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