Flashcards in Midterm 1 Deck (50):
What are phytochemicals and zoochemicals?
Phytochemicals: biologically active compounds found in plants (eg. beta carotene)
Zoochemicals: healthy food components found in animal sources (eg. iron in beef)
What are the 6 classes of nutrients?
Carbohydrates, lipids, proteins, water, vitamins, minerals
What are macronutrients and the types?
- Carbohydrates, fat, protein
- Nutrients that are needed in large amounts of energy
What are macronutrients measured in and talk about the types of macronutrients.
- The amount of energy they provide is measured in kilocalories
- Unit of energy it takes to warm 1 kilogram of water up by 1 C
- Carbs: 4 kcal of energy/gram
- Fat: 9 kcal of energy/gram
- Protein: 5 kcal of energy/gram
- Alcohol: 7 kcal of energy/gram (empty source of calories ie. no nutrients)
What is water and what does it do?
- A macronutrient but doesn’t provide energy
- Provides right environment for chemical reactions, our cells (to grow), our muscles and nerves (to function), hormone signaling, nutrient transport, regulation of body temperature, EVERYTHING
- About 60% of body weight is made up of water
- Human body can last longer without food than water
What are micronutrients and the types?
- Don’t provide us with energy but essential for different functions in the body
- Vitamins: organic (contains C) molecules our body needs in order to function
- Involved in helping body use the energy from macronutrients
- Involved in bone growth, vision, blood clotting, oxygen transport, tissue growth and development, myelination (intermittent messages), methylation (liver detoxifying chemical), DNA
- Minerals: inorganic (from periodic table) our body needs in order to function
- Needed for bone strength, transport of oxygen and the transmission of nerve impulses
What are the characteristics of a nutritious diet?
- Adequate: having sufficient amounts of nutrients to maintain health
- Moderate: watching portion sizes and frequency of consumption of foods
- Balanced: mix and match food choices to ensure adequate nutrient intake
- Varied: there are no super foods, need to eat a variety of foods to ensure adequate nutrient intake
What is undernutrition and the symptoms of starvation?
- Form of malnutrition caused by deficiency of energy of nutrients
- Starvation: most severe; causes weight loss, poor growth, inability to reproduce, death
What is overnutrition?
- Excess of nutrients (usually macronutrients)
- An adverse or toxic reaction may occur as anything is toxic at high levels
- Overnutrition in Canada doesn’t always have immediate toxic effects, but contribute to development of chronic diseases (heart disease, type 2 diabetes, fatty liver disease)
What are the factors impacting food choices?
1. Availability and accessibility (cost, location, cooking skills)
2. Cultural and family background (social acceptability)
3. Personal preference
- Psychological and emotional factors
- Health concerns
- Media messages as to what to eat
Who should you trust and not trust for nutritional information?
1. Educated people with credentials
- Registered dietitians (RD, PDt)
- Nutrition professionals with advanced degrees
- Health Canada, Public Health Agency of Canada
- Statistics Canada
- National Institutes of Health (USA)
3. Professional organizations
- Dietitians of Canada
- Canada Nutrition Society
4. Well known non-profit organizations
- Canada Diabetes Association
- Canadian Cancer Society
- Heart and Stroke Foundation
5. Peer reviewed journal articles
- If you have dietary problem, most doctors will refer you to dietitian because most doctors have very little nutrition training
DO NOT TRUST:
- Nutritionists (not a protected title in Ontario)
- Media (check author credentials)
What are DRIs?
- Dietary Reference Intake (DRIs)
- Used by health professionals in Canada and USA
- Developed by the Institution of Medicine
- Coordinated development by American and Canadian nutrition experts
- Provide set of standards that can be used to plan diets, assess adequacy of diets, and make judgement about excessive intake for individuals and populations
What are the types of DRIs?
1. Estimated Energy Requirements (EER)
- For calculating how many calories are needed to keep body weight stable in a healthy individual
2. Acceptable Macronutrient Distribution Ranges (AMDR)
- Used to see if you are getting the right proportion of macronutrients
- 1-3 years: 45-65% carbs, 5-20% protein, 30-40% fat
- 4-18 years: 45-65% carbs, 10-30% protein, 25-35% fat
- 19+ years: 45-65% carbs, 10-35% protein, 20-35% fat
3. Estimated Average Requirements (EAR)
- Based on solid evidence, meets the needs of 50% of the population; not used for individuals but to assess the adequacy of diet within a population
4. Recommended Dietary Allowance (RDA)
- Meet requirements of 98% of the population; a good goal for individuals
5. Adequate Intake (AI)
- Mean intake of a healthy population; used for nutrients that don’t have evidence to set EAR or RDA
- Good goal for individuals if RDA does not exist
6. Tolerable Upper Intake Level (UL)
- Highest average daily nutrient intake level that poses no risk of adverse health effects
What is Canada's food guide?
- Created based on information form DRIs + foods that make up a healthy diet in 1992
- Lower in fat, sugar, and salt (prevents high blood pressure, less empty calories)
- Have more dark green and orange vegetables (have more vitamins such as A, C, and folate)
- Have more vegetables and fruit than juice (more fibre, fill you up, fewer excess sugar calories)
- Choose whole grains (more fibre and minerals)
- Drink skim, 1% or 2% milk each day (added vitamin D)
- Select lower fat milk alternatives as cheese is often high in fat (55-65%) and salt (associated with higher lipid levels and cardiovascular disease)
- Have meat alternatives more often (beans are high in folate, fibre and protein)
- Have fish twice a week (contain long chain omega-3 fatty acids like DHA and EPA to help mental health and neurological issues)
What are some food tips that should be used with the food guide?
- Choose 2-3 tbsp of oils and fats like canola or olive oil
- Avoid using hard fats like butter, margarine, lard, shortening
- Limit consumption of empty calories
- Enjoy variety of foods
What does the nutrition facts table tell us?
Tells us which food is healthier when comparing and the amount of nutrients we are getting
What are the components of the nutrition facts table?
- % daily value: based on 2000 calorie per day diet of healthy adults
- Not useful for tracking your intake but it can give us a general idea about how much of a nutrient there is
- 5% or less is low, 15% is high
- All the ingredients in the food product are listed in order of greatest to least quantity
- Nutrient claims are a quick and easy way to get information about a food
- Companies have to pay for the claim and must meet certain criteria
What are the functions of the digestive system?
1. Digestion: breaking food into tiny pieces
2. Absorption: moving the tiny pieces from the inside of your intestine into the bloodstream
3. Elimination: getting rid of the waste
4. Barrier function: preventing the absorption of harmful substances
How does the body tell you that you need to eat?
- Through gut-brain axis
- Stomach and intestines sends signals through nervous system or blood to hypothalamus of brain (“we’re empty!”)
- Insulin and glucagon (hormones secreted by pancreas that control blood sugar) levels in blood change as blood sugar drops; telling hypothalamus to eat
What is the digestive process?
- Mechanical: teeth break up food
- Chemical: enzymes in saliva dissolve food to make bolus (moist ball)
- Salivary amylase breaks up carbs
- Lingual lipase breaks up fat
- Peristalsis starts here and continues all through GI tract into stomach via lower esophageal sphincter
- Waves of contractions that move food
- Muscles: inner circular muscles and outer lengthwise muscles
- Mechanical: 3 thick muscle layers churn and break up food into chyme
- Chemical: gastric juice (pH = 3.0)
- Hydrochloric acid: denatures protein
- Pepsin: enzyme that breaks down protein, functions in acidic environment
- Mucus: protects entire GI tract, helping it move easily, prevents pepsin from digesting protein layers of stomach (develop peptic ulcers)
- How stomach churns and how much gastric juice is released is regulated by signals from nerves and hormones
- Brain sends nerve signals that stimulate gastric motility and secretion, preparing stomach to receive food
- Food entering stomach stimulates release of gastric secretions and increases stomach motility
- Gastrin: hormone secreted by stomach mucosa (mucous membrane lining stomach) that stimulates secretion of gastric juice
4. Small intestine
- Chyme delivered from stomach through pyloric sphincter into duodenum (further digestion and some absorption)
- Bile is made in liver but stored in gallbladder which secretes it into small intestine (emulsifies fat molecules; breaks it into small droplets that mix well with water)
- Pancreas produces and adds specific enzymes (amylase for starch/carbs, lipase for fat, protease for protein) and bicarbonate ions (neutralize acid in chyme for enzymes to function)
- Jejunum: digestion continues, lots of absorption
- Ileum: absorption continues
- Brush border: microvilli allow absorption of nutrients into bloodstream or lymph system and transportation to organs and tissues
5. Large intestine (cecum to ascending/transverse/descending/sigmoid colon to rectum to anus)
- No digestion takes place
- Water and some micronutrients are absorbed
- Friendly bacterial (commensals) ferment undigested food products
- Byproducts: gas, vitamin K and fatty acids that large intestine uses
- Gas produced is called “flatus’ (contains nitrogen, carbon dioxide, hydrogen, methane, and hydrogen sulphide)
- Rectum holds faeces until its eliminated
- Water, nutrients, and fecal material may spend up to 24 hours in large intestine
What is the barrier function of the GI tract?
- Protective role of gastrointestinal cells lining entire GI tract from damage
- Special immune cells include phagocytes, lymphocytes (T and B cells)
- Limits absorption of harmful substances (toxins, disease-causing organisms)
1. Detect antigens (foreign substances that stimulate immune response)
2. Phagocytes target invader, engulf it, and destroy it inside itself
3. The broken-up antigens are detected by B cells which produce and secrete antibodies (protein molecules which destroy or inactivate antigens by attacking or binding)
4. Separately, T cells bind directly to infected or foreign cells and destroy them
How are nutrients absorbed?
- Through mucosal cells (villi, microvilli, representative for blood and lymphatic systems) of GI tract into blood and lymphatic systems
1. Hepatic portal circulation system
- Carries water-soluble nutrients through blood from digestive tract to liver via hepatic portal vein
- Liver processes and releases nutrient into general circulation or use by cells
- Some nutrients may be stored in liver (iron, glucose as glycogen) for times of shortages
2. Lymphatic system
- Absorbs fat-soluble nutrients that are too big to fit in capillaries
- Nutrients are packaged into chylomicrons in intestinal mucosal cells, travel into small lacteals and then into blood
- Do not pass through liver before entering general blood circulation
- Also helps us fight infections (transport lymph, fluid containing white blood cells)
How are nutrients transported around the body?
- Nutrients in blood stream can be picked up by body tissues for immediate use or may be stored in body
- Nutrients are transported into cells across cell membrane (maintain integrity of cell and surrounds cell contents)
1. Simple diffusion: movement of substances from higher to lower concentration without energy or carrier (eg. carbon dioxide, oxygen, water)
2. Osmosis: passive movement of water across semi permeable membrane from higher to lower concentration
3. Facilitated diffusion: movement of substances across cell membrane from area of high to low concentration with carrier molecule but no energy
4. Active transport: transport of substances across a cell membrane from low to high concentration with aid of carrier molecule and expenditure of energy
What is metabolism?
- Chemical reaction that happens inside living thing and results in transformation (change in molecular structure) of one molecule into another
- We make energy out of nutrients
- Creating a bond (anabolic) between 2 atoms takes energy
- Breaking a bond (catabolic) between 2 atoms releases energy
- In the body, energy stored in carbs, fat, and protein is released by breaking bonds and converted to heat and adenosine triphosphate (ATP)
- ATP consists of adenosine molecule attached to 3 phosphate groups
- Bonds between phosphate groups release a lot of energy when broken
- Used to power muscle contractions, making new cells and tissues, making DNA, transporting molecules into/out of cells
Discuss cellular respiration.
- Each cell in body makes energy via cellular respiration
- Macronutrients break down into glucose, fatty acids and amino acids
- In the presence of oxygen, glucose/fatty acids/amino acids are metabolized to produce acetyl-CoA
- Acetyl-CoA is broken down in citric acid cycle to yield carbon dioxide and high energy electrons
- The electrons are shuttled to electron transport chain where energy is used to generate ATP, oxygen, and hydrogen (forms water)
- The end products of energy metabolism is carbon dioxide (from citric acid cycle) which we breathe out, water (ETC) which we sweat out, nitrogen (protein) which we pee out, and waste (digestive system)
- Urinary, respiratory, digestive, and integumentary (skin) system work together to get rid of bodily waste
What is constipation, the causes and prevention?
- Stools are infrequent or hard to pass
- Type 1 and 2 on Bristol Stool Chart
- Should be suspected if 3+ days pass between bowel movements
- Stress, travel
- Aging (elasticity of colon changes), drugs, nerve disorders
- Lack of exercise (blood flow stimulates peristalsis)
- Low fluid intake
- Thyroid function (regulates metabolism speed; heart rate affects stools)
- Eat lots of fibre to hold onto water and increase bulk of stools (stimulates peristalsis)
- Drink water to keep everything soft and stimulate intestinal movement
What is diarrhea, the causes and prevention?
- Type 5-7 on Bristol Stool Chart
- Results in dehydration and loss of electrolytes
- Bacteria, viruses, parasites (food borne)
- Stress, medications, food intolerances
- Celiac disease or inflammatory bowel disease
To treat or prevent:
- Probiotics (foods that contain live bacteria or yeasts) to bring back balance between good and bad bacteria in colon
- Make short chain fatty acids to improve gut health (immunity)
- Shown to decrease duration of diarrhea and prevent diarrhea caused by antibiotics
- Increase fibre to soak up water
- Decrease caffeine
What is emesis and the consequences?
- Ejection of stomach contents through the mouth
- Reverse peristalsis occurs to remove bad food
- Protective reflex against toxins caused by bacterial or viral infections, medications and other illness (eating disorders, pregnancy, food intolerance/allergy)
- Can result in electrolyte imbalance and dehydration
- Can damage mouth, gums, esophagus, teeth (acidity)
What is heartburn, the causes and prevention?
- Reflux of acidic contents from stomach into esophagus
- Lower esophageal sphincter may be damaged or not working hard enough
- Diagnosed as GERD (gastroesophageal reflux disease) if occurring twice per week
- 5 million Canadians experience heartburn or acidic reflux at least once per week
Causes may include:
- Genetics of physical damage = dysfunctional esophageal sphincter
- Pregnancy, hiatal hernia, overweight/obesity = extra stomach pressure
- Anxiety and stress
- Alcohol, caffeine, acidic or spicy foods
- Dietary/lifestyle contributors chemically affect muscle tone of digestive tract
- Large meals, high fat meals, citrus fruits, spicy foods, smoking, alcohol, caffeine
- Avoid high fat, spicy meals and citrus
- Avoid caffeine and alcohol
- Eat smaller meals
- Drink between meals, not with
- Don’t lie down for at least 3 hours after a meal
What is lactose intolerance, the causes and treatment options?
- Approximately 70% of people worldwide
- Common among Asian, African, Indigenous and Mediterranean groups
- Occurs due to deficiency of lactase (enzyme in brush border of small intestine)
- Could be rare congenital disorder
- Lactase activity may decrease with advancement of age
Find your tolerance level:
- Cheese has little lactose (processing)
- Yogurt and kefir may be easier to digest (fermented + processing)
- Small amounts may cause no problem
- Other options include lactase-treated milk, lactase tablets, soy milk or other calcium-fortified milk alternatives (rice and almond milks)
What is celiac disease, the causes and symptoms?
- Gluten (a protein in wheat, oats, rye, barley, and spelt) stimulates an immune response
- Immune cells attack the brush border
- Often develops in childhood but could develop anytime
- Caused by genetics (unknown trigger)
Symptoms: GI discomfort, lack of growth in children, diarrhea/bloating, vitamin and mineral deficiency, weak bones, maybe weight loss
If untreated, greater risk of intestinal cancer
What are allergies?
- Immune response (rashes, swelling, itching)
- Severe = anaphylactic shock = can’t breathe
- Common food allergies include cow’s milk, nuts, seeds, eggs, milk, shellfish, soy, wheat, some fruit
What are carbohydrates and where are they found?
- Contain carbon, hydrogen, oxygen
- 2 hydrogen to 1 oxygen
- Occur in many foods (all plant foods and milk) but not a food group
- Fish, poultry and fats have no carbs
- Eggs and cheese have little carbs
- Saccharide = technical term for sugar molecule
What are monosaccharides?
- Basic unit of carbohydrates
- Free glucose and fructose found naturally
- Each contain 6 carbons, 12 hydrogens, and 6 oxygen atoms
- Found in honey, fruit, vegetables, and milk
- Often added as sweeteners to processed foods
- Circulates in blood; most important carb fuel for body
- Produced in plants (photosynthesis; energy from sun converts carbon dioxide and water into glucose and oxygen)
- Occurs as monosaccharide in honey, but often part of disaccharide or starch
- Tastes sweeter than glucose
- Found in fruits and veg, makes up more than ½ the sugar in honey
- Does not cause a great rise in blood glucose
- Most of fructose in our diets come from high-fructose corn syrup (sweeter and less expensive than table sugar)
- Rarely present as a monosaccharide in food supply
- Occurs most often as part of lactose
What are dissaccharides?
- 2 monosaccharides linked together
Sucrose = table sugar
- 1 glucose + 1 fructose
Maltose is found in beer
- Used as food additive
- 2 glucose molecules bonded together
Lactose is milk sugar
- Lactose is less sweet than sucrose
- 1 glucose + 1 galactose
What is starch?
- Storage form of carbohydrates for plants
- Lots of starch in grains, potatoes, and legumes
- A class of polysaccharides = long strings of monosaccharides
What are whole grains?
- Bran layers: good source of fiber and vitamins
- Germ: good source of vegetable oils and vitamin E; powerhouse nutrients
- Endosperm: contains starch and some protein
What are refined grains?
- Made largely from endosperm and are mostly starch
- Germ has healthy fats which can oxidize and go rancid
- Take out germ and put nutrients back in
1. Enrichment: replace nutrients that have been destroyed or removed by processing
- May be enriched with thiamin, riboflavin, niacin (all are B vitamins) and iron
2. Fortification: add extra nutrients that weren’t there in the first place
- May be fortified with folate (mandatory)
What is glycogen?
- Animals store glucose as glycogen (highly branched)
- Found in liver (keeps blood glucose levels stable) and muscle (fast energy for exercise)
- If we eat muscle of a flesh animal, we do not get glucose or glycogen from it
- NOT a dietary source of carbohydrates
What is fibre and the types?
- A class of polysaccharides
- Often made of glucose but can be other monosaccharides
- Provides structure to the leaves, stems, and seeds of plants
- Lots in whole grains, vegetables, fruit and seaweed
- Cannot be digested by the digestive enzymes our bodies produce
- Feeds bacteria (symbiotic relationship)
1. Soluble Fibre
- Absorbs water
- Often used as gelling agents or thickeners
- Pectins, gums, mucilages
- High in oatmeal, beans, oat bran, barley, apples, legumes
- Digested by bacteria in our large intestine
2. Insoluble Fibre
- Does not absorb water
- Give stiff structure to plants
- Cellulose, hemicellulose, lignin
- Found in whole grains, wheat and rye bran, fruit skins and seeds
- Unable to be digested by bacteria; excreted out of the body
What is the carbohydrate digestion process?
1. Starts in the mouth
- Salivary amylase breaks starch into glucose and smaller polysaccharides
- If you don’t chew, your small intestine has to do more work than its designed to do
2. The principal site of carbohydrate digestion is the small intestine with pancreatic enzymes
- NO carbohydrate digestion happens in the stomach
- Pancreatic amylase breaks starch into glucose and maltose
- Sucrase: sucrose = glucose and fructose
- Maltase: maltose = 2 glucose molecules
- Lactase: lactose = glucose and galactose
3. Carbohydrates are absorbed using the hepatic portal system and metabolized by cellular respiration via mitochondria
What do carbohydrates do?
- Provides the quickest source of energy
- Glucose is the preferred energy source for every cell (especially RBC, brain and nerve cells)
- Glucose and glycogen provide fuel for exercise
Hitting the wall:
- Condition caused by the depletion of glycogen stores in the liver and muscle
- Characterized by sudden onset of fatigue
- Common during endurance events and intense exercise
- If you train properly for the distance you are running, you will be using fat as well so you won’t hit the wall so fast
- Your body will steal protein from blood/organs/muscles to make glucose if low
- Amino acids is turned into glucose via gluconeogenesis
Discuss blood glucose levels and the GI.
- The body regulates blood glucose levels closely to make sure we have enough
- Regulated by hormones insulin (increases storage of sugar) and glucagon (stimulates breakdown of glycogen into glucose in process called gluconeogenesis when you haven’t eaten for a while)
- Controlling blood sugar levels decreases risk of developing complications (eg. diabetes); done using Glycemic Index
- Measure of carbohydrate quality compared to 50g of glucose
- Classifies dietary carbs based on scale of 0-100; low = <55, high = >70
- Low GI foods help control blood sugar (less chance of pancreas breaking down) by resulting in gradual increase of blood glucose levels after meals (stimulate less insulin, less sugar taken out of blood and put into storage)
- Low GI foods may help control appetite because tend to be higher in bulk (feeling of fullness) = lower risk of overweight/obesity
- Food processing can affect GI; usually high-fibre foods are low GI (not always, yogurt is low GI and low fibre, high fibre cereals have high GI)
- Each person is unique in their response to food
What are benefits of fibre and how much fibre should we get?
- Women (19-50 years old) need 25g per day and men (19-50 years old) need 28g per day but Canadians on average get 14 g of fibre a day
- Constipation (soluble brings in water for moist stool, insoluble creates bulk, both stretch nerves in GI tract to stimulate peristalsis)
- Obesity (filling)
- Diabetes (slows down CHO digestion, regulates blood sugars)
- Colon cancer (helps with moving waste along, less toxins in contact with GI tract)
Discuss natural and added sugars.
- Natural sugars are found in fruits (fructose, some glucose and sucrose), milk (lactose) and vegetables (some fructose)
- Contain fibre, vitamins, minerals for better health!
- Added sugars are added to foods during processing or preparation
- Related to low quality diet (fewer vitamins and minerals), obesity, low insulin sensitivity, dental cavities
- DRIs say <25% of kcals (125g) should come from added sugars
- WHO say <5% of kcals (25g) should come from sugars