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Lipids. FAT. Lipid Family. triglycerides fats oils predominate in food and in the body phospholipids sterols cholesterol. Lipids. energy storage a lot of calories in a small space generally insoluble in water stored in special ways in the body

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lipid family
Lipid Family
  • triglycerides
    • fats
    • oils
    • predominate in food and in the body
  • phospholipids
  • sterols
    • cholesterol
lipids3
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
fatty acids
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
slide5
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
triglycerides
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
degree of unsaturation
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
slide8
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)
hydrogenation
Hydrogenation
  • also makes oils more manageable at room temp: peanut butter, hydrogenated vegetable oil
trans fatty acids
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
phospholipids
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
sterols
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
lipid digestion
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
slide14
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
lipid absorption
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
slide16

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

lipid absorption17
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
slide18

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

lipid transport
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
slide20
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
slide21
LDL: low density lipoproteins
    • cholesterol rich
    • are available to all tissue cells
slide22
HDL; high density lipoprotein
    • made by the liver to carry cholesterol from cells
    • back to the live and recycled or disposed
hdl or ldl
HDL or LDL
  • LDL: “bad”
    • associated with high risk of heart attack
  • HDL: “good:
    • protective effect for heart
controlling ldl and hdl
Controlling LDL and HDL
  • lower LDL or raise HDL
    • weight control
    • unsaturated instead of saturated fat
    • fibers
    • phytochemicals
    • moderate alcohol consumption
    • physical activity
essential fatty acids
Essential Fatty Acids
  • linoleic acid/omega-6
    • found in vegetable oils and meats
  • linolenic acid/omega-3
    • fatty fish
role of lipids
Role of Lipids
  • provide energy
  • insulation
  • protection against shock
  • cell membrane structure
  • deficiencies
    • retarded growth, skin lesions, kidney and liver disorders
lipid metabolism
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

slide28
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
health effects
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
health benefits
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
obesity
Obesity
  • fat contributes more than 2X the kcalories/gram as carbs or proteins
recommended intakes
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
groceries
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
groceries34
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
groceries35
Groceries
  • invisible fat
    • marbling in steak, cheese, fried foods, baked goods, chocolate
fat replacers
Fat Replacers
  • fat replacers
    • carbs or proteins that replace some of the function of fat
      • still contribute some energy during digestion
artificial fats
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
slide39

Butter and Margarine Labels Compared

Margarine (liquid)

Margarine (tub)

Margarine (stick)

Butter

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.

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: 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.