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Lipids

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... against blood clots, irregular heart beats and lowers blood pressure. Obesity ... fermented milk products may lower blood cholesterol. veggies, fruits, grains ... – PowerPoint PPT presentation

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Title: Lipids


1
Lipids
  • FAT

2
Lipid Family
  • triglycerides
  • fats
  • oils
  • predominate in food and in the body
  • phospholipids
  • sterols
  • cholesterol

3
Lipids
  • energy storage
  • a lot of calories in a small space
  • generally insoluble in water
  • stored in special ways in the body
  • also function as structural components of cells

4
Fatty Acids
fatty acids
  • made up of carbon, hydrogen, oxygen
  • more carbon and hydrogen so they supply more
    energy/gram
  • common building block for most lipids

5
  • the determining factor in whether to call a fatty
    acid saturated, unsaturated, monounsaturated,
    polyunsaturated, or trans fatty is determined by
    its chemical bonds and structure

6
Triglycerides
  • the form of lipid most found in food
  • 3 fatty acids glycerol
  • major class of dietary lipid
  • flabby stuff most of us have is cells filled with
    triglycerides

7
Degree of Unsaturation
  • influences the firmness of fat
  • general impression in regards to food
  • liquid at room temp unsaturated
  • solid at room temp saturated (animal fats)
  • shorter the carbon chain, softer the fat at room
    temperature

8
  • stability
  • when exposed to oxygen, fat becomes rancid
    (oxidation)
  • saturated fats are more resistant
  • protection from oxidation
  • sealed, non-metallic, protected from light,
    refrigerated
  • addition of antioxidants
  • saturate by adding hydrogen molecules
    (hydrogenated)

9
Hydrogenation
  • also makes oils more manageable at room temp
    peanut butter, hydrogenated vegetable oil

10
Trans-Fatty Acids
  • hydrogenated fatty acids
  • more saturated than natural vegetable oils
  • able to pack together more tightly
  • more solid are room temperature
  • behave more like saturated fatty acids
  • hidden in the reporting levels for unsaturated
    fatty acids

11
Phospholipids
  • minor portion of lipids in diet
  • lecithin is most common
  • found in eggs, liver, soy, peanuts
  • important role in cell membranes
  • lecithin is made in liver
  • not an essential nutrient

12
Sterols
  • important players bile, sex hormones, Vit D
  • cholesterol is starting material
  • cholesterol
  • only found in food derived from animals
  • good or bad cholesterol in not a type of
    cholesterol found in food
  • refers to the transportation of cholesterol in
    the blood
  • made in liver from carbs, protein, fat
  • 800-1500 milligrams/day

13
Lipid Digestion
  • mouth
  • slow start
  • some hard fats begin to melt
  • stomach
  • churning mixes chyme and breaks up fat into
    smaller droplets
  • expose fat to enzymes
  • little fat digestion actually takes place

14
  • small intestine
  • gall bladder releases bile
  • acts as an emulsifier
  • brings fats into water solution found in
    intestine
  • fully digested when enzyme lipase is encountered
  • once bile has completed its task
  • reabsorbed from intestine and recycled
  • trapped by fibers in large intestine and
    eliminated
  • reduces blood cholesterol

15
Lipid Absorption
  • small triglycerides can diffuse into intestinal
    cells, then absorbed into blood
  • larger long chain fatty acids merge in micelles
    (emulsified fat droplets)
  • allows for solubility in digestive fluids and
    movement to the intestinal cells
  • once inside cells, reassembly takes place into
    new triglycerides

16
Absorption of Fat
Small intestine
Stomach
Monoglyceride
Short-chain fatty acids
Medium-chain fatty acids
Micelle
Glycerol
Protein
Chylomicrons
Triglyceride
Lacteal (lymph)
Long- chain fatty acids
Capillary network
Chylomicron
Blood vessels
To blood
To liver
17
Lipid Absorption
  • once inside intestinal cells
  • packed with protein into chylomicron
  • released into lymphatic system
  • enter bloodstream near the heart
  • carried by blood for use or storage
  • blood analysis indicates types of fat the diet
    has been delivering to the body

18
Absorption of Fat
Small intestine
Stomach
Monoglyceride
Short-chain fatty acids
Medium-chain fatty acids
Micelle
Glycerol
Protein
Chylomicrons
Triglyceride
Lacteal (lymph)
Long- chain fatty acids
Capillary network
Chylomicron
Blood vessels
To blood
To liver
19
Lipid Transport
  • lipoproteins fat transporters
  • chylomicrons
  • transport diet-derived lipids, mostly
    triglycerides
  • triglycerides are removed as they pass through
    the body
  • within 14 hours, most triglycerides are depleted
  • liver picks up the pieces and use or recycle the
    pieces

20
  • VLDL very low density lipoprotein
  • transport lipids synthesized in live to other
    parts of the body
  • liver uses fatty acids in blood to make other
    fatty acids and cholesterol
  • triglycerides are removed from VLDL at they move
    through the body, becoming cholesterol dense
  • eventually become LDL

21
  • LDL low density lipoproteins
  • cholesterol rich
  • are available to all tissue cells

22
  • HDL high density lipoprotein
  • made by the liver to carry cholesterol from cells
  • back to the live and recycled or disposed

23
HDL or LDL
  • LDL bad
  • associated with high risk of heart attack
  • HDL good
  • protective effect for heart

24
Controlling LDL and HDL
  • lower LDL or raise HDL
  • weight control
  • unsaturated instead of saturated fat
  • fibers
  • phytochemicals
  • moderate alcohol consumption
  • physical activity

25
Essential Fatty Acids
  • linoleic acid/omega-6
  • found in vegetable oils and meats
  • linolenic acid/omega-3
  • fatty fish

26
Role of Lipids
  • provide energy
  • insulation
  • protection against shock
  • cell membrane structure
  • deficiencies
  • retarded growth, skin lesions, kidney and liver
    disorders

27
Lipid Metabolism
  • fat gives us 2X the energy of carbs and proteins
  • efficient storage in adipose tissue
  • food fat is converted to body fat by absorbing
    parts and putting back together again inside the
    cell
  • very little energy is needed

Large central globule of (pure) fat
28
  • fat supplies 60 of body's energy during rest
  • more during activity
  • when needed fat (triglyceride) is dismantled and
    released as glycerol and fatty acids into the
    blood where it is easily accessible by the cells

29
Health Effects
  • heart disease
  • elevated blood cholesterol
  • risks from saturated fats
  • mostly associated with LDL cholesterol
  • risks from trans fats
  • alter blood cholesterol the same way saturated
    fats do
  • dietary cholesterol
  • implicated in raising blood cholesterol

30
Health Benefits
  • monounsaturated and polyunsaturated fats
  • lower possibility of heart disease
  • Omega-3 fats
  • protects against blood clots, irregular heart
    beats and lowers blood pressure

31
Obesity
  • fat contributes more than 2X the kcalories/gram
    as carbs or proteins

32
Recommended Intakes
  • no RDA or upper limits on fat intake has been set
  • suggest a diet low in saturated fat, trans fat,
    cholesterol
  • provides 20-35 of energy
  • Daily Values have been place on food labels using
    30 as guideline

33
Groceries
  • fats and protein in animal foods
  • fats and carbohydrates in plant foods
  • vitamins A, D, E, K go hand in hand with fat
  • flavor, texture, palatability
  • meat
  • trim the fat
  • use soy protein instead of animal protein

34
Groceries
  • milk and milk products
  • fat free and low fat milk provides the same or
    more protein, calcium as whole milk
  • fermented milk products may lower blood
    cholesterol
  • veggies, fruits, grains
  • lower the content of saturated fat, cholesterol,
    and total fat
  • fill up on these little or no fat foods

35
Groceries
  • invisible fat
  • marbling in steak, cheese, fried foods, baked
    goods, chocolate

36
Choose Wisely
37
Fat Replacers
  • fat replacers
  • carbs or proteins that replace some of the
    function of fat
  • still contribute some energy during digestion

38
Artificial Fats
  • chemically produced substances made to mimic the
    sensory and cooking attributes of fat
  • resistant to digestion
  • olestra
  • passes through the system unabsorbed
  • binds to some vitamins
  • food needs to be fortified
  • FDA approved

39
Butter and Margarine Labels Compared
Margarine (tub)
Margarine (stick)
Butter
Margarine (liquid)
INGREDIENTS Vegetable oil blend (partially
hydrogen- ated and liquid soybean oils) water,
sweet cream butter- milk, salt, vegetable
mono- and diglycerides, soy lecithin, citric
acid, artificial flavor, vitamin A, colored with
beta carotene.
INGREDIENTS Cream, salt.
INGREDIENTS Water, liquid soybean oil,
partially hydrogenated soybean oil, sweet cream,
buttermilk, gelatin, salt, vegetable mono- and
diglycerides, soy lecithin, lactic
acid, artificial flavor, vitamin A, colored with
beta
INGREDIENTS Liquid soybean oil, water,
sweet cream buttermilk, salt, partially
hydrogenated cottonseed oil, vegetable mono- and
diglycerides, soy lecithin, citric
acid, artificial flavor, vitamin A, colored with
beta carotene.
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