Unit 3
Lipids and Proteins
Chapter 5
Lipids: Essential Energy-Supplying Nutrients
What Are Lipids?
______________________: diverse class of molecules that are insoluble in water.
______________________
lipids in diets and food.
Three types of lipids are found in foods and in body cells and tissues:
______________________________
Triglycerides (triacylglycerides) contain
Three ____________________________ molecules
Fatty acids are long chains of carbon atoms bound to each other as well as to hydrogen atoms
One ____________________________ molecule
Glycerol is a 3-carbon alcohol that is the backbone of a triglyceride
Fatty acids
Fatty acids are classified by
_______________________ of their carbon chain
Long chain FA
> 12 Carbons
Medium chain FA
6 - 10 Carbons
Short chain FA
< 6 Carbons
Carbons can be numbered
_____________________ end (COOH): ___-carbon (“alpha”- first)
_____________________ end (CH3): ___-carbon (“omega” – last)
Determines lipid digestion, absorption, metabolism, and use
______________________________
Here is where we discuss the main differences between saturated and unsaturated fatty
acids?
Structure: _______________________ Fatty Acid
omega end
alpha end
All carbons are saturated (no double bonds)
Structure: ____________________________ Fatty Acid
One double bond
Structure: ______________________________ Fatty Acid
> 2 double bonds
_______________________
Determined by the saturation of the carbon chains.
Saturated fatty acids can pack tightly together and are ________________ at room
temperature.
Unsaturated fatty acids do not stack together well and are _________________ at room
temperature.
Hydrogen atoms at the unsaturated part can be arranged in different positions:
_______ – same side of the carbon chain
_______ – opposite sides of the chain
________________________: The addition of hydrogen atoms to unsaturated fatty acids.
_______________ liquid oils into a more solid form
Use to create margarine from plant oil
Creates ____________ fatty acids
Increases risk for cardiovascular disease
What is a Trans Fatty Acid?
What is the purpose for Hydrogenation?
Prevention of _____________________
Rancidity
Decomposed oils
Breakdown of the C=C double bonds by ultraviolet rays, O2
Yields unpleasant odor, flavor, and sickness when consumed
________________ more susceptible
Limits shelf life
How to Prevention of Rancidity
__________________________
Addition of vitamin ___
Addition of Butylated hydroxyanisol (______) and Butylated hydroxytolune (______)
Why are Trans Fatty Acids considered harmful if consumed?
Health Dangers of Excessive Trans Fatty Acids
Current intake is ~3% of total kcals
Increases risk for heart disease
Raises ______
Lowers _______
Increases ______________________
FDA now requires on food labels
Minimize Intake of Trans Fatty Acids
Limit use of hydrogenated fats
Limit deep-fat fried foods
Limit high-fat baked goods
Limit use of non-dairy creamers
Observe food labels
Essential fatty acids: two fatty acids cannot be synthesized by the body and must be obtained
from food
________________ acid (omega-___fatty acid)
Found in vegetable and nut oils
___________________ fatty acids found in fish and fish oil
Eicosapentaenoic acid (________)
Docosahexaenoic acid (________)
Reduce risk of heart disease
Stimulate prostaglandins and thromboxanes that reduce inflammatory responses
Reduce blood clotting and plasma triglycerides
Essential Fatty Acids: _________________
Form parts of the vital body structures
Forms cell _______________
____________ Production
Aids the Immune System
Aids in Vision
Linked to improvements in cardiovascular health
Recommendation: ___ servings of fish per week or 1 g/d of fish oil supplements
Signs and Symptoms of Essential Fatty Acids Deficiency
Flaky, itchy skin
Diarrhea
Infections
Retarded growth and wound healing
Anemia
_________________________
Phospholipids contain
___________________ backbone
______ fatty acids
________________ group
Functions of Phospholipids
Makes up cell membrane
Emulsifier
________________ end (attracts water)
________________ end (attracts lipid)
Emulsification
_______________
A multi-ringed structure
Do not readily dissolve in water
Are essential components of cell membranes, bile, and many ________________________Are manufactured in our bodies and therefore are not necessary in our diet
Plant sterols appear to block the absorption of dietary cholesterol
Let’s look at Cholesterol in a little more detail.
Functions of Cholesterol
Essential component of ________________________
Produced by the ______________
Found only in _______________ products
Forms important _____________________
Estrogen
Testosterone
Vitamin D
Precursor to _______________________________
Digestion of Fat
Stomach
~_____% of fat consumed is _____________________
__________________________ works only in an acidic environment
Small intestine
__________________ is secreted from the _______________________ into the small intestine
Bile is produced by the _________________ and __________________ in the gall bladder
Bile disperses fat into smaller fat droplets
___________________ and ________________ will breakdown to __________________________ and
________________________
___________ hormone (Cholecystokinin) stimulates the release of both
If fats and water don’t mix together then how do they get absorbed and transported through the body via the
circulatory system?
Dietary Fat Absorption
Transport of Fat in the Bloodstream
Water (blood) and oil (fat) are incompatible
Unique system of fat transportation is needed
Lipoproteins
_________________________
Type of lipoprotein that __________ comes from intestinal cells (reformed triglycerides)
Chylomicrons enter _______________ circulation to reach bloodstream
Very, Very Low Density Lipoprotein
______________________________ on blood vessel walls breaks down triglycerides in the
chylomicrons into fatty acids and glycerol
Fatty acids are absorbed by cells
Used for ____________________
________________ in adipose cells
Takes 2-10 hours to clear chylomicrons from blood
____________: Very Low Density Lipoprotein & LDL: Low Density Lipoprotein
Liver packages cholesterol and triglycerides for transport as ______________
Transports Triglycerides
Lipoprotein lipase breaks down some triglycerides in VLDL, leaving a ______________
Transports Cholesterol ______ the cell
Causes plaques in arteries (___________________)
How does the plaque build?
_________________ Pathway
Receptors on cell surface (mostly liver cells) bind to LDL
Process enhanced by diets low in cholesterol and saturated fat
____________________ Pathway
Scavenger WBC removes (______________) LDL from circulation
Prevents oxidized LDL from returning to circulation
Build-up of plaque on walls of the blood vessels leads to ___________________
Process enhanced by diets high in cholesterol, saturated fat, and trans fat
Plaque
___________________ Lipoprotein (____________)
Synthesized by _____________ and _____________________
High proportion of protein
Functions
Picks up ___________________ from dying cells and other sources
_______________ cholesterol to other lipoproteins for transport to the liver for excretion
HDL can also transfer directly back to the liver
_________________ oxidation of LDL
Benefits of (a high) HDL (level)
Remove cholesterol from the bloodstream
HDL may block oxidation of LDL
Reduce risk of heart disease
Pre-menopausal women have higher HDL
Lipoprotein Interactions
The Role of Fat
_____________________
Fat is very energy dense: ____ kcal per gram
Fat is the _______________ energy used during __________________
Fat is used for energy during exercise, especially after ____________________ is ___________________
Fat is used for energy _______________________
Fat-soluble vitamins
Vitamins A, D, E, and K
Fat is required for their _________________________
Fat is essential to many body functions
Cell membrane __________________________
Nerve cell ____________________________
Protection of internal ______________________
Insulation to retain body __________________
Fat provides flavor and texture to foods
Fat contributes to making us feel ______________________________ because
Fats are more energy dense than carbohydrates or protein
Fats take longer to _________________
How Much Fat?
Acceptable Macronutrient Distribution Range (AMDR) for fat: _________% of calories
_______________________ saturated and trans fatty acid intake to lower risk of heart disease
Athletes and highly active people may need more energy from carbohydrates and can reduce their fat
intake to 20-25% of total calories.
Dietary Reference Intakes (DRIs) set for essential fatty acids
_________________ acid: AMDR of 5−10% of energy
_______________________ acid: 0.6−1.2% of energy
5:1 to 10:1 ratio of linolenic:alpha-linolenic acid
Saturated fat: less than ___% of energy
Trans fats: _____________________ to the absolute minimum
Food Sources of Fat
Visible fats
Fats we ______________________ add to foods
Butter, cream, mayonnaise, dressings
Invisible fats
Fats ____________________ in foods
Naturally occurring or added during processing
Baked goods, dairy, processed meats
Beneficial fats
Omega-___ fatty acids may be low in diets
Fish, walnuts, soy, canola, flax seeds
Switching to more healthful fats without increasing total fat intake
Use olive or canola oil in place of butter or margarine
Select low-fat or non-fat dairy products
Fat Replacement Strategies
____________________
Diet margarine
__________________ derivatives
Z-trim (bran,oats, peas, soybean, rice,ect)
Fiber cellulose, Maltrin, Stellar, Oatrim
____________________
Gum fiber (diet salad dressing, fat-reduced ice cream)
_____________________
Dairy-Lo (milk, baked goods, frostings, salad dressings)
____________________________ (Olestra = Olean)
Fatty acids linked to sucrose
Yields no calories (no absorption)
Over-consumption may cause cramping and loose stool
“Fat Free” = “All You Can Eat?”
When fat is removed, sugar is usually added in its place
“Fat Free” is ______________ “Calorie Free”
Calorie content is still similar to full-fat version
Eat “Reduced-fat” foods in ____________________
Health Problems From Fat
Cardiovascular disease
Dysfunction of the heart or blood vessels
Can result in _________________ or ______________________
The type of fat in our diet can contribute to or protect against cardiovascular disease.
Cardiovascular Disease
Risk factors for cardiovascular disease include
Being overweight
Physical inactivity
Smoking
Diets high in ______________ fats
Decrease the removal of __________s from the blood
Increase cholesterol levels in the blood
Contribute to the formation of plaques that can block arteries
Diets high in _________ fatty acids:
Can raise blood levels of LDL-cholesterol as much as saturated fat
Are abundant in hydrogenated vegetable oils (margarine, baked goods, and fried foods)
Should be reduced to the absolute ___________________
How can fat intake protect against heart disease?
Diets high in omega-____ fatty acids (along with moderate exercise) can
increase HDL “good” cholesterol levels
decrease VLDL production
Lifestyle changes can prevent or reduce cardiovascular heart disease
Total fat intake: ______% total calories
Saturated fat: less than _____% total calories
Cholesterol: less than ______ mg per day
Trans fat: reduce to absolute minimum
Increase omega-3 fatty acids
Dietary fiber: _________ grams per day
Folate: 400 micrograms/day
Lifestyle changes can prevent or reduce cardiovascular heart disease
Keep blood glucose and insulin within normal limits
Eat throughout the day
No more than 2 alcoholic beverages per day for men and one drink per day for women
Maintain an _____________ lifestyle
Maintain a ______________ body weight
Medicines help reduce risk
Endogenous cholesterol synthesis inhibitors: statins
Bile acid sequestrants
Nicotinic acid
High-Fat Diets and Cancer
Three types of cancer have been studied extensively for their possible relationship to dietary fat intake:
Breast cancer
Colon cancer
Prostate cancer
Until the links with cancer are settled, the American Institute for Cancer Research recommends these
common-sense rules:
Maintain a healthy body weight
Engage in moderate physical activity at least 30 min/day
Limit consumption of sugary foods, empty Calories, red meats, salty foods, and alcohol
Eat a variety of fruits, vegetables, and whole-grain foods
Proteins: Crucial Components of All Body Tissues
What Are Proteins?
Proteins: large complex molecules composed of _________________________
Contain carbon, hydrogen, oxygen, nitrogen
Primary source of nitrogen in our diets
_____ different amino acids are used to make proteins
Amino Acids
Amino Acids
Essential amino acids
_______________ be produced by our bodies
Must be obtained from ______________
Nonessential amino acids
________ be made by our bodies
Amino Acids
Amino Acids
______________________________
Transfer amine group from an essential amino acid to a different acid group and R group
Conditionally essential amino acid
Nonessential amino acid becomes essential
Phenylketonuria (PKU): tyrosine becomes a conditionally essential amino acid that must be provided
by the diet
How Are Proteins Made?
Proteins are long chains of amino acids
______________________ join amino acids together
______________________ is the process by which cells use genes to make proteins
_______________: segment of deoxyribonucleic acid (DNA) that serves as a template for the synthesis
(expression) of a particular protein
The structure of each protein is dictated by the DNA of a ________________
_________________: messenger RNA copies the genetic information from DNA
_________________: the genetic information in RNA is converted into the amino acids sequence of a
protein
Protein Synthesis
What happens after Translation?
Proteins becomes organized
Protein structure determines function
Protein structure
Why do we need to understand Protein synthesis?
Protein ___________________
Existing proteins are degraded to provide the building blocks for new proteins
___________________________ includes amino acids from food and cellular breakdown
Therefore we need proper protein balance in the diet.
Proteins in the Diet
For protein synthesis, all essential amino acids must be ______________________.
Limiting amino acid:
Essential amino acid that is missing or in the smallest supply
____________________ or __________________ protein synthesis
___________________ protein: does not contain all essential amino acids
Not sufficient for growth and health
Considered a “_____________________” protein
__________________ protein: contains sufficient amounts of all 9 essential amino acids
Derived from animal and soy protein
Considered a “________________” protein
_______________________ supplementation: two or more incomplete proteins together to make a
complete protein
___________________________ proteins: two or more foods that together supply all 9 essential amino
acids for a complete protein
Protein Quality
Methods for estimating protein quality
Chemical score
Protein digestibility corrected amino acid score (PDCAAS)
Animal protein and many soy products are highly digestible (90% absorption)
What all is involved in Protein Digestion?
Protein ___________________
Proteins ____________ and lose their _____________________
Caused by heat, acid, base, metals, alcohol
Protein function is ______________
Protein is denatured during digestion
Denatured enzyme cannot do its job
May occur during high fever or when blood pH out of normal range
Protein Digestion
Protein digestion begins in the __________________
___________________ breaks down protein structure and activates pepsin
______________: an enzyme that breaks down proteins into short polypeptides and amino acids
Digestion continues in the small intestine
Pancreatic enzymes, called ______________, complete the digestion of proteins into single amino acids
Functions of Proteins
Cell growth, repair, _____________________
_________________ and hormones
Fluid and electrolyte __________________
_______ balance
___________________ to protect against disease
______________ source
Deamination
Urea excretion
Nutrient transport and storage
How Much Protein Should We Eat?
________________ balance determines protein needs
__________________ nitrogen balance: a person consumes more nitrogen than is excreted
Nitrogen retention occurs during periods of growth, pregnancy, recovery from illness
__________________ nitrogen balance: a person excretes more than is consumed
Protein is lost during starvation, severe illness
Proper protein intake depends on
Example: a sedentary adult requires ____ grams protein per kg of body weight
Recommended Protein Intakes
How do we calculate the RDA?
RDA for Protein of a Sedentary Adult
_____ gm of protein / kg of healthy body weight
Ideal body wt in lbs
= body wt in kg
2.2 kg/lb.
Body wt kg x ____g protein/kg body wt = g protein
Lets calculate RDA for a 154 lb lazy man
Recommended Protein Intakes
Too Much Protein Can Be Harmful
High ________________ and ______________ disease
Diets high in protein from animal sources are associated with high cholesterol
Possible bone loss
High protein diets __________ cause excess calcium excretion leading to bone loss
Kidney disease
High protein diets are associated with an increased risk of kidney disease
Especially for people who may be susceptible to kidney disease
Protein Sources
Meats
Milk-based products
Soy products
Legumes
Whole grains
Nuts
Quorn
What about Vegetarians consuming low quality proteins?
Vegetarian Diets
_____________________: restricting the diet to foods of plant origin
There are many versions of vegetarianism
____________vegetarian
____________vegetarian
____________vegetarian
____________vegetarian
____________ (Strict Vegetarian)
______________________
Macrobiotic Diet
There are many reasons to adopt a vegetarian diet but why?
People chose vegetarianism for
Health benefits
Ecological reasons
Religious reasons
Ethical reasons
Concerns over food safety
Health ________________ of Vegetarianism
Lower intake of fat and total energy
Lower blood pressure
Reduce the risk of heart disease
Fewer digestive problems
Reduce the risk of some cancer
Reduce the risk of kidney disease, kidney stones, and gallstones
Challenges of Vegetarianism
Vegetarian diets can be low in some nutrients
Vegetarians must plan a varied and adequate diet
Vegetarians may use soy products as a protein source
Vegetarians should include complementary proteins
Protein – Energy Malnutrition
_______________________ malnutrition: a disorder caused by inadequate intake of protein and energy
There are two common forms:
_________________: disease resulting from severely inadequate intakes of protein, energy, and other
nutrients
Marasmus symptoms include
Severe wasting of muscle tissue
Stunted physical growth
Stunted brain development
Anemia
_____________________: disease resulting from extremely low protein intake
Kwashiorkor symptoms include
Some weight loss and muscle wasting
______________ resulting in distention of the belly
Retarded growth and development
Genetic Diseases
Some genetic diseases can result in protein abnormalities
The genetic diseases include
Phenylketonuria (_______)
genetic disorder that is characterized by an inability of the body to utilize the essential amino acid,
phenylalanine.
____________________ anemia