Exam 1 - Food & its Properties

6 essential nutrients categories

Water

Carb, lipid (fat & oil), protein (macronutrient)

vitamin, mineral (micronutrient)

nutrient & 3 functions

substance in food that the body can use to obtain energy, synthesize tissues or regulate functions

• Cell & body structure: lipid, protein, water, minerals

• Provide energy: carb, lipid, protein

• Regulate body processes: lipids, proteins, water, vitamins, minerals

Three major functions of dietary functions

1. Contribute to cell & body structure

2. Provide energy

3. Regulate body processes

Organic nutrients

carb, lipid, protein, vitamin

1 kcal

The amount of energy needed to raise the temp of a kilogram of water 1 degree C

1 food calorie = 1 kilocalorie = 1,000 calories

Measuring food energy

Carb: 4 cal/g

Protein: 4 cal/g

Lipid: 9 cal/g

Alcohol: 7 cal/g

% cal from fat

30% or less of total calories should be from fat

Digestion vs. Absorption

Digestion: chemical + physical breakdown of food into smaller units

Absorption: movement of digested nutrients from the GI tract into the bloodstream

Stomach gastric juice composition

HCl (pH 2.0)
Mucus: coats and protects stomach lining
Enzymes: begins breakdown of protein & lipid (fat)
Gastrin: stimulates gastric secretion and movement


Notes: alcohol is absorbed easily on an empty stomach

Small intestine

Absorb nutrients

Duodenum: secretions from pancreas neutralize high acid of stomach contents
Jejunum: digested nutrients are absorbed
Ileum: absorption completes

In-between cells: gap junction - can control distance btw cells → needs to be tight to prevent bacteria from going through

Large intestine

Finishes up absorption, where the microbiome subsides.

Vitamin K is produced and absorbed
Remaining water and electrolytes (sodium, chloride, potassium) are absorbed

Energy Needs

1. Basal Metabolic Rate (BMR): the amount of energy needed to keep involuntary processes going

   1. breathing, body temp

2. Voluntary Physical Activity: the amount of energy needed based on physical movement

   1. only thing we can control

3. Dietary Induced Thermogenesis (DIT): the amount of energy needed to digest, absorb, transport, and metabolize nutrients

   1. depends on what you eat

Caloric imbalance

Gain 1 lb: consume 3500 cal in excess

Lose 1 lb: consumer 3500 too few

Carbohydrates

Sweetness (simple sugar, texture) and texture (polysacch)

Simple sugars (-ose)

• monosaccharides (C6H12O6): glucose & galactose (hexose), fructose (pentose)

• disaccharides: sucrose (glu + fru), lactose (glu + gal), maltose (glu + glu)

Complex polysaccharides:

• starch: digestible, in form of amylose (straight chains) and amylopectin (branched chains)

• dietary fiber: no cal

Sugar alcohol

Sugar replacer, polyols, bulk sweeteners

ex. lactitol, maltitol, isomalt, sorbitol, xylitol, mannitol

cooling effect on tongue

laxative effect may occur

promote dental health (cannot be fermented by bacteria in mouth b/c extra hydroxyl (OH) groups)

Aspartame

synthetic sweetener composed of two amino acids (dipeptide): aspartic acid & phenylalanine

PKU (phenylketonuria): people who cant metabolize phenylalanine - causes brain damage

Sucralose

Sucrose with 3 chlorine atoms sub for 3 Cl groups

PROVIDES NO CALORIES

Saccharin

300x as sweet as sucrose

NO CAL, heat stable, but unpleasant bitter or metallic aftertaste

HFCS

Around equal parts of fructose and glucose

amylose from cornstarch (catalyst amylase) → maltose (catalyst maltase) → glucose (catalyst glucose isomerase) → fructose

50% yield