Food and Nutrition: Midterm #1

Exam #1 Food & Nutrition: Weeks 1-5

Nutrition Studies?

1. Nutrients in the body

2. Nutrients in the food

3. Human behaviour in relation to food

Nutrigenomics

How nutrients affect gene activity

Nutrigenetics

How genes affect a person’s response to nutrients

Nutrients - 6 groups

Carbs

Fats

Proteins

Vitamins

Minerals

Water

Organic Micronutrients

Vitamins (contains carbon)

Inorganic Micronutrients

Minerals (no carbon)

Fat-soluble Vitamins

Vitamins A, D, E, K

Water-soluble Vitamins

Vitamins C and B

Major Minerals

Sodium

Potassium

Chloride

Phosphorus

Calcium

Magnesium

Sulphur

Trace Minerals

Selenium

Fluoride

Iodide

Chromiun

Manganese

Iron

Zinc

Copper

Essential Nutrients

Nutrients the body cannot make

Nurtaceutical

Food product with medicinal (theraputic) effect

Functional Foods

Resemble traditional foods but contain physiologically active components that provide health benefits

Phytochemicals

Non-nutrient foods found in plants that have biological activity on the body

e.g., flavonoids, carotenoids

Influences on Dietary Choice

1. Intrapersonal - MICRO

2. Interpersonal (social) - MICRO

3. Settings - MESO

4. Policies - MACRO

Calorie

Measurement of a unit of energy. In nutrition, measured in kilocalories (kcal).

1 kcal = amount of heat required to raise the temp of 1L of water by 1°C

Energy yielding nutrients per 1g

Protein - 4kcal/g

Carbs - 4kcal/g

Fats - 9kcal/g

(Alcohol - 7kcal/g) not a nutrient: doesn't benefit the body in any way

Energy Density

Amount of energy (kcal) per weight of food

Dietary Reference Intakes (DRIs)

Values refer to general nutrient adequacy. Applicable to healthy persons. Varies by sex and age.

Two types:

1. Nutrient reference values

2. Energy reference values

DRI’s—Nutrient Reference Values

1. Estimated Average Requirements (EAR)—Sufficient for 50% of people

2. Recommended Dietary Allowance (RDA)—Sufficient for 97% of people

3. Adequate Intakes (AI)—if not enough data for EAR or RDA

4. Tolerable Upper Intake Limit (UL)

5. Chronic Disease Risk Reduction Intakes (CDRR)—only sodium

DRI’s—Energy Reference Values

1. Estimated Energy Requirement (EER)—Energy/Calories

2. Acceptable Macronutrient Distribution Ranges (AMDR)—Diet composition

• Protein: 10-35%

• Fats: 20-35%

• Carbohydrates: 45-65%

Nutrition Assessment - ABCD

Anthropometric: height/weight, body fat, head circumference, growth charts

Biochemical: biological markers. Determine covert deficiencies + DNA/enzyme

Clinical: health history and visual assessment

Dietary: assessment of dietary intake. Collect, Quantify, Evaluate, Compare

**Must be used together**

Nutrition Assessment—Community

Nutrition health of a community: use broad health status indicators. Data is used for program development and policy

Chronic Disease + Risk Factors

Characterized by a slow progression and long duration.

Risk Factors: Genetics, lifestyle, elevated blood pressure, cholesterol, and blood glucose.

***Diet as a lifestyle factor can greatly reduce the risk of developing a chronic disease

Diet Planning Principles

1. Adequacy

2. Balance

3. Energy Control

4. Nutrient Density

5. Moderation

6. Variety

Canada’s Food Guide—What to Eat

1. Vegetables and Fruit

2. Protein foods

3. Whole grains

4. Drink water—limit sugary drinks

Canada’s Food Guide—How to Eat

1. Be mindful of eating habits

2. Cook more

3. Enjoy foods

4. Eat with others

5. Use food labels

6. Limit highly processed foods

7. Pay attention to marketing

Food Labels

Regulated by the Food and Drugs Act and enforced by CFIA. Are mandatory. Claims are strictly managed to be true. Based on 2000kcal diet. English and French. Priority allergens. Best before. Name of importer/manufacturer

Gastrointestinal Tract

Long continuous flexible tube from the mouth to the anus.

• Inner spaces within the GI tract called lumen

• A nutrient must penetrate through the GI tract wall to enter the body

• Many materials pass through the GI tract undigested and are excreted

Mouth - GI Tract

• Mechanical (mastication) and chemical digestion begin

• Swallowed food passes into the pharynx

• The epiglottis closes over the airway to allow for food (bolus: lubed-up chewed food) to move into the esophagus (part of GI tract)

Stomach - GI Tract

Upper and lower portions

• Adds digestive juices to form chyme

• Pyloric sphincter—opens to release chyme into the small intestine

Intestine - GI Tract

Small Intestine

• Duodenum, jejunum, ilium

• 3m long

• Digestion and absorbtion

Large Intestine (Colon)

• Ileocecal sphincter

• Water reabsorption occurs

• End at the rectum/anus—muscles contract to hold contents in and relax to release

Mechanical Digestion

Chewing & Swallowing: Break food into smaller pieces

Peristalsis: Contraction and relaxation of circular and longitudinal muscles along the GI tract, 3x/min in the stomach, 10x/min in the small intestine—moves food through the tract

Stomach Action: Thickest walls and strongest muscles of the stomach, 3 layers

Segmentation: contractions of the small intestine continue to break down food—splits up food into smaller pieces

Sphincter Contractions

Sphincter Contractions

• Esophageal—upper lets food into esophagus, lower lets food into stomach

• Pyloric—keeps contents in stomach, opens 3x/min to allow chyme into S.I.

• Ileocecal—allows contents to leave small intestine

• Anal—pervents continuous elimination

Chemical Digestion—5 Organs

Salivary Glands

Stomach

Pancrease

Liver (via gallbladder)

Small Intestine

Chemical Digestion—Enzymes

A protein that facilitates a chemical reaction, remains an unchanged catalyst.

• Digestive enzymes facilitate hydrolysis

Common digestive enzymes

• Carbohydrase

• Lipase

• Protease

Chemical Digestion—Saliva

From salivary glands, contains water, salt, mucus and enzymes

• Salivary amylase starts the digestion of CHO (carbs)

• Moistens food

• Protects teeth, mouth, esophagus, and stomach

Chemical Digestion—Gastric Juice

Secreted from the stomach

• Mixture of water, enzymes, and hydrochloric acid (HCL)

HCL: helps protein digest, protects stomach from bacterial growth, reflux in esophagus is the cause of heartburn

Chemical Digestion—Pancreatic Juice and Intestinal Enzymes

Secreted into the first portion of the small intestine

• Pancreatic Juice; Contains enzymes to work on all 3 macro nutrients and sodium bicarbonate to neutralize acidity of the acidic chyme from stomach

• Intestinal Enzymes: Crypt glands secrete intestinal enzymes on the surface of the cells lining the intestinal wall. Goblet cells create mucus

Chemical Digestion—Bile

Made in the liver, storedin the gallbladder, released in the duodenum

• emulsifying agent for fat (not an enzyme)

• Flows into the small intestine when dietary fat arrives in the small intestine

Absorption

Most absorbtion happens in the small intestine. It is 3m in length but has the surface area of a tennis court, looks smooth but is actually wrinkly.

Villi: fingerlike projections constantly moving ready to trap nutrients

Microvilli: absorptive area on the villi

Crypt Glands: between the villi; secrete intestinal juices (enzymes)

Goblet Cells: secrete mucus

• Most absorbtion happens in the jejunum

Types of Absorption

1. Simple Diffusion

2. Facilitated Diffusion

3. Active Transport