Composition of human diet Flashcards
What is nutrition?
Study of processed by which body recieves and uses material for gorwth and survival
Why does food provide energy?
Basal body activities - hear beat, muscle tone, body temp
Cover expenditure of energy in simple activities - sitting standing
Work activities - energy occupation dependant
Why is energy-body weight high in children?
Expand energy in everyday activities and for growth, intake of food suffiecient for metabolic needs
What are essential components of diet?
Carbohydrate CHO Protein Fat lipid Water Vitamins ADEKBC Minerals g/day
what is the recommended adult daily intake?
2500 for men
2000 kcal for women
What are current daily recommendations?
Protein 10%
Fat <35%
Carbs 50%
Dieatary fibres 30g
What are proteins?
Chains of 20 AA , 8/9 are essential
What is protein needed for?
Degraded and used for energy daily
AA not stored in body to manufacture proteins to repair and build tissue and synthesise enzymes and hormones
What is the nutritional value of protein?
Depends on nature of AA - some readily synthesised in body from ammonia and carbon compounds
others need to be supplied in diet
What are the essential AA?
TV TILL PM
Tryptophan, valine, threonine, isoleucine, leucine, lysin, phenylanine and methionine
What is the essential AA in children?
Histidine
What foods can protein be found in?
Complete proteins in animals - meat fish eggs and milk
Partial proteins from gains, legumes and vegatables becos they lack essential aa
What is kwashiorkor or marasmus a disease of?
Severe protein defiency - where total protein is deficience , causes depression, weight loss, oedemous, plasma albumin low, skin and hair problems
After physical injury, why do patients lose nitrogen?
increased secretion of adrenocortical hormones , patients need high protein and energy diets to restore losses
What does dietary fat consist of?
Triglycerides which are triesters of glycerols and fatty acids
What are the fatty acids like?
Saturated SUFA
monounsat MUFA
polyunsat PUFA
What are 2 families of PUFA?
Omega 6 (proflammatory) and 3(anti-inflammatory) from linoleic acid
What is more unsaturated animals or veg?
Veg is as they are more liquids and animals more solid
What does dietart fats contribute to?
CHD disease to manipulate plasma fat
Why is fat needed?
High energy value and vehicle for fat-soluble vitamins and has essential fatty acids - palatibility of food
What are the 3 unsaturated fatty acids that cant be synthesized by tissuw?
omega 6,3 and eicosapentaenoic acid
Wher can essential fatty acid defiency be found?
With severe malabsorption after intestinal surgery
in animals - scaling and exudative skin lesions appear when unsat fatty a are absent from diet
What does linoleic acid form?
Prostaglandins for local functions
What is recommended fat for women and men?
W 78g
M 97g
What can omega 3 do?
found in oily fish
reduce blood tg levels
reduce fatal heart attacks
Where can carbs be found?
Vegetables cereals pulses in form of plant starch polysac and sugars monosacc milk fruits and dietary fibre
What are carbs used for?
energy sources, as skeletons for synthesising non essential aa prevent ketosis (excessive metabolism of fats to ketones)
Why is a carb a protein sparer?
carb is metabolised instead of protein to preserve functional proteins of cells
What is fibre?
Non-starch polysacc
components ofplans which cant be digested
What can a fibre-depleted diet result in?
intestinal malfunction and colonic carcinoma
What is insoluble fibre?
non digested plant cell wall - bulks intestinal contents to stimulate peristalsis by distension and decrease faecal transmit time
What does insoluble fibres reduce?
Risk of bowel cancers and diverticulitis
Where is soluble fibre found?
Fruit, veg, pulses and it lowers blood cholesterols and protects against cv disease and controls blood glucose - 18g/day
What are vitamins important for?
Metabolic processes
What happens without vitamins?
biochemical breakdowns, lesions develop
What are fat-soluble vitamins?
ADEK
What are water-soluble vitamins?
B complex and C
What do minerals do?
NA,C,CL,CA,FE,PH,I,MG
normal functioning of the body and act as catalyst for enzymes
how much body weight loss without permenant damage?
25%
Why is rapid weight loss dangerous?
Disturbances in electrolyte balances NA K CL - important for nerve and muscle function and at worst result in heart failure
How many people in uk are obese?
68% men >20% of BW fat
58% women >30% of BW fat
What is excess mortality of obese deaths?
20%
What happens in hunger?
Instinctive phenomenon - sense of emptiness
What happens in appetite?
desire for food - learned phenomenon
What is satiety?
when stomach is full with food from filling meal
what is intake of food controlled by?
Neural mechanisms in hypothalamus
What does lateral hypothalamus contain?
If stimulated causes food intake - feeding centre
What does ventromedial hypothalamus contain?
If stumulated, causes cessation of feeding - satiety centre
What can influence feeding and satiety centre?
Higher brain centres by strong emotion or anorexia result in starvation
What do brain stem centres control?
Mechanisms of eating
What is gastro intestinal regulation?
immediate effects of eating on GI
filling initiate inhibitory signals to supress feeding centre can be ghrelin or cck or nutritional - ensures eat at stage GI can cope with
What is nutritional long term regulation?
nutrient stores of the body fall below normal feeding centre is active, influenced by availability of glucose to cells, adipose and thermal effets
What can availaibilty of glucose to cells do?
Fall in BG conc to do with hunger, BG is high when your full
availibilty of glucose to cell determines feeding rather than levels
Why does adipose tissue control feeding?
secretes hormone leptin which surpresses appetite - produce of ob gene and expressed in adipocytes chemically 167 AA - correlates with body fat, some adipose maintained, obese reduced brain sensitivity to leptin
What do thermal effects do?
intake of food becos of metabolic activity rising and heat production increasing known as SDA
