NTR 108 test 1

Food

Any substance the body takes in and assimilates that enables it to stay alive and grow

Nutrients

components of food that are indispensible to the body’s functioning

Essential nutrients

nutrients that body cannot make in sufficient amounts, must be obtained through food/supplements

Non-essential nutrients

nutrients the body can make

Nutrition

science of food and its influence on body

• consumption, digestion and absorption

• transport and storage of nutrients + excretion of end products of metabolism

• function of individual nutrients and their interactions with one another in the body

• r/s b/w nutrient intake, nutritional status, health and disease

• social and economic determinants of food distribution, availablity and selection

Nutrition playing some role in health

osteoporosis, osteoarthiritis, some cancers

Nutrition playing strong role in health

type 2 diabetes, heart disease, stroke, obesity

Nutrition is the cause of health issues

pellagra, scurvy, iron-deficiency, other deficiencies/toxicities

Single-factor nutrition diseases

• onset of signs of deficiency usually rapid

• replacement of lacking nutrient re-establishes “health”

Multi-factor nutrition diseases

• associated with excessive food/nutrition intake

• factors can be non-modifiable and modifiable

• onset of signs of disease may occur over several years

Non-modifiable factors

• age

• gender

• genetic background

Modifiable factors

• diet

• physical activity

• smoking habits

6 groups of nutrients

1. carbohydrates

2. fats and oils

3. proteins

4. vitamins

5. minerals

6. water

Macronutrients

provide energy, body needs relatively large amounts

• carbohydrates

• fats and oils

• proteins

Micronutrients

DO NOT provide energy, body needs relatively small amounts

• vitamins

• minerals

Carbohydrates

• body’s main source of fuel

• simple sugars and complex carbohydrates

• grains, fruits, vegetables, dairy

Fats and oils

• provide energy at rest and energy stores in body

• visible: butter, oil etc.

• hidden: found in meat, fish, nuts, seeds, dairy, cookies, crackers etc.

Protein

• used to build cells and tissues in body e.g. muscle and bone

• animal sources: chicken, meat, fish, seafood, eggs, dairy

• plant sources: beans, nuts, seeds

Vitamins

• function in body in a regulatory/metabolic capacity

• don’t function as structure, many function in chemical reactions involved in energy release from macronutrients

• 13 vitamins with unique structures

• requirements ae small

• organic compounds

• found in variety of foods

Water-soluble vitamins

B vitamins and vitamin C

• high levels excreted in urine, rarely toxic

• not stored well, deficiency sooner

• sensitive to heat and light so fresh foods usually the best sources

Fat-soluble vitamins

Vitamins A, D, E, K

• generally stored well, deficiency later, toxicity sooner

• absorbed with fat so need some fat in diet

• toxic in high levels, esp A and D

Minerals

• function in body in structural (bone and teeth), regulatory (hormones, hemogloin, nerves) and metabolic (cofactor for enxymes) capacities

• inorganic, no carbon

• variety of food sources

Major minerals

require >100mg/day

• calcium

• sodium

• phosphorus

• potassium

Trace minerals

requires <100 mg/day

• copper

• iron

• iodide

• zinc

• fluoride

Water

• most essential nutrient

• fluid balance, waste excretion, thermoregulation etc.

• water (duh), juice, fruits, vegetables

Phytochemicals

• chemicals found in plant foods

• not considered nutrients

• have some important health benefits

Scientific method

standardized process that scientists use to evaluate and test claims, to determine if claim can be substantiated by evidence

Epidemiologic studies

• studies of whole populations/groups

• observe patterns of disease and associated factors (nutrition)

• no intervention/manipulation

• association only - not causation

• incl. observational and case control studies

Laboratory Animal Studies

• learn about nutrition from animal models

• shorter lifespan

• can study interventions not acceptable in humans

• easier to study in some cases

• results can’t be translated to humans, but provide basis for human studies

Clinical Trials

• test effect of intervention

• control and intervention groups to compare outcomes

• control other variable

• can suggest cause and effect

• ideal characteristics are randomization and blinding

Randomization

randomly assign participants into control or experimental groups

Single-blind experiment

participants unaware if they are in control/experimental group

Double-blind experiment

participants and researchers both unaware who is in control or experimental group

Placebo

imitation treatment with no API

Ethical Concerns (Humans)

• informed consent: must receive oral and written explnation of purpose of research and possible risks

• subjects can leave study at any time

Ethcial Concerns (Animals)

animal housing and handling strictly regulated

Conflict of Interest and Bias

• researcher/funder could receive unfair benefit based on results of research

• might lead to researcher bias - some factors influence researcher to favor certain results

• must disclose when publishing/presenting

Credible nutrition information sources

• peer reviewed journals

• credentials

• .gov/org/edu websites (generally)

• Government organizations

• More recently current dates

Desirable nutrition

desirable amount of a particular nutrient which

• supports routine chemical processes

• provides surplus store for use during times of increased need

deviation from “optimal” nutrtional status can occur due to under-nutrition/over-nutrition/imbalance

Under-nutrition

• individual does not consume sufficient amount of nutrient to meet needs for cellular activities

• due to inadequate dietary intake, excessive loss, increased requirements

• results in depletion of tissue stores, biochemical changes, clinical signs/symptoms

Over-nutrition

occurs as consequence of excess nutrient intake

Imbalance of nutrients

e.g. too much copper can limit zinc absorption

Assessment of Nutritional Status

• anthropometrics

• biochemical indices

• clinical examination

• dietary assessment

• economic assessment

24-hour recall

asking patient to list foods eaten over past 24 hours

Food record

patient writes down what they eat over the next week/month

Key Messages of 2020-2025 Dietary Guidelines

1. follow healthy diet at every life stage

2. customize and enjoy nutrient-dense food & beverage choices to reflect personal preferences, cultural traditions, and budget considerations

3. focus on meeting food groups with nutrient- dense foods and stay within calorie limits

4. limit foods and drinks higher in added sugars, saturated fat, sodium and alcohol

MyPlate recommendations

• balance calories: avoid oversized portions

• ½ plate fruits & vegetables

• ¼ plate whole grain

• ¼ plate meats & others

• choose foods with lower sodium

• drink water over sugary drinks

• use healthier oils

• be active

Pros of MyPlate

• easy to visualise as we often eat from plates

• visual of portion size

• website individualizes recommendations based on age, gender, height & weight

• servings for each group are listed in measurable amounts

Cons of MyPlate

• website needs internet access to get personalized info

• exercise not illustrated on plate icon

One serving of dairy

1 cup

• 1 cup of milk/yoghurt

• 1.5 ounces of natural cheese

One serving of protein

1 ounce

• 1 ounce of meat/poultry/fish

• 1 egg

• ¼ cup cooked beans

• ½ ounce nuts

• 1 tbsp nut butter

One serving of vegetables

1 cup

• 1 cup of raw/cooked veg or veg juice

• 2 cups of raw leafy greens

One serving of fruits

1 cup

• 1 cup of fruit/100% fruit juice

• ½ cup dried fruit

One serving of grain

1 ounce

• 1 slice of bread

• 1 cup dry cereal

• ½ cup cooked rice/pasta/cereal

Basic Principles of Food Selection for Nutritional Health

• variety

• balance

• moderation

• adequacy

Nutrient density

ratio dervied by dividing food’s nutrient content by its calorie content

Nutrient-dense foods

foods with limited calories and lots of nutrients

Empty calorie foods

foods with lots of calories and few nutrients

Energy Density

comparison of calorie content of food with its weight

Lower energy density foods

• rich in fiber and water

• <1.5 kcal/g: carrots, broccoli, strawberries, fat-free milk, broiled fish & beans

• recommended to eat more of these foods

Higher energy density foods

• rich in fat and sugar

• >4 kcal/g: cookies, bacon, potato chips, mayonnaise

• recommended to limit consumption and monitor portion consumed

Actions of GIT

1. secretion of substances: enzymes, mucus, bile

2. release of hormones to rest of body for ergulation of digestion, absorption & metabolism

3. digestion (both mechanical & chemical)

4. absorption

5. fermentation

6. excretion

Enzymes

chemicals that speed up body processes, can break apart/create new substances

Hormones

chemical messengers secreted by glands that impact body function at a distant site/organ

Digestion

breakdown of food into smaller components via mechanical and chemical methods

Fermentation

breakdown of non-digestible food components by microorganisms

Products of fermentation

• short-chain fatty acids

• gases

• vitamins

Excretion

elimination of waste products into stool

Major organs of GIT

• mouth

• pharynx & esophagus

• stomach

• small intestine

• large intestine

• rectum

Accessory Organs of GIT

• salivary glands

• liver

• gallbladder

• pancreas

Mouth

• chew and mix food with saliva

• salivary glands make saliva

• saliva contains enzymes amylase and lipase to begin carbohydrate and lipid digestion

Pharynx and Esophagus

swallowing moves food from mouth to stomach via peristalsis

Sphincter

ringlike muscular valves which prevent backflow of chyme

Stomach

• churns and mixes food into liquid mass (chyme)

• secretes acid and enzymes for protein digestion (pepsin) and minimal lipid digestion

• minimal absorption of water, some minerals, drugs and alcohol

Small Intestine

• primary stie of digestion and absorption - long in length

• segmentation: muscles contract and move food back and forth to churn it up

• enzymes secreted + enzymes from pancreas + bile from liver

• carbohydrates, fat and protein digestion into smallest components + absorption along with vitamins, minerals and water

Liver

makes bile to emulsify lipids

Gallbladder

stores bile and releases it into small intestine

Pancreas

makes digestive enzymes and releases them into small intestine

Large Intestine

• minimal digestion - no enzyme secretion

• bacteria action

• water and some vitamin and mineral absorption

• passes waste product and water - mucus secretion

Rectum

• stores waste just prior to elimination

• ileocecal valve opens to excrete feces

Passive Diffusion

• no energy needed

• nutrient goes from high to low conc.

• no protein carrier needed

• water, lipids, some minerals

Facilitated Diffusion

• no energy needed

• nutrient goes from high to low conc.

• with protein carrier

• fructose

Active Transport

• uses energy

• nutrient can go grom low to high conc.

• requires protein to carry across membrane

• glucose, animo acids, some vitamins and minerals

Waste products

• undigested/unabsorbed food

• microorganisms

• water & minerals

• true waste from liver and intestines

Enzymatic reactions

specific bonds, very dependent on:

• acid-base conditions

• substrate (type of bonds)

• presence of co-enzymes (vitamins), co-factors (minerals) and other compounds

Ulcers

• H. pylori degrades protective layer of cells in stomach/duodenum

• pain 1-3h after meal

• not caused by stress/alcohol/smoking but made worse

• treatment: meds to destroy microorganism

Heartburn

• reflux esophagitis due to weakened lower sphincter, which allows backflow of stomach acid into esophagus

• pain in chest behind sternum

• can be aggravated by coffee, alcohol & nicotine because of negative effects on sphincter tension

• treatment: avoid overfilling stomach, eat smaller meals, avoid laying down for a few hours after eating, meds

• chronic heartburn: gastoesophagul reflux disease (GERD)

Gallstones

• blockage of bile duct from gallbladder

• pain in upper-right abdomen/back

• fat malabsorption

• treatment: sometimes removal of gall bladder, low fat diet

Lactose Intolerance

• lack of enzyme lactase

• bloating & diarrhea from fermentation

• majority of adults

• many can still tolerate some dairy, esp. cheese/yoghurt

• treatment: avoidance, alternatives, lactase supplement (ensure adequate calcium)

Constipation

• painful, hard, difficult to pass bowel movements

• lack of fiber & other causes

• treatment: high fiber diet, plenty of fluid, exercise

Hemorrhoids

• swollen veins of rectum & anus due to straining when passing motion

• bleeding, pain, swelling

• lack of fiber

• prevention/management: high fiber diet

Diarrhea

• frequent watery stools

• infections, disease, stress, meds, food intolerance, lack of fiber

• prevent with fiber and avoidance of culprits

• treatment specific to cause

Celiac Disease

• genetic conditoin

• mucosal malabsorption caused by autoimmune disease

• damage to intestinal lining due to physiological response to gluten

• bloating, diarrhea, weight loss, rash etc.

• avoid wheat, rye and barley

Diverticulosis

• small pouches form in colon wall

• inflammation occurs from bacteria/irritants (diverticulitis)

• abdominal pain

• low incidence in high fiber diets

• treatment/prevention: high fiber diet

Monosaccharides

single sugar molecules

• glucose

• fructose

• galactose

Glucose

• produced by plants

• basic unit of starch and cellulose

• most abundant sugar in diet and body

• found in blood, table sugar etc.

• preferred energy source for brain

Fructose

• sugar commonly found in fruit and honey

• sweeter than any other sugar

• e.g. high fructose corn syrup

Galactose

• structure similar to glucose

• found in milk and dairy products

• present as monosaccharide in small intestine after digestion

Lactose

• glucose + galactose

• digested by lactase (most prevalent in children <5yo)

• found in milk products, up to ½ energy in milk, but less in some cheeses & yoghurt

• aka milk sugar

Maltose

• glucose + glucose

• maltose molecules join in food to form starch molecules

• digestible

• aka malt sugar