XNB151 Week 7 Breads & cereals, fruits and vegetables


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  • Dr Philippa Lyons-Wall Overview of Nutrition Science
  • Dr Philippa Lyons-Wall Overview of Nutrition Science
  • XNB151 Week 7 Breads & cereals, fruits and vegetables

    1. 1. XNB151 Food and Nutrition Breads & Cereals, Fruits and Vegetables
    2. 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. 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. 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 4
    5. 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, preventableClassification 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 5
    6. 6. Breads and Cereals
    7. 7. Breads & Cereals Examples Breakfast Cereal Wheat Bread Maize Ugali Pasta Rice Noodles Barley Rice Sorghum Flour Semolina Oats Polenta Rye Couscous Millet Burghul
    8. 8. 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)
    9. 9. 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)
    10. 10. 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
    11. 11. Fruit
    12. 12. Key nutrients obtained from fruit Macronutrients ◦ Carbohydrate Micronutrients ◦ Vitamin C ◦ Folate ◦ Potassium Fibre (primarily soluble) Non-nutrient compounds ◦ FlavonoidsTo meet vitamin and nutrient requirements a range ofdifferent types (and colours) of fruits should be eaten!
    13. 13. Vegetableshttp://www.youtube.com/watch?v=bGYs4KS_djg
    14. 14. 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 ◦ FibreTo meet vitamin & nutrient requirements a range of types (& colours) of vegetables should be eaten!
    15. 15. 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
    16. 16. Summary of Key Nutrients in B&C, Fruits and VegetablesBreads & Cereals Fruit Vegetables LegumesMacronutrients Macronutrients Macronutrients Macronutrients• Carbohydrate • Carbohydrate • Carbohydrate •Carbohydrate•Fibre •Fibre (starchy only) •Protein •Fibre •FibreMicronutrients Micronutrients Micronutrients Micronutrients• Folate • Vitamin C • Vitamin C •Thiamin• Iron • Folate •Folate •Niacin•Niacin • Potassium •Carotene (Vit A) •Iron•Thiamin • Potassium •Zinc•Magnesium •MagnesiumNon-nutrient Non-nutrient Non-nutrient compounds Non-nutrient compoundscompounds compounds•Antioxidants • Flavonoids • Flavonoids •Lignins (phytoestrogen)•Lignins •Isoflavones(phytoestrogen) (phytoestrogen) (Soy)
    17. 17. Benefits Of Key Nutrients From Breads & Cereals, Fruits And Vegetables
    18. 18. 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
    19. 19. 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)
    20. 20. Glycaemic IndexHigh (>70) Glucose, cornflakes, baked potato, white bread, Weetbix, watermelon, honey, sports drinkModerate (55-70) Wholemeal bread, soft drink, brown/white rice, ice cream, ripe banana, mangoes, orange juiceLow (<55) Oats, mixed grain bread, All Bran, milk, flavoured yoghurt, chocolate, unripe banana, pasta, baked beans, red lentils, apple
    21. 21. Benefits of low-GI carbohydratesBetterblood glucose controlLonger lasting satiety and energy after mealsREMEMBER... Low GI does not necessarily mean ‘low energy’
    22. 22. FIBRE Dietary fibre Soluble Insoluble• Soluble in water • Insoluble in water• Forms viscous solutions • Absorbs water while• Fermented into gasses/ passing through digestivephysiologically active by- systemproducts in colon • Resists fermentation
    23. 23. Health benefits of dietary fibre Soluble Insoluble fibre fibreForm complex Formation of Fermentation bacterial Retention of waterwith 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 ofexcretion from absorption of faster transit through colon carcinogenic body sugars compounds More acidicDecreased 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
    24. 24. 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
    25. 25. Carbohydrate RecommendationsNo AI/ UL as data on essentiality insufficient45 – 65% of energy intake to lower chronic disease
    26. 26. 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
    27. 27. Folate deficiency DecreasedDNA synthesis Increased & repair risk cancer Increased homocysteine levels Impaired Impaired replacement cell red blood division cells Cardiovascular disease Neural tube Anaemia defects (babies)
    28. 28. Folate requirements Estimated Average Requirement ◦ adults 320 µg/day Recommended Dietary Intake ◦ adults 400 µg/day ◦ pregnancy & month preceding conception 600 µg/day Suggested Dietary Target ◦ 300-600 µg/day (suggesting need for fortification) Upper Limit ◦ adults 1000µg/day
    29. 29. Vitamin CVitamin C is a water soluble vitamin (can leach into cooking water so food content is affected by cooking methods)Found in
    30. 30. 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
    31. 31. 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
    32. 32. VitaminMore 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)
    33. 33. 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
    34. 34. 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
    35. 35. Vitamin A requirementsRetinol 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
    36. 36. 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)
    37. 37. 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
    38. 38. 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?
    39. 39. Possible Roles of Phytonutrients
    40. 40. 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)
    41. 41. 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)
    42. 42. 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 repairmaintenance of tendons etc eyesight