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
elements.
• To learn the functions and sources of the
micronutrients.
• To learn 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 through 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 cells in 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.
It is found in two forms; retinol in foods from animal
sources and carotenoids (the most abundant of which
is the beta-carotene) from plant sources.
Vitamin A – retinol is found in liver and 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. Severe deficiency 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 to 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, but most of our vitamin D
is made in the body 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.
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Too much or too little?
Deficiency of vitamin D leads to rickets and the
formation of soft bones. This causes the bones in the legs
to bend. Deficiency in adults causes Osteomalacia
resulting in pain and muscular weakness.
Vitamin D can be stored by the body. Too much vitamin
D can lead to excess levels of calcium in the blood.
Young children, housebound older adults, and people
who practice religions where their skin must be covered,
may be at risk of deficiency through lack of exposure of
their skin to sunlight.
© 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.
Vitamin E has a low toxicity, but in very large doses
may interfere with absorption of vitamin A.
© 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 normal
functioning of the nervous system and the heart.
Thiamin is mainly found in whole grains, nuts, meat
(especially pork), fruit and vegetables and fortified
cereals.
© Food – a fact of life 2009
Too much or too little?
Thiamin deficiency can lead to the development of
the disease beri-beri. Symptoms include fatigue,
weakness of the legs and anorexia.
As the body excretes any excess thiamin, there is no
evidence of any toxic effects of high doses.
© Food – a fact of life 2009
Riboflavin (B2)
Riboflavin is needed for 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?
There is no deficiency related disease, however, the
tongue, lips and skin become affected when the body
is low in riboflavin.
As the body excretes any excess thiamin, there is no
evidence of any toxic effects of high doses.
© 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 is also needed for the normal functioning of the
nervous 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?
Deficiency of niacin can result in the disease pellagra.
Symptoms can include:
• dermatitis;
• dementia;
• diarrhoea.
Problems associated with excessive intakes are rare.
© Food – a fact of life 2009
Vitamin B12
Vitamin B12 is needed for the formation of red blood
cells and the normal functioning of the nervous system.
Vitamin B12 also helps to release energy from food.
Vitamin B12 is found exclusively in animal products,
plant products do not provide any vitamin B12.
It 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 pernicious
anaemia.
It can also lead to some neurological problems.
Deficiency is rare, but may be a problem for people
following strict vegan or vegetarian diets.
© Food – a fact of life 2009
Folate (Folic acid)
Folate 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 fetus,
e.g. spina bifida.
Good sources of folate include green leafy
vegetables brown rice, peas, oranges, bananas and
fortified cereals.
© Food – a fact of life 2009
Deficiency of folate
Deficiency of folate can lead to megaloblastic
anaemia. Symptoms can include insomnia, depression
and forgetfulness.
It is recommended that all women who are planning a
pregnancy take a daily supplement of folic acid. Once
pregnant, supplementation should continue for the first
12 weeks to reduce the risk of neural tube defects.
© Food – a fact of life 2009
Vitamin C (Ascorbic acid)
Ascorbic acid is needed to make collagen which is
required for the normal structure and function of body
tissues, such as skin, cartilage and bones.
It also acts as an antioxidant that protects the body
from damage by free radicals.
Sources of ascorbic acid include fresh fruits, especially
citrus fruits and berries, green vegetables, peppers
and tomatoes. Ascorbic acid 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 ascorbic acid. 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.
Some minerals are needed in very tiny amounts, these
are known as trace elements, such as fluoride.
© 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
normal functioning of nervous system and muscles.
It is also involved in blood clotting.
Milk and dairy products are the most important sources
of calcium. Other sources include bread, calcium
enriched soya products, green leafy vegetables and fish
with soft edible bones.
© Food – a fact of life 2009
Too much or too little?
Poor intakes of calcium can result in poor bone health
which can increase the risk of diseases such as
osteoporosis later in life.
Taking high doses of calcium supplements can cause
stomach pains and diarrhoea.
© 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 energy metabolism and has an
important role in the immune system.
Haem iron is present in animal sources 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. Symptoms include:
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feeling of tiredness;
lacking in energy;
general weakness;
poor concentration.
Too much iron in the diet can result in 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 red meat, dairy products, fish,
poultry, bread, rice and oats.
© Food – a fact of life 2009
Potassium (K)
Potassium 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 is needed to regulate body water content and
electrolyte balance.
Sodium is also needed for the absorption of some
nutrients and water from the gut.
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 include bacon,
cheese, yeast extract and smoked fish.
© Food – a fact of life 2009
Too much or too little?
Consuming too much sodium increases the risk of high
blood pressure. High blood pressure is linked with an
increased risk of heart disease and stroke.
Sodium deficiency is unlikely, but can be caused by
excessive sweating or vomiting and diarrhoea.
It is recommended that adults and children over the
age of 11 years cut down on salt and consume no
more than 6g per day.
© Food – a fact of life 2009
Fluoride (F)
Fluoride is needed for the formation of strong teeth
and protects against dental decay (caries).
Fluoride is a trace element, therefore only a small
amount is required for good health.
Fluoride can be found in drinking water and in small
amounts in tea and saltwater fish.
Some areas add fluoride to the drinking water.
Fluoride toothpastes are another important source.
© Food – a fact of life 2009
Too much or too little?
An excessive intake of fluoride 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;
• calcium and vitamin D;
• iron and vitamin C;
• carbohydrates and B vitamins.
© Food – a fact of life 2009
Anti-oxidants
Vitamins A, C and E are anti-oxidants and work
together in the body to protect cells against oxidative
damage from free radicals.
This damage to cells can increase the risk of
developing diseases such as heart disease and
cancer.
© Food – a fact of life 2009
Calcium, phosphorus and fluoride
These nutrients are involved in the mineralisation of
teeth and bones which keep them hard and strong.
Vitamin D and calcium
Vitamin D controls the amount of calcium available.
A lack of vitamin D in the body results in reduced
absorption of calcium.
© Food – a fact of life 2009
Iron and ascorbic acid
Ascorbic acid aids the absorption of non haem iron
(non meat sources of iron) when eaten at the same
time.
This is particularly important for people following strict
vegan or vegetarian diets.
© Food – a fact of life 2009
Carbohydrates and Vitamins B
Riboflavin and thiamin are
involved in the release of energy
from carbohydrate.
© 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
elements.
• To learn the functions and sources of the
micronutrients.
• To learn 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