Nutrition: Lipids and Cardiovascular Disease

Eicosanoids (Ex. Prostaglandins)

*Made from long chain omega-3 and omega-6 fatty acids *"hormone-like" activity, but can have a different effect on different cells *can produce fever, inflammation, and pain as part of the immune response to injury or infection(omega-6), or relaxation, and dilation *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 *basis for healthfulness of omega-3 fatty acids

Enterohepatic Circulation

*is a continuing cycle 1. In the gallbladder, bile is stored 2. In the small intestine, bile emulsifies fats 3. In the colon, bile that has been trapped by soluble fibers is lost in feces OR 4. Bile reabsorbed into the blood 5. In the liver, bile is made from cholesterol

Linolenic acid and the omega-3 family (polyunsaturated)

*must be supplied by food *can make EPA (eicosapentaenoic acid 20:5 w3) and DHA (docosaheaenoic acid 22:6 w3) important for eyes, brains, and heart *deficiency associated with depression, growth, retardation, reproductive failure, and neurological problems

Brown fat and obesity

1. Brown fat(and brite cells) may increase energy utilization, thus assist with weight loss 2. Uncoupling proteins found in brown fat and brite cells(due to increased mitochondria) generate heat without generating ATP(like white adipose tissue), thus are "energy wasting" 3. Since exercise increases brite cells, this explains another mechanism to facilitate weight loss

Dietary patterns associated with lowered risk of cardiovascular disease

1. DASH diet 2.Mediterranean diet 3.Vegetarian diet

Why we need fats/lipids

1. Insulation 2. Taste and texture 3. Membranes of cells 4. Clotting 5. Slows gastric emptying 6. Absorbs fat-soluble vitamins 7. Sex hormones 8. Energy (ATP) 9. Energy storage 10. Regulation of gene expression

Diets rich in trans fatty acids or saturated fats

Are a strong risk factor for heart disease *these food categories still average more than 1.5 grams of trans fats per serving

Linolenic and linoleic acid

Are both essential fatty acids -Linolenic acid, an omega-3 fatty acid 18:3 w3 *flaxseed (rich source), canola and walnut oil -Linoleic acid, an omega-6 fatty acid 18:2 w6 *sunflower, safflower, corn, and soybeans

Triglycerides

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

Saturated fatty acid

all carbon atoms make four bonds with neighboring atoms, therefore there are only single bonds -solid at room temp. -rich in beef, meat, butter, dairy, palm oil, coconut oil

Elevated total blood cholesterol

is a risk factor for cardiovascular disease

Liver repackages

lipids into two other types of lipoproteins for distribution in the body: VLDL and HDL -chylomicrons( high in TG) small intestinal cells-bring TG into body's cells -VLDL(50% TG)-liver,endogenous TG-bring TG into body's cells -LDL(high in cholesterol)-from VLDL fragments-bring cholesterol to body's cells-if high, increase risk for heart disease -HDL(high in protein and cholesterol)-liver and SI- bring cholesterol back to the liver(possible excretion)-if high, decreases risk for heart disease

Carbon lengths of 12-24 are called

long chain fatty acids and are common in meats, fish, and vegetable oils

Chain lengths

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

Replacing saturated and trans fat with

monounsaturated fat and polyunsaturated fat is one of the most effective dietary strategies in preventing heart disease -polyunsaturated fat include veggie oils, nuts, and seeds

Liver

produces 800-1500 mg cholesterol per day(endogenous) *we eat about 300+ mg/day -1 egg=200mg

Mediterranean diet

whole food, red wine, olive oil, social interactions while eating

Recommended intakes of fat

-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

Comparison of Unsaturated and Saturated Fats

-Unsaturated *liquid at room temperature polyunsaturated fats spoil quickly -Saturated *solid at room temperature, more resistant to oxidation, alters texture, flaky crusts -How to protect from oxidation 1. seal from oxygen 2. add antioxidants 3. hydrogenate

White vs. Brown 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 number of mitochondria makes them appear brown *white adipocytes can transform to brite cells in certain biological environments -i.e physical activity

Advanced atherosclerosis

-buildup with clots and platelets -blockage can lead to tissue death

Dietary facts

AMDR:20-35% of total kcals from fat 30% of total kcals from fat is a good goal -7-10% sat. fats -10-15% MUFA's -10% PUFA's Limit trans fatty acids to less than 1% of total kcals Fat quality is more important in many cases than fat quantity

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

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 food: fatty fish(i.e. salmon), eggs from chickens fed omega-3 fatty acids

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 had developed Some types of cancer have a stronger relationship to fat intake. Saturated fat from meat is implicated.

Small Intestine

CCK signals gallbladder to secrete bile. Bile flows in from gallbladder to emulsify fat. Pancreatic lipase flows in from the pancreas and intestinal lipase is present resulting in monoglycerides, glycerol, and fatty acids that can be absorbed. Sterols are absorbed as is. Phospholipids are hydrolyzed.

Essential fatty acids

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 20:4 w6 -supplied primarily by vegetable oils

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 a small role.

Phosolipids

Contain glycerol, two fatty acids, and a phosphate group with a molecule of chlorine and are used as emulsifiers in the food industry Are partially hydrophobic(non-polar or water-insoluble) and partially hydrophilic(polar or water-soluble)

Adding plant sterol to foods

Equals functional foods -plant sterols are structurally similar to cholesterol, they interfere with cholesterol absorption-lowered blood cholesterol levels

In the inside of the SI

Glycerol, short chain fatty acids, micelles, and chylomicrons

Triglyceride

Is composed of a 3-carbon glycerol backbone with three fatty acids extending out from each of the carbons of glycerol.

Lipid Transport

Is made possible by a group of vehicles known as lipoproteins. Chylomicrons are the largest of the lipoproteins.

Healthful Fatty Acids

Monounsaturated fatty acids(MUFA) -avocado,oils,nuts,olives,peanut butter,seeds Omega-6 fatty acids -margarins,oils,nuts,mayonnaise,salad dressing,seeds

Carbon in fatty acids

Most contain even numbers of carbon in their chains, which can be up to 24 carbons in length

Harmful Fatty Acids

Trans Fatty Acids -fried foods,margarine,nondairy creamers,many fast foods, shortening,commercial baked goods,many snackfoods Saturated Fatty Acids -bacon,butter,chocolate,coconut,cream cheese,cream,half and half,lard,meat,milk and milk products,oils,shortening,sour cream

Partial Hydrogenation

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

Large Intestine

Some fat and cholesterol is trapped in fiber, exits the body in the feces.

Mouth

Some hard fats begin to melt and salivary glands release lingual lipase

Hydrogenation

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

Double Bonds

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

When plaque breaks lose 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

Normal blood levels of lipids

Total cholesterol -less than 200 mg/dL desirable 200-239 mg/dL borderline high 240 and above high

Fatty acids

are organic compounds composed of a carbon chain with hydrogen attached H-C...head of chain is a methyl C-O-H...tail of chain is an acid

18 carbon lengths

are the most abundant in our food supply

Balance Omega-6 and Omega-3 intakes

by eating more fish and less meat -include 2. 3oz portions per week of fish -functional foods are being developed -supplements are not the answers -fried fish does not count -grass fed beef-high levels of w-3, but basically very low in saturated fats and total fats

Atherosclerosis

develops when plaque builds on artery walls and leads to inflammation

DASH diet

dietary approaches to stop hypertension

Monounsaturated fatty acid

has one double bond -generally liquid at room temp. -rich in canola oil, olive oil, nuts, and peanuts

Polyunsaturated fatty acid

has two or more double bonds -more liquid at room temp. *18:2 w6 (18 carbons, 2 double bonds, first double bond after 6th C from methyl end) -rich in sunflower, safflower, corn, soybean oils, nuts, and animal fats

Not all saturated fats are created equal

sat fats are a class of compounds not just one compound stearic acid is a long sat fat(18:0) found in meat, but is also the predominant sat 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, arthrogenesis, and vascular disease

Chylomicrons

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

*The class of nutrients known as lipids includes...

triglycerides (fats and oils), phospholipids, and sterols (cholesterol) sat. is a single bond, and unsat. is a double bond