week 9 Flashcards
Nutrition
- Human nutrition describes the processes whereby cells obtain and utilise necessary substances to maintain life
Optimum nutrition
- Food-secure individuals with adequate balances and prudent diets
- Have health, normal development and high quality of life
Undernutrition
- Food insecure individuals living in poverty ignorance, disrupted societies - Decreased physical and mental development
- Compromised immune systems
- Increased infectious disease
- Vicious cycle of undernutrition
Over nutrition
- Overconsumption of food especially macronutrients with low physical activity, smoking, stress, alcohol
- Obesity, metabolic syndrome CVD, diabetes
Malnutrition
- Individuals and communities previously food insecure → confronted with abundance palatable foods → some undernourished
- Double burdon if infectious disease plus NDC’s often characterised by too many macronutrients and too little micronutrients
Nutrient consideration
- The chemical and physical structure and characteristics of the nutrient
- Food sources of the nutrient – food composition and how processing effects nutrient composition and value
- Digestion, absorption, circulatory transport, cellular uptake of nutrient (and regulation
of these processes) - Metabolism of the nutrient, it’s function, storage and excretion
- Physiological needs in health and disease, and states (eg pregnancy), individual
variability - Interactions with nutrients, phytochemicals, antinutrients, drugs - Deficiency and toxicity
- Therapeutics – nutraceuticals, functional foods
Carbohydrate
subclass and examples
Monosaccharides: Glucose, fructose, galactose
Disaccharides: Sucrose, maltose, lactose
Polysaccharides: Starch and fibre
Proteins
Subclass
nutrient examples
plant and animal source proteins: amino acids; aliphatic, aromatic, sulfur containing acid, basic
Fats and oils (lipids)
subclass
nutrient examples
Palmitic & stearic acid, oleic and elaidic fatty acids
Linoleic, a-linolenic, arachidonic, eicosapantaeonic and dochexaneoic acid
minerals
subclass
nutrient examples
minerals and electrolytes
trace minerals
calcium, sodium, phosphate, potassium, iorn, zinc, selenium, copper, manganese, fluoride
Vitamins
Fat soluble : Retinol (A), calciferous (D) Tocopherols (E)
water soluble: ascorbic acid (C), thiamine (B1), Riboflavin (B2), Niacin (B3)
Dietary fat
- Composed of triglycerides, phospholipids, sterols and other minor lipids
- Recommended 20/30% of energy intake
Dietary protein
Should provide essential amino acids though enough amino acid nitrogen to synthesise the non-essential amino acids
Diversity
- We eat food for energy and to provide nutrients that we can’t synthesis ourselves
Seasonality
- We evolved to eat fresh foods in season when they are ripe as that’s when they have their highest nutritional content
- Nutrient composition of plants are affected by season, country of origin, growing conditions and storage.
- Nutrient composition of animals, milk and eggs are affected by season, feeding regime, age of animal
Evolution of diet and disease
40 000 ya
50-80% plant
20-50% meat
10000 BC - 1600
diets based on 1-2 crops
meat intake low; veg up to 90%
earliest consumption of milk
Argiculture –> food surplus drove civilisation
Micronutrient deficiencies
infectious disease
19060 - present
industrial revolution
micronutrient deficiencies
heart disease
increase in animal protein
Water soluble vitamins
- Thiamin B1
- Riboflavin B2
- Niacin B3
- Pantothenic acid B5 - B6
- Biotin B7
- Folate B9
- B12
-C - Excess secreted by kidneys (except folate and B12 - regulated by liver and converted
to bile) - Limited stores in body
- Regular intake requires (except B12)
- Los tin cooking and processing
- Water lenching
- Some heat sensitive depleted in refined grains
Fat soluble vitamins
- A - destroyed by heat, light and oxygen
-D - E - destroyed by heat, food processing, oxygen and storage -K
- Stored in liver and fatty tissues
Macronutrient composition in fruit
- Low energy, protein and fat
- High water, carbohydrate, starch, fibre
Micronutrient composition of fruit
- Low in calcium, phosphorus, iron B vitamins - High vitamin C, vitamin A, and potassium
Macronutrient composition of vegetables
- Low energy and fat
- High moisture content
- Have less sugar than fruit but contain more starch
Nutrient content of root vegetables
- High water
- Low in protein and fat
- Carbohydrates include sgrs and some starched in more mature roots - Reasonable source of fibre
- Micronutrients: calcium, C and some B
- Carrots high in B-carotene
Nutrient content of tubers
- High carbohydrate (amylopectin), protein, fibre
- Low fat content
- Micronutrients: C, small calcium, folate and B vitamins
Phytochemicals
- Chemicals naturally found in fruit and vegetable that prevent it from disease - Protects health in humans eg. antioxidants
- Responsible for colour and smell of vegetable
Fibre
- Plant material that is unable to be broken down by digestive enzymes to absorbable nutrients
- Broken down by intestinal bacteria in large intestine or excreted - Insoluble: cellulose, lignin, resistant starch
- Soluble: pectin & hemicellulose
F&V post-harvest changes
- They perish quickly
- Consumption of energy within cells - Accumulation of waste produces
- Surface microbes
- Loss of water
F&V storage atmosphere
- To retain nutritional value
- Store in crisper or cover
- Refrigerate/freezing to reduce enzyme action - Protect from light and oxygen
F&V cooking
- Increase digestibility of food
- Enhances absorption of some nutrients - preserves food
F&V nutrient losses
- Nutrient are lost during cooking due to:
- Water soluble nutrients dissolve in cooking water
- Heat and cooking medium pH affects certain nutrients
- Increase in enzyme activity, exposure to oxygen & light
Legumes
- Are indigestible and inedible raw - must be cooked
- The final nutrient composition depends on processing and preparation
carbohydrate
- 60% starch
- Good source of slowly digested carb=ohydrate (low GI) - Oligosaccharides
- Fibre - cellulose, hemicellulose and lignin
- Resistant starch
Legume - Processing & nutrient changes
Decortication (removal of skin and germ)
- improves digestibility, loss of thiamin and vitamin E with germ
Soaking
- loss of water soluble vitamins and minerals if soaked in hot water
Boiling
- destroys anti trypsin and haemagglutinins
- loss of water soluble vitamins
Roasting
- destroys thiamin, pantothenate and riboflavin, but not niacin
Fermentation
- increases bioavailability of nutrients eg. tofu, miso
Germination
- increases ascorbic acid, niacin, sugars and reduces phytic acid
Nutrient value of nuts
- Lack vitamin C - Good source of
- VitA
- VitB
- VitE
- Potassium - Magnesium - Calcium
- Iron in seeds
Cereal endosperm
- Largest position of the grain
- Parenchyma cells - storage of scratch granules - Main constituent is white flour
Rice processing Brown rice
- Unmilled rice, contains bran, germ & aleurone - Higher protein, mineral, vitamin, phytate & fibre - Longer to cook
- More prone to rancidity – keep in fridge
Parboiled rice
- Rice is precooked before hulling & milling
- Improves nutritional quality – vitamins from bran & germ + aleurone - Hardens the grain
- Nutty flavour due to
- Enzyme induced browning reaction of sugars & amino acids during drying - Lignin breakdown to vanillin & other compounds
Macronutrients in seafood
- Low carbohydrate
- Major source of protein
- High biological value
- Amino acid composition similar to meat
- Good source of sulphur containing amino acids
fatty acids in fish
low in saturated fats
fish oils contain 3 polyunsaturated fatty acids
Vitamins in fish and seafood
- A and D: high levels in liver, high in oily fish
- E: significant amount in salmon and some shellfish - C and thiamin: very small amounts
- B6: best sources
- Folate, niacin: good course
- B12: rich source
- Low in calcium, iron, zinc sodium
- High in iodine, fluoride, selenium, potassium
Composition of meat
Principle amino acid: alanine, glycine, glutamic acid, and histidine
Muscle fat meat
triglycerides
- Oleic
- Palmitic - Stearic
Phospholipids
Cholesterol
Fat soluble vitamins (A, D, E, K)
Milk vitamins
fat soluble
Fat-soluble vitamins content dependent on type of feed, and are proportional to fat content (vitamins A and D)
- Vitamin A – highest in summer, dependent on green pastures
- Vitamin D – content varies with sunlight exposure of cow and feed
milk vitamins
Water-soluble vitamins
- Riboflavin available in high amounts, but lost on exposure to UV light
- Niacin content low, but tryptophan (niacin precursor) also in milk
- Vitamin C (ascorbic acid) is present in low amounts and is very unstable.
