
Diet too high in saturated fats or trans fats and too low in fish oils increase risk of cancer. invites heart and artery disease. Saturated and trans fatty acids both worsen the blood lipid profile.
saturated fats pose the greatest public health hazard in terms of heart disease, NOT cancers
A diet high in energy-rich fatty foods makes over-consumption of calories likely and encourages unneeded weight gain.
Keep total fat intake between 20-35% of calories from mostly polyunsaturated and monounsaturated fat sources
keep saturated fat intake low, less than 10% of calories, and keep trans fat intake as low as possible.
Fatty Acids
some are essential and help lower cholesterol, and some raise cholesterol
Saturated Fatty Acids
Raise blood LDL by decreasing LDL reuptake in liver, which clogs arteries
helps lower bad cholesterol without affecting HDL, protective against CVD (peanut, canola, and olive oil, avocados)
linoleic (omega 6) acid and linolenic (omega 3) acid
Omega 3/Omega 6
More Omega 3, fewer Omega 6 = less abnormal blood clotting, mildly lower blood pressure, less inflammation, lower risk of heart disease and stroke (benefits from omega 3) too much omega 3 increases risk for hemorrhaging. Only need more omega 3 because Americans tend to get less in their diets. Need specifically more Omega 3, not a proportion of both, because they compete for the same enzymes. Eat more fish!!!
Food Sources of Saturated fats
bacon, tropical oils, meat, butter, lard, animal products, coconut oil (exception to rule)

Food Sources of Monounsaturated fats
olive oil, canola oil, peanut oil, avocados, seeds

Food Sources of Polyunsaturated
vegetable oils (Soy, corn, sunflower, safflower, sesame, cottonseed, walnut), nuts and seeds, fatty fish
Food Sources of Omega 3 (Linolenic)
Linolenic is parent of Omega-3 family
Food Sources of Omega 6 (Linoleic)
Linoleic is parent of Omega-6 family
Hydrogenated Plant Oils
• Makes it stay fresh longer (works against oxidation) • Changes their physical properties- addition of hydrogen across double bonds • Prevents spoilage • Makes them stable and harder when they are heated to high temperatures • Makes food flaky and tender (baked goods) • Higher smoking point
Foods containing trans-fats
• Chips, cookies, and crackers (snack products) • Fast foods • Cake and frosting • Stick margarine • Commercial fried chicken and fish products • Other commercially prepared/processed foods (incl. breads) • partially hydrogenated peanut butter BASICALLY FRIED FOODS (but you can fry food using healthy oil, too - ex Chik-Fil-A uses peanut oil)
Health implications of trans-fats
• Pose risk to heart and arteries by raising blood LDL cholesterol • Higher intakes lower beneficial HDL cholesterol • Increase tissue inflammation, which can lead to heart disease • Hydrogenation changes essential FA into their saturated or trans counterparts, losing health benefits of original raw oil • Compared with the risk to heart health posed by saturated fat, the risk from trans fat is similar or slightly greater. ***Keep trans-fat intake as low as possible (<1% of cals)
adding H to carbon chain where there used to be a double bond(breaking the double bond). (ie making an UNSATURATED fat into a SATURATED fat). If there is a kink in it and it still has the double bond this is called the cis formation- what it’s called when the two hydrogen molecules are on the same side of the double bond, as they are in the unsaturated fatty acid, as opposed to on opposite sides in the trans fatty acid). Trans is when the double bond is not broken, but the structure is altered so that there is no longer a kink and hydrogens attach on different sides of carbon chain - the fat chains can squish closer together.
DGA says less than 10% of daily calories should be saturated fat, <1% trans fats, <300 mg/day cholesterol.
USDA has chart depending on activity, weight, height, etc. Example: active woman (19-30years)= 6.5 oz. daily from meats/legumes and 7 tsp. from oils, or active men (19-30years)= 7 oz. and 10tsp. (table on p. 44).
AMDR: 20-35% fat intake/31g or 7tsp oils (fats) for a 2400 calorie person(?) 480-840 kcal = 53-93g of fat (9 kcal = 1 fat grams) If 20-35% is what you want for fat intake, then 20-35% of 2400 calories is 480-840 kcal, which with the conversion of 9 kcal for every 1 gram of fat, that’s 53-93 grams of fat.
Reducing fat intake
• Look for fat replacers, they are made from carbohydrates and protein and provide same taste and texture as fats but with lower calories • Artificial fats offer sensory properties of fat but none of the calories • Olestra also is a way to reduce fat intake, it is another artificial fat a. Olestra is not digested, and therefore doesn’t provide carbohydrates to the body at all b. Also has side effects including cramps and diarrhea - not really used anymore • Smaller portion sizes • Choosing and reading labels and foods at the grocery store • Cooking with healthier oils rather than solid fats like butter • Flavorful fats (need less in order to flavor) • Unsaturated oils (in PLACE of saturated) • Revamp recipes • Lower fat fast foods • Increase the amount and variety of seafood in place of some meat and poultry. • Cheeses are the single greatest contributor of saturated fat in the diet
the essential amino acid names: Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Lysine, Leucine
Structure of proteins
● A strand of amino acids (Amino acid is the smallest part of a protein) ● All amino acids have the same backbone consisting of a single carbon atom with both an amine group (the nitrogen containing part) and a carboxyl group(acid group) attached to it. ● Each also has a distinct chemical side chain (which determines the amino acid’s function) attached to the center carbon of the backbone ● All AA’s needed for protein synthesis: ● Essential amino acids are required in making a protein because without them, the body cannot make the proteins it needs to do its work. ● All necessary types of amino acids need to be present to build a protein. ● Protein quality makes a difference with the amount and number of AA’s. ● If a protein can’t be completed because of lack of AA’s, the protein will be broken down, they can’t be stored.
Protein Digestion and Absorption (SSiT)
● Stomach: when swallowed food arrives in the stomach, acid denatures the protein strands and an enzyme (pepsin) breaks down the protein ● Small intestine: enzymes from the pancreas and the intestine split peptide strands into tripeptides, dipeptides, and amino acids. The intestinal cells absorb and transfer amino acids and some larger peptides into the bloodstream. The small intestine possesses separate sites for absorbing different types of amino acids, and amino acids of the same type compete for the same absorption sites, so ingesting a large dose of any single one may limit absorption of other of its general type. ● Transportation: The blood transports amino acids into the liver, to be used or released back out to the cells
Protein Metabolism
1. If energy needs not met or excess protein is consumed: a. The Acid-side chain is metabolized and used for energy or stored as fat. (deamination) b. The Amine group (N) is removed, and converted to urea. 2. Dismantled to make nonessential amino acid (transamination)
Roles of Protein
• Production of antibodies • Transporting substances ex: lipoproteins • Maintaining fluid and electrolyte balance (edema is caused by lack of protein) • Maintaining acid-base balance • Blood clotting (against infection) • Provide energy and glucose o (THIS TAKES PRIORITY over other functions WHEN ENERGY IS TOO LOW!) • Growth and maintenance o tendons, ligaments, scars, filaments of hair, nails • Regulation of gene expression • Building enzymes, hormones, etc.
Nitrogen Balance: more protein = more nitrogen
• Amount of nitrogen consumed compared with the amount excreted in a given time period • Balanced - Nitrogen in (consumed) equal Nitrogen out (excreted) • Positive - intake more than you excrete
Foods in terms of protein amount and quality:
Is it close to what your body needs? 1. High-quality - proteins provide enough of all the essential amino acids needed by the body to create its own working proteins. Better quality proteins for humans are found in animals, as they are the most similar to us. (Over 90% absorbed from animal proteins) 2. Low-quality - plant proteins
Complementary Proteins
● Two or more plant proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other. ○ Rule of thumb: a grain paired with a legume. Ex: rice and beans, pita bread and hummus, bread and peanut butter, etc. ○ Most easily digestible: meat (over 90%), legumes (80-90%), grains (70-90%)
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