© livestock & meat commission for northern ireland 2015 micronutrients
Post on 17-Jan-2016
224 Views
Preview:
TRANSCRIPT
© Livestock & Meat Commission for Northern Ireland 2015
Micronutrients
Learning objectives
Identify the sources of nutrients and explain the functions of each nutrient.
Explain the effects on health of deficiency and excess of each nutrient.
Discuss the link between vitamin C and iron, vitamin D and calcium, and factors maximising availability of calcium and iron.
© Livestock & Meat Commission for Northern Ireland 2015
Micronutrients
The body requires micronutrients in tiny amounts.
They are required for a number of important processes in the body but they do not provide energy.
There are two main groups of micronutrients:• vitamins;• minerals and trace elements.
Micronutrients are measured in milligrams (mg) and micrograms (μg) with 1mg = 0.001g and 1μg = 0.001mg.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamins
Vitamins are required by the body in small amounts for a variety of essential processes.
Most vitamins cannot be synthesised by the body so need to be provided in the diet.
Vitamins are grouped into:• fat-soluble vitamins; • water-soluble vitamins.
© Livestock & Meat Commission for Northern Ireland 2015
Fat soluble vitaminsThese can be stored in the body, and include vitamins A, D, E and K.
These vitamins are not required daily as the body can build up stores in the liver and fatty tissues for future use.
These are mainly found in fatty foods and animal products.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin A
Vitamin A is required in the diet for a number of functions:
• Normal iron metabolism;
• To maintain normal skin and mucous membranes in eyes, lungs, and the digestive system;
• To maintain normal vision;
• For normal function of the immune system.
© Livestock & Meat Commission for Northern Ireland 2015
Sources of vitamin AVitamin A (retinol) can be obtained in two forms:
1. Retinol - ready-made from animal sources;2. Carotenoids (e.g. beta carotene) – from
plant sources, from which retinol can be made in the body.
The concentration of vitamin A is usually expressed as retinol equivalents (RE).
6µg of beta carotene is equivalent to 1µg of retinol.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin A
Vitamin A is found (as retinol) in liver and whole milk.
Beta-carotene provided by dark green leafy vegetables, carrots and orange coloured fruit can also be converted to retinol to provide vitamin A.
In the UK margarine must be fortified with vitamin A and D by law. Vitamins A and D are also often added voluntarily to reduced fat spreads.
© Livestock & Meat Commission for Northern Ireland 2015
Sources of vitamin A in Northern Ireland
© Livestock & Meat Commission for Northern Ireland 2015
Cereals and cereal products
Milk and milk products
Eggs and egg dishes
Fat spreads
Meat and meat products
Fish and fish dishes
Vegetables and potatoes
Fruit
Sugar, preserves and confectionary
Non-alcoholic beverages
Miscellaneous
0% 5% 10% 15% 20% 25% 30% 35%
8%
13%
5%
16%
17%
1%
29%
1%
1%
4%
5%
Sources of vitamin A in the diet of Northern Irish adults
Deficiency and excess of vitamin AA severe deficiency in vitamin A is rarely seen in the UK.
Deficiency can result in night blindness (where the eye is unable to adapt to low-level light) and ulceration of the eye which can lead to total blindness.
Conversely, a high intake of vitamin A (>1500µg of RE/day) can be toxic and result in liver and bone damage.
As excess retinol during pregnancy can lead to birth defects, pregnant women should not consume liver and liver pâté as high levels of retinol may be present.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin D
Vitamin D is needed for:
• the absorption and use of calcium and phosphorus;
• normal blood calcium levels;
• the maintenance of normal bones and teeth;
• the maintenance of normal muscle function;
• the normal function of the immune system.
© Livestock & Meat Commission for Northern Ireland 2015
Function of vitamin D
Vitamin D is a pro-hormone in the body, and can be obtained in two forms:
1. ergocalciferol (vitamin D2);2. cholecalciferol (vitamin D3) formed by
the action of sunlight.
Vitamin D is only required in very small amounts and is measured in micrograms (µg).
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin D: sources
Sources include: oily fish (such as salmon, trout, mackerel, sardines, pilchards, herring, kipper), meat, eggs and fortified breakfast cereals and margarine/spreads.
For most people the main source is synthesis in the skin following exposure to sunlight during the summer months in the UK (April – October).
Did you know?The wavelength of UVB during the winter months in the UK does not support vitamin D synthesis.
© Livestock & Meat Commission for Northern Ireland 2015
Sources of vitamin D in Northern Ireland
© Livestock & Meat Commission for Northern Ireland 2015
Cereals and cereal products
Milk and milk products
Eggs and egg dishes
Fat spreads
Meat and meat products
Fish and fish dishes
Vegetables and potatoes
Miscellaneous
0% 5% 10% 15% 20% 25% 30% 35% 40%
14%
3%
13%
22%
35%
10%
1%
1%
Sources of vitamin D in the diet of Northern Irish adults
Deficiency of vitamin D
Deficiency is commonly seen in people who have darker skin, wear concealing clothing or are housebound. This is because they are less able to synthesise vitamin D from sunlight.
There is evidence to show poor vitamin D status across the UK population, in particular during the winter months.
© Livestock & Meat Commission for Northern Ireland 2015
Deficiency of vitamin D
In children, a lack of vitamin D causes rickets, where leg bones become weakened and bent.
In adults, a similar condition called osteomalacia is seen.
Links have also been made between poor vitamin D status and an increase in falls in elderly people, which is thought to be linked to an adverse effect on muscle.
© Livestock & Meat Commission for Northern Ireland 2015
Water soluble vitamins
Water-soluble vitamins cannot be stored in the body and are therefore required daily, i.e. B vitamins and vitamin C.
© Livestock & Meat Commission for Northern Ireland 2015
B vitamins
There are a number of B vitamins, each with a specific function in the body.
Regular intake is required as the body is unable to store water soluble vitamins.
The different types of B vitamins are:• vitamin B1 (Thiamin) • vitamin B2 (Riboflavin)• vitamin B3 (Niacin)• vitamin B6 (Pyridoxine)• vitamin B12 (Cyanocobalamin)• folate• pantothenic acid• biotin
© Livestock & Meat Commission for Northern Ireland 2015
Thiamin (vitamin B1)Functions:• The release of energy from carbohydrate;• Normal function of the nervous system and
heart.
Sources:• Wholegrains, nuts, meat, milk, fruit,
vegetables and fortified breakfast cereals.• White and brown flour in the UK are
fortified with thiamin.
Deficiency:• Rarely seen in the UK;• Causes the nervous system disease beri-
beri.
© Livestock & Meat Commission for Northern Ireland 2015
Riboflavin (vitamin B2)
Functions:• To release energy from protein,
carbohydrate and fat;• Transport and metabolism of iron in the
body;• Normal structure and function of mucous
membranes and the skin.
Sources:• Milk, eggs, rice, fortified breakfast cereals,
liver, legumes (the fruits or seeds of anything that comes in a pod, e.g. beans, peas, lentils), mushrooms and green vegetables.
© Livestock & Meat Commission for Northern Ireland 2015
Riboflavin (vitamin B2)Deficiency:• Rarely seen in the UK;• Characterised by dryness and cracking
of the skin around the mouth and nose;• Painful tongue that is red and dry
(magenta tongue).
There is evidence of low intakes and poor status in teenagers and young adults, especially teenage girls.
© Livestock & Meat Commission for Northern Ireland 2015
Niacin (vitamin B3) Functions:• The metabolism of carbohydrate to enable
energy release from food;• Normal function of the skin and mucous
membranes;• Normal functioning of the nervous system.
Sources:• Meat, wheat flour, eggs, dairy products and
yeast. In the UK, white and brown flour are fortified with niacin.
© Livestock & Meat Commission for Northern Ireland 2015
Niacin (vitamin B3)
Deficiency:• Rarely seen in the UK and other
westernised countries;• Characterised by sun-sensitive skin, known
as pellagra.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin B6
Functions:
• Metabolism of amino acids;• Breaking down glycogen;• Modification of steroid hormone action;• Formation of red blood cells and
metabolism and transport of iron;• Maintenance of normal blood
homocysteine levels (raised homocysteine is a risk factor for cardiovascular disease).
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin B6
Sources:• Poultry, white fish, milk, eggs, whole
grains, soya beans and peanuts.
Deficiency:• Rare as it is widely distributed in foods and
synthesised in body’s gut flora;• May only occur as a complication of
disease of prolonged administration of certain drugs.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin B12Functions:• Normal formation of red blood cells and
the metabolism of folate;• Involved in energy production.
Sources:• Found in almost all foods of animal
origin. Meat, fish, milk, cheese, eggs, yeast extract and fortified breakfast cereals are all dietary sources.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin B12Deficiency:• Rare in younger people, only occurs among
strict vegans.• More common in older people as a result of
impaired absorption.• Deficiency results in the development of
pernicious anaemia, where red blood cells are enlarged, and peripheral neurological damage develops.
© Livestock & Meat Commission for Northern Ireland 2015
Folate/folic acid
Folic acid is the synthetic form of folate. It is used in supplements and for food fortification.
Functions:• Works together with vitamin B12 to form
healthy red blood cells;• Normal cell division;• Normal structure of the nervous system,
specifically the development of the neural tube in the embryo, as this develops into the spinal cord and skull. It is recommended that all women of childbearing age who are planning a pregnancy take a daily supplement.
© Livestock & Meat Commission for Northern Ireland 2015
Folate/folic acidSources:• Green leafy vegetables, brown rice, peas,
orange, bananas and fortified breakfast cereals are sources of folate.
Deficiency:• Deficiency results in neural tube defects in
new-borns and megaloblastic anaemia, which is characterised by the release of immature red blood cells into the blood stream.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin C
Vitamin C (ascorbic acid) can help with the absorption of iron from plant foods when consumed at the same meal.
Functions:• Normal structure and function of
connective tissues such as skin, cartilage and bones;
• Normal structure and function of blood vessels and neurological function;
• Increases the absorption of iron from plant sources in the gut.
© Livestock & Meat Commission for Northern Ireland 2015
Vitamin C
Sources:• Fresh fruits especially citrus fruits and
berries, green vegetables, peppers, tomatoes and potatoes.
Deficiency:• Severe deficiency leads to scurvy, and
is associated with fatigue, weakness, aching joints and muscles. Other symptoms of scurvy are characterised by bleeding gums and poor wound healing.
© Livestock & Meat Commission for Northern Ireland 2015
Minerals
The body requires minerals in small amounts for a number of different functions.
Each mineral is required in different amounts.
Some are required in larger amounts, while others are required in very small amounts and are known as ‘trace elements’.
There are a number of different minerals, however we are going to focus on the following:• Sodium;• Calcium;• Iron.
© Livestock & Meat Commission for Northern Ireland 2015
Sodium
Sodium is a component of salt, also known as sodium chloride (NaCl).To convert sodium to salt, multiply by 2.5:Amount of salt = Amount of sodium x 2.5
Functions:• Regulating body water content and
electrolyte balance;• The absorption of certain nutrients and
water from the gut.
Sodium levels are under homeostatic control, regulated by the kidneys.When supply is excessive, sodium is excreted in urine.
© Livestock & Meat Commission for Northern Ireland 2015
Sodium
Sources:Most raw foods contain sodium chloride (NaCl) in small amounts, yet salt is commonly added to food during processing, preparation and serving.
Deficiency:As intakes of sodium are considered to be too high in Northern Ireland, deficiency is unlikely to occur, however losses can occur in some circumstances:• Excess sweating• Diarrhoea• Renal failure
What ways can you think of to reduce salt when preparing and cooking food?
© Livestock & Meat Commission for Northern Ireland 2015
Calcium
The body contains more calcium than any other mineral in the body. The skeleton contains about 99% of the body’s calcium with approximately 1kg present in adult bones.
Function:• Develop and maintain healthy bones and
teeth;• Normal muscle contraction (including the
heart);• Normal blood clotting.• Calcium levels in the blood are carefully
regulated by hormones such as vitamin D to keep it within narrow limits.
© Livestock & Meat Commission for Northern Ireland 2015
Calcium
Function
If calcium intake is too low, calcium is withdrawn from bones to maintain blood levels.
This means a diet low in calcium can lead to low bone density which, over time, can lead to osteoporosis.
Osteoporosis is characterised by weak and brittle bones.
Low calcium intakes are often seen in teenage girls
© Livestock & Meat Commission for Northern Ireland 2015
CalciumSources:• Dairy products, bread as most bread flour
(except wholemeal) is fortified with calcium by law in the UK, green leafy vegetables such as broccoli, cabbage, fortified soya products, fish eaten with the bones e.g. sardines, tinned salmon.
Deficiency:• Reflected in bone density not low blood
levels, as bone acts as a reservoir in times of need;
• Insufficient calcium in bones can be a result of an inadequate supply of vitamin D, as it is essential for the absorption of vitamin D;
• In children this can result in rickets, and osteomalacia in adults. © Livestock & Meat Commission for Northern Ireland 2015
Calcium
Absorption:• Calcium absorption is influenced by a
number of factors.• Inhibitory factors include phytates (e.g. in
wholegrain cereals, pulses) and oxalate (e.g. in spinach, beetroot).
• Promoting factors include vitamin D, lactose and dietary protein.
© Livestock & Meat Commission for Northern Ireland 2015
Iron
Functions:• Formation of haemoglobin in red blood
cells;• Binding of oxygen and transporting around
the body;• Function of the immune system;• Normal energy metabolism;• Metabolism of drugs and foreign
substances that need to be removed from the body.
© Livestock & Meat Commission for Northern Ireland 2015
Iron
Sources:• Dietary iron is found in two forms:
• Haem iron (from animal sources);• Non-haem iron (from plant sources).
• Haem iron (from animals) is the most bioavailable form of easily absorbed form of iron, but the most common form of iron in our diet is from plants (non-haem iron).
• Non-haem iron can be found in cereals, vegetables, pulses, beans, nuts and fruit.
© Livestock & Meat Commission for Northern Ireland 2015
Iron
Absorption of non-haem iron is affected by phytates (found in plant seeds), fibre, tannins and calcium, by binding non-haem iron in the intestine, reducing absorption.
Vitamin C aids the absorption of non-haem iron when eaten at the same time.
What foods can you think of which contain vitamin C?
© Livestock & Meat Commission for Northern Ireland 2015
Iron
Deficiency:• A lack of dietary iron depletes the body’s
iron stores and can eventually lead to iron deficiency anaemia.
• Teenage girls and women of childbearing age need more iron than males of the same age.
• The average iron intake of teenage girls is 57% of the Recommended Nutrient Intake.
• Intakes are also low in a large proportion of young women.
Did you know?More than 2 billion people worldwide suffer from iron deficiency anaemia, making it the most common nutritional deficiency.
© Livestock & Meat Commission for Northern Ireland 2015
Acknowledgement
For further information, go to: www.food4life.org.uk © LMC 2015
© Livestock & Meat Commission for Northern Ireland 2015
top related