Nutrition Test 2

Gastrointestinal bacteria (flora)

* present in large numbers
* lower in small intestine and large intestine

Probiotics

* Microorganisms in food that benefit health

Prebiotics

* Ferment fibre and complex probiotics
* Produce short chain fatty acids and vitamins

A healthy microbiota is

* high in diversity and an ability to resist change under physiological stress

Dysbiosis

* lower species diversity, fewer beneficial microbes, presence of pathological bacteria
* Transfer of intestinal microbiota from lean donors increases insulin sensitivity in individuals with metabolic syndrome

Saliva

* from salivary glands in the mouth
* lubricate food to allow swallowing
* some enzymes break down carbohydrates (sugar and starch)

Gastric Juices

* from the stomach
* contains a mixture of HCl which denatures proteins, and pepsin which digests proteins
* mucous layer of the stomach protects it

Pancreatic Juice

* from pancreas goes to the small intestine
* contains bicarbonate that neutralizes the acidic secretions of the stomach
* Pancreatic enzymes that digest carbs, fats, and proteins

Bile

* created by the liver
* from the gall bladder goes to the small intestine
* Emulsifies fat so that enzymes can digest it

Intestinal Juice

* created by the crypt glands
* from the small intestine
* digests carbs, fats, and proteins
* mucous membrane protects small intestine

Mouth

* Chewing, swallowing, and a little digestion
* Breaks down carbs

Stomach

* collecting and churning with some digestion
* breaks down proteins

Small intestine

* digesting and absorbing
* digest carbs, fats and proteins

Large intestine

* Absorbs and eliminates
* Fluids, minerals and fibre

Carbs = FUEL

Primary source of energy for:

* RBCs
* Brain
* Neurons

Higher intensity =

more carbohydrate use

Don’t eat glucose and glycogen directly

* Eat foods containing carbs → broken down into glucose which is used as energy or stored

Monosaccharides

\
* Glucose (mono)
* Blood sugar
* Part of every disaccharide

Fructose (mono)

* Fruits and honey
* sweetest of all sugars

Galactose (mono)

* Naturally present in dairy products

Disaccharides

* Pairs of monosaccharides
* Maltose (glucose + glucose, barley)
* Sucrose (glucose + fructose, table sugar)
* Lactose (glucose + galactose, milk)

Polysaccharides

* Large chains of monosaccharides, typically glucose
* Glycogen
* Storage form of glucose
* Highly branched chains
* Reserve energy in animals
* Starch
* Storage form of glucose in plants
* Long, branched and unbranched chains
* Found in grains, legumes, and root crops
* Fibre
* Structural part of plants
* Cant break down - no energy
* Soluble and insoluble
* Functional fibres and resistant starches

Carb Digestion in Mouth and Salivary Glands

* Salivary glands secrete saliva into the mouth to moisten food
* Salivary amylase enzyme begins digestion
* Starch → Amylase → Small Polysaccharides

Carb Digestion in the Small Intestine & Pancreas

* Pancreas produces an amylase that is released into the small intestine through the pancreatic duct
* Strach → Pancreatic amylase → small polysaccharides
* Then, disaccharidase enzymes on the surface of the small intestinal cells hydrolize the disaccharides into monosaccharides whch the intestinal cells absorb

Fibre Digestion in the Mouth

* The mechanical action of the mouth crushes and tears fibre in food and mixes it with saliva to moisten it for swallowing

Fibre Digestion in the Stomach

* Fibre is not digested, delays gastric emptying

Fibre Digestion in the Small Intestine

Fibre isnt digested, delays absorption of other nutrients

Fibre Digestion in the Large Intestine (1-4 hrs after meal)

* Most fibre passes intact through the digestive tract to the large intestine, where bacterial enzymes digest fibre
* Some fibre → bacterial enzymes → short-chain fatty acids and gas
* Fibre holds water: regulates bowel activity and binds substances such as bile, cholesterol, and some minerals and carries them out of them body

Carb Absorption

* lining of mouth
* most via small intestine
* glucose and galactose via active transport
* Fructose via facilitated diffusion
* sports drinks
* Converted to glucose in the liver

Lactase enzyme

* required to help digest and absorb glucose
* high immediately after birth
* 30% of people retain ability to efficiently digest and absorb lactose
* Low activity in Northern Europe and Scandinavian
* High activity in aboriginal and southeast asian

Lactose intolerance is

* the inefficient digestion of Lactose

Symptoms of lactose

* Bloating, abdominal discomfort, and diarrhea

Causes of lactose intolerance

* genetics
* disease causing damage to intestinal villi
* some medicines
* prolonged diarrhea
* malnutrition

Treatment of lactose intolerance

* Manage the symptoms
* Yogurt with live bacteria
* Hard cheeses help
* Lactase enzymes tablets
* Completely restricting is difficult
* Nutrients to be aware of
* Riboflavin
* Vitamin D
* Calcium

Soluble Fiber

* dissolves in water and forms gel
* slows digestion (fermented bacteria)

Insoluble Fibre

* Does not dissolve
* creates bulk
* helps with bowel movements

Digestion

* Monosaccharides, the end products of carb digestion, enter the capillaries of the intestinal villi
* Monosaccharides travel to the liver via the portal vein
* In the liver, galactose and fructose are converted to glucose

Carbs = supply of glucose to cells for energy

* Liver storage
* Hydrolysis for release of glucose into the blood when needed


* Muscle Storage
* Hoards this polysaccharide for its own use
* Excess glucose is converted to fat in the liver

Forms of Carbs (glucose)

* Glucose (CHO) in blood, liver
* Glycogen in muscle and liver
* Triglycerides in adipose tissue and liver

Carb metabolism

* Making glucose from protein
* Gbuconeogensis: conversion of certain amino acids from diet and body tissues

Ketosis

* Alternate metabolism of fat to provide fuel when CHO (glucose) is low
* Fat fragments join to form ketone bodies

Blood glucose homeostasis

* When a person eats, blood glucose rises
* Insulin hormone
* glucose from blood into cells
* Glucagon hormone
* glucose from cells of the liver into the blood
* no action in skeletal muscle

High blood glucose

* pancreas releases insulin into the blood stream
* insulin stimulates uptake of glucose into cells and storage of glycogen in the liver and muscles
* conversion of excess glucose into fat for storage

Low blood glucose

* As the body’s cells use glucose, blood levels decline
* Low blood glucose stimulates the pancreas to release glucagon into the blood stream
* Glucagon stimulates liver cells to break down glycogen and release glucose into the blood
* blood glucose then begins to rise

Type 1 diabetes

Unable to produce insulin

Type 2 diabetes

Cells unable to respond to insulin

Hypoglycemia

* Result of poorly managed diabetes
* weakness, rapid heartbeat, sweating, anxiety, hunger, and trembling
* Long-term hyperglycemia
* glucose damages tissues
* heart disease and stroke
* neural problems
* vision and hearing loss
* kidney failure
* infections and amputations
* Balanced meals at regular intervals help maintain a normal blood glucose homeostasis

Oral Glucose Tolerance Test (OGTT)

* Designed to assess the ability to handle a glucose load and regulate blood sugar
* overnight fast and ingestion of 75g of glucose
* blood glucose response measured over 2-3 hrs

Glycemic response

* speed of glucose absorption, blood glucose rise, and speed of return to normal

Glycemic index

* Food classification based on glycemic response
* may not mean much

Glycemic load

* GI x carb amount

Common harms of sugar

* displace calories that contain nutrients
* nutritious foods first!

Dental caries

* sugars fermented to acid by bacteria (erodes enamel)
* factors that increase (time in mouth, sticky foods, frequency of consumption)
* to reduce (sweets with meals, brush or rinse)

Artificial sweeteners

* non-nutritive sweetners (no energy provided)
* moderate doses considered safe

Stevia (herbal product)

* used on its own or as an additive in acceptable foods/beverages identified by health Canada

Sugar alcohols

* Nutritive (provide some energy) - range 0.2-0.4 kcal/g
* no dental caries, low GI
* Side effects in large quantities: absorbed slower (GI issues)

Health Effects of Soluble Fibre

* Soluble, viscous and more fermentable
* Lower blood cholesterol by binding bile
* slow glucose absorption
* slow transit of food through upper GI tract
* lower risk of :
* heart disease
* diabetes
* colon cancer
* Risk of CHD across increasing levels of total fibre intake

Health Effects of Insoluble Fibre

* Insoluble, non-viscous, less fermentable
* Increase fecal weight and speed of fecal passage through colon
* Provide bulk and feelings of fullness
* May help with weight management
* Reduces caloric intake
* abdominal disconfort
* gas
* diarrhea
* Introduce fibre gradually and drink plenty of fluids

DRI for daily carb intake

* RDA = 130g
* AMDR = 45-65%

Daily fibre intake

* Health Canada DV = 25g/2000kcal
* DRI = 14g per 1000kcal per day
* Daily fibre intake limit
* NO UL SET
* WHO advises less than 40g

Health Effects of Sugars

* Fine in moderation
* NUTRIENTS FIRST


* Nutrient deficiencies
* if it displaces nutrient dense foods
* Dental caries
* fermentation lowers pH of mouth
* Hyperactivity in children is a myth
* long debunked

Soluble fibre

* Slower absorption
* reduced blood sugar spike (and insulin)
* reduced T2D risk
* Reduced heart disease risk
* less calories and binds bile

Insoluble fibre

* Faster movement through colon
* less colon cancer and infections
* Bulk and fullness
* weight loss
* Possible harmful effects
* malnutrition
* GI problems if switch quickly

Obesity

* Complex issue
* BMI is not a great indicator of health on an individual level
* On a pop level, obesity is increasing and is a good indicator of average health of a pop.

Sugars are not the problem

* Sugars vs Kcal’s?
* Obesity rates have paralleled sugar intake
* Starting to diverge but when energy is controlled, sugar doesn’t equal obesity
* Potential issues
* addictive properties of sugar
* liquid sugar
* appetite control
* energy regulation

Insulin’s Response

* Blood glucose rises, which triggers the release of the insulin hormone
* Insulin signals:
* Glucose uptakes by cells
* Fat storage
* Synthesis of cholesterol
* Basis for low glycemic index diets
* Effectiveness unclear

Summary of sugar

* Sugar is apart of the problem that leads to excess caloric intake (but not the main reason)

Lipids

* composed of carbon, hydrogen and oxygen
* Uses of fat:
* to taste food
* providing unlimited energy for low intensity workout
* insulation from cold
* cushioning movement (fat pads)

Fatty acids

* An organic acid
* chains of C with H attached
* Carboxylic acid (COOH)
* Methyl (CH3)
* Chain length
* Even # of carbons
* 18-C is most abundant in food
* Very long (20-24C) - fatty fish
* Long (14-18C) - meats and veg oils
* Medium (6-12C) and short (

Degree of Unsaturation

Saturated

* no double bonds


* Unsaturated fatty acids
* Monounsaturated (1 db)
* Polyunsaturated (2+ db)

18-carbon fatty acids are the most common long chain fatty acids

* Stearic Acid (most animal fats) - saturated
* 18 carbon atoms, 0 dbs


* Oleic acid (olive oil) - monounsaturated
* 18 carbons, 1 db
* Linoleic acid (sunflower oil) - polyunsaturated
* 18 carbon, 2 dbs
* Linolenic acid
* 18 carbon, 3 dbs

Unsaturated Fatty Acids

* Omega number
* location of dbs nearest to the methyl (or omega) end of the carbon chain
* Oleic acid (monounsaturated) is omega-9
* Linolenic acid: 18 carbons, 3 dbs, n-3 is the first double bond location

Triglycerides (type of fat)

* glycerol + 3 fatty acids
* formed via condensation reactions (H2O released)
* Fully saturated (solid at room temp) (animal fat)
* Unsaturated (liquid at room temp) (oils)

Saturated fat

* longer chain lengths
* solid at room temp
* more stable

Unsaturated Fat

* Shorter chain lengths
* liquid at room temp
* less stable (spoil faster)
* exceptions are palm are coconut oil

coconut oil

* mostly saturated fat (shorter chain)
* softer than animal fats
* harder than other veggie oils

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 hydrogenation
* occurs naturally in some animal-based products
* behave like saturated fats in the body
* Banned in 2018 by Canada

Phospholipids

* Glycerol + 2 FA + phosphate group
* soluble in fat (fatty acid) and water (phosphate)
* Emulsifier in the food industry (stabilizes processed food)
* Cell membranes are made of phospholipids

Sterols

* Multiple ring structure
* Cholesterol
* Animal products onlY
* Made by the liver
* Makes: bile acids, hormones, vitamin D
* Structural component of cells
* Concern: plaque formation in arteries
* Plant sterols
* Inhibit cholesterol absorption

Lipid Digestion Challenge

* Challenge:
* Fats are hydrophobic
* Digestive enzymes are hydrophilic

Lipid digestion in the mouth

* Some hard fats begin to melt as they reach body temp
* Sublingual salivary gland secretes lingual lipase

Lipid Digestion in the stomach

* lingual lipase initiates lipid digestion by hydrolyzing one bond of triglycerides = diglycerides and fatty acids
* slight for most fats but higher for milk fats
* Churning of stomach mixes fat with water and acid

Lipid Digestion in the Small Intestine

* Cholecystokinin (CCK) signals the gall bladder to release bile (via the common FA bile duct)
* Fat → Bile → Emulsified fat → Pancreatic lipase → monoglycerides, glycerol, fatty acids

Lipid Digestion in the Large Intestine

* Some fat and cholesterol that are trapped in fibre exit through feces

Emulsification

* In the stomach, fat and watery juices separate, and the enzymes in the GI juice can’t get to the fat
* Gallbladder secretes bile when fat enters the small intestine (which helps bring the fat and GI juices together)
* Biles converts large fat globules into small droplets that repel one another
* After emulsification, more fat is exposed to the enzymes, making fat digestion more efficient
* Bile in GI tract has 2 fates
* reabsorbed and recycled
* excreted (may lower blood cholesterol levels)

Triglycerides are digested

* by pancreatic and intestinal lipase
* hydrolysis adds water

Phospholipids are absorbed

* similar hydrolysis of FA

Sterols

* absorbed as is

Lipid Absroption

* Glycerol and small lipids diffuse directly into the blood stream
* Monoglycerides and long-chain FAs combine with bile to form micelle
* Diffuse across membrane and reform triglycerides
* Combined with other lipids and protein to form chylomicrons
* Chylomicrons enter the lymph

Chylomicrons (clusters of lipids and proteins)

* Are transport vehicles for fat called lipoproteins
* Four types:
* Chylomicrons - large, least dense
* VLDL - (very-low-density-lipoprotein)
* LDL (Low-density lipoprotein)
* HDL (High-density lipoprotein)
* HDL is the healthiest (“good”) because it is the smallest

Typical Lipoprotein

* Interior of triglycerides and cholesterol surrounded by phospholipids
* PPL fatty acid ‘tails’ point towards the interior
* Protein near the outer ends of the phospholipids cover the structure
* proteins determine structure by receptors
* Arrangement allows lipids to travel through watery fluids

Lipid Transport

* Chylomicrons
* transport diet derived lipids to cells


* VLDL
* produced by the liver
* deliver lipids to body (from GI tract and chylomicron reminants)
* LDL
* VLDL that has many triglycerides removed
* High in cholesterol (‘bad cholesterol’)
* delivers it to tissues
* HDL
* Produced by the liver to remove cholesterol from body tissues ('“good cholesterol”)

Lipoprotein Lipase

* Enzyme activated in response to insulin
* Hydrolyzes triglycerides to glycerol and fatty acids
* Now TG can move into cell
* Located on an endothelial cell lining the capillaries
* Capillaries around muscle, adipose, heart
* Once inside the muscle or fat cells
* metabolized for energy
* or reassembled into TGs and stored

Healthy Blood Lipid Profile

* Factors that lower the LDL/HDL ratio
* weight control
* Monounsaturated or polyunsaturated, instead of saturated fat in the diet
* Soluble dietary fibres
* Phytochemical’s (plant sterols)
* Moderate alcohol consumption (red wine)
* Physical activity

Heart disease

* risk factor = elevated blood cholesterol
* Cholesterol
* accumulates in arteries
* restricts blood flow
* can lead to heart attack, stoke, angina, peripheral artery disease

Artheroscleosis

* Damage to the artery wall
* deposition of oxidized LDL
* inflammatory response
* recruitment of monocytes to damaged area (inflammatory response) → become macrophages that ingest LDL cholesterol
* Macrophages accumulate in arterial intimia
* take up loads of cholesterol = foam cells
* Collagen deposition around foam cells = thickening and hardening of the intimal medial layer of artery
* Migration of smooth muscle cells = growth of a fibrous cap
* Artery becomes hard and non-elastic

Saturated fats, trans fats, cholestrol

* increased heart disease risk
* animal fats, processed foods, veggie oils except palm and coconut

unsaturated fats

* decreased heart disease risk
* veggie oils (olive and canola), nuts and seeds, fatty fish

Benefits of MUFA rich diet (monounsaturated fats) vs Sat. fat

* Larger chylomicrons/LDL particles
* Shift from small dense LDL to large LDL
* Larger LDL cannot cross endothelium
* reduced postprandial lipaemia (faster clearance of lipids)
* greater reduction in fast triglyceride levels (fish oils)
* reduction in coagulation factors
* increased fat oxidation rate (greater fat burning and less fat storage)