Lecture 1

• Water is an inorganic, macronutrient
• carbs, protein, lipid are organic macronutrients
• vitamins is an organic micronutrient
• minerals are an inorganic micronutrient
• carbs, 1g=4kcal

  protein, 1g=4kcal

  lipid, 1g=9kcal
• energy expenditure depends on basic metablic rate & amount and intensity of physical activity/illness
• acceptable macronutrient distribution ranges (AMDR):

  1. adequate energy and nutrients
  2. reduce risk chronic diseases
  3. range

  45-65% kcals from carbs

  20-35% kcals from fat

  10-35% kcals from protein
• estimated average requirements = average amount sufficient for half of population
• recommended dietary allowances = recommendations to meet needs of most healthy people, 98%
• adequate intakes = used when insufficient scientific evidence AI value set instead of RDA, expected to exceed average requirements
• tolerable upper intake levels = point where nutrient is likely to be toxic, helps protect against overconsumption
• estimated energy requirement = amount cals needed for all daily functions, includes cals neded for both vital functions of life and physical activity, need meet energy expenditure
• malnutrition = deficiency or excess over time leads to undernutrition or overnutrition
• good diet includes:

  1. adequacy, sufficient energy and nutrients
  2. balance
  3. moderation
  4. variety, among and w/i food groups
  5. calorie control, energy intake = energy expenditure /// high nutrient density diets
• nutrient density - most nutrients for fewest cals
• fibre helps lower cholesterol
• fibre helps diabetes:

  1. slow down carbs digestion
  2. effect on blood glucose
• fibre helps weight:

  feeling full
• fibre helps reducing risk of colon cancer

  diluting/removing toxins from bacteria fermentation
• recommended dose of 30g per day of fibre, excessive fibre can cause abdominal discomfort, gas, constiparion and nutrient absorption
• salivary amylase:

  carbs -> smaller polysac

  pancreatic amylase:

  polysac -> disac

  within small bowel mucosa:

  disac -> monosac
• lactose intolerance:

  1. genetically determined
  2. symptoms of intolerance
  3. can be treated w/ lactase supplements
• length of hydrocarbon chains:

  1. long chain, most common (12-24) meats + veg oil
  2. med-chain (6-10) dairy
  3. short-chain (<6) dairy
• 9 amino acids cannot be synthesised by humans:

  Methionine

  Valine

  Histidine

  Leucine

  Phenylalanine

  Tryptophan

  Isoleucine

  Lysine

  Threonine

  Many Very Happy Little Pigs Take Iced Lemon Tea
• average adult requires 0.8g per kg per day

  proteins constantly being synthesised and degraded - average 250g/day = 3%
• deamination:

  amino acid + water = keto acid + ammonia + CO2
• nitrogen intake = nitrogoen excretion

  negative nitrogen balance: intake < excretion which occurs during fasting, illness, trauma

  positive nitrogen balanceL intake > excretion

  occurs during growth, pregnancy
• vitamins; water or fat soluble

  majority vitamins converted into molecules which act as coenzymes (except vit A,D,E)

  
• Overview of vitamin roles (1)

  
• overview of vitamins roles (2)

  
• key minerals include: sodium, potassium, chloride, calcium, phosphate, magnesium
• 'trace elements' - iron, fluoride, zinc, iodine, cobalt, copper, chromium, manganese, selenium
• sodium and potassium, major electrolytes w/i cells (K+) and in extracellular fluid (Na+)
• recommended sodium intake is <6g/day

  estimated daily salt intake 8.3g men and 6.4g women