Introduction to Nutrition This slide presentation is the
Introduction to Nutrition This slide presentation is the nonillustrated version and is suitable for those with GCSE Science/Biology and above Dr Alan Stewart MB BS MRCP www.stewartnutrition.co.uk Introduction to Nutrition: what you will learn Nutrition - one of the Functions of Life What are the Essential Nutrients Undernutrition and Overnutrition How Common are Nutritional Problems? Deficiencies - How They Develop and Why Who informs you about nutrition? Further Information on Life Functions Written by Dr Alan Stewart www.stewartnutrition.co.uk Do you remember Mrs NERG? The 7 Functions of Life that characterise living organisms Movement Respiration
Sensitivity Nutrition Excretion Reproduction Growth What is the Missing Life Function? Welcome Mrs NERGD! Movement Respiration Sensitivity Nutrition Excretion Reproduction
Growth Defence Adequate nutrition plays a central role in all of these characteristic functions Lack of one or more of the essential nutrients leads to a loss of one or more of these life functions If deficiency is uncorrected then it can lead ultimately to death of the organism Nutritional deficiencies are
often diagnosed due to characteristic disturbance in these life functions Life Functions: What organs are involved? Movement Bone, muscle and nerves Respiration Food + oxygen = energy Sensitivity Special senses, nerves and the brain Nutrition Gut, liver and many other organs
Excretion Liver and kidneys and also skin, gut and lungs Reproduction Eggs, sperm and baby Growth All tissues Defence Immune system (white cells + antibodies), skin Each life function and organ have different nutrient requirements Essential Nutrients There are two types of nutrients essential to life: Macronutrients Nutrients required in large amounts - proteins, fats, carbohydrates. They are needed for energy production
Protein is needed for growth and maintenance functions Water and fibre are also needed in significant amounts Micronutrients Nutrients required in small amounts - vitamins, minerals and essential fatty acids. They are needed for numerous functions Essential Nutrients - Macronutrients Macronutrient Energy Provision in average adult diet Carbohydrates 50% Fats 35% Protein 15% Alcohol (non-essential) 0%-5%
sugars and complex carbohydrates saturated and unsaturated fats provide essential and non-essential amino acids Food Energy Sources National Diet and Nutrition Surveys 1992-2001 60.00% 50.00% 40.00% CHO Fats Protein Alcohol 30.00% 20.00% 10.00% 0.00% Infants Children Adults FreeLiving Elderly Food Energy Sources: % of Total Intake National Diet and Nutrition Survey: British Adults 19-64 yrs Women
Ca, Mg, Na, K, Cl, P Fe, Zn, Cu, Mn, I, Se,? others Vitamins: fat-soluble water-soluble A,D,E, and K B group and C Essential Fatty Acids: n-3 series Linoleic acid and derivatives n-6 series Linolenic acid and derivatives The Six Criteria for Nutrient Essentiality The nutrient. is essential for one or more of the (8) functions of life is not synthesized or synthesized adequately in the body has a function that is either biochemical or structural if deficient, a recognizable loss of function or structure results if deficient the loss of function or structure is proportional to degree and duration of depletion if deficient the loss of function is, in the short term, reversible by the specific nutrient Essential Nutrients and Life Functions Life Functions
Key Essential Nutrients Movement Calcium and vitamin D bones, Protein and potassium - muscles Respiration Vitamin B metabolism, iron oxygen transport, Iodine thyroid hormone and metabolic rate Sensitivity B vitamins - central and peripheral nerves Iron and iodine - intellectual development Nutrition Zinc and iron - appetite Excretion
Water, sodium and potassium - urine excretion Reproduction Iron and B vitamins fertility and pregnancy outcome Growth Energy, protein, iron, zinc, vitamin A infant growth Defence Protein, vitamin A and zinc - immune function Nutrition and Health Nutrition plays a central role in all life functions Animals often spend a large amount of time and energy obtaining food and feeding, but we humans do not Nowadays we can choose between nutritious/non-nutritious foods Food choice makes a big difference to our health and the risk of: deficiency undernutrition excess overnutrition Our food choices are determined by: - habits usually established in childhood
- personal likes and dislikes - cost of food - convenience of shopping and preparing - education about what is nutritious and healthy What are the Common Nutritional Problems? These can be classified relating to the supply of macro and micronutrients: Undernutrition iron, calcium, vitamin D, folate, vitamin B12 and protein-energy Overnutrition energy obesity, sodium salt, saturated fats, sugar, vitamin A The prevalence of these problems in the British and UK populations have been assessed in a series of national surveys called The National Diet and Nutrition Surveys and others conducted by the Food Standards Agency and related organisations The National Diet and Nutrition Surveys Four surveys ages 1.5 to >85 yrs Random samples of the British population Conducted between 1992 and 2002 Collected information on: - 4-7 day weighed dietary macro- and micronutrient intakes - laboratory measures of many essential nutrients - alcohol intake, supplement use - Blood Pressure, cholesterol and other tests
- Height, Weight and Body Mass Intake No clinical assessment See www.fsa.org Problems of Undernutrition Nutrient At-Risk Group(s) Consequences Water All ages Dehydration, collapse and death Protein/Energy Infants/Teenagers Reduced growth/Anorexia Nervosa Iron Infants Anaemia, poor learning ability Zinc
Children/Teenagers Reduced height and poor immunity Fibre All ages Constipation Iron Menstruating women Anaemia Folate Pregnant women Birth defects Vitamin D Pregnant Asian women Reduced bone development in infants Vitamin B12
Vegetarians and elderly Fatigue, poor concentration, anaemia Calcium and vitamin D Elderly Osteoporosis and increased risk of fracture Vitamin C Elderly Increased risk of stroke Prevalence of Undernutrition in the UK Data Taken from National Diet and Nutrition Surveys Nutrient At-Risk Group(s) Prevalence Water All ages Rare except in ill patients
Protein/Energy Infants/Teenagers 1 -3% of adults have a BMI<18.5 kg/m2 Iron Infants/ women Anaemia in 5 -10% Zinc Children/Teenagers 10-33% have low dietary intakes Fibre All ages ~80% have low dietary fibre intakes Iron Menstruating women Anaemia in 10% of women
Folate Pregnant women 5 -10% deficient but all need supplements Vitamin D Pregnant Asian women >50% deficient but all need supplements Vitamin B12 Vegetarians and elderly Deficiency in up to 10% of both groups Calcium and vitamin D Elderly Up to 50% of all elderly Most aged over 80 yrs need supplements Vitamin C Elderly 30% of >85 yrs have mild deficiency
Supplemental Milk and Growth Increase in Height in Inches per Boy in One Year Mann H C Corry (1926) Sp. Rep Ser Med Res Coun. London No. 105. 3 2.5 2 1.5 1 0.5 0 Basic Diet Water- Casein Cress Veget Marg Sugar N-Z Butter Milk
Height 219 Institutionalised boys many of whom were considered to be below the Increase standard for height and weight despite the diet being adequate 41 Boys were given 1 pint of whole pasteurised milk per day Additional sugar, margarine and butter were isocaloric Common Problems of Overnutrition Nutrient At- Risk Group(s) Consequences Energy All ages Obesity Sugar - sucrose All ages Dental caries Sugar - fructose Adults
Gout, liver disease Saturated Fats Adults Heart disease Animal Protein Adults Osteoporosis Sodium All ages High blood pressure Sodium Elderly Heart failure and osteoporosis Iron Genetically predisposed
Haemochromatosis Vitamin A from food/supplements Adults and elderly Osteoporosis Water Elderly and those on antidepressants Sodium depletion - hyponatraemia Prevalence of Overnutrition in the UK Data Taken from National Diet and Nutrition Surveys Nutrient At- Risk Group(s) Consequences Energy All ages Obesity
Sugar - sucrose All ages Dental caries Sugar - fructose Adults Gout, liver disease Saturated Fats Adults Heart disease Animal Protein Adults Osteoporosis Sodium All ages High blood pressure Sodium
Elderly Heart failure and osteoporosis Iron Genetically predisposed Haemochromatosis Vitamin A from food/supplements Adults and elderly Osteoporosis Water Elderly and those on antidepressants Sodium depletion - hyponatraemia Undernutrition vs. Overnutrition Problems of both under and over nutrition are commonplace across the UK
They are usually mild in degree but if they are long-standing they can produce significant adverse health effects Many of them will be adequately addressed by: - simple targets for eating a healthy diet - limiting intake of alcohol - adequate exercise The extremes of life very young and old, are most at risk of undernutrition Socio-economic deprivation is still a significant risk factor for both undernutrition and overnutrition Education is often a vital part in resolving both types of problems Development of a Nutritional Deficiency
Adequacy State of Negative Balance Decline in Tissue Stores Alteration in Function Symptoms Physical Signs Organ Failure Death After M. Brin JAMA 1964;187:762-766 State of Negative Nutrient Balance: Causes 1. Inadequate Intake Loss of appetite Poor quality diet 2. Reduced Absorption Diet: tea inhibits iron absorption Diseases causing malabsorption 3. Increased Losses Heavy periods iron Sweating sodium loss Diarrhoea sodium, potassium 4. Increased Need Growth and pregnancy
5. Altered Metabolism Disease: liver and kidney Drugs, alcohol, genetic variation Time Scale for the Development of a Deficiency State Days Water; 2-7days Weeks Protein/Energy 8 weeks Vitamin B1; 2-8 weeks 2 months 4 months 4 months 2-6 months - fatigue, muscle weakness and necrosis - loss of appetite, loss of night vision and infections
- fatigue, haemorrhage and sudden death - fatigue, skin changes, inanition and infection 2 years 4 years - loss of night vision, infections - fatigue, pernicious anaemia, SACD Years Vitamin A; Vitamin B12; - death from respiratory failure if BMI<12.0 kg/m2 - fatigue, neurological deficit and cardiac failure Months Potassium; Zinc; Vitamin C; Vitamin B - dehydration, renal and circulatory failure Decades Calcium; Chromium;
3-4 decades - osteoporosis and fractures decades - glucose intolerance, type II diabetes and CHD Who informs you about nutrition? Global The World Health Organisation The Food and Agriculture Organisation European European Food Safety Agency National Department of the Environment and Rural Affairs Food Standards Agency Community School/Work place Family Parents/Grandparents/Partner Healthcare Doctor/Dietitian/Nutritionist/Research Scientists Other Books/Magazines/Newspapers/TV/Internet/Friends/Packaging
You! Education and Experience Introduction to Nutrition Sources of Information Standard Reference Texts ABC of Nutrition. A Stewart Trusswell BMJ Publications 2000 - Excellent introductory book that covers the basics 20.00 Modern Nutrition in Health and Disease. Ed. Shils et al. Lippincott Williams and Wilkins. 1999 - This American book in its ninth edition is the only serious reference work 120.00 Dietary Reference Values TSO London 1991 - This old small reference volume is still a good source of information 20.00 National Diet and Nutrition Surveys 1990-2004 All four surveys of the British population (infants, children, adults and the elderly) are available in print from TSO London 40.00 to 160.00 The latest on adults is available from www.defra/ Web sources www.nice.org.uk/CG032 Much needed guidance on nutrition screening and assessment www.ods.od.nih.gov US government website has information about most but not all nutrients www.lpi.oregonstate.edu Website of the Linus Pauling Institute has non-commercial information Introduction to Nutrition: End
Thank you for your attention The full illustrated version of this presentation is presented in person by Dr Stewart to school, college and university students. Please contact Dr Alan Stewart MB BS MRCP [email protected] Tel 01273-487003 For additional lectures see related presentations on: Nutritional Assessment National Diet and Nutrition Surveys How Safe are Nutritional Supplements? at www.stewartnutrition.co.uk Life Functions: Further Information Eight further slides on the effects of undernutrition on life functions One further slide on the effects of overnutrition and life functions Mrs NERGD Movement and Undernutrition Movement requires: muscles, bones and nerves to muscles Muscles, bones and motor nerves need: protein 0.8g of dietary protein per kg body weight per day vitamin B - energy release in muscles calcium, sodium and potassium - muscle contraction magnesium muscle relaxation calcium and vitamin D bone formation
vitamin B motor nerve function Deficiency = loss of muscle bulk and weakness osteoporosis loss of motor nerve function resulting in reduced mobility, falls and fractures Mrs NERGD Respiration and Undernutrition Respiration: food + oxygen = energy + waste Energy sources are macronutrients: fats, carbohydrates and protein (plus alcohol) Respiratory processes need micronutrients: vitamin B for energy releasing enzymes liver and muscles magnesium for the same enzymes iodine controls rate of metabolism through thyroid hormones iron and vitamin B haemoglobin for oxygen transport in the blood Deficiency = fatigue and loss of many functions Mrs NERGD Excretion and Undernutrition Excretion eliminates the waste products of respiration, drugs, toxins and some nutrients Waste is excreted by: kidneys water-soluble compounds: urea, drugs, sodium & other minerals
liver fat-soluble drugs, hormones and some minerals and also the lungs, intestines and skin Excretion processes need: water adequate blood volume and urine output vitamins B, C and potassium many enzyme processes in kidneys and liver zinc in cells for CO2 excretion (enzyme carbonic anhydrase) excretion process require lots of energy Deficiency = reduced renal function altered liver function accumulation of waste products especially drugs Mrs NERGD Nutrition and Undernutrition The metabolism of nutrients are interlinked Being adequately nourished makes it easier to obtain food and maintain a healthy metabolism: vitamin D - absorption of calcium zinc - metabolism of vitamin A copper - absorption of iron Deficiency = changes in: Appetite: Growth: Metabolism: Mobility: iron - loss or alteration in appetite (pica),
zinc - loss of taste vitamin B1 - nausea and delayed stomach emptying protein/energy reduced child growth and adult size and reduced lifelong demand for all nutrients one nutrient deficiency can cause another reduced ability to obtain food and feed themselves Mrs NERGD Sensitivity and Undernutrition Awareness of the external environment requires an intact nervous system and specialized organs The sensory functions require different nutrients: vitamin A retinal function and health of the cornea iodine - hearing and mental development in infants zinc taste and vision vitamin B1 - touch sensitivity vitamin B12 vibration sense and position sense iron, essential fats and vitamin B higher mental function Deficiency = loss of sensory or neurological function The loss is often characteristic of the specific nutrient Mrs NERGD - Reproduction and Undernutrition Reproduction is a vital biological goal and mammals have only a few (high quality) offspring Successful reproduction needs many nutrients protein-energy, body weight (>40 kg) - age of menarche protein-energy - regularity of periods folic acid and vitamin B12 - miscarriage folic acid and vitamin B12 birth defects protein-energy and iron low birth weight many nutrients in maternal diet - breast milk quality and infant nutrition
zinc and folic acid - male sperm quality Deficiency = infertility, reduced fertility poor pregnancy outcome The full consequences of nutritional deficiency on reproduction and growth may take several generations to undo Mrs NERGD Growth and Undernutrition Growth is one of the four main uses of nutrients (reproduction, maintenance and storage) Many nutrients are essential for good growth: protein-energy essential at all ages for good growth calcium and vitamin D for skeletal growth from birth to early 20s vitamin A influences production of growth hormone in infants iodine deficiency results in reduced height and poor mental development zinc deficiency causes poor longitudinal growth and delayed puberty Deficiency = smaller birthweight reduced growth increased health risks in adult life Catch-up growth is possible if deficiencies are corrected quickly Mrs NERGD Defence and Undernutrition
Defence is a life characteristic for most organisms Defence mechanisms involve different organs: protein-energy, vitamin A, vitamin B, zinc, copper immunity (antibody production and white cells) vitamin C, zinc, essential fatty acids skin quality and wound healing iron, vitamin B healthy gut wall vitamin A - reduces the ability of bacteria to adhere to the respiratory tract many nutrients - physical defence (muscles, skeleton, nerves) many nutrients needed for internal protection against cancer developing Deficiency = decline in defence mechanisms death from infection, injury or cancer Life Functions and Overnutrition Movement Obesity reduces mobility Vitamin A excess increase the risk of osteoporosis Respiration Obesity increases energy need by 9 kcl for each kg of weight/day
Sensitivity Water excess can lead to sodium deficiency, mental confusion or a stroke Nutrition Dietary sugar causes dental caries and loss of teeth Excretion Salt and soft drinks increase calcium losses in urine Obesity + high fructose intake cause liver disease Reproduction Vitamin A excess can cause birth defects Growth Obesity increases the risk of small-for-date babies
Defence High doses of vitamins may increase cancer risk High dose zinc supplements may reduce immunity
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