Macronutrients Flashcards
What are the average fat consumed?
What is the reccomendation?
Average UK diet: 88g fat - 40% of total energy intake
Triacylglycerols (TAGS) - small amount of cholesterol (0.5-1.0 g)
UK DoH recommendation 2-5 g /day
UK diet 8-15g /day
deficiency very rare
Why are dietary fats neccasary?
WE NEED Essential fatty acids
major constituents of membrane phospholipids
precursors of eicosanoids (prostaglandins, thromboxanes, prostacyclins
linoleic acid (C18:2 ω6) - 18 carbons, 2 double bonds, 1st double bond is at 6th carbon from methyl length
linolenic acid (C18:3 ω3)
We cannot synthesise these fatty acids as we cant introduce double bonds before 6 - omega 6 and omedga 3 double bond cant be synthesised
high intakes of the ω3 series may additionally provide protection against CV disease (fish oils)
* . also for developing brain
Risk factors of cardiovascular disease?
Risk factors:
* genetic susceptibility
* smoking
* sedentary life style
* high blood pressure (hypotention)
* high serum cholesterol (Low Density Lipoprotein)
* Obesity
* Diabetes
* Trans fat intake?
How is cholesterol increased and decreased?
Increase in saturated fatty acids leads to increase in LDL (low density level) and total cholesterol
* Also decrease HDL
* Reduce Trans fat intake to lower cholesterol
blood cholesterol can be lowered to some extent by increasing polyunsaturated fatty acids in the diet
effect of mono-unsaturated fatty acids less clear
What are the different types of fat and what’s the diffrence in the structures?
trans - looks more like a saturated fatty acid
reduced kink from double bond
What is Carbohydrates?
How much of our diet does it make up?
- 40% of total energy of diet in affluent societies
- 80-90% in poor populations
- Starch
- non starch polysaccharides (fibre)
- sugars, mainly sucrose
Where does carbohydrate originate ?
Is Carbohydrate neccessary?
- mainly plant origin except lactose and v.small amount glycogen
Not in theory needed
* has protein-sparing effect - means we dont have to get as much energy from protein
* low CHO diets lead to fat utilisation and ketosis
What Monosaccharides do we consume?
Where can we find this?
Glucose - small amounts in fruit
fructose – small amounts in fruit
sorbitol – commercially prepared mainly in foods for diabetics - doesn’t raise blood glucose
inositol – in fibre as hexaphosphate (phytic acid) - negatively charged interferes with absorption of iron and calcium due to thier postive charge
What Disaccharides do we consume?
Where can we find this?
Sucrose is most common
* less than 60g/day no dental caries
* UK consumption 105 g/day
lactose (milk)
* no known adverse effects on health
* but many non European populations
* cannot tolerate lactose - don’t have the enzyme to split lactose
Polysaccharides
Starch – Most common
* crystalline and insoluble
**Non-starch (NSP) **term replaces ‘fibre’
* from cereals, vegetables and fruit
* NSP rich foods are low in energy and high in bulk (for proper function of gut)
* low intakes related to constipation, diverticular disease, appendicitis, cancer of the colon
Children need more protein not fibre
Protein diet averages vs reccomendations?
Usually = 10-15% of total energy of diet.
US/UK = 14%
developing countries = 10%
UK recommendations:
* 0.75g/kg body weight for adults and no more than 1.5g/kg/day
* 55g/day for men and 44g/day for women
Why do we need protein?
‘Essential’ amino acids needed for:
- synthesising new protein
- catecholamines
- thyroid hormones
- neurotransmitters
- haem
- glutathione
Why is the quality of protein important?
proteins of animal origin more effective in supporting growth of lab animals than those from plants because Amino acid pattern nearer that of body protein
- ‘high quality’ proteins higher utilisation and less waste.
- low quality proteins (usually plants) deficient in certain amino acids
Mixtures of ‘low quality’ proteins can complement deficit. e.g. wheat and pulses (Each defficinet in one AA and together they make up for it)
* important in poor countries where diet mainly vegetarian
What are the recomendations for babies based on?
infants: based on milk intake of breast fed infants showing satisfactory growth
for pregnancy: compatible with protein deposition for 3.3 kg infant
for lactation: based on protein content of human milk
What could happen with Protein – Energy Malnutrition?
Excessive intake may lead to bone demineralisation or deterioration of renal function in patients with renal disease
Lack of Protien
* Growth Failure
* Marasmus
* Kwashiorkor
* Marasmic kwashiorkor
How does Classification of PEM in chidren occur?
oedema = Fluid retention (oedema) occurs when fluid isn’t removed from the body tissues, including the skin … a feeling of stiffness or aching and weight fluctuations.
