Transcript Introduction to Nutrition - Nutrition Assessment, Vitamins

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
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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%
sugars and complex carbohydrates
• Fats
35%
saturated and unsaturated fats
• Protein
15%
provide essential and non-essential amino acids
• Alcohol (non-essential)
0%-5%
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
Alcohol
Men
Sugar
Fruit
Vegetables
Potatoes
Meat
Dairy
Grains
0%
5%
10%
15%
20%
25%
30%
35%
Essential Nutrients - Micronutrients
• Minerals:
Bulk
Trace
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
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Movement
Calcium and vitamin D – bones,
Protein and potassium - muscles
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Respiration
Vitamin B – metabolism, iron – oxygen transport,
Iodine – thyroid hormone and metabolic rate
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Sensitivity
B vitamins - central and peripheral nerves
Iron and iodine - intellectual development
• Nutrition
Zinc and iron - appetite
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Excretion
Water, sodium and potassium - urine excretion
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Reproduction
Iron and B vitamins – fertility and pregnancy outcome
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Growth
Energy, protein, iron, zinc, vitamin A – infant growth
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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
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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
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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
- dehydration, renal and circulatory failure
• Weeks
Protein/Energy 8 weeks
Vitamin B1;
2-8 weeks
- death from respiratory failure if BMI<12.0 kg/m2
- fatigue, neurological deficit and cardiac failure
• Months
Potassium;
Zinc;
Vitamin C;
Vitamin B
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;
• 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
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Movement
Obesity reduces mobility
Vitamin A excess increase the risk of osteoporosis
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Respiration
Obesity increases energy need by 9 kcl for each kg
of weight/day
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Sensitivity
Water excess can lead to sodium deficiency, mental
confusion or a stroke
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Nutrition
Dietary sugar causes dental caries and loss of teeth
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Excretion
Salt and soft drinks increase calcium losses in urine
Obesity + high fructose intake cause liver disease
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Reproduction
Vitamin A excess can cause birth defects
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Growth
Obesity increases the risk of small-for-date babies
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Defence
High doses of vitamins may increase cancer risk
High dose zinc supplements may reduce immunity