CS代考 u Section 1: Topics related to the digestive system Food Safety

u Section 1: Topics related to the digestive system Food Safety
u Section 2: Food Intake Assessment uNatural Health Products

Physiology Fundamentals

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u 1) Digestion & Absorption
u 2) Transport throughout body
u 3) Metabolism in the cells
u 4) Elimination of metabolic wastes

u Prebiotics and Probiotics
u Breastfeeding and the Infant Gastrointestinal System u Gastric Bypass Surgery
Chapter 3 3

Prebiotics and Probiotics

Large intestine
Intestinal microflora or microbiota or microbiome:
• The slow movement of components favors the growth of bacteria
• bacteria can sometimes breakdown indigestible food components such as dietary fibre
• fermentation
• products include intestinal gas.
Chapter 3 5

• live bacterial culture e.g. Bifidobacterium and Lactobacillus which may be beneficial for health
• added to foods such as the probiotic yogurt
• probiotics
have to be consumed on a continual basis because they are quickly eliminated
• indigestible carbohydrates in fruits and vegetables
• also added to foods in purified form e.g. inulin
• help to support the growth of beneficial microflora.

Your Choice: Should you feed your flora? & Label Literacy: Choosing your yogurt.
Canadian regulations require
• The specific name of the probiotic used be
listed in the ingredients
Permitted health claim
Nutrient-function claim about the role of probiotics in health
Claim about calcium & vitamin D.

colonocytes
Health-promoting bacteria secrete
beneficial bioactive compounds that are absorbed by the colonocytes and may enter the bloodstream to impact organs and systems beyond the gut.
Disease- promoting bacteria have an opposite effect to health- promoting bacteria.
Chapter 3 8

Chapter 3 9

Required Textbook Reading:
u Learn about the possible relationship between obesity and the microbiota by reading:
u Chapter 3: Critical Thinking: Obesity & Microbiota pg. 111
u Be sure you can answer the Critical Thinking Questions in the textbook.
Chapter 3 10

Breastfeeding and the Infant Gastrointestinal System

Lifecycle Nutrition:
The Infant Digestive Tract and the Composition of Breast Milk (pg 664-671)
Colostrum:
• breast milk produced during the first week after delivery
• composition varies from mature breast milk.
• contains immune factors of help protect the infant from infection particularly in the GI tract
• antibodies which pass from the mother’s bloodstream into the milk.
Chapter 3 12

Lifecycle Nutrition:
The Infant Digestive Tract and the Composition of Breast Milk
Main carbohydrate in breast milk- lactose
• behaves like a prebiotic, promoting the growth of
Lactobacillus bifidus,
• reduces the risk of gastrointestinal infections in the infant’s gut
Fat in breast milk
• very high in fat, 52% kcal (the AMDR for adults: is 20-35%
• supports the very rapid growth rate of the newborn

Lifecycle Nutrition: The Infant Digestive Tract and the Composition of Breast Milk
The infant digestive tract is compatible with the composition of breast milk.
• Infants are able to absorb some proteins which in the
adult are broken down to amino acids
• antibodies in breast milk are absorbed intact & enhance the infant’s immune system.
• To digest other milk proteins infant stomach produces the enzyme rennin, which is absent in adults.
Chapter 3 14

Lifecycle Nutrition: The Infant Digestive Tract and the Composition of Breast Milk
• gastric lipase plays a more important role in the digestion
of the fat, in the infant than the adult.
• Pancreatic digestive enzymes do most of the fat digestion
in adults, but they are present in lower levels in the infant.
Carbohydrates:
Nostarchinmilkàlowamylaseintheinfantgut.
the enzyme lactase, which breaks down lactose, is present in large amounts in brush border.
the production of lactase declines with age àlactose intolerance.

Lifecycle Nutrition: The Infant Digestive Tract and the Composition of Breast Milk
Infants are unable to consume solid food for the first six months of life:
• asucklingreflexwhichallowsthemtodraw
liquid from a nipple placed toward the back of the mouth
• notpossibletospoonfeedanewbornasthissucklingreflex causes a spoon placed at the front of the mouth to be pushed out by the tongue
• reflexdiminishesat4to6monthsofageandteethbeginto grow in, allowing the introduction of solid food.
Chapter 3 16

Lifecycle Nutrition: The Infant Digestive Tract and the Composition of Breast Milk
Until 6 months of age, Health Canada recommends that infants be exclusively breastfed***
• Ifbreastfeedingisnotpossible,infantformulacanbeused. • formulaisformulatedtobeascloseaspossibletobreast
milk, in nutritional composition.
• itcannotduplicatetheimmunefactorsofbreastmilk.
*** and supplemented with vitamin D from birth

Lifecycle Nutrition: Critical Thinking: The Prevalence of Exclusive Breastfeeding in Canada (pg 667-668)
Chapter 3 18

Lifecycle Nutrition: Critical Thinking: The Prevalence of Exclusive Breastfeeding in Canada (pg 667-668)
This same survey also collected information on factors that influenced breastfeeding. It found that exclusive breastfeeding is more common among:
• mothers with partners (compared to single mothers)
• non-smoking mothers (compared to smoking mothers)
• women who gave birth at home (compared to women
who gave birth in hospitals)
• Non-working mothers (compared to working mothers.)

Gastric Bypass Surgery

Chapter 3: Chapter Opener and Case Study Outcome (pg 91-92 & pg 127)
Sabrina, 38
• BMI is 41.5- normal is less than 25
• high blood pressure and high cholesterol
• Elevated blood sugar
• Her efforts at weight loss have been unsuccessful and she has been
overweight for 20 years.
• at high risk for chronic diseases such as type 2 diabetes and
cardiovascular disease
• her doctor has recommended gastric bypass surgery.

Chapter 3: Chapter Opener and Case Study Outcome (pg 91-92 & pg 127)
Gastric bypass surgery
• Reduces the size of the stomach
• Shortens the length of the intestines so less food is
• Very effective for weight loss
• But there are problems…

Chapter 3: Chapter Opener and Case Study Outcome (pg. 91-92 & pg 127)
Gastric dumping syndrome
• food going directly from the stomach to the small intestine – the sphincter is bypassed.
• if too much food is consumed and enters the small intestine rapidly then
• water to moves by osmosis from the body into the lumen of the gut, as the
dumped food is a region of high solute concentration
• symptoms of dumping syndrome include dizziness, nausea and diarrhea.
• Regions from which vitamins and minerals are absorbed are bypassed so supplements or vitamin injections are required to prevent deficiency
Despite these risks, as you can read in the case study outcome, the benefits
outweighed the risks for Sabrina.
Chapter 3 23

Typical symptoms of foodborne illness
u Vomiting uAbdominal pain u Diarrhea
u Headache

Microbes make you sick
uFood infection
uIngestion of the living microbes à illness
uFood intoxication
uIngestion of toxins secreted by microbes à illness
uCan occur even after all microbes are killed by heat treatment, if toxin is heat-resistant.

Many, many microbes make you sick…
Bacteria Viruses Parasites

Chapter 3 28

Meet some famous microbes
u Listeria monocytogenes
u Causes food infection
u Survives cold temperatures u Vulnerable foods
uLuncheon meats
uBecause they are often eaten
without cooking
u Processor must ensure a very low bacteria load on food produced so that dangerous amounts do not grow out while consumer stores and uses product

Summer 2008
Canadian Food Inspection Agency (CFIA)
http://www.cbc.ca/news/listeriosis-outbreak-timeline- 1.694467

Salmonella
u Salmonella
uFood infection uVulnerable foods
uChicken and eggs uDestroyed by
thorough cooking

Microwave cooking of raw chicken products is not recommended because heating can be uneven.
u http://www.cbc.ca/news/canada/nova-scotia/salmonella-outbreak-from-chicken-products-leads-to-44-canadian-cases- 1.3131087

E. Coli 0157:H7
u E. coli 0157: H7 uFecal bacterium uFood intoxication
uToxinàhemolysis of RBCà fragments of cells damage tubules of kidney à kidney failure
u hemolytic uremic syndrome uToxin is destroyed by high
temperatures uVulnerable food
uVegetables grown near cattle

http://www.theglobeandma il.com/news/national/walke rton-e-coli-outbreak- declared- over/article1041067/
7 people died
http://www.cbc.ca/news/canada/inside-walkerton-canada-s-worst-ever-e-coli-contamination- 1.887200

https://www.canada.ca/en/public-health/services/public-health-notices/2017/public-health-notice-outbreak-e-coli-infections-linked-romaine-lettuce.html

Staphylococcus aureus
u Staphylococcus aureus
uFood intoxication
uToxin is heat-resistant
uBacteria is spread from humans to foods via coughing and sneezing uVulnerable foods
uEggs, meat, potato & macaroni salads
uBecause heating is not a foolproof way to destroy toxin it is also
important to keep food refrigerated to limit the growth of bacteria

Avoid unsafe temperatures

Clean Chill Cook Separate

Don’t cross contaminate.
Which photo illustrates cross- contamination?

Colour code your cutting boards and knives.

Food Intake Assessment Natural Health Products

3-day food record
u Limitations:
uTask is demanding
uNeed to record food may influence food choices
u Strength:
uIf done properly, accurate record of food consumed, especially if a food scale is used to quantify food portions

Food Intake Assessment
uAssessing food intake
u3-day food record
uFood Frequency Questionnaire u24-hour recall

24-hour recall
u Individual is interviewed about their food intake
uInterview consists of a series of questions intended to provide detailed information about the type and quantity of food
uParticipants asked to recall everything consumed the day before the interview
u Interview
uIn person- Usually one-on-one but group settings
have also been used uBy phone

Simulated 24-hour recall
u Three parts: uQuick list
uDetailed description u Review

Meal or Time eaten
Method of preparation
Recording sheet 24-hour recall:

Forgotten Foods
u Drinks such as tea, coffee, soft drinks, juices, etc; added cream or sugar u Alcoholic beverages such as beer, wine, whiskey, gin, vodka, etc
u Sweets such as candies
u Savoury snacks such as chips
u Vegetables
u Breads, rolls, muffins; type of bread
u Contents of sandwich: don’t forget spreads like butter, mayonnaise u Cheese
u Type of cereal and whether milk or sugar was added
u Type of milk (e.g. skim. 1%, 2%, etc)
u Salad dressing

24-hour recall
(compared to 3 day food record)
u Strengths:
udoes not alter eating patterns (compared to 3-day
record which may)
umost of the work done by interviewer while 3-day food record requires commitment from participant
u Limitations:
urelies on memory
uprovides info for only one day (need multiple recalls to estimate individual’s usual intake)

Food Frequency Questionnaire (FFQ)
u Survey designed to determine the typical pattern of food intake over a period of time
u Survey can be completed with a trained interviewer or independently
uCan be completed quickly (1-1.5 hours)
u Props or photos are provided to assist in estimating amounts consumed

FFQ: Example: Questions about fish
the last 12 months
Source: Cancer Research Center: Sample FFQs. Accessed August 31, 2010. http://www.fhcrc.org/science/shared_resources/nutriti on/ffq/gsel.pdf

FFQ responses used to determine relationship between food intake and health outcomes
Fish consumption: Number of servings
Relative Risk
Differences are statistically significant
u Accumulated Evidence on Fish Consumption and Coronary Heart Disease Mortality: A Meta-Analysis of Cohort Studies
Source: He et al 2004 Circulation. 2004 Jun 8;109(22):2705-11

u Strengths:
u if FFQ is comprehensive (many foods) and estimates portion size, then estimates of
nutrient intake (e.g. vitamins, minerals, macronutrients) are possible u Validation:
uFFQ can be validated by comparing results of multiple 24- hour recalls
uIf FFQ is well-designed, then food and nutrient intake calculated from multiple 24-hour recalls will agree with the estimates from FFQ

Limitations of FFQ
u Relies on memory of participants
u Participants require a higher degree of literacy than 24 hour recall (although this can be partly addressed by using an interviewer)
u Although FFQ can be used to estimate nutrient intake (see previous slide) it is more reliable as a relative measure of nutrient or food intake (i.e. comparing high vs low intakes) such as the fish consumption study (see previous slide)

Technology Assisted Food Intake Assessment
Food is photograph before and after meal
Checker board marker used with image analysis to identify food and estimate volume
L, Schap TE, Ettienne-Gittens R, M, , J, S, A, Boushey CJ. Novel technologies for assessing dietary intake: evaluating the usability of a mobile telephone food record among adults and adolescents. J Med Internet Res. 2012 Apr 13;14(2):e58. doi: 10.2196/jmir.1967.

uNatural Health Products

Natural Health Products
u“to ensure that Canadians have ready access to natural health products that are safe, effective and of high quality while respecting freedom of choice and philosophical and cultural diversity.”

Question 1
u“Current NHP regulation effectively protect Canadians from harmful products.”
uA) Agree uB) Disagree

Natural health products try to achieve a balance between:
Tradition Scientific evidence
u Natural health products can be marketed provided there is scientific evidence of effectiveness for its stated purpose
uOne or a small number of
RCTs is sufficient for many
proposed uses
u Natural health product can be marketed on the basis of traditional use
uIn use >50 years
u There may not be strong scientific evidence to support its use

Question 2
u“Current NHP regulation effectively protects Canadians from harmful products.”
uA) Agree uB) Disagree

Watch the Video & Read the Article
Natural Health Products: Buyer Beware
u Watch the video : https://globalnews.ca/video/3158463/how-effective-are-natural-health-
Read the following article:
https://globalnews.ca/news/7783257/federal-oversight-canadian-natural- health-products/
and then answer the question again
u “Current NHP regulation effectively protects Canadians from harmful products.”
u A) Agree
u B) Disagree

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