EXAM - TEST 1 & 2

6 Classes of Nutrients

1. carbohydrates
2. fats
3. proteins
4. vitamins
5. minerals
6. water 

Macronutrients

* energy-yielding
* carbs, fats, proteins 

Organic Nutrients

* contain carbon
* carbs, fats, proteins & vitamins

Vitamins

* essential, organic molecules
* support production of energy 
* 13 types - fat & water soluble

Minerals

* inorganic & indestructible
* do not yield energy
* 14 essential

Nutrient Density

nutrients a food provides relative to the energy it provides (nutrients per kcal)

Energy Availability in Foods

carbohydrates & proteins = 4 kcal/g

fats = 9 kcal/g

Energy Density

energy a food provides relative to the amount of food (kcal/g)

Gold Standard Study Design

double blind, randomized, placebo-controlled, crossover trial

Dietary Reference Intakes (DRI)

* amounts of energy, nutrients, other dietary components that best support health for healthy individuals
* clustered by age & gender
* guide to avoid nutrient deficiency/toxicity

Estimated Average Requirements (EAR)

enough to cover half of all people

Recommended Dietary Allowances (RDA)

enough of that nutrient for 98% of all people

Adequate Intakes (AI)

normal intake of the average healthy person

Tolerable Upper Intake Levels

highest level of daily intake that is likely to pose no adverse health effects in most human individuals

Acceptable Macronutrient Distribution Ranges (AMDR)

carbohydrate: 45-65% kcal

fat: 20-35% kcal

protein: 10-35% kcal

Iron Deficiency

1. low iron intake or excessive blood loss → less iron storage in ferritin
2. blood levels of ferritin low but hemoglobin remains normal
3. ferritin stores exhausted & hemoglobin levels lower → less red blood cells → anemia

Food Labels Must Include…

1. nutriton facts
2. ingredient list (descending order)
3. claims (nutrient & health)

Best Before Date

anticipated amount of time an unopened food product keeps its freshness, taste, nutritional value when stored properly

Expiry Date

must be consumed before that date or discarded after

Canada's Food Guide Changes

* evidence informed
* dairy removed
* no mention of servings
* plate model

Canada’s Food Guide

* 1/2 fruits & veg
* 1/4 protein
* 1/4 whole grains
* glass of water

DASH Diet

* eating plan by NIH
* daily and weekly serving goals with caloric intake goals

MyPlate

* American food guide
* fruits, vegetables, grains, protein, dairy

Peristalsis

* small intestine
* inner circular contract → push food forward
* inner circular relax outer → longitudinal contract

Segmentation

* small intestine 
* inner circular contract → segments food
* chyme broken up & mixed with digestive juices
* brings nutrients in contact with intestinal lining for absorption

GI Tract

mouth → upper esophageal sphincter → esophagus → lower esophageal sphincter → stomach → pyloric sphincter → small intestine → ileocecal sphincter → large intestine → rectum → anus

Saliva

from: salivary glands

target: mouth

action: ease swallowing, break down carb

Gastric Juice

from: gastric glands

target: stomach

action: HCl denatures proteins, enzymes digest proteins, mucus protects stomach cells

Pancreatic Juice

from: pancreas

target: small intestine

action: bicarbonate neutralizes gastric juice, enzymes digest carb, fat, protein

Bile

from: gallbladder (created in liver)

target: small intestine

action: emulsifies fat

Intestinal Juice

from: intestinal (crypt) glands

target: small intestine

action: enzymes digest carb, fat protein, mucus protects intestinal wall

Types of Absorption

1. simple diffusion
2. facilitated diffusion - carrier protein
3. active transport - ATP, against gradient

Determining % Daily Value

1. divide caloric intake by 2000
2. multiply answer by daily value
3. multiply amount per tbsp by tbsp consumed
4. divide answer by step 2 answer & multiply by 100

Liver Function

1. vessels gather nutrients, water & salt from GI tract
2. vessels collect into hepatic portal vein → sent to liver
3. hepatic artery brings oxygenated blood to liver
4. capillaries branch throughout liver → brings oxygenated blood & nutrients
5. hepatic vein gathers all blood in liver & send to heart

Lymphatic System

* one way route
* circulates between cells
* collects into tiny vessels
* lymph collects in thoracic duct
* enters bloodstream into left subclavian vein

Gastrin

responds to: food in stomach

from: stomach wall

stimulates: stomach glands

response: HCl to stomach, reduce pH

Secretin

responds to: acidic chyme in small intestine

from: duodenal wall

stimulates: pancreas

response: bicarb-rich juices to small intestine, increase pH

Cholecystokinin (CCK)

responds to: fat or protein in small intestine

from: intestinal wall

stimulates: gallbladder & pancreas

response: bile to duodenum / bicarb & enzyme-rich juices to small intestine

Monosaccharides

* single sugars
* glucose, fructose, galactose
* 6 C, 12 H, 6 O

Disaccharides

* pairs of monosaccharides
* maltose, sucrose, lactose

Polysaccharides

* large chains of monosaccharides
* starch, fiber

Glucose

* monosaccharide
* blood sugar
* part of every disaccharide

Fructose

* monosaccharide
* fruits & honey
* sweetest sugar

Galactose

* monosaccharide
* naturally present in dairy products

Maltose

* disaccharide
* glucose + glucose
* ex. barley

Sucrose

* disaccharide
* glucose + fructose
* ex. table sugar

Lactose

* disaccharide
* glucose + galactose
* ex. milk

Glycogen

* polysaccharide
* storage form of glucose
* highly branched chains
* reserve energy in animals

Starch

* polysaccharide
* storage form of glucose in plants
* long, branched & unbranched chains
* found in grains, legumes & root crops

Fibre

* polysaccharide
* structural part of plants
* cannot break down
* soluble & insoluble

Soluble Fiber

* dissolves in water & forms gels
* low digestion - fermented by bacteria
* blunts blood glucose spikes
* reduces cholesterol
* nuts, fruits, seeds

Insoluble Fiber

* does not dissolve
* creates bulk
* helps w/ bowel movements
* wheat, grain, vegetables

Starch Digestion

mouth: amylase → small polysaccharides, maltose

stomach: acid inactivates amylase

pancreas/small intestine: pancreatic amylase → small polysaccharides, maltose

small intestine: disaccharide enzymes

Starch Digestion by Disaccharide Enzymes in Small Intestine

maltose (maltase) → glucose + glucose

sucrose (sucrase) → glucose + fructose

lactose (lactase) → glucose + galactose

Fiber Digestion

* large intestine - bacterial enzymes → short-chain fatty acids, gas
* passes through mostly undigested

Carbohydrate Absorption

* lining of mouth, small intestine
* glucose & galactose via active transport
* fructose via facilitated diffusion
* converted to glucose in liver

Lactase Enzyme

* required to help digest & absorb lactose
* highest immediately after birth
* \~30% retain ability to digest & absorb lactose

Glucose Storage in the Body

liver: hydrolysis for release of glucose into blood, excess converted to fat

muscle: uses for own use

Gluconeogenesis

conversion of certain amino acids

Ketone Bodies

* provides fuel when CHO is low
* formed from fat fragments
* ketosis

Hormones Involved in Blood Glucose Homeostasis

Insulin - glucose from blood into cells

Glucagon - glucose from cells of liver into blood, no action in skeletal muscle

Constancy of Blood Glucose

1. person eats, blood glucose rises
2. pancreas releases insulin into bloodstream
3. stimulates uptake of glucose into cells & storage as glycogen in liver & muscles
4. cells use glucose, blood levels decline
5. pancreas releases glucagon into bloodstream
6. stimulates liver cells to break down glycogen & release glucose into bloodblood glucose rises

Diabetes

type 1: unable to produce insulin

type 2: cells unable to respond to insulin

Hypoglycemia

* low blood sugar
* results from poorly managed diabetes
* glucose damages tissues

oral glucose tolerance test (OGTT)

assesses ability to to handle glucose load & regulate blood sugar


1. fast overnight
2. ingest 75g of glucose as oral load
3. blood glucose measured over 2-3 hr
4. hormonal measurements

Glycemic Response

speed of glucose absorption, blood glucose rise & speed of return to normal

Glycemic Index

food classification based on glycemic response

Glycemic load

GI x carbohydrate amount

Common Harms of Sugar

* nutrient deficiencies
* dental caries: sugars fermented to acid → erodes enamel

Alternative Sweeteners

artificial sweeteners: no energy provided

stevia: herbal

sugar alcohols: no dental caries, side effects when consumed in large quantities, absorbed slower

Harmful Effects of Fibre

* reduced caloric intake/malnutriton
* GI problems w/ suddenly introducing fibre

DRI for carbohydrates

RDA = 130g

AMDR = 45-65%

Insulin Signals…

* glucose uptake by cells
* fat storage
* synthesis of cholesterol

Lipids are Composed of…

carbon, hydrogen & oxygen

Organic Fatty Acids

* chains of C w/ H attatched
* carboxylic acid (COOH)
* methyl group (CH3)

Fatty Acid Chain Length

* even # of carbons
* 18-C is most common in food
* S (

Saturated Fatty Acids

* no double bonds
* longer chain lengths
* solid at room temp
* more stable

Unsaturated Fatty Acids

* double bonds
* shorter chain lengths
* liquid at room temp
* less stable (spoil faster)

Monounsaturated Fatty Acids

1 double bond \= point of unsaturation

Polyunsaturated Fatty Acids

2+ double bonds

Omega Number

location of double bonds nearest to the methyl end of the carbon chain

Triglycerides

glycerol backbone + 3 fatty acidsformed via condensation reactions

Hydrogenation

* H atoms added to unsaturated fatty acids
* makes liquid fat more solid at room temp.
* increases shelf life of food

Trans Fatty Acids

* derived from process of hydrogenation
* occur naturally in some animal-based products
* behave like saturated fats in body

Phospholipids

* glycerol + 2 FA + phosphate group
* soluble in fat & water
* functions as emulsifier in food industry
* cell membranes made of phospholipids

Sterols

* multiple-ring structure
* plant sterols inhibit cholesterol absorption

Cholesterol

* animal product only
* made by liver
* makes bile acids, hormones, vitamin D
* structural components of cell
* concern: plaque formation in arteries

Lipid Digestion - Stomach

* lingual lipase
* hydrolyzes one bond of triglycerides
* produces diglycerides & fatty acids

Lipid Digestion - Small intestine

* cholecystokinin (CCK) signals gallbladder to release bile
* bile: fat → emulsified fat
* pancreatic lipase: emulsified fat → monoglycerides, glycerol, fatty acids

Lipid Digestion - Large Intestine

some fat & cholesterol trapped in fibre exits in feces

Fate of Bile in GI Tract

* reabsorbed & recycled (enterohepatic circulation)
* excreted (may lower cholesterol)

Lipid Digestion - Triglycerides

* digested by pancreatic & intestinal lipases
* hydrolysis (adds water)

Lipid Digestion - Phospholipids

hydrolysis

Lipid Digestion - Sterols

absorbed as is

Lipid Absorption

* glycerol & small lipids
* diffuse directly into blood stream

Lipid Absorption - Monoglycerides & Long-chain FAs

1. combine w/ bile to form micelle
2. diffuse across membranere
3. form triglycerides
4. combined w/ other lipids & protein to form chlyomicrons
5. chylomicrons enter lymph

Lipoproteins

chylomicrons - largest & most dense

VLDL (very-low-density lipoprotein)

LDL (low-density lipoprotein)

HDL (high-density lipoprotein)

Lipoprotein structure

* trylcerides & cholesterol interior surrounded by phospholipids
* phospholipid fatty acid tails point inside
* outer proteins (determine recognition)

Chylomicrons

transport diet derived lipids to cells

VLDL

* produced by liver
* deliver lipids to body