Science of Nutrition Final

DRI (dietary reference intakes)

DRI (dietary reference intakes)

• created by National Academies of Science, Engineering, and Medicine (NASEM)

• allows us to calculate daily nutrient recommendations for calories, macronutrients, vitamins, and minerals

EAR (Estimated Average Requirements)

• created by The US Department of Agriculture

• Average amount sufficient for half of population (50%)

RDA (Recommended Dietary Allowance)

• created by the Food and Nutrition Board

• Recommendations to meet needs of most healthy people (98%)

  • Set near the top end of the range of EAR

AI (Adequate Intake)

• created by estimates of nutrient intake by a group (or groups) of healthy people

• For some nutrients, when insufficient scientific evidence to establish EAR

  • Expected to exceed average requirements

UL (Tolerable Upper Intake Levels)

• created The World Health Organization

• Point where nutrient is likely to be toxic

• Helps protect against overconsumption

AMDR (Acceptable Macronutrients Distribution Ranges)

• Adequate energy and nutrients

  • Reduce risk of chronic diseases

• Ranges

• 45-65% kcalories from carbohydrate

• 20-35% kcalories from fat

• 10-35% kcalories from protein

Scientific Method

Systematic process for conducting research

Steps in scientific method

1. Observation and Question

2. Hypothesis and Prediction

3. Experiment

4. Results and Interpretations

5. Hypothesis Supported

   1. theory

6. Hypothesis Not Supported

   1. restart w/ new

Double-blind Experiments

• Neither subjects nor researchers know which subjects are in the control or experimental group

Epidemiological Studies

• the study of the distribution (frequency, pattern) and determinants (causes, risk factors) of health-related states and events (not just diseases) in specified populations

• Examples

  • Cross-sectional studies

  • Case-control studies

  • Cohort studies

Experimental Studies

• where researchers introduce an intervention and study the effects

• Examples

  • Laboratory-based animal studies

  • Laboratory-based in vitro studies

  • Human intervention (clinical) trials

Dietary Guidelines for Americans

• created by the USDA and HHS

• Evidence-based advice

  • Attain and maintain a healthy weight

  • Reduce risk of chronic disease

  • Promote overall health

MyPlate Recommendations

• Educational tool combines USDA Food Patterns and Dietary Guidelines

Nutrient Dense Choices

• Food that is high in nutrients but relatively low in calories

Discretionary kcalories

• Difference between kcalories needed to supply nutrients and those to maintain weight

Food Labels

• Product not required to have

• On label

  • serving size/number of servings

  • kcal info

  • quantities for nutrients per servings (% Daily Values)- 2000 cal intake

  • kcal per gram reminder

  • daily value reminder

  • ingredients decreasing by weight

Nutrient Facts Label

• product required to have

• on label

  • Total food energy and food energy from fat

  • Total fat

  • Saturated fat, trans fat, and cholesterol

  • Sodium

  • Total carbohydrate, dietary fiber, and sugars

  • Protein

  • Vitamins A and C, iron, and calcium

Nutrient Claims

• Meet FDA definitions

• characterize the level of a nutrient in the food

• example

  • fat free

  • less sodium

Health Claims

• characterize the relationship of a food or food component to a disease/health related condition

• Example

  • reduce risk of heart disease

Structure/Function Claims

• describe the effect that a substance has on the structure or function of the body and do not reference a disease

• Example

  • supports immunity

  • calcium builds strong bones

saliva

• pH=7

• Fluid eases swallowing

• salivary enzyme breaks down some carbohydrate

salivary glands

• produces saliva

chyme

• A mixture of partially digested food, water, and gastric juices

• made by the stomach

gastric juices

• pH = 2

• mixture of water, enzymes, and hydrochloric acid

• acts primarily in protein digestion

mucus

• protects stomach wall cells from acid

HCL (hydrochloric acids)

uncoils proteins

villi

• Select and regulate nutrients absorbed

• found in the small intestine

microvilli

• Enzymes and ‘pumps’ recognize and act on different nutrients

• found in the small intestine

Monosaccharides

• single sugars

• Simple carbohydrates

• Example

  • Glucose

  • fructose

  • galactose

Disaccharide

• sugars composed of pairs of monosaccharides

• Example

  • Maltose

  • sucrose

  • lactose

Polysaccharide

• large molecules composed of chains of monosaccharides

• Example

  • Complex carbohydrates

Dietary Fibers

• are the structural parts of plants

• polysaccharide

• Found in

  • veggies

  • fruits

  • whole grains

  • legumes

Starches

• Glucose molecules linked together in branched or unbranched chains

• polysaccharide stored in plants

• the bonds between their monosaccharides can be broken down by digestive enzymes in the body.

Glycogen

• Glucose molecules linked together in highly branched chains

• A polysaccharide stored by animals

• Hydrolysis to release glucose when needed

• stored in

  • liver

  • muscle

What hormones involved in blood glucose homeostasis?

insulin: lowers

glucagon/epinephrine: increases

Diabetes

• Blood glucose rises after a meal and remains above normal levels due to Insulin inadequate or ineffective

type 1 diabetes

• Less common

• Pancreas fails to produce insulin (inadequate)

type 2 diabetes

• More common

• The cells fails to respond to insulin (ineffective)

• Chronic condition tends to occur as a consequence of obesity

saturated fats

• tend to be solid

• single bonds

• full of hydrogens

• animal fats

unsaturated fats

• tends to be liquid

• double bonds

• missing hydrogens

• vegetable oils

goal of fat digestion

• to dismantle triglycerides  into smaller molecules the body can absorb and use

• occurs mostly in small intestine

fat digestion in mouth

• produces lingal lipase

• big role for infants

• small role for adults

fat digestion in stomach

• produces gastric lipase

• Break up fats into smaller droplets

• little fat digestion occurs here

fat digestion in small intestine

• most fat digestion occurs here

• Hydrolysis of triglycerides and phospholipids by fat-digesting enzymes

• produces pancreatic lipases

• produces intestinal lipases

fat digestion in liver

synthesizes bile

fat digestion in gallbladder

• stores bile

Bile

• emulsifies fats in small intestine

• Cholecystokinin (CCK) signal release

Role of triglyceride

1. provide the cells w/energy

2. Secretes hormones (adipokines)

3. Regulate energy balance, influence body functions

4. Skin insulation

5. Shock absorption

6. Cell membrane material

7. Cell signaling pathways

essential fatty acids

• Omega-6 and omega-3 fatty acids

  • Linoleic acid

  • Linolenic acid

Linoleic Acid

• Omega-6 fatty acid

• Desaturation

• Elongation

• Sources

  • vegetable oils

  • meats

Linolenic Acid

• Omega-3 fatty acid

  • Cannot be made in the body

• fatty fish (herring, mackerel, salmon, sardines, tuna), flaxseed, chia seed, and etc.

essential amino acids

• Must be supplied by the diet

Nonessential amino acids

• Body can synthesize

Transamination

the transfer of amino groups from an amino acid to a keto acid forming a new nonessential amino acid

deamination

• Stripped of nitrogen-containing amino group

protein synthesis’ 2 main steps

1. transcription

2. translation

How does protein synthesis occur

• Transcription (DNA to mRNA)

• mRNA carries code to ribosome

• mRNA specifies sequence of amino acids

  • Translation to tRNA

• Sequencing errors

gene expression

the process by which the information encoded in a gene is turned into a function

protein denaturation

• Disruption of stability and shape

• Uncoil and lose shape

• Allows the breaking of proteins during digestion

incomplete proteins

• a protein that does not contain all nine essential amino acids

• examples

  • Nuts and seeds.

  • ‌Whole grains

  • ‌Vegetables.

  • Legumes

complete proteins

• contain all nine essential amino acids in consistent amounts.

• examples

  • Fish

  • Poultry

  • Eggs

  • Beef

Hydrochloric Acid in protein digestion

• denatures proteins

hormones/enzymes in the stomach for protein digestion

• Hydrochloric acid

• Pepsinogen

• Pepsin

hormones/enzymes in the small intestine for protein digestion

• Peptidase enzymes

Functions/roles of protein (10)

1. Building blocks for most body structures (collagen matrix)

2. Replacement of dead or damaged cells

3. Act as enzymes

4. Hormones

5. Regulators of fluid balance

6. Acid-base regulators

7. Maintain a strong immune system

8. Source of energy and glucose

9. Blood clotting

10. Vision

Phenylketonuria (PKU)

a condition in which your body can't break down an amino acid called phenylalanine

Sickle Cell Anemia

an abnormal form of hemoglobin that causes the red cells to become rigid, and sickle shaped

Cystic Fibrosis

have a faulty protein that affects the body's cells, tissues, and the glands that make mucus and sweat

ATP

• Provides energy for all cell activities

• The bonds connecting the three phosphate groups are high-energy bonds

How do we get energy from ATP

• When the bonds break, splitting one or two phosphate groups and releasing energy

coenzymes

• Organic

• Associate with enzymes

• Without coenzyme, an enzyme cannot function

phosphorylation

• the addition of a phosphoryl (PO3) group to a molecule

• allows for storage and transfer of free energy using energy carrier molecules

oxidation reduction reaction

• any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron

• energy is released when an electron loses potential energy as a result of the transfe

glycolysis

• It is an anaerobic reaction

• enables carbohydrates to enter the TCA cycle in order to participate in energy production.

• refers the reaction from glucose to pyruvate.

• 2 to 4 to 2 ATP

beginning products of glycolysis

2 ATP

end products of glycolysis

2 ATP

TCA cycle

• occurs in inner mitochondria

• final common metabolic pathway for carbohydrates, fats, and amino acids

• produces energy

end products of TCA cycle

two GTP, six NADH, two FADH2, and four CO2.

beta oxidation

• where fat is converted to acetyl CoA.

• occurs in mitochondria

end products of beta oxidation

• one molecule of acetyl CoA and a fatty acyl CoA

gluconeogenesis

• glycogen is used up and protein may be broken down from muscle for energy

• occurs during starvation

alcohol metabolism

• The conversion of alcohol to acetyl CoA requires the B vitamin niacin in its role as a coenzyme. When the enzymes oxidize alcohol, they remove H atoms and attach them to the niacin coenzyme.

alcohol effects on liver

• Fat accumulates in the liver

alcohol effects on brain

• cells die after excessive exposure to alcohol

BMI

• is a person's weight in kilograms (or pounds) divided by the square of height in meters (or feet)

• healthy=  18.5 to 24.9

distribution of body weight

• healthy =18.5-24.9

• overweight = 25-29.9

• obese = 30-39.9

hormones that increase satiety

• leptin

• CCK

hormones that decrease satiety

• Ghrelin

components of total energy expenditure

1. physical activities = 30-50%

2. thermic effect of food = 10%

3. Basal metabolism = 50-65%

detriments of physical activity

• Muscle mass

• Body weight

• The level of activity

detriments of thermal effect of food

• high protein vs. high fat

• meal consumption time frame

detriments of basal metabolic

• gender

• age

• weight/height

• physical activity

Effects of gender on energy expenditure

• Women have a lower BMR than men due to less lean body mass

Effects of age on energy expenditure

• BMR declines during adulthood as lean body mass

Effects of body composition/size on energy expenditure

• Height

  • BMR is higher in people who are tall and have a large surface area

• Weight

characteristics of anorexia

• Distorted body image

• Malnutrition

• Denial

characteristics of bulimia

• Recurrent episodes of binge eating

• Recurrent inappropriate compensatory behavior to prevent weight gain

• Self-induced vomiting

• Misuse of laxatives

female athlete triad

• Disordered eating

• Amenorrhea

• Osteoporosis

role of thiamin

• Assists in energy metabolism

  • Conversion of pyruvate to acetyl CoA

  • TCA cycle

• Nerve activity and muscle activity

thiamin deficiency causes

• Beriberi

  • Dry – affects nervous system

  • Wet – affects cardiovascular system