XNB151 Week 7 Breads & cereals, fruits and vegetables
1. XNB151 Food and Nutrition
Breads & Cereals,
Fruits and
Vegetables
2. Some background information...
Core food groups
◦ Foods grouped into 5 key groups
Breads & cereals
Fruit
Vegetables
Meat & meat alternatives
Milk & milk based products (Dairy)
◦ Recommendations for core foods based on
minimum amounts of food required for good
health
3. Background - Macronutrients
Required by the body in large amounts for
survival and growth (excepting alcohol)
Source of energy
Dietary manipulation central to
prevention/treatment of a number of
chronic conditions
(protein, fat, CHO, alcohol)
4. Background – Micronutrients: vitamins
organic compound, natural component of food
essential for physiological function, small amounts (mg,
µg/d)
not synthesised by the host
prolonged absence causes a distinct deficiency
13/14 known vitamins, each has a specific function
one cannot replace another but some overlap in
function
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5. Background – Micronutrients: minerals
elements in their inorganic form
~4% body weight
optimal body function when present within specific range
continued absence causes a distinct deficiency accompanied
by specific & reproducible biochemical changes, preventable
Classification on basis of requirement by body:
Macrominerals:
◦ needed in amounts > 100 mg/ day eg Ca, P, Mg, Na, K
Microminerals:
◦ needed in amounts < 100 mg/ day eg Fe, Zn, I, Se
Ultratrace elements:
◦ eg boron, cobalt
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9. Which breads and cereals are best?
Wholegrain breads and cereals
provide benefits above refined (e.g.
white)
◦ Less processed
◦ Higher fibre
◦ Lower Glycaemic Index (GI) (will
discuss shortly)
10. Key Nutrients from B&C
Macronutrients
◦ Carbohydrates
Micronutrients
◦ Folate
◦ Iron (low bioavailability)
◦ Magnesium
◦ B Group Vitamins (thiamin, niacin)
Fibre
Non-nutrients
◦ Anti-oxidants
◦ Phytoestrogens (lignan)
11. Carbohydrate Controversy
Many popular diets based on low CHO intake
At odds with most traditional nutrition advice
Unlimited CHO not appropriate either
Yes – there is such a things as too much CHO and it
CAN contribute to excess weight gain, especially if in
the form of sugar or high GI carbohydrates
Thisdoes not then mean that ALL CHO needs to be
minimized
14. Key nutrients obtained from fruit
Macronutrients
◦ Carbohydrate
Micronutrients
◦ Vitamin C
◦ Folate
◦ Potassium
Fibre
(primarily soluble)
Non-nutrient compounds
◦ Flavonoids
To meet vitamin and nutrient requirements a range of
different types (and colours) of fruits should be eaten!
17. Key Nutrients from Vegetables
Macronutrients
◦ Carbohydrate (starchy veg & legumes only)
Micronutrients
◦ Vitamin C
◦ Carotene (Vitamin A precursor) (especially orange)
◦ Folate (especially dark green/brassica)
◦ Potassium
◦ Fibre
To meet vitamin & nutrient requirements a range of
types (& colours) of vegetables should be eaten!
18. Variety in the Vegetable Group
• Folate
• Vitamin C • Vitamin C
Green andK
• Vitamin brassica Other
• Potassium
•Carotenoids
• Vitamin A • Carbohydrate
• Carotenoids • Carbohydrates
Starchy
Orange • Iron
Legumes
• Potassium
• Flavonoids
20. Benefits Of Key Nutrients From Breads
& Cereals, Fruits And Vegetables
21. CARBOHYDRATES!!!!!
Derived from simple sugars (monosaccharides)
◦ Main monosaccharides are glucose, fructose and
galactose
Main source of energy in diet
◦ Breads & cereals – complex carbohydrates
◦ Fruits & vegetables – simple carbohydrates (mono- &
disaccharides)
◦ Dairy – disaccharides (lactose)
◦ Extras – disaccharides (refined, sucrose)
Wholegrain B&C, fruit and some starchy veg
provide low GI carbohydrates
22. Glycaemic Index (GI)
Ranks foods according to rate of
glucose absorption into blood
◦ High GI food absorbed rapidly
◦ Low GI food absorbed slowly
(better control, longer lasting
energy)
Influenced by:
◦ particle size
◦ degree of processing/cooking
◦ presence of fat, protein
◦ ripeness of some fruit (banana)
23. Glycaemic Index
High (>70)
Glucose, cornflakes, baked potato, white bread,
Weetbix, watermelon, honey, sports drink
Moderate (55-70)
Wholemeal bread, soft drink, brown/white rice,
ice cream, ripe banana, mangoes, orange juice
Low (<55)
Oats, mixed grain bread, All Bran, milk, flavoured
yoghurt, chocolate, unripe banana, pasta, baked
beans, red lentils, apple
24. Benefits of low-GI carbohydrates
Betterblood glucose control
Longer lasting satiety and energy after meals
REMEMBER... Low GI does not necessarily
mean ‘low energy’
25. FIBRE
Dietary
fibre
Soluble Insoluble
• Soluble in water • Insoluble in water
• Forms viscous solutions • Absorbs water while
• Fermented into gasses/ passing through digestive
physiologically active by- system
products in colon • Resists fermentation
26. Health benefits of dietary fibre
Soluble Insoluble
fibre fibre
Form complex Formation of Fermentation bacterial Retention of water
with cholesterol viscous solution proliferation
causing it to in gut slowing
enter colon digestion of
Increase in stool mass – Dilution and
promoting starch &
softer bulkier stools & faster removal of
excretion from absorption of
faster transit through colon carcinogenic
body sugars
compounds
More acidic
Decreased risk Decreased risk Decreased risk colonic
of CVD of diabetes/ of constipation/ environment
better glycaemic diverticular diminishes
control Decreased risk
disease/ other toxicity of other
of colon cancer
large bowel bacterial
diseases metabolites
27. Fibre Recommendations
Adults
◦ 30g/day used as rough guide
NRV
◦ AI male adult 30g/day
◦ AI female adult 25g/day
Children
◦ some say 0.5 g/kg body weight of child
◦ others say age in grams + 5 = minimum
◦ NRV AIs for different age & gender
28. Carbohydrate Recommendations
No AI/ UL as data on essentiality
insufficient
45 – 65% of energy intake to lower
chronic disease
29. Folates
Compounds that exhibit biological
activity of ‘folic acid’
◦ Aid in cell division and protein synthesis (important for DNA
synthesis)
Plant based-foods
Found in:
Animal foods
‘Storage sites’ (liver)
‘Conjugated form’ requires
‘Free-form’ readily absorbed in enzyme for hydrolysis before
small intestine absorption can occur
30. Folate deficiency
Decreased
DNA synthesis Increased
& repair risk cancer
Increased
homocysteine
levels
Impaired
Impaired replacement
cell red blood
division cells
Cardiovascular
disease
Neural
tube Anaemia
defects
(babies)
32. Vitamin C
Vitamin C is a water soluble vitamin (can
leach into cooking water so food content
is affected by cooking methods)
Found in
33. Role of Vitamin C
Collagen formation Strong ligaments,
Wound healing &
(primary component tendons, dentin,
tissue repair
of much of the skin, blood vessels
connective tissue) & bones
Vitamin C
Antioxidant functions Aids in the
absorption of non-
haem iron
↓d risk cancer, CVD &
cataracts
34. Vitamin C requirements
Physiological requirements to prevent scurvy 10-20 mg
Estimated Average Requirement
◦ adults 30mg
◦ pregnancy 40mg
◦ breastfeeding 60mg
Recommended
◦ adults
Dietary Intake
45mg
60
◦ pregnancy
◦ breastfeeding
60mg
85mg mg
Suggested Dietary Target
◦ Men 220mg, Women 190mg
Upper Limit
◦ not set but 1000mg prudent limit
35. Vitamin
More biologically
active
Retinol Carotenes
Retinol supports reproduction (& major transport
storage form of Vitamin A)
Retinal vision & conversion of retinol to retinoic acid
Retinoic acid modulator of gene expression (controls
mRNA synthesis, cell differentiation growth & embryonic
development)
36. Vitamin A
deficiency
Major nutritional
problem worldwide
◦ Night blindness
◦ Xerophthalmia (failure
to produce tears) leads
to blindness
Rare in Australia as
stored well in liver
37. Vitamin A excess
Highcarotene intakes from food not toxic but can
cause yellowing of skin
Chronicintakes of Vit A > 1000 μg/kg body mass
(~100 x RDI) can induce toxicity
◦ Vit. A is fat soluble so it is stored in the body
◦ Symptoms:
Loss of appetite, headache, blurred vision, irritability, hair loss, general
drying & flaking of skin, bony growths or fractures, liver damage &
death
In pregnancy, can cause congenital abnormalities
38. Vitamin A requirements
Retinol
Adequate intake
◦ Infants 250µg/day
◦ Infants 7 – 12 months 430µg/day
Estimated
Average Requirement
◦ Men 625µg RE Vary according to
◦ Women 500µg RE age for children,
pregnancy and
lactation
Recommended Dietary Intake
◦ Men 900µg RE
◦ Women 700µg RE
Upper Limit (adults) 3000µg
39. What about supplements?
Previously belief existed that it is impossible to obtain
all nutrients from food multivitamins required for
health
Beware! Can have excess; low dose multi usually
preferred vs. single large dose
Consider the cost
Sometimes are needed (e.g. vegans; very low fat diets;
for allergies; post surgery or illness; malabsorption
problems; pregnancy etc)
40. Other Substances …
There is more to food than nutrients
Many substances may have benefits however
there is much that we do not know
Many important future areas for nutritional
research
Seemsto be more than nutrients/single
components – need more “food” focus due to
unknown elements & interactions likely
41. Phytonutrients
Compounds in food that have the ability
to alter chemical & enzymatic reactions &
therefore the potential to impact on
health which are NOT traditional
micro/macro nutrients
May be beneficial or harmful
Much we still do not know
Nutrients or pharmaceuticals?
43. Breads & Cereals Group Long-term Benefits
Consumption of diets rich in wholegrain
breads and cereals may be protective
against
◦Heart Disease
◦Diabetes
◦Some Cancers (e.g. stomach, colon)
◦And is associated with better long-term
weight control
(www.gograins.com.au)
44. Fruit & Vegetables Long-term Benefits
Protective against many major Cancers (stomach & colo-
rectal)
Evidence also exists for protection against
◦ Stroke
◦ High blood pressure
◦ Diabetes
◦ Obesity
◦ Macular degeneration
◦ Dementia
Yet to identify specific protective components - studies of
particular nutrients have found no benefit or harm (Vit-C,
beta-carotene)
45. Summary of benefits of food groups
Breads & Improved
cereals glycaemic
Low GI CHO
control/ ↓d risk
diabetes
Fruits Fibre
↓d risk
Folate gastrointestinal
disorders
Vegetables
Vitamin C ↓d risk CVD
Vitamin A
↓d risk cancer
Improved Strong
↓d risk birth Wound & tissue
eyesight/ muscles,
defects repair
maintenance of tendons etc
eyesight
Editor's Notes
Dr Philippa Lyons-Wall Overview of Nutrition Science
Dr Philippa Lyons-Wall Overview of Nutrition Science
