Nutrition chapter 5

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30 terms · Lipids: triglycerides, phospholipids, & sterols

lipid digestion in the small intestine

-cholecystokinin (CCK) signals the gallbladder to release bile
-pancreatic & intestinal enzymes hydrolyze lipids into monoglycerides & fatty acid
-phospholipids are hydrolyzed, & sterols are absorbed as is

VLDL (very-low-density lipoproteins)

-composed primarily of triglycerides
-made by the liver
-transport lipids to the tissues & get smaller & more dense as triglyceride portion is removed

LDL (Low-Density Lipoproteins)

-composed primarily of cholesterol
-transport lipids to the tissues
-the "bad" cholesterol; associated with higher risk of heart attack

HDL (high-density lipoproteins)

-composed primarily of protein
-transport cholesterol from the cells to the liver
-the "good" cholesterol; protective

factors that lower LDL & raise HDL

-weight control & physical activity
-replace saturated fat with monounsaturated fat & polyunsaturated fats in diet
-soluble fibers
-phytochemicals
-moderate alcohol consumption
**genes effect lipid transport

roles of triglycerides

-energy reserve when stored (storage form of fat!)
-use carbohydrate & protein efficiently
-insulation
-shock protection

lipids in the body

-triglycerides & essential fatty acids play important roles
-the body can store unlimited amounts of fat when it's consumed in excess
-the liver can convert excess carbohydrate & protein to fat

ketone bodies

~formed from inefficient breakdown of fat (could be caused by starvation)
-fat needs carbohydrate to break down efficiently

The essential fatty acids

-they cannot be made by the body
~linoleic acid & the Omega-6 family
*(in vegetable oils & meats)
~linolenic acid & the Omega-3 family
*(in food-is important for eyes, brain, & heart)

lipid metabolism: storing fat as fat

-provides 2x the energy as carbs & protein
-adipose tissue readily stores fat

lipoprotein lipase (LPL)

hydrolyzes triglycerides as they pass & directs the parts into the cells to be used for energy or storage

lipid metabolism: using fat for energy

-hormone-sensitive lipase inside the adipose cells hydrolyzes triglycerides when needed for energy

using fat for energy: fasting

it metabolizes fat, but fat requires carbs & protein for complete breakdown
*ketone bodies can be made from fat fragments

recommended intakes of lipids

-total cholesterol < 200 mg/dl
*(200-239= borderline high; > or equal to 240= high risk)
-LDL cholesterol < 100 mg/dl
-HDL cholesterol >or equal to 60 mg/dl
-triglycerides < 150 mg/dl

blood lipid profile

reveals concentrations of lipids in the blood
**hypercholesterolemia/hyperlipidemia/hypertriglyceridemia= all mean high lipid levels

risk factors for heart disease

-high intake of saturated fat & trans fat which help cause high blood LDL cholesterol

what happens when cholesterol accumulates in the arteries?

blood flow is restricted & blood pressure rises
-is a risk factor for heart disease

foods with high saturated fats

whole milk, cream, butter, cheese, high-fat cuts of beef & pork, & coconut, palm, & palm kernel oils

food with high trans fats

deep-fried foods using vegetable shortening, cakes, cookies, doughnuts, pastry, crackers, snack chips, margarine, imitation cheese, & meat & dairy products

health risks from cholesterol

dietary cholesterol has less effect on blood cholesterol than saturated fat & trans fat

food sources of cholesterol

egg yolks, milk products, meat, poultry & shellfish (animal foods)

health benefits from monounsaturated fats & polyunsaturated fats

using these to replace saturated fat & trans fat in your diet is the most effective way to prevent heart disease

food sources of monounsaturated fat

olive, canola, & peanut oil & avocados

food sources of polyunsaturated fat

vegetable oils (safflower, sesame, soy, corn, & sunflower), nuts & seeds

Omega-3 fatty acids health effects

in the diet, they appear to have a protective effect in reducing risk of heart disease & stroke

food sources of Omega-3 fats

vegetable oils (canola, soybean, & flaxseed), walnuts, & flaxseeds, & fatty fish (mackerel, salmon, & sardines)
-avoid fish with high levels of mercury

how to balance Omega-6 & Omega-3 intakes

-eat more baked, broiled, or grilled fish (2-3oz portions per week & LESS meat
-functional foods are being developed

causes of obesity

-can be a consequence of high-fat, high-kcalorie diets in excess of energy needs

how to lower risk of heart disease through diet

-limit fatty meats, milk products, & tropical oils
*use food labels to choose those lowest in saturated fat
*choose leaner, low-fat animal products
-limit hydrogenated foods which contain trans fats (convenience foods)

recommended intakes of fat

the DRI & the 2005 dietary guidelines recommend fat at 20-35% of energy intake
-we need some fat to absorb fat-soluble vitamins!

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