Notes on Nutrition by Chamali Samarasekara. Notes on Nutrition

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1 Notes on Nutrition Patient groups particularly affected by their nutrition Pregnant and lactating women Babies (constipation) Children (malnutrition) The elderly (immobility/ visual impairment) Inpatients (high calorie/ low salt diets etc) Hypertensive/ overweight/ CHD patients (decrease cholesterol/ saturated fats) Malnourished patients (drug addicts/ alcohol dependent/ patients with eating disorders/ excessive processed food use/ special diets e.g. vegans) Patients with renal failure (decreased protein) What are the components of a healthy diet? Carbohydrate 55% daily intake (with 10% as free sugar) Fat 30% daily intake (unsaturated 20%, saturated 10%, cholesterol <300mg) Protein 15% daily intake (0.75g/kg required per day which is roughly 40-50g, essential amino acids must be included in diet) What are the components of a healthy diet? 2 Water ~1l/day Dietary fibre 30g/day Vitamins Minerals Salt <6g/day Nutrient A substance that must be consumed as part of the diet in order to sustain energy or growth Mineral Any of a group of substances that are required in very small amounts for healthy growth and development Trace elements Selenium Found in seafood, meat, chicken, grain cereals, egg yolk, milk, mushrooms and garlic Antioxidant Prevents chromosome breakage May play role in preventing some birth defects 1

2 Chromium Found in high concentrations of brewer's yeast, wine, some brands of beer Enhances normal activity of insulin in carbohydrate and lipid metabolism Fluoride Thought to improve tooth structure and inhibit tooth decay Stored in bones, teeth and other tissues Zinc Found in many foods, particularly meat Component of enzymes: carbonic anhydrase (carbon dioxide metabolism), peptidases (protein digestion) Needed for normal growth and wound healing, normal taste sensation and appetite and normal sperm count in males Cobalt Constituent of vitamin B12 (thus required for erythropoiesis) Copper Some stored in liver and spleen (most excreted in faeces) Sources: eggs, whole wheat flour, beans, beets, liver, fish, spinach, asparagus Required with iron for haemoglobin synthesis Component of: coenzymes in electron transport chain, enzyme needed for melanin synthesis Manganese Some stored in liver and spleen (most excreted in faeces) Activates several enzymes Needed for: haemoglobin synthesis, urea formation, growth, reproduction, lactation, bone formation Iodide Sources: seafood, iodised salt, vegetables grown in iodine-rich soils Essential component of thyroid hormones (regulate metabolic rate) Iron Found in meat, liver, shellfish, egg yolk, beans, legumes, dried fruit, nuts, cereals Component of haemoglobin and some cytochromes involved in electron transport chain 2

3 Magnesium Sources: green leafy vegetables seafood, whole grains Required for normal muscle and nervous tissue function Constituent of many coenzymes Important cation in intracellular fluid Chloride Normal salt intake supplies regular amounts Important anion in extracellular fluid Plays role in acid base balance of blood Also involved in water balance and HCl formation in the stomach Fat soluble vitamins A D E K Vitamin A AKA retinol (from retinoid family) Sources: liver (richest), fish oils, egg yolks, milk, butter, cheese Stored in liver and bound to retinol-binding protein and carried in plasma Teratogenic Vitamin D 7-dehydrocholesterol in skin converted by sunlight into cholecalciferol (vitamin D3) Enzyme in kidneys converts this to calcitriol (active form of vitamin D) Dietary sources include: fish liver oils, egg yolk, fortified milk Essential for absorption and utilisation of calcium and phosphorus from GIT Works w/ PTH to maintain calcium homeostasis Defective calcium utilisation can lead to rickets (children) or osteomalacia (adults) Vitamin E (tocopherols) Found in: fresh nuts, wheat germ, seed oils, green leafy vegetables Antioxidant (inactivates free radicals) Involved in DNA, RNA and RBC formation Inhibits catabolism of certain fatty acids that help for cell structures especially membranes 3

4 Vitamin K Produced by intestinal bacteria Also found in: spinach, cauliflower, cabbage and liver Coenzyme essential for liver synthesis of several clotting factors e.g. prothrombin Water soluble vitamins B 12, Biotin, Pantothenic acid, Folic acid, C, B 6, Niacin, B 2, B 1 Folic Acid AKA folate, folacin Sources: green leafy vegetables, broccoli, asparagus, breads, dried beans, citrus fruits Some synthesised by bacteria in GIT Essential for normal red and white blood cell production Higher risk of neural tube defects in babies born to folate deficient mothers Vitamin B 12 AKA cyanocobalamin Absorption reliant on intrinsic factor Sources: yeast, liver, eggs, milk, cheese, meat, kidney Needed for formation of red blood cells and choline Facilitates entrance of some amino acids into the Krebs cycle Biotin Synthesised by bacteria in GIT Sources: yeast, liver, egg yolk, kidneys Essential coenzyme for conversion of pyruvic acid to oxaloacetic acid Vitamin B 6 AKA pyridoxine Synthesised by bacteria in GIT Also found in salmon, yeast, tomatoes, yellow corn, spinach, whole grain products, liver, yogurt Essential coenzyme for amino acid metabolism Niacin AKA nicotinamide Derived from tryptophan (amino acid) Found in: yeast, whole grain products, liver, meat, fish, peas, beans and nuts Pellagra (niacin deficiency): diarrhoea, dermatitis, psychological disturbances 4

5 Vitamin B 2 AKA riboflavin Found in yeast, whole grain products, liver, peanuts, peas, beef, asparagus, eggs, beef, veal and lamb Involved in carbohydrate and protein metabolism especially in the blood, eye and intestinal mucosa Vitamin B 1 AKA thiamine Sources: whole grain products, eggs, pork, nuts, liver, yeast Coenzyme for breaking down carbon-carbon bonds Involved in carbohydrate metabolism of pyruvic acid into CO 2 and H 2 O Deficiency can result in beriberi or polyneuritis Pantothenic Acid Some synthesised by bacteria in GIT Found in: green vegetables, kidney, liver, yeast and cereal Constituent of co enzyme A (transfers acetyl group from pyruvic acid to Krebs cycle Involved in glucose formation from lipids and amino acids, and synthesis of cholesterol and steroid hormones Vitamin C AKA ascorbic acid Sources: citrus fruits, tomatoes, green vegetables Antioxidant Promotes wound healing and many metabolic reactions, especially protein metabolism Deficiency can cause scurvy and impaired wound healing References Tortora 9 th edition (pages 906-8) Kumar and Clark 5 th edition (pages ) Oxford Concise Colour Dictionary article on obesity (worth a look) Note These notes were written by Chamali Samarasekara as a medical student in They are presented in good faith and every effort has been taken to ensure their accuracy. Nevertheless, medical practice changes over time and it is always important to check the information with your clinical teachers and with other reliable sources. Disclaimer: no responsibility can be taken by either the author or publisher for any loss, damage or injury occasioned to any person acting or refraining from action as a result of this information 5