Dietary Requirements Flashcards
What elements of food intake and lifestyle have been linked to cancer?
Excess energy rich foods (fat and sugar), physical inactivity, carcinogens, nitrates used in preservation, accidental contaminants (moulds producing aflatoxin and fungi).
Foods with high sugar and fat content predispose us to?
Dental caries and obesity
In the UK, dietary reference values for food energy and nutrients are stated as?
Reference Nutrient Intakes
Reference Nutrient Intakes provide sufficient intake standards to meet the demands of what % of the population?
97.5%
Most individuals intakes are below the RNI therefore what other value is presented which represents the amount adequate for most?
Estimated Average Intake EAR
The Lower Reference Nutrient intake fails to meet the requirements of what % of the population?
97.5%
What is the SI measurement of energy?
joule
How many kilocalories are in 1kilojoule?
0.239kcal
What is the conversion factor of kj to kcal?
4.2kj per 1kcal
What are the two approaches in assessing energy requirements for weight-stable subjects close to their energy balance?
- Assessment of their energy intake
2. Assessment of their total energy expenditure
Total energy expenditure is the sum of?
TEE = Basal metabolic rate (BMR) x [Time in bed + (Time at work x PAR) + (Non-occupational time x PAR)]
Total energy expenditure can be measured using?
Double-labelled water technique
What is involved in the double-labelled water technique?
Water containing stable isotopes 2H and 18O is given orally. As energy is expended, Co2 and H20 are produced. The difference between the rates of loss of the two isotopes is used to calculate Co2 production which is then used to calculate energy expenditure.
How is BMR calculated?
You can measure oxygen consumption and CO2 production but usually its taken from standardised tables of age, weight and sex.
One mol of glucose produces how many mol of ATP?
36 mole of ATP
In the UK the estimated average daily energy requirements for 55 year old male and female would be?
Male - 2550kcal (10600kj)
Female - 1940kcal (8100kj)
In the UK the current diet comprises what % of each macronutrient?
50% carbohydrate, 35% fat, 15% protein and 5% alcohol
In what instances would energy requirements increase?
Pregnancy, lactation, trauma, infection
In general the increased BMR associated with inflammation or trauma is counteracted or more than counteracted by a decrease in?
Physical activity so requirements are not increased
In the basal state what are the % energy demands for resting muscle, abdominal viscera, brain and the heart?
Resting muscle 20%, abdominal viscera 35-40%, brain 20% and heart 10%
Virtually all body fat and glycogen is available for oxidation but how much protein is?
<50%
Which macronutrient accounts for the largest reserves in energy for lean and obese subjects?
Fat stores
A gain or loss of how much energy would increase or decrease body weight by 1kg?
25-29MJ / 6000-7000kcal
In the UK what is the adult daily RNI for protein?
0.75g/kg
Most affluent individuals consume around how much protein per day in grams?
80-100g
The balance between protein breakdown and synthesis is measured by?
The total amount of nitrogen excreted in urine
In order to maintain nitrogen balance, how much protein is needed in grams?
40-50g of dietary protein
The amount of protein oxidised can be calculated from?
The amount of nitrogen excreted in the urine over 24 hours using the equation: Gram of protein required = urinary nitrogen x 6.25 (most proteins contain around 16% of nitrogen)
Urinary urea is more easily measured in practice and forms what % of the total urinary nitrogen?
80-90%
In healthy individuals what does urinary nitrogen excretion reflect?
Protein intake
In what conditions does urinary nitrogen not reflect protein intake?
Catabolic (negative N balance) or during growth or repletion following an illness (positive N balance)
What are the 9 essential amino acids?
Phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, lysine
How can you increase your amino acid intake on a vegan diet?
Combine foodstuffs e.g. maize (cereals) and legumes
Inadequate protein and inadequate energy intake can lead to?
Loss of protein from the body (negative nitrogen balance)
What happens to protein when there is a loss of energy from the body?
More protein is directed towards oxidative pathways and eventually gluconeogenesis for energy
What is the role of the amino acid Glutamine?
The most significant amino acid in the circulation and in inter-organ exchange
What is the role of the amino acid Alanine?
It is released from muscle, deaminated and converted into pyruvic acid before entering the krebs cycle
What is the role of the amino acid homocysteine?
It is a sulphur containing amino acid derived from methionine in the diet. A raised plasma concentration of homocysteine is an independent risk factor for vascular disease