Nutrition

Question 1

COMPONENTS OF FOOD

Answer 1

• Nutrients→ organic molecules (carbs, proteins, lipids) water, vitamins and minerals the body needs for development and growth, repair and maintenance of structures and physiological processes

2 types of nutrients;

• Macronutrients→ needed in large amounts in diet (in gram amounts)
• Micronutrients→ needed in small amounts in diet (in mg or less)

Question 2

Macronutrients

Answer 2

Carbohydrates (sugars, starches and fibre)
Lipids (fats and oils)
Proteins
Water

Question 3

Micronutrients

Answer 3

Vitamins

Minerals

Question 4

Essential Nutrients

Answer 4

Nutrients that can’t be produced by body (vitamins, minerals, essential fatty acids and amino acids)

Question 5

CARBOHYDRATES

Answer 5

Composed of carbon, hydrogen and oxygen; 3 types

• Monosaccharides→ single sugar molecules (glucose, fructose, galactose)
• Disaccharides→ 2 sugar molecules joined together (e.g. lactose (the sugar in milk) = glucose + galactose)
• Polysaccharides→ chains of sugar molecules (e.g. plant starches)
• Principally derived from plant products; grains, fruit and veg
• Principal function of carbs→ source of glucose to be used to generate energy (ATP) in cells
• Some forms of polysaccharide (e.g. cellulose plant fibres) can’t be digested; serve as dietary fibre function

Question 6

PROTEINS

Answer 6

• Proteins→ chains of amino acids (20 different amino acids found in proteins)
• Some amino acids; synthesised from carbon skeletons derived from other metabolic pathways
• Some are essential amino acids (histidine, lysine etc) and can’t be synthesised by humans; must be included in diet
• Need to include essential acids in diet as complete proteins contain essential amino acids at levels needed (eggs, milk, meat etc) but some plant proteins are missing 1 or more essential acids
• Major sources of protein in diet→ meat, fish, dairy, eggs, nuts and legumes

Question 7

LIPIDS (FATS AND OILS)

Answer 7

• Composed of Carbon, Hydrogen and Oxygen
  Most important in nutrition are:
• Fatty Acids→ long chain of carbons flanked by hydrogens
• Triglycerides→ 3 fatty acids linked to glycerol
• Saturated fats→ Carbon in chains of fatty acids joined together exclusively by single bonds
• Mono or polyunsaturated fats→ Carbon in fatty acids chained joined by combination of single or double bonds
• Domestic animal fats→ rich in saturated but poor in unsaturated
• Plants often rich in polyunsaturated

Question 8

ESSENTIAL FATTY ACIDS

Answer 8

• Naturally occurring unsaturated fats fall into 3 groups; based on where in the carbon chain the first double appears (e.g. n-3, n-6 or n-9)
• Humans can’t synthesize certain n-3 and n-6 fatty acids (required for body)

Question 9

WATER

Answer 9

• Beverages are major source of water but so are foods (e.g. fruit and veg)
• Body can produce small amount of water but can’t meet its total requirements
• Can last several weeks without eating but going 3-4 days without water will kill you

Question 10

VITAMINS

Answer 10

• Vitamin→ essential carbon-containing compound required in small amounts in diet
• Generally can’t be synthesised by body- some exceptions; some can be synthesised inside body
• Vit D→ synthesized from cholesterol and sunlight
• Vit K and some B→ synthesised by intestinal bacteria
• 2 types of vitamins
  Water soluble→ B group and Vit C
  Fat soluble→ Vit A, D, E and K

Vitamins regulate and support many chemical reactions in body; in reactions they aren’t consumed but may be reversibly modified

Question 11

MINERALS

Answer 11

• Chemical elements required in diet; all are essential nutrients
• Functions→ support and regulation of chemical reactions in body (e.g. as components of proteins such as iron in haemoglobin)
• Major minerals→ minerals whose required intake is 100 mg or more/day (e.g sodium, calcium, magnesium)
• Trace minerals→ minerals whose required intake is less than 100 mg/day (iron, zinc, iodine, copper)
• Important to not exceed daily intakes; excess levels can be toxic