Flashcards in Midterm 2 Deck (86):
1
What are lipids and the groups?
- Large class of organic molecules that are not soluble in water
- Contribute to texture, taste, flavour and aroma of foods
- 1 g of lipid yields 9 kcal of energy
1. Fatty acids (long hydrophobia chains of carbon and hydrogen)
2. Triglycerides (usually what we’re talking about when we say “fat” such as beef)
3. Phospholipids
4. Sterols
2
What are triglycerides?
- 85% of dietary lipid
- We eat triglycerides and we store our body fat as triglycerides
- Made of 1 glycerol molecule “backbone” with 3 fatty acids
3
What are phospholipids?
- Has a hydrophilic and hydrophobic end
- Form a lipid bilayer in cell membrane
- Maintenance of membrane integrity; regulates what passes in and out
- If there is too much saturated fat in the diet, the structure of cell membrane can change
- Made of glycerol as a backbone with 2 fatty acids
In place of a 3rd fatty acid is a phosphate group attached to a variety of other molecules (eg. lecithin in milk, eggs, lightly cooked meats, wheat germ)
- Eg. egg yolk, fish, milk, beef
4
What are sterols?
- Large group of hydrophobic compounds found in plants and animals
- Most common in animals (eg. cholesterol)
- 90% of cholesterol in body is found in cell membranes
- Cholesterol is needed to make sex hormones and myelin sheath (insulating material on every nerve in the body)
- Too much LDL is a cardiovascular risk factor
5
How does length of fatty acids affect fat?
Affects how fat is digested and metabolized in body
1. Short chain fatty acids: fewer than 8 C atoms
2. Medium chain fatty acids: 8-12 C atoms (eg. lauric acid)
3. Long chain fatty acids: 13+ C atoms
6
How does saturation level of fatty acids affect fat?
Affects properties at room temperature, how fat is processed in the body and their effects on the metabolism of nutrients
1. Saturated: no double bonds between C atoms
- Long, straight chain
- Animal fats and tropical oils (eg. palmitic and stearic acid in meat/dairy, coconut oil)
- Have longer shelf life and are more stable
2. Unsaturated: 1+ double bonds between C atoms
3. Monounsaturated (MUFA): 1 double bond (eg. oleic acid)
- Plant based (eg. olive oil, table olives, avocado, canola oil)
- Liquid at room temperature
4. Polyunsaturated (PUFA): 2+ double bonds (eg. linoleic acid and linolenic acid)
- Liquid at room temperature; the more unsaturated bonds the more liquid they are
- Mostly plant based (eg. soybean oil, safflower oil, corn oil, fish, nuts and seeds)
7
How does configuration of double bond of fatty acids affect fat? Discuss hydrogenation.
1. Cis
- Most fatty acids have the cis configuration
- H molecules on same side rather than opposite side of double bond
2. Trans
- Have higher melting point and more shelf stable
- Favoured by food industry, found on nutrition labels
- Trans fat raise blood cholesterol levels and increase risk of heart disease
- Occurs naturally in meat and dairy or in partially-hydrogenated fats (eg. margarine, crisco, processed peanut butter)
HYDROGENATION:
- Some/all of double bonds in oil accept hydrogen and become saturated
- Fully hydrogenated oils are considered more like saturated fats (increased stability against rancidity and higher melting point = solid)
- Trans fatty acids are in partially hydrogenated oils (some bonds remain unsaturated and shift to trans configuration)
8
Discuss the location of double bonds and fatty acids.
- Where the double bonds are will change physical structure of fatty acids
- Double bond is a C-C bond with methyl (CH3) aka the omega (ω) end and the alpha end (acid)
- Position is relative to the ω end of the molecule
- Affects how our body metabolizes fatty acid
- Ratio of omega-3 to omega-6 (proinflammatory) is important for the health
1. Omega-3 fatty acids: double bond between 3rd and 4th C from ω end (eg. alpha-linolenic acid; a polyunsaturated fatty acid)
2. Omega-6 fatty acids: double bond between 6th and 7th carbons from ω end (eg. linoleic acid; a polyunsaturated fatty acid)
3. Omega-9 fatty acids: double bond between 9th and 10th carbon from ω end (eg. oleic acid; a monounsatured fatty acid)
9
Discuss nomenclature of fatty acids.
Fatty acids are given common names and numerical notation
Eg. 18:2 ω-6 (Linoleic acid numerical name)
18 = number of carbon atoms
2 = number of double bonds
ω-6: where the first bond is from the omega end
10
Discuss fat digestion.
1. Mouth
- Chewing and lingual lipase begins to do some digestion
- Important for babies who do not have full set of digestive enzymes in small intestine to break off fats
2. Stomach
- Churning into small droplets and gastric lipase
- Mainly proteins get digested here because it is acidic
3. Small intestine (majority of fat digestion)
- Pancreatic lipases break fatty acids off glycerol to form free fatty acids and monoglycerides/monoacylglycerols
- Bile from gallbladder emulsifies fat into smaller droplets called micelles
- Allows products of fat digestion to get close to brush border, where there is access to lymph system
- Very little fat lose in stool; most is absorbed otherwise problem
11
How is fat absorbed?
- The products of triglyceride digestion (cholesterol, esters, monoglycerol, free fatty acids and fat soluble vitamins) mix with bile to form micelles
- Nutrients move through the blood made of water
- Lipoproteins allow fat to mix with blood
12
Discuss lipoproteins in the blood stream.
- Membrane made of protein and phospholipids
- Phospholipids are on outside = hydrophilic and can float easily through blood stream
1. Chylomicrons: type of lipoprotein made in cells of small intestine to bring fat closer to brush border
- Carries dietary fat to the liver and rest of the body for burning or storage
Other types of lipoproteins are made in the liver
2. Once chylomicrons arrive at liver, disassembled into very low density lipoproteins (VLDL)
- Some triglycerides get knocked off by circulatory lipase to form intermediates (IDL)
- Eventually turn into low density lipoproteins (LDL) in the bloodstream
3. LDL circulates around the bloodstream to cells (necessary to make hormones and myelin sheath)
4. High density lipoproteins (HDL) takes excess cholesterol out of circulation to ensure never too much
- Extremes in cholesterol and insulin are both associated with heart and metabolic disease
- Want moderate amount of LDL and high amount of HDL
Process from chylomicrons to HDL involves increasing density, decrease size, decreasing amounts of triglycerides and increasing amounts of cholesterol
13
What are the functions of lipids?
1. Structure and lubrication
- Provide insulation: adipose tissue (fat cells) insulate body from changes in temperature
- Protect bones, joints and organs: provide cushion to protect internal organs against shock
- Make and protect nervous system: form mytelin shealth made out of cholesterol
- Lubricate body surfaces: glands secrete oils lubricate tissues
2. Cell structure
- Lipids make up cell membranes
- Phospholipids keep membranes fluid (especially if more unsaturated fatty acisd)
- Cholesterol prvents membrane from being too fluid/permeable
3. Regulation of body processes
- Vitamin absorption (A, D, E, K) need fats to be absorbed
- Make hormones using adequate cholesterol
- Blood pressure regulation using cholesterol
- Some fats are essential (can’t be synthesized in body) to make other fats
- Regulate blood clotting and inflammation
4. ATP production for energy
- High fat foods have high energy content
- Burned more doing moderate intensity activity
- High intensity activity = glucose and glycogen used
- Fatty acids are transported into mitochondria, where beta-oxidation splits carbon chains into 2 C units that form acetyl-CoA and produce high energy electrons
- Note: cannot make glucose from fatty acids
- Then, if oxygen and carbohydrates are available, acetyl-CoA combines with oxaloacetate to enter citric acid cycle
- If carbohydrates are not available, ketone bonds are produced
5. Energy storage
- Triglycerides stored in adipose tissue to give you energy reserves
- Protect against starvation
14
What are ketone bodies and cautions about it?
- Acetoacetate, beta-hydroxy butyrate, acetone
- Alternative source of energy for brain cells if glucose is insufficient
- Ketogenic diets: brain no longer accesses glucose as fuel and uses ketone bodies from fat instead
- Ketosis seems to halt some forms of unrelenting seizure disorders
KETOACIDOSIS:
- Ketoacidosis: ketone bodies accumulate in blood; if prolonged may lead to coma and death
- Can be excreted in urine but if excess ketone bodies; kidneys can be overwhelmed
- Ketones build up in bloodstream
15
Discuss fat and weight distribution.
- Excess body fat in upper half (apple body shape) associated with a higher risk of high blood pressure, type - 2 diabetes, heart disease, stroke
- Layer of fat putting pressure on stomach puts pressure on organs and blood vessels
16
What are the essential fatty acids? Discuss omega-3.
1. Linoleic acid (aka omega-6)
- 18:2 w-6
- Gotten by oils, margarine, nuts, seeds
2. Alpha-linolenic acid (aka omega-3)
- 18:3 w-3
- Necessary for regulating blood clotthing, inflammation in the body and normal brain development
- Gotten by canola oil, flax seed oil, soy oil, fatty fish, omega eggs
- DHA and EPA are premade in fish oil; plant sources (flax, hemp, chia seed) require chemical conversion using enzymes that some of us may not have a lot of
- Note: omega-3 chickens do not eat fish oil but rather use flax seed oil
17
How much fat do we need?
- DRIs have adequare intakes (AIs) for linolenic acid and alpha-linolenic acids (essential fatty acids)
- Linoleic acid: 12g/day for females, 17g/day for males
- Alpha-linolenic acid: 1.1g/day for females, 1.6g/day for males
- AIs are based on how much essential fat you need to keep clotting under control
- For a healthy adult, use AMDR for fat generally (20-35% of calories)
- AMDRs state that keep cholesterol, saturated and trans fat as low as possible
18
What is cardiovascular disease?
- Disease of the heart and blood vessels
- Includes heart disease, high blood pressure, heart attacks and strokes
- 30% of all deaths in Canada are from CVD
- 2nd leading cause of death in Canada after cancer
- Largely lifestyle factors in CVD which cannot be said for cancer
- CVD costs Canadian economy more than $20.9 billion every year
19
What is atherosclerosis?
- Inflammatory response to injury within the artery walls
- Lipids and fibrous materials are deposited within artery walls due to action of immune system
- Reduces elasticity of blood vessels or responsiveness to changes of blood flow = blockage
- Blockage of blood flow to heart leads to heart attack (cerebral hemorrage, aneurysm) and to brain leads to stroke
20
What is the process of atherosclerosis?
1. Injury to normal artery causes arterial wall to become permeable
- LDL cholesterol can infiltrate artery walls and get oxidized to become even worse cholesterol
2. Macrophages in white blood cells engulfs LDL cholesterol and get puffed out, cannot leave
3. Other platelets come and form foam cells (lots of macrophases with LDL) in arterial walls that can burst
4. If foam cells burst, leaves fatty streak on inside of arterial wall = plague = platelets come and cause fibrous cap to keep everything under control
5. If fibrous cap ruptures, you can get blood clot
21
What are the risk factors for CVD?
1. Age (more plaque as we age)
2. Gender (men appear to be at higher risk, perhaps due to estrogen)
3. Family history of CVD
4. Being overweight/obese
5. Being physically inactive
6. Smoking (oxidative stress = free radicals = damage blood vessels)
7. Diabetes
8. Diet
- Saturated and trans fat increase risk of heart disease by adding rigidity to cell membranes
- Trans fat is not needed but saturated fat is needed in small amounts
- Omega-3 and omega-6 polyunsaturated fats decrease risk of heart disease
22
How is CVD risk measured?
Blood lipids are measured to assess CVD risk:
1. LDL-cholesterol: measure # of LDL particles
- Don’t want too high
2. HDL-cholesterol: measure # of HDL particles
- Want to be very high
- LDL to HDL ratio measures which “dump-trucks” are winning
3. Triglycerides: measure # of triglyceride-rich particles
- More associated with blood sugar level management
23
Discuss factors affecting blood lipids.
- Saturated fats increase LDL
- Trans fat increase LDL and decrease HDL
- Added sugars increase triglycerides (VLDL)
- MUFA decrease LDL
- Omega-3 PUFA fats decrease LDL and triglycerides (VLDL)
- Omega-6 PUFA fats decrease LDL; some types can raise HDL
- Exercise increases HDL and can decrease LDL
- Thyroid function can affect LDL cholesterol levels (hyperthyroidism = fast metabolism = low LDL cholesterol)
24
Discuss fats and how they are gotten from the diet. Discuss risks.
1. Cholesterol
- Gotten through animal foods (meat, milk, eggs)
- However, liver can make more cholesterol than we take in if eating a normal healthy diet
- Dietary cholesterol is not associated with higher blood levels of cholesterol
2. Omega-3 polyunsaturated fats
- Affect cell function
- Helps infant brain develop, prevents cognitive decline with aging in the elderly, decreases risk of CVDs (improve blood lipid levels, decrease blood clotting, resolves inflammation)
3. Long chain omega-3 fats
- Eicosapentaenoic acid or EPA: (20:5) and docasahexaenoic acid or DHA: (22:6)
- Most heart healthy, reduce inflammation (reduce atherosclerosis)
- Fully formed omega-3 fats are found in fish from algae they eat (eg. sardines, salmond, trout, herring, mackerel)
- Canada’s Food Guide recommends eating at least 2 servings of fish per week
- If you dislike fish, eat eggs or eggs fortified with DHA, fish oil capsules or microencapsulated fish oil
- Vegetarians and vegans can obtain alpha-linoleic acid (ALA) from flax seed and canola, soy and walnut oils
- Conversion is not very efficient; assocation with CVD benefits is not clear
- Closer source would be algae
- Eating too many omega-3 fats due to fortification can lead to adverse health effects (possible dysfunction of immune system, weight gain from fat)
25
What are some diet tips about fat?
1. Not always healthier to eat less fat
- Lower fat products use thickeners (carbohydrate plant gums such as guar gum and carrageenan), fruit purees to moisten and milk/egg proteins for creamy texture
2. Replacements to fat are similar in structure but aren’t absorbed
- OLESTRA: may cause GI discomfort, bloating, diarrhea, reduces absorption of fat soluble vitamins, not approved for use in Canada due to side effects
3. Limit cholesterol (or know limits based on family history), trans and saturated fats
- Choose lower fat cuts of meat
- Opt for chicken without skin
- Try a vegetarian meal 1x a week
- Use low in fat milk, yogurt and cheese
- Cut down on packaged foods with trans fat
4. Increase mono and polyunsaturated fats to have a balance
- Choose olive oil, peanut oil or canola oil for cooking and salads
- Use corn, sunflower or safflowe roil for baking
- Snack on nuts and seeds
- Add olives, avocados and seeds to your salads
5. Get enough omega-3s
- Use ground flaxseed or walnuts
- Have leafy green vegetable with dinner
- Aim for 2 servings of fish a week
6. Watch total fat
- Instead of frying, baking/broil/barbecue/roast/steam
- Have smaller servings of ice cream
- Try oven-baked rather than deep fried
- Limit amount of butter you use
26
Discuss fish and fish oil safety.
- Research indicates fish oil intake is associated with decreased inflammation, depression, neurodevelopmental disorders, cognitive decline among elderly, and improved cardiac health
- Fish have been swimming in contaminated water
- Mercury (neurotixin), polychlorinated biphenols (PCBs), dioxins/furans and dioxin-like PCBs, pesticides, perfluroalkyl and polyfluoroalyl substances (PFAs)
- High mercury levels are associated with lower cognition for babies in pregnant women
- Mercury is released into environment, methylated by bacteria (activated) and enters small aquatic animals eaten by others
- The larger the fish (swordfish, tuna, shark), the higher the heavy metal and PCB concentration than smaller fish (haddock)
- Continue to eat fish during pregnancy but choose varieties with lower mercury contamination
- Use molecularly distilled and 3rd party tested fish oils
27
What is coffee and its components?
A beverage made from the seeds of the coffee plant (Coffea arabica)
1. Caffeine
2. Phenolic substances
3. Antioxidants
28
What is caffeine? Discuss physical effects, absorption and average intake.
- A stimulant
- Most widely consumed drug worldwide (81% coffee, tea, then pop/cola)
- ⅔ of Canadians consume at least 1 cup of coffee per day
- Average intake is 3 cups per day
Physical effects of caffeine vary from person to person:
- Can include nervousness, irritability, restlessness, insomnia and heart palpitations
Caffeine dependency is possible:
- Withdrawal includes headache, fatigue, drowsiness, irritability, difficulty concentrating, depressed mood
- Can be addicting with repeated usage
Caffeine is rapidly and completely absorbed in humans:
- 99% absorbed within 45 minutes of ingestion
- Lipophilic to pass through all biological membranes and readily cross blood brain barrier very quickly
- Metabolized in liver and excreted by kidneys
- Takes around 8-10 hours to leave system, 4-5 to leave bloodstream
29
Discuss the effects of caffeine on the health.
1. Hypertension
- Increases blood pressure for 3 hours
- Not necessarily in regular caffeine users
2. Bone health
- May increase urinary excretion of calcium (diuretic) or inhibit absorption of calcium
- Those who consume caffeine + lower recommended intakes of calcium + low bone mineral density are at risk (if you consume milk, OK)
3. Pregnancy
- Caffeine crosses placenta = baby can consume
- High amounts of caffeine may increase risk of low birth weight and preterm birth = health complications
- Recommendation is same for nonpregnant women (300 mg/day) officially
- Regular coffee consumers for long time appear to have less impact
4. May increase/decrease anxiety, depression and other mental health conditions depending on physiology and genes
5. May help prevent Parkinson’s disease
6. Affects sleep patterns
- Lack of sleep can lead to obesity, chronic diseases and mental health disorders
7. Can improve sports performances
- WADA (World Anti-Doping Agency) removed ban in 2004
- To be added to prohibited list of WADA, substance must have ⅔: potential to enhance performance, health risk to athletes, violates spirit of sport
30
Discuss energy drinks and mention sports drinks.
- Main ingredient is caffeine (50-200 mg per can)
- Eg. Monster, Red Bull, Rockstar
- Not to be confused with sports drinks (eg. Gatorade and Powerade) which rehydrate the body and provide sugars (energy) and electrolytes (maintain Na and K balances)
- Should not be taken on an empty stomach, replace food or mixed with alcohol
- Now classified as foods and not natural health products (stricter labelling and nutrition data)
31
What are the caffeine recommendations?
- Adults: <400 mg/day or about 2-4 cups of coffee per day
- Women of childbearing age: <300 mg/day
- Children under 6 should not onsume more than 45 mg/day
- FDA or the USA does not have any caffeine recommendation
32
What are oily substances in coffee?
- Kahweol and cafestol
- Increase blood LDL levels and associated with increased risk of heart disease
- Filters in normal coffee keep these oily compounds out
- Mostly found in Turkish coffee, boiled coffee or French press coffee
33
What are antioxidants? Discuss coffee.
- A study in Finland found that 66% of antioxidants in diet came from coffee
- In coffee, include quinines, flavonoids and melanoidins
- Antioxidants prevent/reverse oxidation and repair cell damage
- Oxidation: change in electron structure of atoms (electrons taken off) due to oxygen metabolism
- Can damage cells/tissues and their DNAs as unstable atom will try to get replacement electron
- Free radicals are created (chain reactions of electrons getting pulled off stable atoms)
The more roasting of coffee, the more heat exposure and the more degradation of antioxidants (maximum is medium-roasted)
34
Is coffee healthy?
It is hard to tell because of confounding factors
- Smoke (historically; not as much now)
- Drink alcoholic beverages
- Have less healthy lifestyles (diet, exercise)
- Coffee contains niacin (B3 vitamin), potassium and magnesium
- Moderate intake of coffee is related to decreased risk of type 2 diabetes, some cancers, Parkinson’s disease and liver disease due to antioxidants
- Concerns due to caffeine: sleep, mental health, pregnant women, bone health and children
35
What is tea and its components? Discuss black and green tea.
- Soaked leaves of the tea plant Camellia sinesis
- Black tea: leaves are picked, oxidized/fermented and dried (consider free radicals)
- Green tea: the leaves are not oxidized
1. Caffeine
2. Antioxidants
3. Tannins
36
What are the antioxidants in tea?
1. Catechin
- A polyphenol
- Protects against oxidative stress
- Highest content in white and green teas
- Black tea still contains a lot
2. L-Theanine
- A non-protein amino acid derivative
- Has a calming effect
- Helps strengthen the immune system
37
What are tannins in tea?
- Bind to non-heme (plant sources) iron in digestive tract to inhibition absorption
- Can interfere with iron absorption from food
- Those with low blood iron should avoid having tea with meals or taking supplements
38
Discuss health benefits of tea.
1. Improved cardiovascular health
- More than 3 cups a day
- Decrease blood pressure by protecting the health of blood vessels
2. Body weight maintenance
- Green tea may result in small increase of energy expenditure (5%) and fat burning
3. Bone health
- May prevent age-related bone loss
- Slight improvement in bone mass
4. Dental caries/cavities
- Due to fluoride in tea
5. Immune system
- Delivering immune cells faster all the way around
6. Mental health
- Flushing brain with oxygen, blood and nutrients
BUT:
- No standarization of what a dose is or amount of caffeine in teas
- “Dose” of tea required to see effects range from 1-6 cups/day
- More confounding factors (lifestyle or genetic differences) between tea drinkers and nontea drinkers
- Antioxidant content depends on geographical location, growing conditions and processing of tea
- Action of antioxidations in body may differ from in test tube in a lab
39
What are proteins? Where are they found in the diet?
- Macromolecule that contains carbon, hydrogen, oxygen, nitrogen
- Made up of long strings of amino acids
- Found in largest quantities: meat, poultry, fish, dairy products/eggs, legumes, nuts, seeds
- Some protein in grain products
- Little protein in fruit and vegetables
40
Discuss amino acids; structure and types.
- Amino group (N) and acid group (COOH); top has H, bottom has side chain unique to each amino acid
20 amino acids in total
1. 9 are essential (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine)
2. Some are conditional-essential (during growth development, some are needed more)
- Arginine, cysteine, glutamine (most comon in stomach, IBD flares can lose 60% of glutamine), glycine, proline, tyrosine
3. 11 are nonessential
41
What is transamination?
- Conversion of amino acids to nonessential amino acids
- Donation of amino group (N) to create new amino acid
42
What are peptide bonds?
- Bond between acid group of 1 amino acid and amino group of another
- Peptide: amino acids attached using peptide bond
- Dipeptide, tripeptide, oligopeptide (a few), polypeptide)
- Proteins are made of 1+ polypeptide strands
43
Discuss protein shape.
- Different amino acids in the chain are attracted to each other
- Complex folding of molecule determines 3D shape
- Shape determines function in body
44
Talk about genetic mutations. Mention sickle cell anemia.
Proteins that do not work
Example: sickle cell anemia
- Hemoglobin has 4 polypeptide chains with a heme group (iron) attached to each chain
- Oxygen binds to iron (4 sites on hemoglobin for carrying oxygen)
- Every red blood cell has potential to carry 4 oxygens
- 1 amino acid difference = sickle shape with sharps sticking out
- Get stuck on capillaries, rupture, lose iron transporation
45
Discuss protein digestion.
1. Mouth
- Mechanical digestion only (chewing)
2. Stomach (principle site of protein digestion)
- Hydrochloric acid denatures protein, making protein strands more accessible for proteolysis
- Pepsin breaks long proteins into smaller chunks and single amino acids
- NOTE: once proteins are denatured, they are nonfunctional (which is why don’t take hormones/enzymes orally unless they work before hit acid or have special coating)
3. Small intestine (neutral = bicarbonate from pancreas)
- Pancreatic enzymes trypsin and chymotripsin break down remaining proteins into oligopeptides, tripeptides, dipeptides and amino acids
- Free amino acids and di/tripeptides can be absorbed into intestinal cells
- Peptidases (enzymes) in intestinal cells break down into single amino acids
- Amino acids pass from mucosal cell into blood and travel to the liver, which regulates distribution of amino acids
46
What is the amino acid pool? Discuss protein turnover.
- Dietary protein is used to make body proteins
- Proteins get broken down into amino acids into amino acid pool
- From amino acid pool, protein can also be used to make energy, new glucose molecules or new fatty acids or non-protein molecules with N (eg. urea, creatine, creatinine)
- Protein turnover: balance between protein synthesis and protein degradation
- Ensure constant supply of amino acids available for many functions in body
- If there aren’t enough essential amino acids, your body cannot synthesize key proteins
- Solution: break down proteins to release amino acids
47
What are the functions of proteins?
1. Provide structure
- About 15% of our body weight is from protein
- Many cell structures contain structural proteins (muscle, skin, bones, organs, blood cells, tendons)
2. Allow chemical reactions to happen
- Enzymes are protein molecules
3. Transport proteins in cell membranes (facilitated diffusion and active transport)
4. Transport proteins within blood
- Albumin: transports nutrients such as calcium, zinc, vitamin B6
- Lipoproteins transfer cholesterol and triglycerides
5. Support immune system by enhancing cellular immune mechanisms
- Antibioties are proteins that destory invaders
6. Contractile proteins
- Actin and myosin are protein in muscles that allow them to contract/relax
- Sarcomere: portion of muscle that has interlocking myosin and actin filaments
- During muscle contraction, come together
7. Protein/peptide hormones (chemical signals in body between cells and tissues)
- Glucagon: breaks down glycogen to release glucose into blood
- Insulin: takes sugar out and stores it
- Prolactin: stimulates milk production, produced by pituitary gland
- Gastrin: stimulates secretion of gastric acid, produced by GI cells
8. Maintain acid/base balance
- Some proteins are buffers
- Help maintain constant pH by attracting/releasing H+
9 .Provide energy
- Body prefers to use carbohydrates and fat
- If you get rid of amino group on molecule, you can do deamination
- Burn acid group for energy (form intermediates in citric acid cycle to go into ETC)
- Turn acid group into fat (2 C, made into acetyl-CoA to enter citric cycle or synthesize new fatty acids)
- Turn the acid group into glucose (only some amino acids)
- Gluconeogenesis: create new glucose
- 3 C
48
What occurs when you don't get enough protein?
- Body breaks down muscle then enzymes to make proteins
- Can lead to impaired cell function, impaired nutrient transport, acid-base balance, death
- Not very common in wealthy countries
49
What is marasmus? Discuss emaciation.
- Severe protein and energy malnutrition (low in protein, calories, carbs, fat, vitamins, minerals)
- Chronic condition
- Emaciation: slowly starving to death (body fat stores and proteins)
- Common in young, impoverished children (6-16 months old)
- Often occurs when infants/children are fed diluted baby formula (not adequate supply for nutrients)
- Less common in breastfed infants
- Results in stunted growth, dehydration, increased risk of infections, heart failure
50
What is cachexia?
- Marasmus in Canada due to chronic illness
- Increased requirements due to illness or decreased digestion, intake or absorption of nutrients
- Often occurs in cancer, anorexia, AIDS, elderly who get depressed
- Reduced food intake coupled with abnormal metabolism
- Increased catabolism
51
What is kwashiorkor?
- “The disease the first child gets when the second child is born”
- Common in children 1-3 years old in impoverished countries
- Children are weaned from breast milk and given diet low in protein and high in fibre (GI tracts not ready)
- Severe protein malnutrition (not necessariy low on energy)
- Results in stunting in growth, skinny legs, big stomach, moon face
- Big stomach caused by excess fluid and fatty liver
- Low blood protein causes fluid imbalance in space between cells (cell membrane doesn’t have enough protein to work)
- Causing swelling of tissues in which pitting occurs
- Fluid/water moves from intracellular (inside the blood vessels) to extracellular/interstitial (outside the blood vessels) and accumulate
- Blood proteins can’t transport fat
- Frequently die of infections (immune system is compromised), and dehydration due to damage and death of cells of GI tract
52
Can you treat the wasting diseases? What is refeeding syndrome? Consider relapse.
- Both marasmus and kwashiorkor can be cured to an extent
- Can suffer longterm effects of lower nutrient intakes
- Negative effects on growth, bone health, cardiac health, brain development, cognitive abilities
- Must be accompanied with zinc (protein is vehicle for zinc) to experience catch-up growth
- Refeeding syndrome: treat patients slowly or system cannot handle it and can cause death
- Relapse will happen in returned to impoverished environment
53
What is the effect of too much protein?
Associated with high saturated fat intake and lower intake of grains, fruit and vegetables
1. Increases risk of heart disease and cancer
2. Affect fluid balance
3. May contribute to bone loss with aging by increasing calcium urinary excretion
4. Increases risk of kidney stones as kidneys work hard to get rid of nitrogen from extra amino acids
- Calcium may concentrate as kidney stones
5. Inflammation or gout
- Proteins, purines and uric acid has cystalline structure that deposits in joints and causes localized inflammation
6. Weight gain
Amino acid pool does not store much protein; extra amino acids are stripped of N (excreted as urea) and the remaining is turned into glucose to be used or stored as fat
54
Discuss protein intake and athletes.
- Most athletes meet their protein needs by consuming the RDA of 0.8 g/kg or slightly more (1.0-1.2 g/kg)
- Endurance athletes and bodybuilders may need more than the RDA (1.2-1.4 g/kg body weight)
- Ultra-marathoners, long-distance cycling: helps maintain blood glucose levels
- For body builders: helps with the building of muscle
- These needs can be met through the diet without protein supplements (isolated protein without nutrients or fortified so risk of excess)
55
How much protein is enough for the basic population? Discuss AMDR.
1. For adults, the RDA is 0.8 g/kg body weight
- Based on protein needed to maintain good health
Some people need more protein to meet needs for rapid growth or increased metabolic stress
1. Infants (0-6 months = 1.52 g/kg)
2. Children (4-13 years = 0.95 g/kg) and adolescents (14-18 years = 0.85 g/kg)
3. Pregnant and lactating women (need an extra 25g per day)
4. Athletes (0.8-1.4 g/kg)
5. Recovering from illness (wasting disease), burns or surgery to repair tissues (as high as 2g/kg body weight)
6. Vegetarians and vegans: protein from grain products is less well digested and absorbed
- For someone who is overweight, we would use their ideal weight in calculating protein requirements
- Most Canadians consume 15% calories from protein
- Meet AMDR (10-35%)
- Majority comes from meat, poultry, fish, eggs, dairy
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How is the healthiness of protein determined?
1. Quality
2. Digestibility of protein
- Meat, milk, eggs and beans have high digestibility
- Grains, fruit and vegetales have low digestibility
3. Other nutrients found in the protein foods
- Low in saturated fat, salt
- High in fibre, iron, calcium, B vitamins
- Provide omega 3 fats
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What is protein quality?
- A measure of how efficiently a protein in the diet can be used to make body proteins
- Proteins that don’t contain all the essential amino acids are considered lower in quality
- A varied diet allows us to meet these needs
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What are the types of proteins?
1. Complete proteins (9)
- Provides all essential amino acids in proportions needed to support protein synthesis
- Eg. meat, fish, poultry, eggs, milk, soy products
2. Incomplete protein (11)
- Protein that is deficient in 1+ esential amino acids relative to body needs
- Grain protects are low in isoleucine and lysine (oats, rice, wheat, rye)
- Legumes are low in methionine and tryptophane (black, pinto, chickpeas, kidney)
3. Complementary proteins
- Process of combining proteins from different sources so they collectively provide the proportions of amino acids required to meet needs
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What are types of vegetarianism?
- Semi-vegetarians eat fish and/or poultry in addition to milk and eggs
- Lacto-ovo-pesco vegetarian eats milk, eggs, and fish
- Lacto-ovo vegetarian eats eggs and milk
- Lacto vegetarian eats milk, not eggs
- Ovo vegetarian eats eggs, not milk
- Pescatarian eats fish, but no meat, poultry, eggs and milk
- Flexitarian eats meat occasionally
- Vegan eats no food from animals
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What are the reasons for vegetarianism?
1. Religious (Hinduism, Buddhism, some Christians such as Seventh Day Adventists)
2. Ethical (belief that animal treatment is inhumane)
3. Food safety (eg. Mad Cow disease, hormones, antibiotics)
4. Ecological (greenhouse gases from cattle, destroying forests for pasture land for animals to feed off of, water usage)
- NOTE: almond milk is turned into a profit driven economy = monoculture production of almonds (cannot protect against disease) + lots of water
5. Health (high in fibre = better gut microbiota, vitamins, minerals, low in saturated fat)
- Decreased risk for cardiovascular disease, obesity, many cancers, diabetes and kidney disease
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What are the challenges of a vegetarian diet?
1. Iron
- Avoid eating calcium and iron together
- Eat with vitamin C to enhance iron absorption
2. Calcium & vitamin D
- Get from fortified foods ro supplements
3. Zinc
- Blocked by phytates and fibre
4. B12
- Only found in animal foods
- Must supplement with pills, injections or yeast extracts
5. Omega-3 fats
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What are the food sources that vegans should look out for?
- Protein: soy-based products, legumes, seeds, nuts, grains and vegetables
- Calcium: tofu processed with calcium, broccoli, kale, bok choy, legumes, products fortified (soy beverages, grain products, orange juice)
- Vitamin D: sunshine, products fortified (soy beverages, margarine, orange juice)
- Iron: legumes, tofu, dark green leafy vegetables, dried fruit, whole grains, iron-fortified cereals and breads (absorption is improved by vitamin C)
- Zinc: whole grains, wheat germ, legumes, nuts, tofu and simulated meat products
- Omega-3: canola oil, flaxseed and flaxseed oil, soybean oil, walnuts, sea vegetables such as seaweed, DHA-rich microalgae
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What is obesity associated with?
- A large portion of world has BMI between 25 and 27
- Associated with heart disease, type 2 diabetes, cancer (inflammation), reproductive problems, joint problems, sleep apnea (insuffient oxygen), depression
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What is EER?
- Estimated energy requirements - Energy balance that occurs between energy intake and energy expenditure
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How many calories do each macronutrient give you?
- Carbohydrates give you 4 kcal of energy/gram
- Fat gives you 9 kcal of energy/gram
- Protein gives you 4 kcal of energy/gram
- Alcohol gives you 7 kcal of energy/gram
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Discuss energy out.
1. Basal metabolic rate (BMR)
- How many calories you produce when you are at rest (eg. sitting still for long periods of time, sleeping)
- Energy needed to maintain body’s resting functions (breathing, keep heart beating, etc.)
- 60-70% of our total energy expenditure
- Factors include lean body mass (muscle), gender (men), growth (children, pregnancy), body size (larger), age (younger), stress/injury/illness (increase), low energy diets (decrease), thyroid levels (hypothyroid = decrease)
2. Energy expenditure due to exercise
- Varies depending on the individual
- You burn more energy when exercise is intense, long
- Burn through cholesterol and sugars faster (reduce cardiovascular risk and diabetes)
- Increase blood volume to brain and muscles (oxygen and nutrients)
- Stretches blood vessels (decreases risk of high blood pressure and stroke)
3. Thermic effect of food (5-10% impact)
- The energy needed to digest, absorb, transport and metabolize food
- Fat takes less energy to metabolize than carbohydrate and protein
- Increases with size of meal
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What is protein deamination?
- Protein deamination results in ammonia production
- Can cross blood-brain barrier (neurotoxin)
- Can be toxic to liver so liver turns ammonia into urea
- Urea travels through blood to kidney where it is filtered into urine, and excreted (get rid of N)
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How is energy required measured?
1. Direct calorimetry
- Measures amount of heat released by body
- Can take 1 day
2. Estimated using equations
- DRIs have EER equations that let you calculate energy needs based on age, sex, height, weight and physical activity
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What happens if energy in > energy out?
- Firstly, amino acids from protein are used to synthesize needed body proteins
- Carbohydrates are used to maintain blood glucose and build glycogen stores
Some of fats are used to meet needs
- Excess kcals from all macronutrients are generally stored as fat
1. Triglycerides (stored in adipose tissue)
- Adipocytes grow in size as they accumulate more triglycerides and shrink (but do not disappear) as they are removed
2. Glycogen (stored in muscles and liver)
- Body stores about 200-500g of glycogen
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What is weight cycling or yo-yo dieting?
1. Dieting → rapid weight loss, decrease in BMR, fatigue and decrease in activity = burning less calories, food cravings
2. Return to former eating habits
3. Overeating → shame, guilt, rapid weight gain as BMR is decreased
4. New determination to diet → cycle continues
- Best not to start cycle as retriggering BMR is difficult to do
- Eat normal amount, higher quality foods with micronutrients, exercise more
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What is a healthy body weight? What happens outside of this?
- A body that has enough body fat and enough lean muscle for health but not too much
- Too much fat ↑ risk of disease
- Too little fat ↑ risk of death, disease, body functioning
- Too little muscle ↓ ability to move and function independently
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What is body mass index and how do you use it?
- The main way health professionals determine if our body weight is healthy
- Based on reference population
- BMI = body weight in kg/height2 in m
- Height in m = (height in in x 2.54)/100 = (height in feet x 30.48)/100
- Weight in kg = weight in lbs/2.2
BODY WEIGHT CLASSIFICATION:
- Underweight: < 18.5 (increased risk)
- Normal weight: 18.5 - 24.9 (lowest risk)
- Overweight: 25.0 - 29.9 (increased risk)
- Obese class I: 30.0 - 34.9 (high risk)
- Obese class II: 35.0 - 39.9 (very high risk)
- Obese class III: > 40 (extremely high risk)
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Discuss BMI in children.
- BMI or weight of children is compared to other children of same weight and sex
- Percentiles: a measurement that shows how the child is doing relative to children from the same age and gender group
- A higher percentile means child is heavier compared to other children of that age and gender (25th percentile means 25% have lower BMI)
- Some controversy as children are growing in different places at different rates
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What are flaws in the BMI?
- BMI is a screening tool not a diagnostic tool
- Cannot directly assess % body fat
- Inaccurate for muscular people, people with low muscle mass and pregnant/breastfeeding women
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Discuss skin folds; pros and cons.
- Take caliper to measure thickness of skinfolds (eg. triceps, back, thigh)
- Measures subcutaneous (under skin) fat levels
- Portable and measures body fat at multiple areas
- Training is necessarity to be accurate
- Less accurate in obese individuals and elderly who may have low subcutaneous but still have visceral fat
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Discuss bod pods; pros and cons.
- Measure volume by air displacement to calculate density
- The more density, the more muscle; the less density, the more fat
- Very accurate method, but expensive
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Discuss fat distribution patterns.
1. Visceral adipose tissue: fat around organs
- More metabolically active
- Related to increased risk of diseases (diabetes, CVD)
- People who carry weight in apple shape have more visceral adipose tissue
2. Subcutaneous adipose tissue: fat under the skin
- Rather than amount of fat, where it is is more important
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How do you measure weight circumference? What is the risk numbers for males and females?
- Measure halfway between ribs and hip bone OR an inch above belly button
- Risk for males: >120 cm or 40 in
- Risk for females: >88 cm or 35 in
- Easy to do and gives idea of disease risk
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Discuss genetics and obesity.
- We inherit our body shape and characteristics from our parents
- Responsiveness of blood sugar to insulin, production of leptin
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What is the set point theory?
- The theory that when people finish growing, their weight remains stable for long periods of time despite changes in energy intake/output
- Partly genetic, partly environment
- Dieting lowers BMR to have a higher set point
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Discuss social factors and obesity.
- Time constraints
- Social pressure, social norms
- Availability of food or exercise opportunities
- Nutrition education, food skills
- Sleep patterns (overtired = increased risk of gaining weight)
- Support systems
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What are the appetite hormones?
1. Leptin (satiety)
- Secreted by adipose cells
- Overweight people produce more leptin but have leptin resistance (decreased sensitivity to leptin), resulting is inability to detect satiety despite high energy stores
- Regulates fat stores; signals to hypothalamus to stop eating because body has enough energy
- Hypothalamus then sends signals to increase metabolic rate and decrease energy intake = weight loss
- This doesn’t occur in overweight people
2. Ghrelin (hunger)
- Produced in stomach
- Secreted when stomach is empty and stops when stomach is stretched
- Hypothalamus sends signals to increase hunger and increase gastric acid secretion (must eat to stop acid)
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Discuss losing weight safely.
- If you lose weight too quickly, you risk nutrient deficiencies, losing muscle (lower BMR), and gaining weight back
- Reasonable weight loss goal is 0.5-2 lb per week
- Should be sustainable or else you will yo-yo diet
- 1 pound of fat contains 3500 kcals of energy
- People who are trying to lose weight are successful at losing - 5% of body weight and keeping it off
- No one diet is deemed better in long-run but low-calorie diets that reduce energy intake by 500-100 kcal/day tend to be most common among successful weight losers
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What are some tips to losing weight?
- Eat smaller portions
- Eat smaller portions
- Avoid high fat foods
- Avoid high in sugar foods
- Avoid high calorie beverages as they fill you up less
- Have more fibre (whole grains and vegetables) as it fills you up more
- Have protein with each meal as it keeps you feeling satisfied
- Eat out less often; big portion sizes and higher fat content
- Or use a take out container
- Drink more water to stretch out stomach
- Record what you eat
- Exercise more to gain muscle
- You can gain weight in muscle without increasing risk factors
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What is bariatric surgery? Who is eligible?
- Can result in loss of 20-25% of body weight
- May remove parts of stomach/small intestine or slow entry of food into stomach
- Eligible if you have BMI of 40 kg/m2 or between 35-40 with life-threatening complications
- Many people gain weight back because underlying issues have not been addressed
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