NUTR 3200 midterm

Modern nutrition has changed from knowing how to prevent nutrient deficiencies to…..

understanding the effects of over nutrition,

goal = understand optimal levels of nutrients req for health

we dont eat nutrients, we eat \*food\*

focus on personalized nutrition

1. what is an essential nutrient
2. what are the 2 reasons they are essential to the human diet

chemical that is req for metabolism

CANT be synthesized *or* not synthesized rapidly enough to meet needs


1. removing it causes deficiency and decline in heath
2. putting it back corrects problem, heath returns

1. what is a nutritional deficiency
2. what are some examples and the diseases they cause?

person’s nutrient intake consistently falls *below* the recommended requirement

ex, iron = anemia (not enough red blood cells to transport o2)

thiamine = beri beri (abnormalities in nervous system, less energy production)

vitamin c = scurvy (no collagen= haemorrhaging)

vitamin d = rickets (bad bone growth)

how does a fixing a deficiency differ from nutritional requirements

deficiency = prevention of disease *(bare minimum)*

nutritional requirement = ensure **optimal** health

nutritional requirements were prompted by WW1 and limited food rations… what are some of the limitations with their recommendations… what did they not consider

age, gender, body size, physical activity (soldier on the front line) were NOT considered but have a big effect

Daily values on a “Nutrition Facts” label is based on a 2000 calorie diet. They are made using ______________ which are established by the national academy of sciences

Dietary Reference Intakes

*these values are general and need to be adjusted for a specific person*

what is a dietary reference intake

set of reference values for nutrients

ex: 130 g of carbs a day for a female

what is the EAR (estimated average requirement)

* needs of 50% of the population is met

what is RDA (recommended dietary allowance) and what is the formula for it

* needs of 97% of population is met
* RDA= EAR + 2 Std Dev

what is the tolerable upper limit (UL)

highest level of continuous daily nutrient intake that causes no risk of adverse effects

*amount right at the end of the sweet spot,*

what is the adequate intake (AI)

**THE SWEET SPOT**

when u cant make up an EAR or RDA .. u do this

* determined based on intake in healthy people who are assumed to have an adequate nutritional status (i.e., normal blood levels of a nutrient)
* The AI is expected to __meet or exceed__ the needs of *most individuals.*

what were the outcomes of the Minnesota Starvation Experiment in 1944

obvi weight loss …. BUT also

irritability, dizziness, tiredness, hair loss, low libito, depression

took 2 years to overcome these effects in patients

1. what are the 4 characteristics of a nutritious diet
2. what are the ==meanings== of each

ADEQUATE- enough calories, essential nutrients, fibre to keep you healthy

MODERATE - dont consume excess calories of eat more of a food or food group than recommended

BALANCED - eat nutrient dense foods

VARIED - wide selection of foods to get necessary nutrients

cell culture, animal models and human studies are used to study genomics.

what are some challenges with human studies ?

genetics, lifestyle, cultural habits

nutrients are classified into organic (carbon containing) and inorganic.


1. classify carbs, minerals, proteins, lipids, water, vitamins


1. classify them into macro nutrients and micro

Say the major things that happened in nutrition in each era… slay

500 BC -

400 BC -

1614 AD -

17th century -

19th century -

20th century -

21st century -

***500 BC -*** nutrients

***400 BC -*** medicine should focus on individual

***1614 AD -*** body uses food, metabolism

***17th century -*** dietary supplementation can improve the health w particular diseases \*nutrients are essential

***19th century -*** vitamins and prevention of disease

***20th century -*** how much of each nutrient is needed for optimal health

***21st century -*** nutritional genomics, diet and genes interact

anabolism is energy going into the body… what is an example of this ?

insulin, oversees ==building== things in the body

promotes the ==synthesis of protein and glycogen== and it inhibits the degradation of these compounds in muscle tissue.

catabolism is energy out into the body… what is an example of this ?

glucagon

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Stimulating the liver to break down glycogen to be released into the blood as glucose

Breaking down stored fat (triglycerides) into fatty acids for use as fuel by cells

what is the average water intake of an adult?

2\.7L-3.7L

20% comes from foods

what are the 5 functions of water?

\-solvent in biochemical rxns

\-catabolism (hydrolysis) breakdown

\-maintains vascular volume

\-nutrient transport

\-temperature regulation

explain water toxicity

water intake is **greater** than the kidney’s ability to process water

1. what is hyponatremia
2. how can this occur, and how can it be avoided
3. what are the effects of it

1. too little sodium in blood ratio of water to sodium too big
2. occurs from excessive fluid intake, under replacement of sodium or BOTH. avoided by urination


1. central nervous system edema (swelling) and muscle weakness

food analysis gives us information about foods, and allows us to produce safe and nutritious foods so consumers can make *informed decisions*

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how does food analysis have applications in the modern world?

government regulations - maintain quality of foods, ensure food industry makes safe foods w high quality, food allergies!

quality control - food composition doesn’t change

caloric content does not equate nutrient content in foods, as 1/2 cup of broccoli has many more nutrients than a cupcake that has more calories

a feed sample is left to air dry and becomes dry matter once the moisture leaves

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why is determining water content in feed important? (4 reasons)… think moisture and its effects

* water contributes to weight aka price of feed and shipping costs
* storage conditions, too much = spoils fast, too little = less tasty
* moisture dilutes energy and nutrients in food
* moisture important for optimum intake and performance of animals

% moisture formula

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dry matter formula

what is the difference between human and agricultural applications of % moisture and dry matter

\-agricultural industry interested in dry composition

\-human food labelling based on wet weight

what are some potential sources of error/limitations when drying wet weigth

\-drying can remove volatile compounds such as short chain fatty acids and some minerals

\-this causes an under-estimation of dry weight

% crude fat formula

what are some limitations when extracting fats

\-other non nutritious/non dietary fats (ex: chlorophyll, resins, waxes = used in structure etc) show up in the dried down solution and cause it to overestimate the crude fat determination

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there is newer and more sensitive methods that exist to fix this

what do you need to do to dry matter to get it to ether extract

add organic solvent, this extracts the ether

anything thats not fat precipitates out

dry it down and measure the weight of the solid (fat) that is left

1. how do you determine ash content from an ether extract (precipitate)


2. what is ash content

1. ignite it !!


2. mineral content

% ash formula

why is ash content aka mineral content important

quality and taste of food

microbiological stability

nutritional requirements

manufacturer processing

what are some limitations when determining ash/mineral content

\-volatile minerals can be lost

\-no info abt individual minerals

how do you get dry matter to nitrogen….


1. what are the two assumptions
2. what are the 3 steps

1. all nitrogen is in protein
2. all protein contains 16% nitrogen

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1\. **digestion** - food sample mixed w sulfuric acid, converts nitrogen to ammonia

2\. **distillation** - separates the ammonia

3\. **titration** - quantifies the amount of ammonia

% crude protein formula

**conversion factor**=?

6\.25 used to estimate crude protein

what are some sources of error with the Kjedahl analysis (dry matter to nitrogen)

1) assumes all proteins have 16% nitrogen (actual range is 13-19%)

2) there are other sources of nitrogen (aka nitrates, nitrites, urea, nucleic acids, in food sample would be part of crude protein calculation… which would over estimate it )

how do you get crude fibre from dry matter

*mimicked digestive system*


1. take ether extract and boil it in acid
2. filter it and take residue and boil it in alkali
3. filter that and you are left w ash and crude fibre
4. ignite that to eliminate ASH
5. left w crude fibre

formula for % crude fibre

how would the conversion factor change is the % nitrogen in food was 20%

how does crude fibre vary from dietary fibre… how does this contribute to sources of error

crude fibre tels about the celluose and lignan content (insoluble fibres)

dietary fibers describe ALL fibres (both insoluble and soluble)

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source of error = unable to distinguish fibre components… crude fibre understimates dietary fibre

formula for NFE (nitrogen free extract)

what are some potential sources of error

accumulates all the errors that exist for the other components

what does NFE (nitrogen free extract estimate

starch and sugar content

proximate analysis is the basis of human food labelling but… whats wrong w it

\-no info on digestibility of food, we dont know what will be absorbed by organism

\-no info on specific AA’s minerals, lipids or carbs

2 more accurate fibre analyses to complement the proximate analysis exist:

1) Van Soest method

2) Southgate method

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explain both

1) Van Soest method - differentiates insoluble fibres

(cellulose, hemicellulose, lignin)

\-determines fermentabe and non-fermentable carbs (has big time %%__*agricultural*__%% applications.. bc it doesn’t differentiate between sugars, starches and soluble fibres)

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2) Southgate method - provides info about sugars starch and various fibres

\-useful for %%__*human nutrition*__%% and food labelling

\-does not differentiate sufficiently between various insoluble fibre components adequately.. therefore not good for agricultural applications

dietary fibre- non digestible carbs - what are characteristics of insoluble fibre

cellulose, lignin, hemicellulose

\-remains %%intact%% through intestinal tract, ==does not dissolve in water==

dietary fibre - non digestible carb - what are characteristics of soluble fibre

pectins, gums, mucilages

\-forms gel, ==dissolves in water==

example problem for calculating NFE

GI tract is synonymous with digestive track… these are NOT the same as the __**digestive system…**__ what does the digestive system refer to

GI tract (mouth, esophagus, stomach, small and large intestine, caecum, rectum) and associated organs like liver, pancreas and gallbladder

what is the purpose of the caecum

hint 70% of total energy needed for host comes from: ___________

has an abundance of gut bacteria bc its a huge hindgut

FERMENTATION AND PRODUCTION OF ==SCFA’s==

70% of total energy needed for host comes from SCFAs

site of %%production of vitamins%%

connection between small and large intestine

purpose of gall bladder and both intestines

stores and concentrates bile from the liver.

The small intestine is involved in the digestion of food and absorption of nutrients.

The large intestine is involved in the absorption of water and in the production of vitamins.

how is __solubility of carbohydrates__ determined by in the aqueous environment of the digestive environment

solubility determined by physiochemical properties of carbohydrates

ex: being small,polar and containing OH groups would make them hydrophilic

hydrophobic = insoluble

how is the digestibility of carbohydrates in a organism determined

hin think fiber

by the host’s digestive enzymes

ex: being able to digest cellulose bc you’re a cow

fibre is non-digestable carbs

what would it be called if an organism’s ==gut bacteria== has the enzymes to break down a carb

fermentable

SIMPLE DIGESTIVE SYSTEM w/o functional caecum


1. what are key features
2. what type of diet is ideal for this
3. whats some animal examples

\-monogastric (simple stomach)

\-non-functional ceacum **no fermentation**

\*considered a hindgut fermenter

\-suited for a nutrient dense, low fibre diet

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ex: human, pig, cat, dog

what happens in the oral cavity (what enzymes released)

mechanical breakdown bc food is chewed, mixed w saliva to form bolus

a-amylose and lingual lipase released

what happens in the stomach a) what does food become here

b)what is secreted

c)what are the sections

d)what is pH

a) food becomes chyme

b) gastric glands secrete gastric juice (HCl, electrolytes, H2O, enzymes)

c) cardia, fundus, body, antrum

d) \~2

1. how long does gastric emptying take


2. what is the capacity of the stomach when empty and full

1. 2-6 hours


1. empty = 50mL, filled = 1-1.5 L

describe digestion in the small intestine:

a) 3 sections

b) what happens to chyme

c) what 2 things is food digested by

d) main site for _________ ___________

a) duodenum, jejenum, ileum

b) chyme is neutralized by pancreatic juice which is basic

c) pancreatic juice and bile acids digest food

d) main site for nutrient digestion and absorption

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notes: 30m^2 SA, and muscles move food along

large intestine aka colon:

a) site of ______________

b) production of ___________

c) what is absorbed here

a) fermentation

b) SCFAs (aka volatile fatty acids) are produced here by fermentation

c) water

1. what do short chain fatty acids influence


2. how are they made

1. cholesterol metabolism


2. through fermentation of carbohydrates by bacteria in large intestine

what would fibre do to the transit time of food in the large intestine

decrease transit time

speeds everything along bc its insoluble

what are the three structures in the small intestine that increase its surface area

1. kerckring folds
2. villi (on the folds) and crypts (crypt is like an inverted villi)
3. microvilli (on outside of villi)

microvilli compose the ________________ in the small intestine

brush border enzyme

a nutrients transport across enterocyte membrane in intestine of either (1. passive diffusion a) simple diffusion b) facilitated diffusion or 2. active transport )

WILL depend on what 3 things?

1. solubility
2. concentration gradient
3. molecular size

there is SOOO much bacteria in the gut aka GI tract… there aare 500-1000 species identified per person, w us having our own unique combo.

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what factors are important for determining the # of bacteria in different regions? (6)

regional oxygen level

pH

bile acids

gut transit time

mucus

immune factors

____ anaerobic: aerobic in the gut

1000: 1

this makes sense bc the GI tract is mostly anaerobic like the large intestine

where do you find the most bacteria in the digestive tract and why

large intestine/colon

bc bacteria are needed for fermentation of non-digestable carbs

fun fact: gut microbes contribute to weight

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also look at types of bacteria in diff sections of digestive track

SIMPLE DIGESTIVE SYSTEM w functional caecum


1. what are key features (what is a pseudo-ruminant)
2. what type of diet is ideal for this
3. whats some animal examples

a) hindgut fermenter

%%pseudo-ruminant =%% an animal that eats large amounts of roughage but does not have a stomach with several compartments.

everything else functions like the monogastric system (humans)


2. high fibre diet with %%lots%% of fodder and foraging
3. horse, rabbit, hamster

what type of diet do hindgut fermenters like horses like

Hindgut fermenters are able to extract more nutrition out of %%small%% quantities of feed. The large hind-gut fermenters are bulk feeders: they ingest %%***large quantities of low-nutrient food***%%

\n \*\*only get 1 chance to digest

Hindgut fermenters have a shorter passage time than ruminants, and hence are less efficient in cellulose digestion, for which they compensate with a %%higher intake of food%%

signs of energy or nutrient deficiency in animal

coprophagy (eating poop)

\-purpose is to get more vitamins and colonize their guts w bacteria

where are the following absorbed in horses?

&

what are the following broken down/ absorbed as when digested?

a) indigestible fibre

b) fermentable fibre

c) fat

d) protein

e) sugar and starch

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a) moves alllll the way through, never digested

b) large intestine & cecum // SCFAs

c) small intestine // fatty acids, any unused leaves

d) small intestine.. any unbroken down goes to large intestine to be broken down // amino acids in both

e) small intestine (fast transit time) // glucose in small intestine and lactic acid in large intestine

why is it dangerous to feed horses a high carb diet

bc horses can’t vomit, so lactic acid from broken down carbs just sits there and causes ==colic==

MULTIPLE DIGESTIVE SYSTEM


1. what are key features
2. what type of diet is ideal for this
3. whats some animal examples

1. RUMINANT

large stomach w 4 chambers : reticulum, rumen, omasum, abomasum
2. high amount of plant material, don’t need to each as much as hindgut formenters bc they can regurgitate to re-extraact nutrients

\-all other regions similar to monogastric
3. cow, sheep, goats

what are the four chambers of a ruminant’s stomach

rumen

reticulum

omasum

abomasum

what is unique about the reticulum

hint: think appearance..

Honeycomb appearance; can capture \n nutrients and trap foreign materials (wire, \n nails, etc.) that are accidently swallowed \n “hardware disease” \n • Rich in bacteria (fermentation vat)

what is unique about the rumen

hint: think appearance..

also 60-80% of total energy produced here as ______

The largest section of the stomach \n • Rich in bacteria (fermentation vat) \n • Rumen papillae  increases surface area for \n absorption (like microvilli in the human intestine) \n • Food is mixed & partially broken down, and stored \n temporarily \n • 60-80% of total energy produced here as SCFA

what is unique about the omasum

hint: think appearance..

Resorption of water and some electrolytes \n • Filters large particles

\-book w leaflets

what is unique about the abomasum

igestive enzymes secreted from gastric \n glands (HCl, mucin, pepsinogen, lipase, etc)

in ruminants… fermentation takes place before entering the intestine aka foregut digestion…

what does this mean for the nutrients produced

\-nutrients produced by bacteria then become available for digestion & absorption by the ruminant

what are some pros and cons about the ruminant digestive system?

PROS: - generates vitamins

\-non-protein nitrogen used for making protein

@@Ruminants have the ability to metabolize non protein nitrogen like urea into protein. The non-protein nitrogen's are a less expensive form of protein.@@

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CONS: -carbs degraded into gases and lost through belching

\-heat production (heat stress, bad for body functions and homeostasis)

AVIAN DIGESTIVE SYSTEM


1. what are key features
2. what type of diet is ideal for this
3. whats some animal examples

1. beaks and claws are important for breaking up foods into smaller pieces that birds can swallow
2. rapid digestion - need constant grazing, they will starve if deprived of food for even a short time
3. chicken, turkey

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the crop is an enlarged part of the esophagus in avians, and it comes in many shapes and sizes, what is its purpose.. what happens here?

temporary storage location for food so the bird can eat and quickly fly away and not have to hold in mouth

\-food is softened here, and often regurgitated to feed babies \*\*\*there is no mechanical breakdown in mouth bc birds have no teeth

two chamber stomach in avians,

what are the two portions and

what are their purpose

1st = glandular portion aka proventriculus - %%chemical%% breakdown, HCl and gastric enzymes secreted

2nd = muscular portion aka gizzard - grind and digest tough foods ==\*mechanical ==and sometimes even rocks here

True or False: the small intestine in avians is the nutrient gateway… and it functions the same as other systems

true

what goes on in the 2 ceca of avians

minor site of bacterial fermentation

(bc they dont eat lots of foods that need fermentation)

what goes on in the large intestine of avians, what are key features about it

very short, serves predominantly to connect sml intestine and cloaca

\-bit of water absorption and storage of undigested material

what happens at the cloaca of avians

digestive, urinary and reproductive systems meet

1. what is digestibiity


2. how is it calculated
3. what does it represent

1. measure of the fraction of a specific nutrient (or of energy) that is extracted by the GI tract
2. from the amount of nutrient in diet vs amount in feces
3. represents a combo of nutrient release from the \*==food matrix\*==, microbial fermentation, and absorption

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A ==food matrix==, as defined by USDA, is "the nutrient and non-nutrient components of foods and their molecular relationships, i.e., chemical bonds, to each other." The nutritional components are the vitamins, minerals and other health-influencing constituents in foods, such as antioxidants, while the non-nutrient components are the physical structures of the food, such as its form (solid, semi-solid, gel or liquid) and chemical bonds.

explain why digestibility is important for food science

prevents deficiencies by ensuring essential nutrients are available to the organism and being taken up

Explain the total collection method (5 steps)

what is the thing it measures

\-allow animal to adapt to the diet over a 7-21 day period

\-isolate animal for quantitative analyses

\-measure intake over 3-10 day period

\-collect and weigh ==**all**== feces

\-analyze for nutrient of interest

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measures the apparent digestibility coefficient

what is the formula for apparent digestibility coefficient

total intake - total feces / total intake

what are some limitations with the total collection method

hint: they use metabolic cages to capture urine and feces

\-accuracy in measuring food intake

\-the metabolic cages used cause anxiety in animals, which makes them behave abnormally

\-labour intensive

\-animals confined in costly environment

\-not feasible for captive wild animals

we loveeee the indicator/marker method for measuring digestibility


1. it requires a marker, what are the 2 used
2. what are the steps
3. what are the advantages
4. whats the thing it measures

1. internal (a natural component of the feed.. normally in food but we know it wont be absorbed ex: insoluble fibre)

external (a component added to the feed)

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1. same as other, adapt animal to test diet w marker
2. collected a feed & fecal sample (**just a sample needed not everything)**
3. analyze each for marker and nutrient of interests relative to your indicate

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3\.less labour intensive, good for ==WILD== animals


4. measures the apparent digestibility coefficient

for the following chart. calculate the apparent digestibility coefficient of protein for:


1. total collection method
2. indicator/marker method

1. 96.5 % digestible
2. 96.5 % digestible

\*to note that you should be able to use a chart that has grams or percentages

true or false, apparent digestibility overestimates true digestibility

false, it under estimates it

explain why apparent digestibility underestimates true digestibility (3)

the following things are not considered when calculating apparent digestibility


1. endogenous secretions

\-epithelial cells , ex fatty acids released from dying intestinal cells
2. bacterial growth in gut

\-nutrient synthesis, ex biotin produced by gut bacteria
3. digestive enzymes

-protein synthesis ex digestive enzymes released by cells (from pancreas)

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SUMMARY - if we acknowledge the presence of these for true digestibility we can eliminate them from the presence of the nutrient we are isolating for like protein which actually makes the overall digestability higher.

1. what are the 4 steps of calculating true digestibility
2. what is the formula for it

1. perform digestibility study using a TEST DIET (ex contains protein)
2. switch to diet containing none of the nutrient of interest/ ZERO NUTRIENT DIET (no protein)
3. analyze feces after TEST DIET is cleared, same w zero nutrient


1. subtract level of nutrient in feces of animals fed the zero nutrient diet from the test diet

given the chart, calculate the true digestibility coefficient for protein