Studied by 6 people
Module- 4 4- Carbohydrates and fibre
What is a carbohydrate (CHO)?
Contains C, H, and O, but in the same proportion as water (H2O)
What are the two types of CHO?
simple (mono and disaccharides)
complex
All CHO are made up of sugars called…
monosaccharides
do sugars go into the blood or the lymph?
blood, the only thing that goes into the lymph are the longer chain f.a
3 examples of monosaccharides? and how many carbon do they each have?
glucose, galactose, fructose
6 carbons each
Each monosaccharide chemically contains…
6 carbon, 12 hydrogen, and 6 oxygen atoms, but just arranged differently
Glucose (def)
A monosaccharide that is the primary form of carbohydrate used to provide energy in the body. It is the sugar referred to as blood sugar
What is special about the monosaccharide (sugar) fructose?
it is 5-sided (instead of 6-sided like the others)
Disaccharides; 3 of them
Maltose
Sucrose
Lactose
What process is used to break down disaccharides
hydrolysis (using water to break things apart)
H2O “breaksdown” the sugar
What are the disaccharides Maltose, sucrose, and lactose comprised of?
Maltose= 2Glucose
Sucrose= Glu+Fru
Lactose= Glu+Gal
sucrose is commonly known as…
table sugar or white sugar
lactose is commonly known as…
milk sugar
maltose is made when…
starch breaks down
What digestive enzymes breaks down maltose, sucrose, and lactose?
Maltase, sucrase, and lactase
What process is used to create disaccharides?
Condensation, OH and H group comes together and the product are a disaccharide and water, however we cannot do this process only plants
Oligosaccharides
3-10 monosaccharides
also known as prebiotics- food for healthy bacteria (Inulin and soluble fibre are great for feeding healthy bacteria)
some are formed in the gut during the break down of polysaccharides
some are found naturally in foods (legumes, bananas, chickery…). they are not digestible, they go to the colon and are broken down by the intestinal microflora
promote gastro intestinal health (GI), that is why it is recommended that you feed your baby breast milk
Polysaccharides
“poly”
hundreds-thousands of monosaccharides
What is a complex CHO?
Starch
Polysaccharide; glycogen
the storage form of carbohydrate in animals
highly branched chains of glucose allows it to broken down easily when glucose is needed
stored in muscles and liver to feed body when sleeping
made of glucose
Polysaccharide; starch
the storage form of carbohydrate in plants
stored in plant’s roots
Complex CHO
made of glucose
made up of two types of molecules; amylose, amylopectin
Polysaccharide; fibre
can’t be broken down (can’t be digested)
2 types of fibre; soluble and insoluble
soluble- dissolves in water or absorbs water to form viscous solutions and can be broken down by bacteria in the large intestine (pectins, gums, and some hemicelluloses)
insoluble- for the most part does not dissolve in water and cannot be broken down by bacteria in the large intestine (cellulose, some hemicelluloses, and lignin)
made of glucose but the bonds are different
Refined
Refers to foods that have undergone processes that change or remove various components of the original food
DRI/AMDR for carbohydrate
45-65% of kcal
fibre should be ___g/1000 kcal
14g of fibre
Carb; foods that contains starch; Vegetables
potato, corn, green beans, green peas (‘green’ because they are fresh, if you let them dry out they would be legumes, and therefore be put in the meat+alt category
Carb; foods that contains starch+ sugars; Fruit
starch- banana
sugars- all fruit
Carb; foods that contains starch; grain products
“all”- contains barn, germ
Carb; foods that contains starch; Meat+ alt
meat- non because the glycogen is gone by the time we eat it
alternatives- nuts/seeds, legumes
Carb; foods that contains starch; milk+alt
milk- lactose
alternatives- soy beverage (cane sugar, oligosaccharides)
CHO diets around the world; Africa
80% of kcal, because of a root food called Cassava
CHO diets around the world; Caribbean
65% of kcal
CHO diets around the world; North America
53% of kcal
right range but not the right types
since 1900 in N.A, CHO intake reduced 25-30% and moved to ^ in refined CHO+ sugars (white flour), ^protein (animal), ^fat
CHO digestion; in the mouth
some starch are broken down by salivary amylase (enzyme) into maltose
What happens if you let a soda cracker sit in your mouth?
you will detect a sweet taste because of the salivary amylase breaking down the starch into maltose
CHO digestion; in the stomach
no digestion happens in the stomach
HCl acid denatures(inactivates) salivary amylase
CHO digestion; in the small intestine
most starch digestion+breakdown of disaccharides occurs
the break down of starch is done by pancreatic amylase (enzyme) into maltose and then by maltase into 2 glucose
enzymes attach to the intestinal vili, here di and oligo are broken down into monosaccharides
CHO digestion; in the large intestine
fibre and other indigestible carbohydrates are partially broken down by bacteria
they form short chain f.a and gas, and some is excreted in feces
Monosaccharides metabolism; in the liver; glucose
fructose and galactose gets turned into glucose
meets the kcal needs of the liver
stored in liver as liver glycogen
makes some non-essential amino acids
converts excess glucose to fat→ VLDL→ stored
releases glu into blood
every body cell can use _______ as a fuel source
glucose
Monosaccharides metabolism; in the bloodstream
kcal (energy) for all body cells (red blood cells, central nervous system/brain→ only prefer glucose)
muscle glycogen storage→ selfish, only uses it for themselves
Glucose; basic facts
found only in very small amounts in plant foods (fruit)
Needs to be provided in the diet ideally as a fibre-rich carbohydrate source
insulin is produced by the …
pancreas
Insulin is a …
anabolic hormone “build tissue”- it tells the body to store and make things while meals are good
what does insulin do?
facilitates ”escorts” uptake of blood glucose into cells (glucose needs an escort in order to go into body cells)
following a meal, blood glucose levels return to “normal” (basal value)
what does insulin tell the body to do?
make+ store liver (+muscle) glycogen
allows the use of glucose by cells
tells the body to store the rest in case
when you feel a hunger pang→blood glucose dropping, (body needs kcals) what does your body do?
insulin secretion decreases and glucogon from the pancreas gets released. Glucogon mobilises liver gylcogen (that was being stored) to be broken down into glucose and released into the blood. And as a result blood glucose level return/ rise to normal
diabetes mellitus
“honey sweet”
they found glucose in the urine
Type 1 diabetes: what percent of population? What happens? develops when? how is it determined and what do they think it is caused by?
5% of population
pancreatic release of insulin fails (you can’t put glucose away, so you have to take insulin in order to do that)
develops in teen years or early 20s
genetically determined
they think it caused by early viral infections→ autoimmunity (antibodies to yourself)
Type 2 diabetes: what percent of population? What happens? develops when? how is it determined
95% of population
body tissues don’t listen to insulin, they resist insulin (insulin resistance)
so when the insulin escorts the glucose the receiving body cell doesn’t see the insulin
the pancreas believes that it didn’t release enough insulin so it releases more, therefore glucose and insulin rises (hyperinsulinemia)
connected to overweight and lack of exercise
after many years of type-2 diabetes the person would have to take insulin because the pancreas is exhausted
What is the drug that is given to diabetics to promote insulin sensitivity
metformin
what is glucose tolerance?
a measure of a persons ability to remove excess blood glucose following a meal
what is the range of glucose tolerance of a normal individual?
4.5-5.5 mM
what are the ranges of glucose tolerance
from normal individual (4.5-5.5mM) to→ a person with type 2 diabetes
if it is increasing from left to right then that is increasing glucose Intolerance
what is a glucose tolerance test
give glucose drink
take blood samples periodically over 2-3 hrs
blood glucose increases as glu is absorbed from GI tract
blood (pancreas) respond by making insulin
measure every 30min
what would a “normal” glucose tolerance curve look like?
After the glucose drink, glucose levels would hit a peak and start to go down, it would go below ‘normal’ before it corrects itself and goes back to normal wall within about 2 hours
it never touches the ‘renal threshold’ (10mM)
what would a ‘uncontrolled’ glucose tolerance curve look like?
an uncontrolled glucose tolerance curve will start above ‘normal’, like 7.5mM. there will be a delayed peak and there will be glucose in the system for longer. The peak goes above the ‘renal threshold’ for a long period of time. Finally the glucose level goes back to where it started, all within 3-4 hours
Glycemic response
“blood glucose response following eating certain foods”
e.g., whole grain bread, legumes takes longer to digest fibre, therefore they have a low Glycemic index
what kinds of foods contain fructose? and what other stuff does it have?
honey- just CHO
fruits- high in fibre, vitamins/minerals, and low in kcal
HFCS- high fructose corn syrup
if you have ‘diabetes’ during pregnancy, but after it goes away what is it called? and also what are you now at risk for?
gestational diabetes, at risk of developing type 2 diabetes
what complications are there with type 2 diabetes?
stroke, kidney failure, heart attack, blindness, and amputation
fructose; HFCS
Cariogenic (cavity causing)
liquid sweetener
made from corn
55% fructose
found in almost all condiments
less$ then sucrose (table sugar)
risen from 0% of sugar intake to 1000% of all sugar intake (1970-now)
average american around 62lbs/year
130 kcal/day
what do they think that high fructose corn syrup is contributing to?
obesity
why do they think HFCS is contributing to the obesity epidemic?
the body can use fructose differently than other sugar:
does not stimulate insulin secretion, or enhance leptin production→”you are full” (lowers satiety cues)
stimulates liver fat synthesis+ boost TG (VLDL)→ CHD
may promote high blood pressure which leads to risk of CHD
Humans never consumed anything close to current fructose intake: body cannot handle large amounts
Just 1 daily 16-oz (2 cups/500mL) bottle pop= 200kcal can add up to 20lb weight gain in 1 year
Disaccharides: Sucrose; facts
Glu+Fru
table sugar isolated/purified from sugar beet or sugar cane
both crops yield more kcal/acre than any other crop
the only real evidence of sugar is that it is cavity causing
do sugars cause obesity?
trend with ‘low fat’ foods, they made up the difference in carb (flour, sugar)
form of carbs affects satiety, liquid form of kcal is not detected as well as food forms. Foods with simple sugars and refined carb are less filling than fibre-rich carb foods
sugars have no nutritional value (vitamins+minerals) other than 4kcal/g
do sugars cause heart disease?
what causes obesity?
overeating anything causes obesity
metabolic syndrome; constitutes 5 features
abdominal obesity
increase fasting glucose (insulin resistance)
increase TG in blood
decrease HDL
increase blood pressure
if you have three or more then you will be diagnosed with metabolic syndrome
what is the dietary connection to metabolic syndrome? and what should you eat instead?
sugars+refined carbs (carbs that have the fibre taken away)
you should instead eat high fibre carb sources, intact V+F, and lower juice intake
what is the recommended amount of added sugar per day for women? for men?
women- 6tsp of added sugar/day
men- 9tspof added sugar/day
lactose; relative sweetness value
0.2, compared to sucrose=1
when does lactase deficiency start?
ages 3-16
of which descent maintain the ability to make lactase?
Northern Europe
consequences of undigested lactose:
lactose doesn’t get broken down in the GI tract because of the lack of lactase, it attracts H20 which causes bloating+cramps. When it arrives at the colon it gets fermented by the bacterial enzymes that break it down, the products are gas (H2, CO2, and CH4) and diarrhea because the water could not be reabsorbed
what is a milk allergy?
an exaggerated immune response to a protein in food
when the milk protein is consumed, in the GI tract the milk protein gets broken down into chunks, some of the chunks get into the bloodstream. An immune response will happen and will produce antibodies against it resulting in anaphylaxis
fortified
stuff added that were not really there
what is dietary fibre?
indigestible plant material
what is the distribution of soluble to insoluble when eating plants
1/3 sol: 2/3 insoluble (we get both in our omnivorous diet)
what are some examples of soluble fibres? what are some food examples?
gums, pectin, agar, carragecnin
food sources- oatmeal (oatbran: Beta-glucan), insides of legumes+fruit
what are some examples of insoluble fibres? what are some food examples?
cellulose, hemicellulose, lignin (strawberry seeds)
food sources- outside (skin/peel) of legumes, V+F (like those strings of celery)
transit time
time it takes from eating→elimination
depends on how much fibre is in the diet
What does fibre do in the colon?; soluble fibre
slows the movement of digesta (what remains of your meal) through GI tract
From the small intestine into the colon:
‘digesta’ comes into the colon the soluble fibre is now in a gel form because it mixed with water. the bacteria in the colon will go to town to ferment because the soluble fibre makes the digesta accessible. from the fermentation the products are: gases (H2, CH4) and short chain f.a: 2:0-acetate which will be absorbed, 3:0-propionate absorbed, and goes to liver and reduces liver chol. synthesis. 4:0 butyrate, preferred energy source by the colon
What does fibre do in the colon?; insoluble fibre
increases/speeds up the movement of digesta thru GI tract
very densely packed interwoven structure
bacteria has a hard time accessing it , so there is less fermentation happening, therefore you will have a greater fecal bulk
what does fibre do for the colon
soluble and insoluble fibre in the colon adds bulk and absorbs water. This increases stool weight, speeds transit, and makes the feces larger and softer
what kind of condition could happen if you have a low fibre (specifically insoluble) intake
a condition called Diverticulosis
there is too much pressure in the colon causes weak spots that bulge out
what is the net effect of eating fibre?
because 1/3 sol and 2/3 insoluble, fibre increses the movement of digesta thru GI tract
parts of a whole grain (wheat, rye, barley, rice)
Bran- outer layer
Aleurone layer- just under the bran layer (B--vit, iron)
Germ- PUFAs/MUFAs, vit E, Fe, B vit
Endosperm- starch and protein
how does fibre help prevent colorectal cancer? soluble and insoluble
Soluble fibre
short chain f.a acids (4:0)←preffered energy source of colon cells
low pH (acidity) favourable environment
stimulate growth of healthy microbiome
results in lower levels of NH3 (ammonia)
Insoluble
because of its bulking effect, dilution of colonic contents (less of the bad stuff gets into contact with the cell walls)
Provides a surface for adsorption (sticking to)(so the nasties will come out)
reduces intestinal transit time(removing waste products on a regular basis)
Altered bile acid metabolism(bile acids have the potential of being acted upon by pathogenic bacteria which turns them into secondary bile acids which are cancer promoters, but insoluble fibre will block the reaction)
fibre; blood cholesterol: which fibre lowers Total chol. +LDL
Soluble fibre
how does _______ fibre lower blood cholersterol?
soluble
soluble fibre binds onto bile acids, which prevent bile acid absorption
Soluble fibre is readily fermented into 3:0 propionate which lowers liver chol synthesis
from the short chain f.a that are produced after fermentation in the colon from soluble fibre, what are they each associated with?
2:0 Acetate→ just gets absorbed
3:0 Propionate→ lowers liver chol synthesis
4:0 Butyrate→preferred energy source of the colon cells
Panacea
a cure all for anything
e.g., protein for weightl oss or weight gain
AI for fibre
14g fibre/1000kcal
Note
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