Nutrition Exam 2 Lipids and Cardiovascular Disease

In a saturated fatty acid, all carbon atoms make four bonds with neighboring atoms,

therefore there are only single bonds. These are generally solid at room temperature.

A polyunsaturated fatty acid has two or more double bonds in its structure. Generally more liquid at room temperature.

18:2 ω 6 (first double bond after 6th C from methyl end) Rich in: Sunflower, Safflower, Corn, Soybean oils, nuts and animal fats

The presence or absence of double bonds and the location of double bonds creates different physical and functional characteristics.

A triglyceride is composed of a 3-carbon glycerol backbone with three fatty acids extending out from each of the carbons of glycerol. Found in all foods containing fat

White Fat Stores energy in the form of fat for other cells to utilize Long-term storage form of energy

Brown Fat Releases stored energy as heat (uncoupling proteins) Protects infants who cannot shiver from cold but depot decreases with age Large # of mitochondria makes them appear brown White adipocytes can transform to brite cells in certain biological environments. Physical activity

Dietary fat has an association with risks for some types of cancer

But it is not as strong as the link to heart disease. Fat does not initiate cancer development but may be a promoter once cancer has developed. Some types of cancer have a stronger relationship to fat intake. Saturated fat from meat is implicated.

Lipid transport is made possible by a group of vehicles known as lipoproteins.

Chylomicrons are the largest of the lipoproteins.

Carbon lengths of 12 to 24 are called long chain fatty acids

Common in meats, fish and vegetable oils.

Normal Blood Levels of Lipids Total cholesterol <200 mg/dL Desirable 200-239 mg/dL Borderline High 240 and above High

Elevated total blood cholesterol is a risk factor for cardiovascular disease Contributes to atherosclerosis Develops when plaque builds on artery walls and leads to inflammation

Linolenic and linoleic acids are both essential fatty acids

Essential Fatty Acids (FA) cannot be made by the body Linoleic Acid and the Omega-6 Family (polyunsaturated) Can make arachidonic acid, which is a conditionally essential fatty acid Supplied primarily by vegetable oils

C atoms are not fully saturated with H atoms at one point. Rich in canola oil, olive oil, nuts, peanuts

Fatty acids with only single bonds are saturated; C atoms are saturated with H atoms. Rich in beef, meat, butter, dairy, palm oil, coconut oil

Triglycerides are hydrolyzed into monoglycerides and two fatty acids or a glycerol and 3 fatty acids by pancreatic lipases.

Glycerol, short chain fatty acids, micelles & chylomicrons

Diets rich in trans fatty acids or saturated fats are a strong risk factor for heart disease.

How to protect from oxidation: 1.Seal from oxygen 2.Add antioxidants 3.Hydrogenate 4.Refrigerate

Hydrogenation stabilizes polyunsaturated fats by adding hydrogen, thus converting them to saturated fatty acids (more resistant to oxidation).

Partial hydrogenation produces C=C double bonds where the position of hydrogen atoms shifts from being on the same side (cis) to opposite sides (trans). Rich in: solid vegetable oil products, snack foods, low amount in beef/animals

Although the quantity of fat and the kcalorie content of food are not affected by the differences in fatty acids, the body's risk of cardiovascular disease is affected. Thus, there are different "quality" aspects to different fatty acids. Lipoproteins are used by the body to carry fat. They have different functions and therefore different effects on the health of the body. High density lipoproteins (HDL) generally carry cholesterol back to the liver to be reused, and are associated with a decreased risk of cardiovascular disease. Low density lipoproteins generally carry cholesterol and fat to the body and are associated with an increased risk of cardiovascular disease.

Improvement in both the quantity and quality of dietary fat is recommended for most Americans. To improve the quantity of fat, major sources of dietary fat need to be altered and less consumed. To improve the quality of dietary fat, the type of fat consumed needs to be altered, but fat must still be consumed, i.e. consuming a very low fat diet does NOT improve the quality of fat consumed. Diet changes and increased physical activity along with maintaining desirable body weights reduce risk of cardiovascular disease and hypertension.

Balance Omega-6 and Omega-3 Intakes by eating more fish and less meat.

Include 2 3-oz. portions per week of fish. Bake, broil or grill the fish. Functional foods are being developed. Supplements are not the answer. Fried fish do not count! Grass fed beef -higher levels of ω-3, but basically very low in sat fats and total fat

S. I.:CCK signals Gallbladder to secrete bile.Bile flows in from Gall bladder to emulsify fat Pancreatic lipase flows in from the pancreas and intestinal lipase is present resulting in monoglycerides, Glycerol, and fatty acids that can then be absorbed. Sterols are absorbed as is. Phospholipids are hydrolyzed

L. I.:Some fat and cholesterol is trapped in fiber exits the body in the feces.

Linolenic Acid and the Omega-3 Family (Polyunsaturated)

Linolenic Acid and the Omega-3 Family (Polyunsaturated) Must be supplied by food Can make EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), important for eyes, brain and heart Deficiency associated with depression, growth retardation, reproductive failure and neurological problems

Key concepts

Lipids are composed of triglycerides (fatty acids), sterols and phospholipids. Fatty acids differ in the length of the carbon chain, degree of saturation, and location of first double bond. Fats rich in saturated fatty acids generally are from animal sources and/or are solid at room temperature, e.g. butter, lard, milk, shortening. An exception to this guideline is coconut oil, which is rich in saturated fat. Fats rich in monounsaturated fatty acids tend to be specific plant sources -- olive oil, peanut oil, and canola oil. Fats rich in polyunsaturated fatty acids (PUFA) generally are from plant sources and are liquid at room temperature, e.g. corn oil, safflower oil. An exception to this guideline is fish oils, which is an animal source of PUFA. Hydrogenation of fatty acids benefits for food preservation, but have a negative effects on its quality.

Eicosanoids

Made from longer omega-3 and omega-6 fatty acids Each eicosanoid plays a role in regulating activity within the body Sometimes these actions are in opposition Prostaglandins - specific type of eicosanoid Made from AA - contribute to inflammation EPA eicosanoids (omega-3): decrease BP, prevent clot formation, protect against irregular heart beats and reduce inflammation. NSAID's (Aspirin, Ibuprofen) inhibit formation of prostaglandins.

Eighteen carbon lengths are the most abundant in our food supply.

Medium chains (6-10 carbons) and short chains (<6 carbons) occur in small amounts in foods such as dairy products.

Stomach:Churning action mixes fat with water and acid.Lingual Lipase ( acid stable) begins to initiate fat digestion. Not appreciable at this point. Gastric lipase present, small role.

Mouth:Some hard fats begin to melt andsalivary glands release Lingual Lipase

Healthful Fatty Acids Monounsaturated Fatty Acids (MUFA) Sources Oils (canola, olive, peanut, sesame) Avocado Nuts (almonds cashews, filberts, hazelnuts, macadamia nuts, peanuts, pecans, pistachios) Olives Peanut Butter Seeds (Sesame)

Omega-6 Fatty Acids Sources Margarine (non-hydrogenated) Oils (corn, cottonseed, safflower, soybean) Nuts (pine, walnuts) Mayonnaise Salad Dressing Seeds (pumpkin, sunflower) Omega-3 fatty acids have an FDA qualified health claim

Adding plant sterols to foods = Functional Food

Plant sterols are structurally similar to cholesterol Interfere with cholesterol absorption=Lowered blood cholesterol levels.

Fatty Acid Deficiencies

Rare - Adequate intake is met by small amounts May occur in infants and children with low-fat diets

AMDR: 20-35% of total kcals from fat 30% of total kcals from fat is a good goal 7-10% saturated fats 10-15% MUFA's 10% PUFA's Limit transfatty acids to <1% of total kcals

Recommended intakes of Fat Daily Values 65 g fat based on 30% of 2000-kcal diet 20 g saturated fat based on 10% of 2000-kcal diet 300 mg cholesterol USDA Food Guide considers saturated fats empty calories. Too little fat can be detrimental to health. An association found between very low fat diets and inability to conceive.

Not all saturated fats are created equal!

Remember, saturated fats are a class of compounds not just one compound. Stearic acid is a long saturated fat (18:0) found in meat, but is also the predominant saturated fat found in dark chocolate. It appears that stearic acid has no harmful effects. Palmitic (16:0) and myristic (14:0), on the other hand, have been shown to increase inflammation, contribute to elevated lipids, atherogenesis and vascular disease. So, the plot (or artery?!) thickens! We cannot assume a one-name-fits all approach to saturated fat intake.

Dietary patterns associated with lowered risk of cardiovascular disease 1.DASH diet 2.Mediterranean Diet 3.Vegetarian Diet

Replacing saturated fat and trans fat with monounsaturated fat and polyunsaturated fat is one of the most effective dietary strategy in preventing heart disease.

EPA and DHA are two long-chain omega-3 fatty acids that can be synthesized in the body's cells from linolenic acid

Rich sources of preformed EPA and DHA in foods: fatty fish (i.e. salmon), eggs from chickens fed omega-3 fatty acids

Unsaturated Liquid at room temperature Spoil more quickly

Saturated Solid at room temperature More resistant to oxidation Alters texture-flaky crusts

Harmful Fatty Acids Transfatty acids Sources Fried foods (hydrogenated shortening) Margarine (hydrogenated or partially hydrogenated) Nondairy creamers Many fast foods Shortening Commercial baked goods (including doughnuts, cakes, cookies, etc.) Many snack foods (including microwave popcorn, chips, crackers)

Saturated Fatty Acids Sources Bacon Butter, lard, cream cheese, sour cream Chocolate Coconut Cream, half-and-half Meat Milk and milk products (whole) Oils (coconut, palm, palm kernel) Shortening

Sterols are the starting material for some hormones, and make up the structural component of cell membranes

Starting material for bile acids, sex hormones, adrenal hormones and vitamin D Structural component of cell membranes Liver produces 800-1500 mg cholesterol per day (endogenous). We eat ~300+ mg/day. 1 egg=200 mg.

Phospholipids are partially hydrophobic (non-polar or water-insoluble) and partially hydrophilic (polar or water-soluble).

Sterols are the starting material for some hormones, and make up the structural component of cell membranes

Chylomicrons travel from inside the intestinal cell into the lymphatic system and enter into the blood system near the heart.

The liver repackages lipids into two other types of lipoproteins for distribution in the body: VLDL and HDL

Advanced Atherosclerosis Buildup with clots and platelets Blockage can lead to tissue death Actual Cross section

When plaque breaks loose, the result is: Thrombosis Blood clot sticks to artery -grows large enough to close off blood vessel. Leads to heart attack or myocardial infarction. Embolism Blood clot breaks free lodges in a small artery Shuts off blood flow to tissues

Fatty acids are organic compounds composed of

a carbon chain with hydrogen attached.

Most fatty acids contain even numbers of carbon

in their chains, which can be up to 24 carbons in length

Fatty acids have an acid group at one end and a

methyl group at the other end.

The class of nutrients known as lipids includes

triglycerides (fats and oils), phospholipids, and sterols.