Transcript Micronutrients - Food a fact of life

Micronutrients
© Food – a fact of life 2009
Extension
Learning objectives
• To understand the importance of micronutrients.
• To recognise the difference between water soluble
and fat soluble vitamins, major minerals and trace
minerals.
• To know the functions and sources of the
micronutrients.
• To know the problems caused by malnutrition.
• To understand some interactions between nutrients.
© Food – a fact of life 2009
Micronutrients
Micronutrients are needed in much smaller amounts
than the macronutrients.
In general vitamins are needed to regulate the
maintenance and growth of the body, and to control
metabolic reactions in cells.
Most vitamins are provided to the body by the diet,
however, the body can make vitamin D, vitamin K and
niacin.
© Food – a fact of life 2009
Vitamin A (retinol, carotene)
Vitamin A is fat soluble vitamin needed for the normal
structure and functioning of the skin and body linings,
e.g. in the lungs.
This vitamin also helps with vision in dim light, as well a
keeping the immune system healthy.
Found in two forms, retinol in foods from animal sources
and carotenoids from plant sources.
Vitamin A – retinol is found in liver, whole milk,
Vitamin A – carotenoids are found in dark green leafy
vegetables, carrots and orange coloured fruits.
© Food – a fact of life 2009
Too much or too little?
Deficiency leads to poor vision in dim light or night
blindness. In severe deficiency it can lead to total
blindness.
Vitamin A is stored in the liver and too much vitamin A
can be toxic.
Consuming too much vitamin A whilst being pregnant
has been linked with birth defects.
© Food – a fact of life 2009
Vitamin D (Cholecalciferol)
Vitamin D is needed for the absorption of calcium and
phosphorous from foods, to keep bones healthy.
Recent research also suggests that vitamin D enhances
immune function and improves muscle strength.
Vitamin D is found in the diet as well as being made by
the action of ultra violet rays on the skin.
Vitamin D occurs naturally in some animal
products, including fish liver oils, oily fish,
egg yolk, and butter.
Cereals, margarine and low fat spreads
are also fortified with vitamin D.
© Food – a fact of life 2009
Vitamin D deficiency
Deficiency in vitamin D leads to rickets and the
formation of soft bones. Bones in the legs may bend
due to body weight.
Osteomalacia may also occur in the older adults, as
pain and muscular weakness.
Vitamin D can be stored by the body and so too much
will result in the body absorbing too much calcium.
Young children, housebound older adults, and people
who practice religions where their skin must be
covered, may be at risk of deficiency.
© Food – a fact of life 2009
Vitamin E (Tocopherol)
Vitamin E is a group of similar molecules with common
properties and functions.
Vitamin E acts as an antioxidant and protects cells in
the body against damage.
Vitamin E is mainly found in vegetable oils, nuts,
seeds and wheat germ.
© Food – a fact of life 2009
Deficiency and excess of vitamin E
A deficiency in this vitamin is rare because it is so
widely available in the diet.
In very rare cases neurological disabilities such as lost
reflexes have developed.
There are no recorded adverse reactions to large
doses of vitamin E.
© Food – a fact of life 2009
Vitamin K
Vitamin K is needed for normal clotting of blood and is
also required for normal bone structure.
Infants are given vitamin K at birth.
Vitamin K is also produced by the bacteria in the gut.
Vitamin K is found in green leafy vegetables e.g.
broccoli, lettuce, cabbage, spinach and meat and
dairy products.
© Food – a fact of life 2009
Too much or too little?
Deficiency of vitamin K is rare
in adults, but is sometimes
seen in new born babies.
© Food – a fact of life 2009
Thiamin (B1)
Thiamin is needed for the release of energy from
carbohydrate. It is also involved in the nervous sytem
and the heart.
Thiamin cannot be made or stored in the body, so it is
necessary to obtain this from the diet.
Thiamin is mainly found in whole grains, nuts, meat
(especially pork), fruit and vegetables and fortified
cereals.
© Food – a fact of life 2009
Thiamin deficiency
Thiamin deficiency can lead to the development of
the condition called Beri-beri. This leads to symptoms
such as fatigue, weakness of the legs and anorexia.
Alcohol can prevent absorption of this vitamin causing
Wernick-Korsakoff syndrome (a neurological disorder
characterised by numb limbs, confusion, vision
changes and lack of co-ordination).
© Food – a fact of life 2009
Riboflavin (B2)
Riboflavin is needed for normal growth and the release
of energy from carbohydrate, protein and fat.
It is also involved in the transport and metabolism of
iron in the body and is needed for the normal structure
and function of skin and body linings.
Riboflavin is found in milk, eggs, rice, fortified
breakfast cereals, liver, legumes, mushrooms and green
vegetables.
© Food – a fact of life 2009
Too much or too little?
The tongue, lips and skin become affected when the
body is low in riboflavin.
Over nutrition of this vitamin is rare.
© Food – a fact of life 2009
Niacin (B3)
Niacin is important for releasing energy from food, and
is important for the normal structure of the skin and
body linings.
Niacin also maintains the health of the nervous and
digestive system.
Niacin can be found in meat, wheat and maize flour,
eggs, dairy products and yeast.
© Food – a fact of life 2009
Too much or too little?
A deficiency in niacin can lead to pellagra including
the development of:
• dermatitis;
• dementia;
• diarrhoea.
Over nutrition is rare.
© Food – a fact of life 2009
Vitamin B12
Vitamin B12 is needed for the formation of red blood
cells and synthesising fatty acids in the myelin of nerve
tissue.
Vitamin B12 also helps to release energy from food.
Vitamin B12 is found in meat, fish, cheese, eggs,
yeasts extract and fortified breakfast cereals.
© Food – a fact of life 2009
Deficiency of vitamin B12
Deficiency of vitamin B12 can lead to megaloblastic
anaemia.
It can also lead to some neurological problems.
Vegetarians and vegans are often at risk of
malnutrition.
© Food – a fact of life 2009
Folate (Folic acid)
Folate describes a group of molecules with common
properties and functions. Folic acid is the most stable
form of folate.
It is important for the formation of healthy red blood
cells. It is also needed for the nervous system and
specifically for the development of the nervous system
in unborn babies. It can reduce the risk of neural tube
defects in a foetus, e.g. spina bifida.
Good sources of folate include yeast extract, green
leafy vegetables and fortified cereals.
© Food – a fact of life 2009
Deficiency of folate
Deficiency of folate can lead to megaloblastic
anaemia – where the red blood cells become
enlarged.
Women planning on becoming pregnant are
recommended to increase their intake of folate to
prevent neural tube defects in the foetus. It is
recommended that these women take a supplement
because it is difficult to achieve such high levels of
folate through diet alone.
© Food – a fact of life 2009
Vitamin C (Ascorbic acid)
Ascorbic acid is needed for the normal structure and
function of body tissues, e.g. collagen.
It also acts as an antioxidant that protects the body
from free radicals.
Sources of ascorbic acid include fresh fruits, especially
citrus fruits and berries, green vegetables, peppers
and tomatoes. Vitamin C is also found in potatoes
(especially in new potatoes).
© Food – a fact of life 2009
Too much or too little?
Scurvy can result from lack of vitamin C. It tends to
occur in infants and the older adults.
Scurvy leads to spots on the skin, bleeding gums and
loose or loss of teeth.
Over nutrition of ascorbic acid is rare.
© Food – a fact of life 2009
Minerals
Minerals are inorganic substances needed by the
body for many different functions.
These are needed in different amounts in large (major
minerals) and small (trace minerals) amounts.
© Food – a fact of life 2009
Calcium (Ca)
Calcium is important for the formation and
maintenance of strong bones and teeth, as well as the
functioning of nervous and muscles.
It is also involved in blood clotting.
Sources of calcium can be found in milk, cheese and
other dairy products, green leafy vegetables, soft edible
bones in fish, calcium enriched soya bean products and
bread.
© Food – a fact of life 2009
Too much or too little?
Rickets (develops in children) and Osteomalcacia
(develops in adults) may both develop, but this will not
be due to calcium deficiency alone.
Tetany may also develop, where muscles contract
rigidly.
Too much calcium can lead to deposits in the body,
eventually causing death.
© Food – a fact of life 2009
Iron (Fe)
Iron is needed for needed for the formation of
haemoglobin in red blood cells which transport
oxygen around the body.
It is also required for normal metabolism and for
removing unwanted substances from the body.
The immune system also requires iron.
Haem iron is present in animal sources (including
eggs) in the form of haemoglobin.
Non haem iron is present in plant sources such as
beans, nuts, dried fruits, wholegrains, soya bean
flour and dark green leafy vegetables.
© Food – a fact of life 2009
Too much or too little?
A lack of iron will lead to anaemia. The
symptoms of this are:
•
•
•
•
feeling of tiredness;
lacking in energy;
general weakness;
poor concentration.
Too much iron in the diet will lead to constipation,
nausea and vomiting.
© Food – a fact of life 2009
Phosphorus (P)
Phosphorus is essential for the structure bones and
teeth, for the structure of cell membranes and for
energy metabolism.
Phosphorus is found in all foods.
© Food – a fact of life 2009
Potassium (K)
Potassium is found in body fluids and is essential for
water and electrolyte balance and normal functioning
of cells, including nerves.
Potassium is present in all foods, but found richly in fruit
(dried fruits, bananas, berry fruits), leafy green
vegetables (e.g. broccoli and spinach) meat, nuts,
seeds and pulses.
© Food – a fact of life 2009
Sodium (Na)
Sodium helps to regulate body water content and
electrolyte balance, and is involved in energy
utilisation and nerve function.
Sodium is present in very small amounts in raw
foods. It is often added as salt during processing,
preparation, preservation and serving.
High salt processed foods are bacon, cheese,
yeast extract and smoked fish.
© Food – a fact of life 2009
Too much or too little?
Consuming too much sodium can lead to hardening
of the artery walls and high blood pressure or
hypertension.
Consuming too little sodium can be caused by
excessive vomiting, diarrhoea and is accompanied by
a loss of water from the body.
© Food – a fact of life 2009
Fluoride (F)
Fluoride helps with the formation of strong teeth and
protects against dental decay (caries).
This is a trace element, therefore only a small amount
of this mineral is required for good health.
Fluoride can be found in drinking water and in small
amounts in tea and saltwater fish.
Some areas choose to have fluoride added to the
drinking water.
© Food – a fact of life 2009
Too much or too little?
Excess fluoride in the diet can lead to mottling or
discolouration of teeth.
© Food – a fact of life 2009
Nutrient interactions
Some nutrients work together in the body completing
different functions.
For example:
• the vitamins A,C and E;
• calcium phosphorus and fluoride;
• iron and vitamin C;
• carbohydrates and B vitamins.
© Food – a fact of life 2009
Anti-oxidants
Vitamins A, C and E all create anti-oxidant activities in
the body. These work on protecting the body from
free radicals.
Free radicals are atoms or groups of atoms with an
unpaired or spare electron. Cells within the body may
function poorly or cease to function as a result of free
radicals acting on the DNA structure of cells.
© Food – a fact of life 2009
Calcium, phosphorus and fluoride
Together, these nutrients help teeth and bones to
harden.
Vitamin D controls the amount of calcium available.
Less vitamin D means less available calcium.
© Food – a fact of life 2009
Iron and Vitamin C
Vitamin C will increase the body’s absorption of non
haem iron (non meat sources of iron).
This is particularly important for vegetarians and
vegans.
© Food – a fact of life 2009
Carbohydrates and Vitamins B
For the body to use the energy contained in
carbohydrates there are two B vitamins that help in the
production of energy.
These are:
• riboflavin;
• thiamin.
© Food – a fact of life 2009
Review of the learning objectives
• To understand the importance of micronutrients.
• To recognise the difference between water soluble
and fat soluble vitamins, major minerals and trace
minerals.
• To know the functions and sources of the
micronutrients.
• To know the problems caused by malnutrition.
• To understand some interactions between nutrients.
© Food – a fact of life 2009
For more information visit
www.nutrition.org.uk
www.foodafactoflife.org.uk
© Food – a fact of life 2009