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 needed for vision in dim light, healthy skin
and eyes and for growth.
This fat soluble vitamin and protects against cancer.
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 growth and maintenance
of healthy bones and teeth and to help calcium and
phosphorous absorption.
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, butter and
meat.
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 elderly, 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, the housebound elderly, and people
in religions who cover themselves, 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. The exact functions are not
clear, but it is suggested that they protects against
heart disease and also help cell membrane
maintenance.
Vitamin E is mainly found in vegetable oils, wheat
germ, eggs, liver, meat, oatmeal and margarine and
low fat spreads.
© 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 helps blood to clot and build strong bones.
Infants are given vitamin K at birth.
Vitamin K is also produced by the bacteria in the gut.
Vitamin K is found in fresh green vegetables e.g.
broccoli, lettuce, cabbage, spinach and beef liver.
© 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
carbohydrates.
Thiamin cannot be stored in the body, so it is necessary
to obtain this from the diet.
Thiamin is mainly found in whole wheat, bran, pork,
milk, and fortified breakfast 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 coordination).
© Food – a fact of life 2009
Riboflavin (B2)
Riboflavin is needed for normal growth and the release
of energy from protein, carbohydrates and fat.
Riboflavin is found in liver, milk, cheese, eggs, some
green vegetables, and yeast.
© Food – a fact of life 2009
Too much or too little?
The body is not dependent on diet for this nutrient as it
can produce it. It also can be stored in the body in the
liver, spleen and kidneys.
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
carbohydrate.
Niacin also maintains the health of the nervous and
digestive system.
Niacin can be found in cereals, yeast, meat, fish,
eggs, and milk.
© 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
Folate
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 and can reduce the risk of neural tube defects in
a fetus, e.g. spina bifida.
Good sources of folate include, liver, yeast extract,
and green leafy vegetables.
© 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 fetus. 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 B12
Vitamin B12 is needed for the formation of red blood
cells and synthesising fatty acids in the myelin of
nerve tissue.
Vitamin B12 is found in animal sources only.
Good food sources are eggs, milk and meat.
© 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
Vitamin C (Ascorbic acid)
Ascorbic acid is needed for the production of a
protein called collagen which helps bones to grow
and wounds to heal.
It also acts as an antioxidant that protects the body
from free radicals.
Sources of ascorbic acid include strawberries, citrus
fruits, tomatoes and vegetables including cabbage,
cauliflower, and broccoli.
© 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 elderly.
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 for building strong bones and teeth, blood
clotting and muscle contraction.
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.
© 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 to death.
© 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
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 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
Potassium (K)
Potassium is found in body fluids and is essential for
water and electrolyte balance and proper functioning
of cells, including nerves. It is needed for clotting of the
blood, after injury.
Potassium is present in all foods, but found richly in fruit
(dried fruits, bananas, berry fruits), leafy green
vegetables (e.g. broccoli and spinach) and milk.
© 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
Fluoride (F)
Fluoride hardens tooth enamel and ensures bones
have correct amounts of minerals deposited in them.
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, 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 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.foodafactoflife.org.uk
© Food – a fact of life 2009