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
Which amino acid is required for haem production?
Glycine
Which amino acid is required for melanin and thyroid hormones?
Tyrosine
Which amino acids are required for nucleic acid bases?
Glutamine, Aspartate and Glycine
Glutamate, cysteine and glycine are amino acids required for glutathione. What is glutathione?
Part of the defence system against free radicals
What is dietary fat in the form of?
Triglycerides
What are triglycerides?
Esters of glycerol and free fatty acids
What do fatty acids vary in?
Chain length and saturation
Hydrogen molecules in fatty acids related to double bonds (cis or trans) are mostly in which form in foods?
Cis
What are the two essential fatty acids?
Linoleic and alpha-linoleic
Alpha-linoleic and linoleic acids are precursors for what?
Prostaglandins
What two acids can linoleic and linolenic acid make?
Eicosapentanoic (EPA) and docosahexanoic (DHA)
Dietary fat provides how many kj/kcal per gram?
37kj / 9kcal
What is the main source saturated fat is derived from?
Animals
What is the main source omega-6 fatty acids are derived from?
Vegetable oils and other plant foods
What is the main source omega-3 fatty acids are derived from?
Vegetable foods, rapeseed oil, fish oils
What is the main source trans fatty acids are derived from?
Hydrogenated fat or oils e.g. margarine, cakes and biscuits
What impact do trans fatty acids have on the body which is similar to saturated fatty acids?
Increase circulating LDL and decrease HDL which raise the risk of CVD
N-6 polyunsaturated fatty acids are components of?
Membrane phospholipids, influence membrane fluidity and ion transport. They also have antiarrhythmic, antithrombotic and anti-inflammatory properties which prevent CVD.
What is the role of N-3 fatty acids in the body?
Increase circulating HDL cholesterol and lower triglycerides which may reduce CVD.
What do the British Nutrition Foundation and the American Heart Association recommend regarding the intake of n-3?
Two-fold increase in N-3
3 PUFAs by eating more fish or ingesting fish oil capsules
What products is cholesterol found in?
All animal products
What is the average daily cholesterol intake in the UK?
300-500mg
What can affect blood cholesterol levels?
Either very high or very low cholesterol diets
Which patients are at risk of essential fatty acid deficiency?
Patients on long-term parenteral nutrition given glucose, protein and no fat
What is the recommended dietary fat intake including total fat, sat fat, cis mono and cis poly?
Total fat - 15-30%, Sat fat <10%, Cis monounsaturated 20%, Cis polyunsaturated 6%
What is the recommended healthy dietary intake of cholesterol in mg/day?
<300
What is the recommended healthy dietary intake of salt per day?
<6g
What is the recommended total dietary fibre intake per day?
30g >25g/day
How many kilojoules/kcal in one gram of carbohydrate?
17kj / 3.75kcal
Carbohydrate intake comprises?
Polysaccharide starch, disaccharides (mainly sucrose), monosacharides (glucose and fructose)
The WHO suggests sugar intake should be how much of a persons intake?
<5%
Dietary fibre is largely in what form?
Non-starch polysaccharides
Dietary fibre is often removed when?
In the processing of food
When dietary fibre is removed during processing food what is left?
Highly refined carbohydrates such as sucrose which contributes to dental caries and obesity
What is lignin?
Its included in dietary fibre in some classification systems but is not a polysaccharide just a minor component of the diet
What are the principle classes of Non-starch polysaccharides?
Cellulose, hemicelluloses, pectins, gums
Cellulose, hemicelluloses, pectins and gums are not digested by gut enzymes however NSP is partly broken down in the GI tract by colonic bacteria producing what?
Gas and volatile fatty acids e.g. butyrate
Bran is the fibre from which NSP?
Wheat
What effect does consuming bran have on health?
Increase faecal bulk and helpful in the treatment of constipation
What is our average daily intake of NSPs?
16g
What should we increase in our diet to reach 30g/d fibre?
Potatoes, bread, fruit and veg
Each gram of daily fibre contributes which weight of stool?
3-5g
Which NSPs are added to food to slow down monosaccharide absorption and is beneficial for those with Type 2 Diabetes?
Pectins and gums
A diet high in plant foods has been linked to protection against ischaemic heart disease, stroke and certain cancers by what mechanism?
It has a lipid-lowering effect and contains protective substances such as vitamin and non-vitamin antioxidants and other vitamins such as folic acid which is linked to homocysteine metabolism which is a risk factor for CVD.
Fermentation of fibre in the colon may protect you against?
Colon cancer
In the UK milk and margarine are fortified with which vitamins?
A and D
In the UK flour is fortified with which 4 things?
Calcium, iron, thiamine and niacin
What are cereals fortified with?
Several vitamins and iron
What is Olestra and what has it been used for?
A polymer of sucrose and 6/+ triglycerides and used to combat obesity in snack foods because it is not absorbable so reduces total calorie intake
What are some side effects of Olestra?
Loose stools and abdominal cramps
Define Nutrient Goals?
National intakes of nutrients that are considered appropriate for optimal health in the population. Based on scientific information linking nutrient intake to disease
Define Dietary Guidelines?
Refer to the dietary methods used to achieve the nutrient goals
What are the nutritional consequences of underlying disease?
Anorexia, increased nutrient requirement
What are the nutritional consequences of muscle weakness (respiratory and peripheral muscle) or severe arthritis in hands and arms?
Problems with shopping, cooking and eating
What are the nutritional consequences of swallowing problems, GIT and painful obstructions of the mouth?
Inadequate food intake and risk of aspiration or pneumonia
What are the nutritional consequences of GIT symptoms including nausea, vomiting, diarrhoea and jaundice?
Food aversion, malabsorption (small bowel disease), anorexia
What are the nutritional consequences in those with a sensory deficit (impaired sight, hearing etc)
Difficulties in shopping, cooking and decreased food intake
What are the nutritional consequences of loneliness, depression, bereavement, confusion, living alone, alcoholism and drug addiction?
Self-neglect, inadequate intake of food or poor quality of food
What are the nutritional consequences of polypharmacy’?
Confusion, sedation, depression and GIT side effects including malabsorption of some nutrients
