Case 15- Nutrients Flashcards
Essential nutrients
46 in total
• Carbohydrates- glucose or carbohydrates that yield glucose
• Fat- Linoleic acid (omega-6), linolenic (omega-3)
• Protein- 9 essential amino acids
• Vitamins- A, D, E, K, B1, B2, Niacin, Biotin, B12, Folate, C, Pantothenic acid
• Minerals- Ca, Cl, Mg, P, K, Na, S, Cr, Cu, Co, F, Fe, I, Mb, Mn, Se, Zn, As, B, Ni, Si
• Water
How much macro nutrients do you need
Total fat- 70g Saturated fat- 20g Carbohydrates- 260g Sugars- 90g Protein- 50g
Carbohydrate energy
1g of carbohydrate= 17kj (4kcal)
Carbohydrates
1) Ratio of hydrogen to oxygen is 2:1.
2) Available CHO is sugars and starch, unavailable CHO is dietary fibre. Available sugars can be used in metabolic processes, unavailable cant.
3) Contributes the greatest proportion of energy in our diet (50%). Limited storage capacity (glycogen). It is required by all cells but the brain, NS and developing red blood cells are obligatory users.
Carbohydrates- DNA and RNA
Ribose and deoxyribose are linked via N-glycosidic bonds to purine and pyrimidine bases
Carbohydrates- sources
Cereal products- 29% Vegetables- 11% Sugars, confectionary- 5% Beverages- 4% Milk and milk products- 9% Meat and meat products- 17% Fruit and nuts- 4%
Recorded and actual sources of carbohydratea
% of total energy= 50% (rec) 47.7% (actual) Non-milk extrinsic sugars= <10% (rec) 20.7% (actual) Complex CHO (starch)= >40% (rec) 27.1% (actual)
Proteins
Contains nitrogen. Function:
• Growth of new cells (muscle, bone, skin etc)
• Repair of tissues
• Formation of enzymes, transporters and hormones (signal transduction)
• Neurotransmitters - tryptophan (serotonin), glutamine
• Movement (actin and myosin)
• Immune function (antibodies, interleukins)
• Excess used for energy (gluconeogenesis)
Proteins kcal
1g of protein= 16kj (4kcal)
Essential amino acids
Essential amino acids= Phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine and histidine
Conditionally essential= arginine, cysteine, glycine, glutamine, proline, serin, tyrosine
Sources of amino acids
- Meat and meat products- 37%
- Cereal products- 23%
- Milk and milk products- 14%
- Vegetables- 8%
- Fish and fish dishes- 7%
- Egg and egg dishes- 3%
- Fruit and nuts- 1%
- Beverages- 2%
Recomended and actual daily intake of proteins
Recommended= 0.75g/kg body weight
Daily intake males= 55.5g (rec) 88.1g (actual)
Daily intake females= 45.0g (rec) 65.4g (actual)
Types of fatty acids
Unsaturated
1) Essential= omega-3 (alpha linolenic acid), omega-6 (Linoleic acid)
2) Non-essential= omega-3 (EPA and DHA), omega-6 (GLA), omega-9 (Oleic acid)
Saturated
1) Non-essential (Butyric acid, Palmitoleic acid and Stearic acid)
Omega 6 series
- Derived from linoleic acid (18:2n-6)
- Produces 2-series prostaglandins (PG) and 4-series leukotrienes (LT) from arachidonic acid
- Pro-inflammatory and involved in immune function, important cell signalling molecules
Omega-3 series
- Derived from alpha-linolenic acid (18:3n-3)
- Produces 3-series Prostaglandins and 5-series Leukotrienes from eicosapentaenoic acid (EPA)
- Appear to be anti-inflammatory
Functions of essential fatty acids
Structural components in membranes (phospholipids), production of myelin sheets. There is a high content of omega-3 and omega-6 fatty acids in myelin and other brain membranes, therefore there is a high demand for C24 and C26 PUFA in the first two years of life. Breast milk is assumed to provide enough EFA.
Dietary source of fats
- Linoleic and alpha-linolenic acids: plant foods, especially vegetable oil. Margarines and other spreads
- Arachidonic acid- animal fats
- EPA and DHA- fish and shellfish
Dietary recommendation for EFA
- At least 1% of total energy as 18:2n-6 (omega 6)
* At least 0.2% of total energy as 18:3n-3 (omega 3)
Vitamins
Organic compounds are required in small amounts for the normally functioning of the body and the maintenance of metabolic integrity. Organic (contain carbon). Easily destroyed (cooking, processing). Deficiencies can be fatal. Found in low amounts in plant and animal sources.
Water soluble and fat soluble
- Water soluble vitamins- are not stored (except vitamin B12), exit the body via urine relatively unchanged. Function as co-enzymes in energy, protein and nucleic acid metabolism.
- Fat soluble vitamins- readily stored, not excreted as readily, can be toxic in high amounts (vitamin A and D).
Vitamin A
- Functions- Structural role (vision and differentiation of epithelial cells), Humoral role (growth and reproduction)
- Animal Sources: Eggs, Butter, milk, milk products, liver, fish, fish oils, fortified margarine.
- Plant Sources: carrots,
- RNI (UK): 700ug/d
- Toxicity- Upper Level set at 3000 ug/d. Affects the liver (Fibrosis, hepatomegaly, hyperlipidemia), CNS (increased intracerebral pressure, headaches) and skin (excessive dryness, scaling, desquamation)
Vitamin D
- Function- Can be produced in man from sunlight. Maintenance of Calcium homeostasis: release of Ca from bone, higher rates of reabsorption from Kidney, higher absorption of Ca from intestine
- Sources: Oily fish, eggs, fortified milk, fortified breakfast cereals, fortified yogurt
- RNI 10 ug/d. Intakes (UK): 3- 3.8 ug/d
- Deficiency- Lack of Ca: Osteoporosis (bone loss). Lack of vitamin D: Osteomalacia in adults and Rickets in children (lack of bone mineralization)
Thiamin (vitamin B1)
- Functions- Part of nerve cell membranes, synthesize and regulate neurotransmitters
- Energy metabolism- plays role in decarboxylation and helps form Acetyl Co A from pyruvate
- Dietary recommendation- RDA for adult men is 1.2 mg for women is 1.1 mg per day. Higher needs in pregnancy; most diets with variety and adequate energy supply ample thiamin
- Sources: Pork, Whole and enriched grains, Fortified cereals, Most animal foods contain little thiamine
Cobalmin- vitamin B12
- Found as adenosyl cobalamin or methyl cobalamin; acts as carrier of 1-C units
- Involved in conversion of propionyl CoA to succinyl CoA and homocysteine to methionine
- Requires presence of intrinsic factor, produced in parietal cells of stomach, to enable absorption in the ileum
- Food sources and requirements- Milk, meat, animal foods in general
- RNI = 2.4 mg day
- Dietary deficiency rare except in strict vegans
- Symptoms due to absorption failure: pernicious anaemia (enlarged, immature blood cells), demyelination of nerves
Folic acids
- Exists in di- and tetra-hydrofolate forms; acts as carrier of 1-C units
- Involved in: amino acid metabolism (homocysteine to methionine) , purine metabolism, nucleotide synthesis , formation of the neural tube in the foetus
- Food sources and requirements: Fortified cereals, breads (USA, Canada, soon in the UK), Red meat, Some green vegetables
- RNI 200μg/day
Potassium
1) Needed for normal nerve and muscle function
2) Needed for keeping the right amount of water in different parts of your body
3) Sources- milk, bananas, tomatoes, oranges, melons, potatoes
Sodium
1) Needed for normal nerve and muscle function
2) Needed for keeping the right amounts of water in the different parts of your body
3) Sources- salt, milk, cheese, beets, celery, pork
Magnesium
- Principally related to enzyme activity (>300 enzyme systems are dependent on Mg+2)
- Acts as an allosteric activator of enzyme action
- Mg causes muscle relaxation after contraction due to Ca
Sources of Mg
Nuts, Shellfish => 400 mg/100g Some fruit and veg => 50-100 mg/100g Beer => 50 mg/pint Spirits => Low Water (hard water) => Up to 20% intake
Recommended sources of Mg
Females= 320mg/day Males= 420 mg/day
Calcium
- Function- building and maintaining bones and teeth, nerve transmission and regulation of heartbeat, muscle contraction, ionized form initiates formation of blood clots, cofactor in conversion of prothrombin to thrombin
- Requirements -(Adults: 800 mg/day, Teenagers 800mg/day; pregnancy 800mg/day)
Calcium contents in food
Milk => 120 mg/100g Cheese (hard) => 670mg/100 g Yogurt => 100 mg/100g tinned sardines => 550 mg/100g Plant food => Not very good e.g. carrots => 25 mg/100g but Tofu(soya) => 510 mg/100g
Iron
- Sources- red meat, enriched grains, fortified cereals
- RNI is 8.7 mg/day for adult male
- RNI is 14.8 mg/day for adult female
- Assumes that 18% of dietary iron is absorbed
- Average intake for women often below RNI
- Function- forms Haemoglobin, Myoglobin in muscle cells, part of the electron transport chain, enzyme cofactor, immune function, drug detoxification pathway
Zinc
- Sources- animal products, shellfish and legumes
- RDA for adult women is 7 mg/day
- RDA for adult men is 9.5 mg/day
- Function- cofactor to many enzymes, synthesis of DNA and RNA, protein metabolism, wound healing, immune function, growth, development of sexual organs and bones, insulin function
- Deficiency- growth retardation leading to stunting, slow sexual maturity, loss of taste, lethargy, emotional disorders, slow wound healing
Energy balance
- Energy balance- intake=expenditure
- Positive energy balance- intake>expenditure
- Negative energy balance- intake
Basal metabolic rate
The minimum rate of energy utilisation, the energy required for sustaining the basic processes of life. Its based on sex, age, body weight and height. About 2/3 of total energy expenditure.
How to measure the basal metabolic rate
It is measured 12 hours after eating, in a dimly lit warm room. Tends to be in the morning. The resting metabolic rate is only 4 hours after a meal and can be at any time of day, tends to be slightly higher then BMR. The sleeping metabolic rate is 5-10% lower then the basal metabolic rate.
What is included in energy expenditure
Basal metabolic rate, Physical activity (Exercise and Non-exercise activity thermogenesis (NEAT)), Thermic effect of food.
What to consider when measuring the basal metabolic rate
Sex, age, body weight and height
Non exercise activity themogenesis (NEAT)
Energy expended during spontaneous/unstructured physical activity. Its energy used that isn’t sleeping, eating or exercise i.e. brushing your teeth. Can be measured using fitbits.
How much energy tends to be used in exercise
10%
30% if highly active
Has to be planned exercise
Thermic effect of food (TEF)
Its the energy expended when eating (digesting, absorbing and storing food). Its about 10% of total energy expenditure
How to calculate energy expenditure
For different ages and sex you multiply your weight by a set value. This calculates your BMR. You then multiply your BMR by your physical activity level (PAL). PAL is dependent on non-occupational activity and occupational activity
Body mass of reference man and woman (Behnke)
- Male- body mass 70kg, lean body mass 62kg, bone 10.4kg, body fat 10.5kg
- Female- body mass 56.7kg, lean body mass 48.2kg, muscle 20.4kg, bone 6.8kg, body fat 15.3kg
Methods to measure body composition
- Indirect- Anthropometry (surface measurements to make estimates of fat), Bioelectrical impedance analysis (uses electrical current).
- Atomic and cellular- Neutron activation, Isotope dilution, total body counting. Costs more and takes a lot of time.
- Criterion- Densitometry, Imaging (CT, MRI), Underwater weighing, air displacement plethysmography
Assumptions about body method composition
They are based on assumptions regarding the density of body tissue, concentration of water and electrolytes and/or biological interrelationships between body components and body tissues.
Malnutrition
Deficiencies, excesses or imbalances in a persons intake of energy and/or nutrients.
Can be undernutrition or overnutrition
Stuntuing
Low height for age
Wasting
Low weight for height
Underwight
Low weight for age
Importance of adequate nutrients
1) Helps improve your immune system
2) Aids good academic performance
3) Economic development
4) Helps with recovery from illness
4 types of malnutrition
- Specific- deficiency of a particular nutrient
- Long standing- the clinical appearance of energy and nutrient deficiencies after a period of inadequate eating, often linked to neglect
- Sudden- due to a sudden marked change in food intake, often have a sudden disruptive life event like a fall or bereavement
- Recurrent- existing inadequate nutritional status followed by a period of illness and subsequent malnutrition causing repeated cycles of illness.
What is globally severe undernutrition linked to
- Lack of dietary education- inappropriate weaning
- Limited or unstable food supply- poverty, famine, war
- Presence of infections- due to poor hygiene. Reduced appetite, reduced absorption/utilisation of food, increased nutrient loss
Kwashikor syndrome
Pure protein deficiency without energy deficiency. Stunting, susceptibility to infection, hair colour changes (melanin not made), flaking skin (structural proteins not available for elasticity and support). Impaired nutrient absorption (GI tract cells die and are not replaced). Bloated belly (fat accumulation in liver and fluid accumulation in abdomen). Often due to a lack of dietary education
Marasmus
Energy and protein deficiency. Emaciated (body fat stores used for energy), ketosis. Energy and protein deficiency
Why do individuals become malnourished
- Inadequate nutrient intake
- Increased metabolic requirements- sepsis, burns, trauma, fever
- Excessive nutrient losses- vomiting, diarrhoea
Consequences of malnutrition
- Individual- Pressure ulcers, Respiratory failure, General infections, Hypothermia, Infertility, DVT and embolism, Wound complications, infections
- Health and social care services- Increased hospital admissions and length of stay, loss of earnings/employment, increased healthcare costs
The methods used to assess nutritional status
- Surveillance- assess health of group to identify risk of under/over nutrition and inform policy
- Screening- individual risk for over/under nutrition
- Clinical management of individuals- confirm diagnosis, identify reasons, monitor effectiveness of intervention
- Research-improve understanding
Nutritional screening
A rapid procedure to detect risk of malnutrition, done by a healthcare worker
Nutritional assessment
A detailed assessment of a subjects nutritional status, done by a nutritional expert
