Topic 4: Diet And Nutrition Flashcards
What are the essential components of the diet
Carbohydrate - energy
Protein - energy and amino acids (can convert to ATP)
Fat - energy and essential fatty acids
Minerals - essential
Vitamins - essential
Water - hydration
Fibre normal GI function and lowering cholesterol
Define the components of daily energy expenditure
Vary between age, sex, body composition and physical activity
70kg adult male - 12000KJ/day
58kg adult female - 9500 KJ/day
It is the sum of basal metabolic rate, diet-induced thermogenesis, physical activity level
Describe the factors involved in regulation of body weight
Physical activity -
Reflects energy demands of skeletal muscle, heart muscle and respiratory muscles
Sedentary - 30kJ/kg/day
Moderate - 65 kJ/Kg/day
Active - 100 kJ/Kg/day
When overweight - down ro lipds/adipose tissue
Energy intake bigger than energy expenditure - more fat, measured in BMI
Explain the clinical consequences of protein and energy deficiency
Require stores of energy’usualky as adipose
Under extreme conditions muscle proteins can be converted to energy
Low protein intake can result in insufficient blood protein synthesis (albumen) leading to a decrease in plasma on droid pressure and oedema - in disease Kwashiorkor
What is metabolism
The chemical process that occur within a living organism in order to maintain life
- oxidative pathways, food into energy
- fuel storage - when not eating, eg: fat and glycogen
- bio synthetic pathways - produces basic building blocks for cells
- detoxification pathways - remove toxins, eg: P450 in liver
What are catholic processes
Break down to release energy
What are anabolic processes
Uses energy and raw materials to make larger molecules for growth and maintainence
Why do we need energy
Bio synthetic work- synthesis cellular components
Transport work - movement of ions and nutrients across membranes
Mechanical work - muscle contraction
Electrical work - nervous conduction
Thermogenesis
Detoxification
What type of energy do our cells use
Chemical bond energy
ATP
Energy is procured by oxidation fo what
Lipids
Carbs
Proteins
Alcohol
ATP-ADP cycle
ATP -> ADP + Pi
-> CO2 and H2O and heat
What are the units of food energy
Kilojoules
Calorie is also used - kilocalorie - 1000 calories
1kcal - amount of energy required to raise the temperature of 1kg of water by one degree Celsius
1kcal= 4.2kJ
Key information of carbohydrate
(CH20)n
Contains aldehyde and keto group
Multiple OH groups
Monosaccharides - single sugar
Disaccharides - two sugar like lactose, sucrose
Oligosaccharides 3-12 units, eg: dextrin
Polysaccharides - 10-1000 units like glycogen, starch, cellulose
Starch
- amylose and amylopectin
In plants
Polymer of glucose
Sucrose
Glucose and fructose
Table sugar
Disaccharide
Lactose
Galactose and glucose
Milk sugar
Disaccharide
Fructose
Fruit sugar
Monosaccharide
Glucose
Sugar in human blood
Red blood cells don’t have mitochondria so rely on glucose for glycolysis as can’t do ETC
If glucose conc falls below Km of glucose transporter then glucose can’t be transported to brain = coma
Maltose
Glucose - glucose disaccharide
Glycogen
Storage molecule
Polymer of glucose
What is digestion
Coverts larger carbohydrates to monosaccharides which are absorbed into blood
Protein
Composed of amino acids
Enter blood
20 different amino acids used for protein synthesis in body
9 essential ones can’t be synthesised so must be obtained from diet
What are the 9 essential amino acids
Isoleucine Lysine Threonine Histidine Leucine Methionine Phenylalanine Tryptophan Valine
(If learned this huge list may prove truly valuable)
Deficiency in some of these amino acids in plant origin
Which amino acids are conditionally essential
Children and pregnant women possess a high rate of protein synthesis so require also some ARGININE, TYROSINE and CYSTEINE in diet
Fat
Lipid composed of triacylglycerols (3 fatty acids esterified to one glycerol)
Can be saturated, unsaturated and trans (unsaturated by H bonds on either side - increases shelf life)
Less oxygen so more rescued so yield more energy when oxidised
Used for absorption of fat soluble vitamins from gut
Provides essential fatty acids such as linoleic and linolenic - plasma membrane and prostaglandins
Omega 3 - 3 carbons down there is a double bond
Minerals
Electrolytes establish ion gradients across membrane
Maintain water balance
Ca and P - structure
Ca - signalling
Enzyme co factors - Fe, Mg, Manganese, Co, Cu, Zn and molybdenum)
Fe - haemoglobin
Electrolytes
Sodium
Potassium
Chloride
1mmol/kg/day each
Minerals
Calcium Magnesium Phosphorus Sulphur. Without no cysteine etc so no thymine so can not start protein synthesis Iron
Trace minerals
Copper
Zinc
Iodine - to make thyroid hormone
Selenium - protect against oxidative stress
Ultra trace
Chromium
Manganese
Molybdenum
Vitamins
Required in micro or milligram Fat or water soluble Deficiency diseases Excess vitamins also a problem See PP slides for deficiency
Dietary fibre
Made of cellulose, lignin, pectins and gums
(Do not have enzymes to break down cellulose)
Recommended intake - 18g/day but currently below this
Low intake x constipation and bowel cancer
Reduces cholesterol and risk of diabetes
What are dietary reference values
Series of estimates of the amount of energy and nutrients needed by different groups of healthy Uk population
- Reference nutrient intake - proteins, mineral and vitamin , eniugnt o ensure needs of 97.5% are being met
- estimated average requirement - energy, 50% will require more
- lower reference nutrient intake - proteins, mineral and vitamin. For those who have low requirements (2.5%)
- Safe intake (used when insufficient data)
Depend on age, gender and level of activity
Basal metabolic rate
Maintains resting activities if the body
Maintenance of cells - ion transport and biochemical reactions
Function of organs - skeletal muscle (30% BMR)
liver, brain (20%)
Heart - 10%
Other - 20%
Affected by body size, gende, temperature, endocrine status, body temp
How to measure body mass index
Weight (kg) / height^2 (m^2)
Measure height without shies
Weight with minimal clothing
Major weakness - very muscular individuals
Could measure instead waist/hip ratio
Male (kg/m2) Female (kg/m2) Classification
Male < 18.5 18.5 - 24.9 25 - 29.9 30 - 34.9 >35
Female < 18.5 18.5 - 24.9 25 - 29.9 30 - 34.9 >35
Classification Underweight Desirable weight Overweight Obese Severely obese
Diseases associated with body fat in upPer body (abdomen)
Insulin resistance Hyperinsulinism Type 2 diabetes Hypertension Hyperlipidaemia Stroke Premature death
Clinical consequences of severe protein deficiency in children
Growth failure (height and weight below normal).
• Impaired physical development (tiredness, weakness and
p1
poor exercise tolerance due to reduced muscle mass).
• Impaired mental development (low IQ).
• Negative nitrogen balance due to Nin < Nout
• Oedema due to reduced albumin synthesis in the liver.
• Increased risk of infection due to reduced immunoglobulin
synthesis.
• Anaemia due to reduced haemoglobin synthesis.
• Fatty liver due to reduced lipoprotein synthesis.
Define obesity
Obesity is a chronic condition characterised by excess body fat. It is usually defined on the basis of determination of the Body Mass Index (BMI). A individual with a BMI of ≥30 is considered to be obese. Obesity is a risk factor for the following chronic conditions: hypertension, cardiovascular disease, type 2 diabetes, gall bladder disease, osteoarthritis & cancer.
How much water do you need each day
2.5 litres
What is used for screening malnutrition
MUST tool
- BMI
- unplanned weight loss
- Acute ill
If more than 3 - high risk
What is dietary fibre needed for
Reduce cholesterol
Better digestion
Need 18g
What are the two types of malnutrition
Marasmus
Kwashiorkor
What is marasmus
Insufficient energy intake Negative energy balance so mobilisation of fat stores and muscle proteins broken down for amino acids Nutritional deficiencies - energy, protein, vitamins and minerals, dehydration Typically in children Chronic slow onset Severe weight loss Muscle wasting, protruding rubs Diarrhoea No protruding abdomen Insuffience protein intake No oedema
What is kwashiorkor
Insuffient protein intake Deficit of essential amino acids Rapid acute onset Some weight loss High mortality Poor appetite Typically when displaced from breast milk as toddler - carbohydrate rich diet when new baby arrives Found in developing countries Bilateral pitting oedema Hair changes (brownish, scanty, straight) Flaky skin Protuberant abdomen - enlarged liver Anemia - not enough amino acid to make Hb
What is bilateral pitting oedema
Normal thumb pressure applied to both feet for 3 secs
Shallow pit remains on both after lifted - oedema
What causes oedema
Net flow of fluid from plasma into interstitutial fluid
Decreased plasma protein - net flow of fluid into interstitium (oedema). As in kwashiorkor unable to make essential amino acids, limits ability of liver to produce serum albumin so net flow increases
Net flow=
Different in on oncotic - diffference in hydrostatic
Why does a fatty liver occur in kwashiorkor
Liver functions to synthesise lipoproteins to transport this fat around body but without this ability of the liver, lipds accumulate in liver as can’t be transported - fatty liver - hepatic dysfunction
How do you reintroduce food to someone with marasmus and kwashiorkor
Marasmus - slowly, small, monitored
Kwashiorkor - can not be given protein rich foods as no enzymes present in urea cycle so can lead to build up of ammonia which is toxic. So small amounts of protein at regular intervals
What is re-feeding syndrome
Rapid influx of food
Can lead to confusion, coma, convulsion and death
Usually by ammonia toxicity as no urea cycle,, ammonia build up
Or by rapid increase in metabolism, chemical pathways work very quickly, which requires phosphate, run out of phosphate eas already depleted, so hypophosphataemia
Re feed at 5-10 kcal/kg/day over 1 week
