Review Notes - Summary GEH 1019 PDF

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GEH1019 Review Notesremember to read summary as reviewLecture 1 Knowing about NutritionNutrition misinformation: reasons for existing: > profit: sale of products; internet traffic > personal beliefs: faith healer, promotion of health supplements without economic interest may hold on ...

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GEH1019 Review Notes remember to read summary as review Lecture 1 Knowing about Nutrition Nutrition misinformation: 1) reasons for existing: > profit: sale of products; internet traffic > personal beliefs: - faith healer, promotion of health supplements without economic interest - may hold on to theories and beliefs even after they have been disapproved or not scientifically substantiated ! - news reporters may lack understanding of subjects to interpret research correctly 2) methods: > Testimonials from Hollywood stars, famous sports man > Exploiting misconceptions: some people tend to believe certain avenues of information (like certain organisations, TV shows) > Saying what they want to hear when individuals seeking alternative solutions to health care > Science as a marketing tool: Miraculously, The only product to use, No side effects, World’s best, Natural, FDA approved Keys to identifying reliable nutrition information 1) language: the definition and clearness of the claim 2) truth: the consistence with recent research 3) research: the data, process, and the conclusion of their research Keys to identifying reliable nutrition 1) sentence: identify + scrutinise the claim > focus can be:! - may cure or will cure - being an extrapolation, a manipulation, or a misinterpretation of the information cited 2) source: > reliable sources - consensus: nonprofit, professional health organisations; scientific organisations; government publications; nutrition textbooks - single opinion: registered dieticians

> reputable medical and scientific journals: Indexed research journals on PubMed > pay attention to year of publication > good research has to be consistently reproduced and validated by other scientists 3) science: Bottom line, evaluate the study design Methods of Scientific studies 1) laboratory studies > cell line studies: - formulation of hypothesis - initial confirmation of cause and effect > animal studies: - confirmation in complex systems like multiple organs - additional observations of other effects 2) human studies - verification of effects in humans - observations of side effects > case studies: - A study of individuals - Anecdotal evidence but observations can lead to further research or hypothesis > epidemiological study - observational (do not ask subjects to do anything) - includes: cross-sectional: data; case-control; cohort - reveals a correlation / association > intervention study - A parameter is altered for a certain duration - Experimental versus controlled group - Reveals cause-effect - informed consent needed - baseline: measurements made before randomisation - placebo control Some illustrations:! 1) cross-sectional: data from a population / a representative subset at a specific point in time 2) case control: > case: with disease > control: no disease

3) cohort: longitudinal (repeated observations of the same variables, like people, over short or long periods of time) > analysis on how risk factors affect the incidence of diseases > used to identify the causes of diseases in the first place 4) placebo control > single blinded: subjects are blinded > double ~ : ~ and scientists ~ - people who analyse the data or do measurements all do not know - only manufacturers or packers know Placebo effect: changes in (perceived) health actually result from expectations that a treatment will produce an effect > likely to be seen in anecdotal evidence, case studies, and poorly controlled intervention studies > can sometimes be measured Limitations of nutrition research 1) nutrition is complex > nutrients can interact with each other > Ripple effect: nutrition-related disease caused by more than one single nutrient ! > Side-effects are not apparent 2) the long term impact is not apparent 3) Individual differences 4) the lack of good placebo for whole food or diets > e.g.: reduction in fat will reduce the kcal as well; we can increase protein to balance but this also introduces another factor Meta analysis:

> the size of the diamond indicates the accuracy: smaller means more accurate

Lecture 2 Digestion & Absorption Macronutrients: > carbohydrates > proteins > fat Three things about enzymes:! 1) only break down specific things 2) only work in specific PH 3) specific temperature range Digestion 1) Hydrolysis is the basic chemical process in digestion 2) Specific digestive enzymes in our body helps hydrolysis to occur > amylase enzyme — carbohydrates - sucrose + water -> 1 glucose + 1 fructose - starch + water -> many glucose (glucose: blood sugar; Starch: from bread, rice…)! > protease enzyme (pepsin, trypsin) —- protein - protein + water -> amino acids + small peptides > lipase enzymes —- fat - triglyceride + water -> 1 monoglyceride + 2 free fatty acid Process of digestion and absorption 1) mouth: chews and mix food with saliva > digestion: - carbohydrates: starch is broken down by amylase - fat: some are broken down by lipase - protein: NO > absorption: NO 2) stomach: change in pH(~2) by gastric juice - activate protein digestive enzyme: pepsin - denature food protein - destroy many bacteria (not all) > digestion: - carbohydrates: continues to be digested - fat: some gets digested; float on top of the mixture - protein[main]: broken down by pepsin 3) small intestine + pancreas + liver + gall bladder > digestion:

- carbohydrates: starch broken down by pancreatic amylase on starch; disaccharides - > monosaccharides by intestinal enzymes (sucrase, lactase, maltase) - fat: emulsified by bile (-> for better lipase digestion); digested by pancreatic and intestinal lipase -> fatty acids and glycerol (emulsification: let small drops of fat mix with water, which exposes it to more lipase enzymes) - protein: broken down by trypsin -> amino acids / small peptides > absorption: - carbohydrates: simple sugars - fat: occurring - protein: amino acids 4) large intestine: - carbohydrates: partial undigested carbohydrates broken down by intestinal bactera - fat: some fatty material carried out as waste - protein: carried out as waste micro-nutrients: vitamins & minerals > most do not require hydrolysis by digestive enzymes (can be directly absorbed) > optimal absorption: depends on the chemical form in food - Iron from meat is better than from vegetables > Some are absorbed in an inactive form and converted to an active form in the body eg. Vitamin D ! Water: largest single component of our food and our bodies 1) function: > Maintains normal internal temperature > import medium for - Chemical reactions! - Transport of nutrients - Enzyme action > Normal elimination of waste products in urine and stools > Participates in energy formation 2) percentage in the body: 60-65% – Blood 83%! – Muscle 75% – Bone22%! – Fatcells10% 3) adequate intake:

> Women 11 cups/day > Men 15 cups/day ! 4) the need for water to replace water lost in urine, perspiration, stools, and exhaled air pH range of blood > normal: 7.35 - 7.45 > death: > 8.0 or < 6.8 Water deficiency 1) Symptoms of dehydration : nausea, rapid heartbeat, increased body temperature, dizziness, difficulty moving > Ingestion of fluids generally produces quick recovery > Unresolved dehydration can lead to kidney failure or death Water toxicity 1) Symptom of hyponatremia: confusion, headache, vomiting, seizure, coma, death ! 2) reason: Excess water intake can lead to low blood sodium > Drinking too much water too quickly Alcohol metabolism: > an energy dense, empty calorie food (7 cal / gram: protein: 4; fat: 9; carbohydrate: 4) > a drug / stimulant (Modifies body functions)! 1) digestion: no need 2) absorption: quick in stomach and small intestine > In the small intestine, alcohol absorption gets priority over other nutrients ! 3) Circulated to body tissues quickly and easily 4) primarily broken down in the liver ! > alcohol dehydrogenase: alcohol -> acetaldehyde ! > acetaldehyde dehydrogenase: acetaldehyde to acetic acid / acetate ! 5) Absorbed more slowly with food, decreasing effects of alcohol and blood alcohol concentrations The positives:! 1) Moderate alcohol consumption by healthy adults who are not pregnant appears to cause no harm > man: 2 drinks / day; women: 1 2) Protects against heart disease, type 2 diabetes, hypertension, stroke, dementia

> may be due to the phytochemical content of the fruit, vegetable, or grain fermented to produce it - Pigments in red wine and to a lesser extent in beer and white wine act as antioxidants; but Similar groups of antioxidants can be found in purple grape juice, other purple and blue-coloured fruit juice too ! The negatives 1) Heavy drinking (>= 5 per day): > Increases risks of high blood pressure, stroke, dementia, some cancers (throat, stomach, and bladder), central nervous system disorders > nutrient deficiency due to overall poor diets 2) Alcoholism (Alcohol dependency): health, family, social relationships and job performance 3) alcohol poisoning: Mental confusion, vomiting, seizures, slow or irregular breathing, low body temperature 4) long term: > liver diseases: - steatohepatitis: fatty liver causing liver inflammation - cirrhosis: widespread fibrous tissue buildup, causing disruption of normal liver structure and function

2) alcohol is not considered as nutrients; it is small molecules; but can be absorbed 3) adequate intake: not enough scientific evidence to support, but generally considered okay 4) specific blood PH range (narrow) is due to the sensitivity of red blood cells 5) Why liver tries to clear it as quickly as possible: to prevent alcohol from reaching the inner core of brains, which control heart rate 5) suggestions when drinking alcohol: Do not drink too quickly; avoid drink with a straw; dance more 6) milk: energy dense, nutrient rich; low fat yoghurt: not energy dense but nutrient rich Lecture 3 Macronutrients

Other effects of alcohol 1) Intoxication: correspond to blood alcohol levels > 0.08%: legal limit > 0.13%: speech, vision, reflexes, and body movements are impaired > >=0.35%: can cause death 2) Dehydration: Suppress anti-diuretic hormone in brain so urine output increases, loss of water leads to thirst 3) hangover: > caused by - dehydration - by-products of alcoholic fermentation: formaldehyde detoxified from methanol or congeners) congeners: impurities within the drink in addition to ethanol: > bourbon gives worse hangover than vodka > mix drinks: brings in more congeners Other reminders: 1) fibre may trap fat and becomes waste

>water and alcohol are directly absorbed in stomach instead of mouth; water is the only one still absorbed n large intestine

Six categories of nutrients: protein, carbohydrate, fat, vitamin, mineral, water > water is neither macro or micro nutrient > macro: require in large amount (g and milli g); provide calories for energy > micro: ~ small(milli g, micro g or less); does not provide calories for energy Evaluation of the overall nutritive value of a food item: 1) energy-dense: relatively high in calories / unit weight of food 2) empty-calorie: excess energy / calories in relation to nutrients 3) nutrient-dense: relatively high amounts of nutrients compared to their calorie value Protein Basics 1) function: > an essential structural component > involved in almost every biological process > can be broken down for energy but not primary energy source 2) formation:! > amino acids -> peptide -> protein: - Chains can have > 25,000 amino acids - Chains fold into complex structures: Primary, secondary, tertiary and quaternary 3) 20 common amino acids > essential / indispensable: 9; must be obtained from diets > nonessential: 11 A, C, G, Pro, S, Tyros -ic acid / -ine 4) Order and shape determine protein function Protein quality: 1) High quality protein = all essential amino acids in amounts needed for protein tissue formation ! > If one essential amino acid is missing, all proteinproduction shuts down ! > Most food sources of protein also provide vitamins and minerals, particularly iron ! 2) Complete Proteins: ~ high quality protein > Found in animal products like meat, milk, and eggs ! > In comparison to plant proteins, animal proteins are

likely to be higher in fat content ! 3) incomplete protein: deficient in one or more essential amino acids > Proteins in plants are sometimes incomplete; however, “Complementary”plants sources can be combined to form a “complete” source of protein > Soybeans are considered a complete protein for adults Protein deficiency: > can occur by itself, or with a deficiency of calories and nutrients (e.g.: Iron, zinc, vitamin B12, niacin) > results: reduces strength, lowers immunity, causes abnormal organ functions and death - diseases: Marasmus, Kwashiorkor Protein in excess > Consumption of 45% of total calories from protein is considered too high; recommendation is 10 – 35% of total kcals ! 1) results: nausea, weakness, diarrhea! 2) reasons: > people in developed countries > the use of supplements - amino acids: no safe level; purity, dose and safety is not guaranteed - protein: Muscle size and strength is built from diet and resistance training; Protein from food is as effective Carbohydrates basics > definition: Chemical substances in foods that consist of a simple sugar molecule or multiples of them in various forms

1) energy source - simple sugars (mono- and di- saccharides): 4 cal / g - complex carbohydrates (polysaccharide amylose): 4 cal / g - total fiber (polysaccharide cellulose): ~ 0 to 2 cal / g > Calories as defined in nutrition is kilocalorie (kcal), amount of heat energy produced by food to raise the temperature of 1 kg of water by 1 degree Celsius.

Effects on blood glucose 1) Some types of simple sugars (eg. sucrose) and starch (a type of complex carbohydrate) in foods elevate blood glucose levels 2) dietary fiber (a type of complex carbohydrates that is not digested by digestive enzymes) > can delay or reduce the rise of blood glucose levels > Important for people with insulin resistance and type 2 diabetes. May be helpful in prevention of diabetes

Simple sugars: Require little or no digestion before use in the body! 1) mono: - glucose (blood sugar or dextrose): directly use for E - fructose (fruit sugar): ~ (naturally present: in fruits) - galactose: readily converted to glucose 2) di: - maltose (malt sugar): 2glucose - sucrose (table sugar): glucose + fructose (in sugarcane; naturally present) - lactose (milk sugar): glucose + galactose 3) added sugar: > high fructose corn syrup (in soft drinks): a liquid mixture of 55% fructose and 45% glucose 4) effects on health: > Food that are sweet from added sugar are more likely to be energy dense and empty calories > Problems associated with high sugar intake - increased blood triglycerides - excessive calorie intake - tooth decay ! but it does not cause obesity, type 2 diabetes or hyperactivity Complex carbohydrate: Form of carbohydrate found in starchy vegetables, grains, dried beans, and many types of dietary fibre 1) polysaccharide: containing many molecules of mono-saccharides linked together > 3 major types: - starch (like amylose): found in food - dietary fibre (like cellulose): ~ - glycogen: the storage form of glucose in muscle!

Glycemic index: Measurement of how much blood glucose is raised by a 50-gram portion of a carbohydrate-containing food, compared to 50 grams of glucose or white bread > high -> raise blood glucose level to a higher extent than low GI food 1) low glycemic index: most fruits and vegetables, beans, minimally processed grains, pasta, low-fat dairy foods, and nuts > should choose food in this category 2) moderate: 56 ~ 69: White and sweet potatoes, corn, white rice, couscous 3) high: >= 70: White bread, rice cakes, most crackers, bagels, cakes, doughnuts, croissants 4) suggestions:

Dietary fibre: 1) function: > reducing our glycemic response > major source of ‘food’ for our gut microbes - gut microbes can determine our health status and our risk to diseases -> important to maintain a diversity of good gut microbes Fats: 1) some corrections of misconception: > Not all fats are bad

> Excess calories cause weight gain, not fat 2) position and composition:

> some are essential to the body 3) dietary cholesterol Saturated & unsaturated acids 1) Definition > Saturated acids: Carbon chains saturated with the maximum number of hydrogen atoms (all single bonds) - solid at room temperature - found in animal products > Unsaturated - poly-: >=2 double bonds - mono-: 1 ~ (the double bonds are the points of unsaturation)

3) function: > energy source: 9 cal / g > energy stores: Excess calories are converted to triglycerides > Carriers of fat-soluble nutrients ! - essential fatty acids - vitamins D E K A > components of all cell membranes, VD, and sex hormones > cushion to protect internal organs > insulation against cold Type of fat in food 1) triglycerides: > 98% of fat intake > most of out body’s fat store > composition

2) fatty acids: > saturated / unsaturated > most in the diet are from triglycerides

2) hydrogenation: a method to transform unsaturated fats into saturated fats ! > turn liquid oils into solid fats > Helps extend shelf life of processed foods ! > also converts natural cis form of unsaturated fat into trans fat 3) Effects of trans fats > Raise blood cholesterol levels more than any other type of fat ! > increase the risk by just 2.2 g / day! > required on labels 4) Essential polyunsaturated fatty acids: Component of all cell membranes, especially in nerves and brain! > omega-6: Linoleic acid! > omega-3 - Linolenic acid - EPA (eicosapentaenoic acid): important for blood clotting and blood pressure regulation - DHA (docosahexaenoic acid): needed for brain and eye formation (EPA and DHA can reduce risk of heart disease and stroke)! > food source:

- EPA and DHA are found in fish and shellfish; adequate intake for adults: 250 - 500 mg / day = 230g of fatty fish per week Dietary cholesterol 1) source: > 2/3 produced by liver > the rest: from the diet - dietary cholesterol refers to cholesterol found only in animal products in the diet - from high to low: meat, egg, milk and milk products, other food, fat 2) prevent heart disease: > reduce saturated fat intake (fried food) > but reduce dietary cholesterol intake (seafood) is not as essential as

: only 1/3 of it comes from diet

cholesterol (target Water soluble (B-complex, C) ! - Only B12 can be stored in the body (but still watersolvable), all others become deficient in weeks to months if not consumed - Niacin, B6, choline, and C cause ill effects if consumed in excessive amounts ! > Fat soluble (D,E,K,A) ! - Excess can build up in fat and lead to toxicity ! 3) fourteen common ones:

Function of blood cholesterol 1) Lipoproteins carry cholesterol in bloodstream 2) category: > good cholesterol: HDL (High density lipoprotein) - less lipid, more protein - carries away bad cholesterol from plaque - function: scavenging (clean) - heart attack risk: reduce > bad cholesterol: LDL (low ~ ) - more lipid, less protein - forms plaque in blood vessels - function: delivery - heart attack risk: increase 3) formation:

! LDL/HDL ratio in blood more meaningful than total

Vitamin A:! 1) different forms (pay attention to the direction of arrows)

2) function > gene regulation by retinoic acid - cell growth - immune function > process of light perception > maintenance of healthy cornea 3) deficiency:! > night blindness > impaired immunity

> growth abnormalities 4) toxicity:! > skin rashes > bone abnormalities > birth defects Vitamin D (sunshine vitamin) 1) our body can synthesise all we need > source: sunlight - energy from ultraviolet rays is absorbed and initiates conversion of cholesterol derivative to active VD - stops producing VD when adequate (10 - 15 mins of sunlight exposure; however, SPF > 15 broad-spectrum suntan lotions can block vitamin D production) 2) function: > helps absorption of calcium and phosphorus > maintain bone integrity > maintain nerve and muscle activity 3) deficiency: > rickets 4) toxicity:! > deposition of calcium in organs > mental retardation in young children > abnormal bone growth and formation Vitamin C 1) function: > connective tissues - ma...