HUNT141

What is nutrition?

The intake of food, considered in relation to the body's dietary needs.

Good nutrition

an adequate, well balanced diet combined with regular PA

Poor nutrition

can lead to reduced immunity, increased susceptibility to disease, impaired physical and mental development, and reduced productivity

Double burden

Undernutrition and overnutrition (obesity) in the same population

Food contains six types of nutrients

1. water

2. carbohydrates

3. lipids

4. proteins

5. vitamins

6. minerals

Nutrients

Molecules found in food and beverages needed by the body fo energy, growth, development and reproduction

Macronutrients

Required in the diet in large quantities (i.e. grams). Carbs, protein, fat, alcohol.

Micronutrients

Required in the diet in small quantities (ie. grams, milligrams). Vitamins, minerals.

Non communicable disease (NCD)

Can't be caught, long duration, combination of genetic, physiological, environmental and behavioural factors e.g. cancer, high blood pressure

Communicable disease (CMNN)

(communicable, neonatal, nutritional, disease). Is contagious e.g. covid, chicken pox

Energy density

how many calories food has relative to it's size and weight.

Gross energy

the total chemical energy of a food

Atwater factor def

used to calculate metabolizable energy , energy content (KJ) per gram of nutrient.

Atwater factor calc

Carbohydrate: 17kj/gram

Protein: 17kj/gram

Fat: 37kj/gram

Alcohol 29kj/gram

Total energy in a food

Energy kj = macronutrient g x Atwater factor kj/g

Total energy =

Energy fat + energy protein + energy carb + energy alcohol

Calculate proportion of total energy % from diet

((g of macronutrient x atwater factor kj/g)/total energy kj/g) x 100

Nutrient reference values (NRV's)

A set of recommendations for nutritional intake based on currently available scientific knowledge.

NRV factors

apply to almost all (97-98%) healthy people. Achieved by consuming a variety of foods, applies to average daily intakes

NRV types

Acceptable macronutrient distribution range (AMDR)

Estimated energy req. (EER)

Estimated avg. req. (EAR)

Recommended daily intake (RDI)

Average intake (AI)

Upper level of intake (UL)

Estimated energy req. (EER)

Avg. dietary energy intake that's predicted to maintain energy balance in a healthy adult of defined age, gender, height, weight etc.

Meets needs of 50% of population.

Estimated average req. (EAR)

Daily nutrient level estimated to meet req. of half healthy individuals in a particuar life stage & gender group. Meets needs of 50% of population.

Recommended dietary intake (RDI)

Avg. daily dietary intake level sufficient to meet nutrient req. of nearly all (97-98%) healthy indivudals in a partcular life stage + gender group.

RDI = EAR + 2std. dev

Adequate intake (AI)

Avg. daily nutrient intake level based on observed or experimentally determined approximations or estimates of healthy pepole assumed to be adequate. (use when RDI can't be determined)

Upper limit of intake (UL)

Highest avg. daily nutrient intake level likely to pose no adverse health effect to almost all individuals in apopulation.

groups/people focused for each NRV

AMDR = groups + individuals

EAR = groups/populations

RDI = individuals

AI = individuals

UL = groups + individuals

Digestion

The process of breaking down food through physical (chewing) and chemical (enzymes) digestion.

Peristalsis

How food moves through digestive tract - the involuntary contraction of muscles, creating wave like motions pushing the contents in the canal forward.

Mechanical digestion in the mouth

Teeth grind food into small pieces. Tongue mixes food with saliva, pushes food to the back of the mouth.

Chemical digestion in the mouth

Salivary glands release saliva - moistens food.

Amylase breaks down carbs (starches) into simple sugars (maltose), lipase breaks down fats (triglycerides) into smaller molecules

Digestion in the oesophagus

Saliva moistens & lubricates food. The food is swallowed and squeezed down the oesophagus to the stomach by a wave like motion called peristalsis. Sphinctor muscles control movement from one section to another.

Digestion in the stomach

Mechanical: Muscle walls contract churning the food into chyme.

Chemical: Hydrochloric acid breaks down food and kills bacteria. Pepsin breaks down protein.

Digestion in the small intestine

Mechanical: Villi microvilli increase surface area for absorption.

Chemical: Pancreas produces amylase, protease, lipase. Liver secretes bile. Further breakdown of carbohydrates into simple sugars and proteins into amino acids, fats into fatty acids and glycerol

Digestion in the large intestine

Removes excess water from stool and holds it until its ready for elimination

Gastric glands

Secretes gastric juice in the stomach.

Enzymes to breakdown protein

Pancreas

Secretes pancreatic juice in the small intestine.

Aids digestion by neutralizing stomach acid and breaking down carbohydrates, proteins, and fats with various enzymes.

Gallbladder

Secretes bile from the gallbladder. Emulsifies fats.

Transporting nutrients from gut

nutrients are absorbed by the epithelial cell and travel via hepatic portal vein --> liver

Pro & prebiotics

Help with good bacteria & get rid of "bad"

Probiotics are bacteria found in

yoghurt, miso, kimchi, pickles etc.

Prebiotics are foods such as

apple, artichoke, banana etc. used by the intestinal bacteria

Carbohydrates formula

6CO2 + 6H20 --> C6H12O6 +6O2

CHO include

Starches, sugar, dietary fibre, glycogen

Monosaccharides are

single/simple sugars (glucose, fructose, galactose)

Glucose

A simple sugar that serves as the essential energy source.

Fructose

simple sugar naturally in fruits, honey and some vegetables

Galactose

a simple sugar found in milk and dairy products

Disaccharides

2 monosaccharides (always including glucose)

Disaccharide examples

Maltose (glucose + glucose)

Sucrose (glucose + fructose)

Lactose (glucose + galactose)

Oligosaccarides

Few glucose units

Polysaccharides

Many glucose units

Starch

Storage form of glucose in plants. Found in grains, tubers and legumes.

Glycogen

Multi-branched polysaccharide of glucose.

Main storage form of glucose in the body, and provides glucose during "fasting" state.

Dietary fibre

Parts of plants that cannot be digested, which helps the body eliminate waste.

Non-starch polysaccharide (NSP)

complex carbohydrates found in plant cell walls that are not digested like starch

Starches break down into

monosaccharides and disaccharides (sugars)

Amylose + amylopectin

Glucose, fructose and galactose linked together

Free sugars

Sugars added to food & naturally occurring sugar (like in fruit, honey etc.)

Added sugars

Sweeteners added to food during processing or preparation (the extracted, concentrated and refined from sugar cane, fruit, coconut etc)

Intrinsic sugars

Naturally occurring sugars found in whole, unprocessed foods such as fruits, vegetables, dairy, honey and some grains.

WHO recommend reducing free and added sugar intake to

less than 10%

Carbohydrate digestion

Begins in the mouth with salivary amylase breaking down starch, continues in the small intestine where pancreatic amylase and brush border enzymes (like lactase, sucrase, and maltase) break down complex carbohydrates into simple monosaccharides (glucose, fructose, galactose), and concludes with absorption into the bloodstream

How to reduce (free/added) sugar intake

Sugar tax, labelling, non-nutritive sweeteners, modify the taste for sweet.

Lactose intolerance

The inability to completely digest the milk sugar lactose due to a deficiency of the enzyme lactase.

Glycemic index

a method of classifying foods according to their potential for raising blood glucose

Low GI

0-55

Carbs which breakdown slowly, releasing blood sugar gradually into bloodstream e.g. lentils, broccoli, cabbage

Medium GI

56-69

Carbs which break down moderately releasing blood sugar moderately into bloodsteam e.g. kiwi, wholegrain bread, muesli

High GI

70-100

Carbs which break down quickly, releasing blood sugar rapidly into bloodstream e.g. white bread, fries etc.

Why does nutella have a low GI of 33

Fat dampens the response - slows absorption of glucose into the blood.

Issues with GI

- Two people, different responses to the same food

- Serving size isn't taken into account

- combining food can give unpredictable GI

Glycemic load (GL)

Similar to glycemic index but looks at the response to the food when you eat a typical serving.

GI versus GL (watermelon example)

GI of 80 but a GL of 5

Irritable bowel syndrome (IBS)

periodic disturbances of bowel function, such as diarrhea and/or constipation, usually associated with abdominal pain

FODMAP

Fermentable

Oligosaccharides

Disaccharides

Monosaccharides

And

Polyols

s

Chains of amino acids used by the body to build and maintain cells and tissues.

functions of proteins

structural support, catalyst, transport, defense, movement, regulation

Indespensible amino acids

Essential amino acids that cannot be synthesized by the body and therefore must be obtained from diet

Dispensible amino acids

Non-essential amino acids the body can make if needed.

How many different types of amino acids are there?

20

Structure of proteins

primary, secondary, tertiary, quaternary

Primary structure of proteins

structure of protein determined by amino acids

Secondary structure of proteins

determined by weak electrical attraction within polypeptides. Provides strength and rigidity.

Tertiary structure of proteins

Polypeptide chain twists and fold; side groups attracted = intricate shape

Quaternary structure of proteins

interactions between multiple polypeptides e.g. haemoglobin

Kiwis eat _ times the recommended protein amount

2

Protein quality

based on the content of essential amino acids in a food and their digestability

protein digestability corrected amino acid score (PDCAAS)

mg of limiting amino acid/mg of amino acid in reference protein x true fecal digestability

Protein efficiency ratio (PER)

weight gain of test subject/intake of food

Limiting amino acid

the essential amino acid in lowest concentration in a food or diet relative to body needs

Complementary proteins

two or more incomplete protein sources that, when eaten together, provide all nine essential amino acids needed by the body, essentially creating a complete protein

limitations of plant based diet

low protein, lower digestability, lower essential amino acid content

advantages of plant based diet

lower greenhouse gas emissions, lower T2 diabetes, SFA and CVD risk, increased dietary fibre, phytochemicals and antioxidants

Peak protein synthesis includes

eating a variety of plant and animal proteins throughout the day to provide the essential amino acids.

Protein digestion

Begins with mechanical chewing. Then down in stomach, stomach acid and enzymes (pepsin) break proteins into smaller polypeptides. In the small intestine, pancreatic enzymes (trypsin & chymotrypsin) further break down these polypeptides. Then breakdown into individual amino acids before absorbed into the bloodstream.

Four possible fates for an amino acid when it joins the amino acid pool

1. used to make proteins

2. used to make dispensible AA's

3. used to make other compounds

4. used for energy

Lipids

a diverse group of organic compounds that includes fats, oils, waxes, and steroids, characterized by their insolubility in water

functions of lipids

source of energy, component of cell membranes, precursors for hormones and signaling molecules, provides insulation and protects internal organs

Types of fats/lipids

triglycerides, phospholipids, sterols

Triglycerices structure

Glycerol + 3 fatty acids = triglyceride

Fatty acids

chains of carbon molecules with a methyl group at one end of chain & a carboxyl group at the other end