Carbohydrates

Proteins

Fats

Minerals

Vitamins

Water

Fibre (Roughage)

C = carbo H20 = hydrate

Basic formula (CH20)n

All Carbohydrates are converted to glucose and absorbed into

the blood

Glucose – vital fuel: n = 6 C6 H12 O6

CHO have a reciprocal relationship with fat ↑ CHO → ↓ Fat

Chemically carbohydrates are defined by their number of

saccharide units in their structure

Monosaccharides

Disaccharides

Oligosaccharides

Polysaccharides

Originate from plants – CO2 + H2O – Photosynthesis

Not all carbohydrates are digestible

1 gram of carbohydrate = 4kcal

In our diet, starches and sugars are main sources of dietary

carbohydrate

Function of Carbohydrate – supply energy, protein sparing,

prevents ketosis – breakdown fatty acids

Intrinsic sugars: sugars which are incorporated within intact

plant cell walls; eg. fruit and vegetables

Extrinsic sugars: refined sugars; eg. Fruit juices, honey and

milk

Non-milk extrinsic sugars: sugars are present in a free and

readily absorbable state eg. sucrose

Total carbohydrate intake should provide up to 50% energy

Non-milk extrinsic sugars should not exceed 11% energy

intake

Starches, intrinsic and milk sugars should contribute to 39%

energy intake

Certain diets promote restricted intake of carbohydrates

Atkins Diet – low carbohydrate diet

GI Diet – Encourages foods with low glycaemic index (GI)

<60

Contains carbon, hydrogen, oxygen and nitrogen

Protein regulates and maintains body functions; structural

(skeleton, connective tissues), protective (tears, mucus),

transport (plasma proteins and hormones) and enzymatic

(protein synthesis)

Protein are made up of 20 different amino acids bonded

together in different sequences to form may SPECIFIC

proteins

Twenty amino acids are important in nutrition

All amino acids have an acid group and an amino group

attached to a carbon atom

The rest of the amino acid is represented by R and is different

for every amino acid

The carbon to which the carboxyl is attached is the alpha-

carbon

Amino acids have 4 different groups around the alpha carbon

resulting in optically active L or D isomers or enantiomers

Essential (indispensable) Amino Acid

- One that the body is unable to make or can only make in

inadequate quantities

- Need to be consumed from the diet

- 8-10 essential amino acids

Nonessential (dispensable) Amino Acid

- One that the body can make in large enough quantities

(Made from essential amino acids)

- Not necessary to consume these in the diet

- 10-12 nonessential amino acids

Essential Amino

Acids

◦ -Phenylalanine◦ -Valine◦ -Threonine◦ -Tryptophan ◦ -Isoleucine◦ -Methionine ◦ -Histidine◦ -Arginine◦ -Leucine◦ -Lysine

Nonessential Amino Acids

-Alanine-Asparagine-Aspartic acid-Cysteine-Glutamic acid-Glutamine-Glycine-Proline-Serine-Tyrosine

Conditionally essential Amino Acids

-Cysteine -Glutamine -Tyrosine

Used in body organs and soft tissues

Enormous functional diversityCell membrane structure and functionEnzymesHormones and other chemical messengers

Immune factors (antibodies)

Fluid Balance

Transport

Source of energy

Structural and Mechanical – Collagen in bone and skin; Keratin

in hair and nails; Motor proteins, which make muscles work

Enzymes

Proteins that catalyze (speed up) chemical reactions

without being used up or destroyed in the process

Anabolic (putting things together) and catabolic (breaking

things down) functions Eg. Digestion – salivary amylase

Hormones

Chemical messages that are made in one part of the body

but act on cells in other parts of the body Eg. Insulin, some

reproductive hormones

Immune Function

Antibodies are proteins that attack and inactivate bacteria and viruses that cause infection

Fluid Balance

Proteins in the blood help to maintain appropriate fluid levels in the vascular system.Fluid is forced into tissue spaces by blood pressure generated by pumping action of heart.

Transport substances in the blood

Lipoproteins (transport lipids)

Hemoglobin ( transports oxygen and carbon dioxide)

Transports materials across cell membranes

Proteins are the last to be used for energy

Occurs in starvation and low carbohydrate diets

When the body has excess protein stores, some amino acids

are converted and stored as fat in body

Sources of protein

Functions include;

Provide energy

Efficient storage of energy (adipose tissue)

Insulation

Essential nutrients required for; metabolic and

physiological processes, structural and functional integrity

of cell membranes

Control body temperature

Physical protection to internal organs

Transport fat soluble vitamins

Flavour and mouth feel

Simplest form – composed of a chain of carbons with

hydrogen atoms attached, methyl group and a carboxylic

groupMethyl group

Acid group

Double Bond

High energy component – 9 kcal per gram

Most important contain 16-18 carbons

Whether a fat is saturated, monosaturated or polysaturated

depends on the location of the double bond

Only single bonds

High melting temperature

Solid at room temperature

Chemically stable

Examples include animal fats and

their products

Linked with risk of cardiovascular

disease

Contain one double bond

Usually liquid at room temperature

Examples include olive oil, rapeseed

Oil, nuts and seeds

Most beneficial type of fatty acid

Lower LDL cholesterol

Contain 2 or more double bonds

Liquid at room temperature

Susceptible to oxidation

Omega 3 and 6

Polyunsaturated fatty acids are

needed in brain development

Processed margarines contain

significant amounts of trans fat

Same adverse affects as

saturated fatty acids

Wax like substance

Produced by the liver

Belongs to steroid family

Important to limit dietary

cholesterol

Cholesterol is essential to life

required for synthesis of bile acids

steroid hormones and vitamin D

Less than 35% of energy intake should come from fats

No more than 10% from Saturated fatty acids

No more than 12% Monounsaturated fatty acids

No more than 6% N-6 Polyunsaturated fatty acids (PUFA)

0.2g/day minimum N-3 Polyunsaturated fatty acids (PUFA)

<2% Trans fats

◦ Certain populations may need higher intakes of n-3

Reduced fat = at least 25% less fat than the standard

product

Low fat food = <3g fat/100g or 100ml

Fat free = <0.15g fat/100g or 100ml

Essential organic substances, they yield no energy, but

facilitate energy-yielding chemical reactions

Essential nutrients in maintenance of normal health

Obtained from food because the body can’t make them

But you need only small amounts (micronutrients) because

the body uses them without breaking them down, unlike what

happens to carbohydrates and other macronutrients

13 compounds have been classified as vitamins

Vitamins A, D, E, and K, the four fat-soluble vitamins, tend

to accumulate in the body

Vitamin C and the eight B vitamins (biotin, folate, niacin,

pantothenic acid, riboflavin, thiamin, vitamin B6, and vitamin

B12) dissolve in water, so excess amounts are excreted

(water-soluble vitamins)

Vitamin A = Retinol,

retinaldehyde, retonoic acid

(performed) and

carotenoids (provitamin A)

Vitamin B1 = Thiamin

Vitamin B2 = Riboflavin

Vitamin B6 = Pyridoxine,

pyridoxal, pyridoxamine

Vitamin B12 = Cobalamin

Vitamin C = Ascorbic Acid

Vitamin D = Calciferol

Vitamin E = Tocopherol,

tocotrienol

Vitamin K = Phylloquinone

Function – Promote Vision and Growth, prevent drying of skin and eyes

Food Sources – Performed (Liver, fish oils, fortified milk and eggs)

Proformed (Dark leafy green, yellow orange vegetables & fruits

Deficiency – Cause night blindness, skin changes and nutritional anaemia

Those at risk – Urban poor, breast fed infants (mother’s poor diet) elderly, schoolchildren (poor veg. intake)

Function – Calcium absorption, regulate bone metabolism, healthy immune system

Food Sources – Herring, eel, salmon, tuna, milk, some fortified cereals, pork sausage, egg yolk (sunlight)

Deficiency – Rickets in children, Osteomalacia in adults

Those at risk – Elderly (stay indoors) People living in Northern Climate, People with fat malabsorption

Function – Antioxidant, protects cells from attacks by free radicals, role in iron metabolism

Food Sources – Vegetable oils, nuts, seeds, green leafy vegetables and a variety of fish

Deficiency – Nerve degeneration

Those at risk – Premature infants, smokers, people with fat malabsorption

Function – Role in coagulation process (blood-clotting)

Food Sources – Liver, green leafy vegetables, broccoli, peas and

green beans

Deficiency – Bleeding disorders, fractures

Those at risk – People taking antibiotics for long periods

Function – Aids in calcium / iron absorption, immune functions

Food Sources – Citrus fruits, potatoes, green peppers, cauliflower, broccoli, strawberries

Deficiency – Scurvy, fatigue, bleeding gums and joints

Those at risk – Infants, elderly, alcoholics, smokers

The major minerals present in the body include sodium,

potassium, chloride, calcium, magnesium, phosphorus, and

sulfur.

Trace minerals are present (and required) in very small

amounts in the body. The most important trace minerals are

iron, zinc, copper, chromium, fluoride, iodine, selenium and

manganese.

Adults are 60-70% water

Functions - Maintain the health and integrity of every cell in the body.Help eliminate by-products of the body’s metabolism, excess electrolytes (sodium & potassium). Regulate body temperature through sweating.

Dehydration occurs when the water content of the body is too low. This is easily fixed by increasing fluid intake. Symptoms of dehydration include headaches, lethargy, mood changes and slow responses, dry nasal passages, dry or cracked lips, dark-coloured urine, weakness, tiredness, confusion and hallucinations.

Recommended intake depends on age, hot environment etc. Averages between 6-10 cups/day