NUTRITION

Substances contained in food that an organism needs to function properly, to grow, to repair itself, and to supply the organism with energy

NUTRIENTS

REASONS FOR EATING• Physical need• Environment/Culture ex. Movies, • Religion, family gatherings• Emotions• Hunger: natural drive that protects the

organism from starvation• Appetite: a desire to eat rather than a

need to eat• Nutrition: process by which the body takes

in and uses food

CARBOHYDRATES

• Starches and sugars found in foods• Formed through a condensation reaction

where water is released by joining the hydroxyl group from one sugar to the hydrogen of the hydroxyl group of another sugar molecule

• Release of water is also called hydrolysis or dehydration

CARBOHYDRATES• Compounds containing carbon,

hydrogen, and oxygen atoms

• Two Types1. Monosaccharide:

• 5- or 6-carbon simple sugar• Open chain or cyclic• Monomers that bond to form

polymers (more complex)

GLUCOSE

CARBOHYDRATES

• Two Types2. Disaccharide:

• Two monosaccharide linked together by condensation reaction (H + OH → H2O)

• Examples –– Fructose (fruits)– Lactose (milk)– Maltose (grains)– Sucrose (table sugar)

DISACCHARIDE FORMATION

CARBOHYDRATES

• Polysaccharides– Polymers of simple sugars– AKA complex carbohydrates– Examples

• Starch (short-term energy storage in plants)• Cellulose (cell walls in plants → fiber)• Glycogen (short-term energy storage in animals)

SOURCES OF CARBOHYDRATES

• Complex Carbs– Must be converted to glucose to provide energy– When too many are eaten, are converted to fat– Sources: grains, seeds, nuts, legumes, tubers

(potatoes, yams, cassava, taro)

• Fiber– Cannot be digested but is important for movement of

wastes– May reduce risk of some cancers and heart disease– Sources of fiber: whole grain, bran, brown rice

oatmeal, corn

CARBOHYDRATES and HEALTH

• 60% Calories from carbohydrates recommended

• Provide most of the body’s energy

• Supply 4 Cal/g• Sources: grains,

fruits, vegetables

PROTEIN FORMATION

• Synthesized when the hydroxl group (–OH) of one amino acid combines with a hydrogen from the amine group (–NH2 ) of another amino acid

• Water is released as the protein is formed• Consequently, called condensation reaction

PEPTIDE BOND

• Bond formed when two amino acids combine to form an amide

• Dipeptide

Proteins – Major structural components of living things.

• Major structural components of living things• Organic polymers are made of amino acids

(multiple repeating units)• Made from elements: C, H, O, N, and S• The amino acid is the basic building block or

monomer• Amine = NH2 Acid = COOH

PROTEINS and HEALTH

• Made from long chain (50–1000) of amino acids.

• 20 different amino acids form all necessary proteins

• Eight amino acids are essential• Amino acids are not produced by body so

must be consumed as foods• Proteins make up muscle, bone, brain cells,

blood cells, genetic matter, skin, hair, fingernails, etc.

• Proteins in food supply 4 Calories/g

SOURCES OF PROTEIN

• Complete proteins contain all essential amino acids– Found in fish, meat, poultry, eggs, milk,

cheese, yogurt

• Incomplete proteins lack some amino acids– Legumes, seeds, whole grains

LIPID FORMATION

• Formed when a fatty acid combines with a glycerol molecule

• The hydroxyl group (–OH ) from one fatty acid combines with the hydrogen (–H) from the hydroxyl group (–OH) of the glycerol molecule

• Water is released, making it a condensation reaction

Glycerol + 3 Fatty Acids → Lipid (fat) + 3 water molecules• Glycerol has alcohol group (–OH)• Fatty acid has long carbon chain + COOH (acid)

LIPID FORMATION

• Large, nonpolar, biological molecules

• Contains C, H, O• Make up structures

of cell membranes (phospholipids)

• Fatty Acid is the building block

• Triglyceride is fat formed from three fatty acids.

LIPIDS or FATS

TYPES OF FATS• Saturated fats, such as butter and lard, come

from animals– Contain only single bonds– Holds all hydrogen atoms (transfats)

• Unsaturated fats, called oils, come from plants – Contains one or more double bonds– Missing one or more pairs of hydrogen– Healthier than saturated fats

FATS & HEALTH• 30% Calories from fat

recommended• 10% (maximum) from saturated fats• Supply 9 Cal/g; most concentrated

form of energy• Stored energy in the body• Insulates, supports, and protects

vital body parts• Protective barrier for skin• Involved in hormone production• 2/3 of the brain is fat!

ROLE OF FATS

• Add flavor to foods• Carry vitamins A, D, E and K• Cholesterol, found in foods of animal

origin, is needed to make and maintain cell membranes– HDL (high density lipoproteins) – “good”

cholesterol– LDL (low density lipoproteins)- “bad”

cholesterol that clogs arteries

VITAMINS

• Regulators for body processes• Do not supply energy• Two Types

– Water-soluble vitamins pass easily into the bloodstream; include Vitamin C and all B vitamins

– Fat-soluble vitamins are stored in fatty issues; Vitamins A, D, E, and K

MINERALS

• Inorganic substances that regulate body processes – For example, iron is essential for hemoglobin

• Hemoglobin carries oxygen in the blood• Iron is available in foods, such as meat and fish• Lack of iron can lead to anemia

– Calcium is necessary for bone strength and development• Lack of calcium leads to poor bone density and

possibly osteoporosis in later life

WATER• Essential for body functions• Body uses about 10 cups per day• More water is necessary in high temperatures or

while exercising• Role of water:

– Carries nutrients to the cell– Transports waste from the cell– Lubricates joints and membranes– Aids in swallowing and digesting foods– Perspiration– Absorbs nutrients– Absorbs wastes from body

• Energy is released through chemical reactions during metabolism.

• Different nutrients are used as fuel for burning or as building material for the body.1. Carbohydrates are nutrients burned as

fuel. 1 gram carbohydrate = 4.0 Cal energy

2. Building nutrients include fats, proteins, vitamins and minerals. 1 gram fat = 9.0 Cal energy 1 gram protein = 4.0 Cal energy

Nutrients and Calorimetry

• The energy unit for measuring energy in foods is the nutritional or food Calorie (Cal).

1 Cal = 1 kcal = 1000 cal

• Recall: The specific heat of water is equal to

1.00 cal/g°C

Nutrients and Calorimetry

q = cm∆T

Heat Equation with Foods

Variable Representation Unit

q = cm∆T

Heat Equation with Foods

Variable Representation Unit

q The heat absorbed or released cal

q = cm∆T

Heat Equation with Foods

Variable Representation Unit

q The heat absorbed or released cal

c The specific heat cal/g°C

q = cm∆T

Heat Equation with Foods

Variable Representation Unit

q The heat absorbed or released cal

c The specific heat cal/g°C

m The mass of substance g

q = cm∆T

Heat Equation with Foods

Variable Representation Unit

q The heat absorbed or released cal

c The specific heat cal/g°C

m The mass of substance g

∆T The temperature change °C

RECALL 1 gram carbohydrate provides 4 Cal of energy 1 gram fat provides 9 Cal of energy 1 g protein provides 4 Cal of energy

Nutrition labels give information about the grams of carbohydrates, fats, and proteins in each serving.

NUTRITION LABELS

FACTORS AFFECTING CALORIC NEED

• Activity level• Age• Gender• Metabolic rate• Rate of growth

• To lose weight safely, cut 500 calories per day

THE END