Nutrition and Health

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Nutrition and Health

Micronutrients - Minerals



• Minerals

– iron

– calcium – sodium – iodine





• Minerals are micronutrients

• Human body needs them in very small quantities

• Minerals are used in the human body to help form bones, skin and tissue and are necessary for many body functions

• Two minerals most often lacking in the diet are calcium and iron



Minerals Functions Sources (Examples) Deficiency Reference

values for adults per day**

Iron Forms part of the red blood cell protein, haemoglobin, which carries oxygen around the body

Meat, liver, kidneys, some breakfast cereals, fortified bread, green leafy

vegetables, dried fruits, pulses

Iron-deficiency anaemia may occur, with

symptoms of dizziness, pale skin, weakness and tiredness

Men: not less than 11.4mg Women: not less than 24.5mg Calcium Important for bones and

teeth, muscle contraction, blood clotting and enzyme secretion

Milk, cheese, yoghurt, fish that is eaten with the bones (e.g. sardines), green leafy vegetables, nuts, seeds, dried fruits, oranges

Too little calcium results in stunted growth and rickets in children, muscle cramps, brittle fingernails, osteoporosis

Not less than 1,000mg

Sodium Maintains fluid balance.

Excess sodium has been associated with raised blood pressure

Table salt, salty snacks, fresh meat and poultry, processed foods,

condiments and sauces

Deficiency in sodium may cause muscle cramps, in serious cases coma and death can result

Not more than 2,000mg (i.e.

5g of salt)

Iodine Essential part of the thyroid hormones which help to regulate growth and metabolic rate

Fish, shellfish, milk and dairy products, fruits, vegetables, cereals

Iodine deficiency causes enlargement of the thyroid gland and causes goitre

Not less than 150 µg and not more than 1,000 µg




Functions of Iron

• Iron is needed to make a red-coloured protein called haemoglobin in red blood cells (which is why blood is red)

• Red blood cells in the blood carry oxygen to body cells


Sources of Iron

• The best sources of iron are found in offal such as liver and kidney

• Other good sources of iron include:

– red meat – oily fish – poultry

– green leafy vegetables such as broccoli and spinach


Types of Iron

There are two types of iron:

• Haem iron:

– more easily absorbed and used by the body

– found only in animal foods (i.e. meat, poultry, fish and seafood) – about half of the iron in animal foods is in the form of haem


• Non-haem iron:

– not so easily absorbed by the body

– plant foods, eggs, milk and dairy products have non-haem iron only

– also found in animal foods


Deficiency of Iron

• Anaemia (inadequate haemoglobin), caused by lack of iron in the diet, is one of the most common nutritional problems world-wide

• Women and children are at greatest risk of developing iron deficiency anaemia

• Vegetarians need to make sure they obtain an adequate iron supply from foods such as

cereals, pulses and vegetables



Shortage of iron intake

Inadequate amounts of haemoglobin are formed

Blood is unable to carry sufficient oxygen to the cells

The body becomes tired easily



Symptoms of anaemia include:

• tiredness, weakness, lack of energy

• a pale complexion, pale inner eyelids

• brittle fingernails



Prevention of


Develop healthy eating habits

Eat plenty of iron- rich foods

Iron supplements are only recommended when iron deficiency

anaemia actually occurs. *


If iron supplements are given to young children who have adequate iron stores, growth may be



Iron and Other Nutrients

• Vitamin C helps the body absorb iron from foods

• Vitamin C increases the amount of non-haem iron absorbed, so foods containing iron from plant sources should be eaten with foods rich in vitamin C preferably at the same meal




Functions of Calcium

• Calcium helps to form bones and teeth

• The adult body contains more than 1 kilogram of calcium, most of which is found in the


• Calcium is also needed for blood-clotting, muscle contraction and enzyme secretion


Sources of Calcium

• Milk and dairy products such as cheese and yoghurt are important sources of calcium

• Bean curd and soya bean products are good sources of calcium in Asian diet

• Other foods that are also good sources of calcium include:

– green, leafy vegetables

– nuts, seeds and dried fruits

– fish that is eaten with the bones, such as sardines


Sources of Calcium

Pressed bean curd, spiced

Sesame seed, black

eese, Cheddar, Processed

e, canned in oil, with bone

Bean curd, firm


Bean curd, soft


azil Nut, Raw Or Blanched

d flowering white cabbage

Full cream milk

same dessert/ sweet soup

Soya milk 0

200 400 600 800 1000 1200

Amount of calcium (mg) per 100 grams of edible portion


Deficiency of Calcium

• Inadequate dietary calcium will cause some calcium from the bones to move to the blood.

• Poor intake of calcium will cause less calcium deposition in the bones, and will result in a lower bone mass and a weaker


• Calcium deficiency can also cause rickets in children, though rickets is more commonly associated with vitamin D deficiency.

• If a pregnant woman does not have enough calcium in her

diet, calcium will be removed from her bones and transmitted to the unborn baby to enable the bones of the baby to grow.

This will weaken the woman’s bones and teeth.



• Osteoporosis is the condition of weakening

and thinning of the bones. It is more common in elderly people, especially women.

Inadequate calcium deposition in the bones Weakening and thinning of the bones




Protect against osteoporosis

A diet with a good supply of calcium, particularly during childhood and the

teenage years

Regular exercise, especially weigh-

bearing exercise

Avoidance of smoking and drinking excessive amount of alcohol


Calcium and Other Nutrients

• Vitamin D is needed, together with calcium and phosphorus, to help build and maintain strong bones and teeth

• Vitamin C helps in the absorption of calcium.

• Magnesium is essential for absorption and metabolism of calcium




Functions of Sodium

• Sodium is essential for normal body functions

• It helps maintain the extra-cellular fluid balance and acid-base balance in the body

• It is required for nerve transmission and muscle contraction


Sources of Sodium

• Most raw foods contain a very small amount of sodium

• Sodium is found in sodium bicarbonate which is a raising agent in baked foods such as cakes and biscuits

• The most common form of sodium in the diet is salt (sodium chloride) –salt comprises 40% sodium and 60% chloride (1g of sodium chloride

(NaCl) contains about 393mg of sodium)

• During the processing, preparation, preservation and serving of foods, salt is added

–salt is added in foods to enhance taste and flavour (e.g. enhance sweetness, mask metallic tastes)

–salt can also:

prevent microbial growth

extend product shelf life

improve the product texture (e.g. control the stickiness of doughs,


Sources of Sodium (cont’d)

• Salt is added to foods, for example:

– condiments and sauces (e.g. soya sauce, oyster sauce,

monosodium glutamate (MSG) and stock powder/cubes, salad dressing and ketchup)

– processed vegetable products (e.g. preserved leaf mustard, preserved mustard, preserved cabbage)

– processed meat products (e.g. roast pork, sausages, meat balls, preserved fish and seafood, salted eggs)

– snacks (e.g. crisps, salted nuts/seeds, preserved fruits, dried/preserved meat snacks, preserved seafood snacks) – instant foods (e.g. instant noodles, canned soup)


Deficiency of Sodium

• Sodium deficiency can be seen in people who work or take part in sports in very hot


• Chronic conditions like kidney failure or heart failure may also cause loss of sodium from the body


Deficiency of Sodium

Work or take part in sports in

very hot conditions

The body loses sodium through


Muscle cramps

Sickness and diarrhoea

The body loses too much sodium

Headache, confusion, decreased


Excess of Sodium

• Excessive sodium intake can be detrimental to health, such as increasing the risk of developing hypertension, which in turn increases the risk of coronary heart diseases and stroke

• Salt and salt-preserved food items may also increase the risk of stomach cancer

• The World Health Organization (WHO)

recommends a maximum daily sodium intake of 2,000mg, i.e. 5g of salt


Excess of Sodium

• Kidneys are responsible for regulating the

amount of sodium in the body

• Some people are more sensitive to sodium; they tend to retain sodium

more easily and may have higher risk of

developing hypertension

Low sodium level in the


Kidneys conserve


High sodium level in the


Excrete the excess amount



Excess of Sodium

Excessive sodium intake

Kidneys cannot excrete enough sodium

Sodium and fluid retention


Increase the risk of coronary heart disease and stroke


Ways to Reduce Dietary Intake of Sodium

Reduce dietary intake of sodium (salt)

Read nutrition labels and choose food with lower sodium


Change dietary habits by reducing the amount of salt or

sodium-containing seasonings added to


Use natural ingredients (e.g.

garlic, ginger, lemon/lime juice, parsley) to replace

seasonings and sauce

Reduce the intake of processed food


Salt Reduction in Prepackaged Foods by

Product Reformulation




Functions of Iodine

• Iodine is needed to make thyroid hormones in the thyroid gland

• Thyroid gland is located in the neck

• Thyroid hormones control the metabolic rate of the body – the rate at which chemical

reactions take place inside the body


Sources of Iodine

• Iodine is found in seafood, such as

– saltwater fish

– seaweed (including kelp, nori) – shellfish

• Iodine is also found in milk and dairy products as well as some plant foods, depending on the iodine content of the soil where cattle are

grazed or plants are grown


Deficiency of Iodine

• The person will feel tired, lethargic (does not want to do anything) and will gain weight

• The thyroid gland in the neck will swell up to form a goitre


Deficiency of Iodine

Inadequate intake of iodine

Thyroid tries to keep up with demand for thyroid hormone production

Thyroid progressively enlarges

Development of a goitre

Symptoms of choking, and difficulty in swallowing and


Deficiency of Iodine

Prevent against

iodine deficiency

Eating foods high in iodine

Taking iodine supplement*

Introduction of iodised

salt (only in North America)

*A supplement for the most susceptible groups – pregnant and lactating women and children 7-24 months of age –

assessment is necessary

* Source: Joint Statement by the WHO and the United Nations Children’s Fund, 2007

Reaching Optimal Iodine Nutrition in Pregnant and Lactating



Centre for Food Safety, Food and Environmental Hygiene Department - Nutrients Definition and Function.

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Centre for Food Safety, Food and Environmental Hygiene Department – Report of study on sodium content in local foods.

Centre for Food Safety, Food and Environment Hygiene Department – Reduction of Dietary Sodium and Sugar.

Centre for Food Safety, Food and Environmental Hygiene Department – Food Safety Express (for Food Trade).

Centre for Food Safety, Food and Environmental Hygiene Department (2012) . Study on Sodium Content in Local Foods (Rep. No. 49).

Insel, P. M., Ross, D., McMahon, K., & Bernstein, M. (2019). Discovering nutrition.

Burlington, MA: Jones & Bartlett Learning.

Otten, J. J., Hellwig, J. P., & Meyers, L. D. (2006). Dietary reference intakes: The essential guide to nutrient requirements. Washington, D.C.: National Academies Press.




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