Diet and nutrition

HBS1B

Nutrient groups

Your body needs food, because food contains a number of nutrients needed by the body. These are:

1.Carbohydrates2.Proteins3.Lipids4.Vitamins5.Minerals6.Water

Carbohydrates (Polysaccharides or sugars)

These substances are used by the body mainly for energyNon-absorbable and non-digestible carbohydrate (eg

cellulose) is called roughage or fibre. It is important to the body because it helps movement of food

through the intestines, and prevents bowel cancer and other problems eg constipation.

Carbohydrates are stored in the liver and muscles as glycogen.

Foods containing carbohydrates include: cereals eg rice, wheat, oats; bread, pasta, cakes, biscuits, potatoes and other starchy vegetables

Proteins (polypeptides)

These substances are used by the body for body structures eg hair, muscle, skin; enzymes; blood components eg haemoglobin, clotting factors

They are made up of amino acids, which are joined by peptide bonds to produce peptides.

There are 20 different types of amino acids, of which 9 are essential amino acids and 11 are non-essential.

An essential amino acid is one that the body can’t make. We must get this amino acid by eating food that contains the essential amino acid

Complete proteins are proteins containing all 9 essential amino acids.Most complete proteins come from animal products: hence vegetarians

must be careful to eat a variety of different plant proteinsFoods containing proteins include: meat, fish, poultry, eggs, soy, nuts,

legumes – eg peas, beans

LIPIDS (fats)

These are used by the body for energy reserves, insulation an protection and to make cell membranes, hormones and for normal skin and brain function

They are made up of units called glycerol and fatty acids.

Some fatty acids are essential, this means that the body can’t make them. We must get them by eating food that contains them.

Foods containing lipids include: butter, margarine, oils, milk, cheese, cream, nuts, fish

Vitamins

There are a number of vitamins needed by the body. Most act as co-factors for enzymes in metabolic reactions.

The fat-soluble vitamins are A, D, E and K and the water-soluble vitamins are B and C.

Sources of vitamins include fruit and vegetables

Water-soluble vitamins are easily lost in cooking and preserving, so the best sources are fresh or raw fruit and vegetables

VitaminsVitamin Good food sources Signs of Deficiency

A Milk, butter, cheese, liver, green and yellow vegetables, yellow fruits

Reduced immunity, poor night vision, dry cornea, rough skin

B group (eg B1, B2,

niacin, folate)

Cereals, green vegetables, milk, meat, poultry, mushrooms, yeast, liver, legumes, eggs, orange juice

Beri-beri, anaemias, spina bifida (folate), reduced metabolism

C Most fruit – especially citrus fruit, strawberries, tomatoes, leafy vegetables, potatoes

Scurvy, delayed wound healing

D Eggs, cod liver oil, cream ( made in the skin when exposed to air)

Rickets, bowed limbs

E Vegetable oils, wheat germ, milk

K Green leafy vegetables, tomatoes Delayed blood clotting

Minerals

There are many minerals used by the body.

Most act as cofactors for enzymes in metabolic reactions.

Excesses of some minerals can also cause problems, eg copper is poisonous if taken in large amounts.

Sources of minerals include milk and dairy products, bony fish (eg sardines, tuna), liver, kidney, meat, baked beans, chicken, egg yolk, wheat germ

Minerals

Mineral Good food sources Signs of Deficiency

Calcium Milk and dairy products, bony fish (eg sardines, tuna)

RicketsOsteoporosis - after menopause

Iron Liver, kidney, meat, fish, baked beans, chicken, egg yolk, pate

Anaemia, tiredness

Iodine Milk, sea food, iodised salt Cretinism, goitre

Copper Liver, nuts, peas, beans, fish, shellfish

Anaemia

Fluorine Water Poor tooth enamel

Zinc Oysters, wheat germ, meat, chicken, cheddar cheese, wholegrain wheat

Impaired growth and reproduction

Water

Water is used for hydration - dissolving chemicals and transport, regulation of body temperature and waste removal

Sources of water include water and other drinks, fruits and vegetables

A balanced diet

A balanced diet should contain a mixture of foods, with plenty of fresh fruit and vegetables (2 serves of fruit, 5 of vegetables) – a good guide is 1 serve of meat or alternatives, 2 serves of dairy, 3 serves of fruit, 4 serves of vegetables, 5 serves of bread/pasta/cereals & no more than 2 serves of ‘indulgences’ eg cake, ice cream, etc

Dietary needs 1

Dietary needs can differ between different people, and can change during a person’s life (eg childhood, adolescence, pregnancy, old age, etc).

Babies need small amounts of food often because they are so small and fast growing.

Their food needs to be soft or liquid because they have not got any teeth.There are some foods they shouldn’t eat eg foods with caffeine or alcohol

because they can cause problems eg allergies or they are not nutritious.

They need food high in energy, proteins, vitamins and minerals eg calcium

Growing children and adolescents need diets high in energy, proteins, vitamins and minerals because they are growing rapidly

Dietary needs 2

Adults and older people usually need smaller amounts of food because they are not growing.

Old people may have trouble with teeth and digestion

Pregnant women need more minerals (eg calcium) and protein because they need it for the growth of the baby and to make milk.

Athletes need more food – especially for protein and energy because they are working so hard. Some sports have higher need for particular nutrients (eg weight lifters need to bulk up their muscles so have high protein need, sprint runners need more energy foods to run fast)

Dietary problems• Too much sugar can lead to obesity, diabetes, tooth decay and cardiovascular disease

• Too much fat can lead to cardiovascular disease, high cholesterol, bowel cancer and obesity

• Too much salt can lead to hypertension and other cardiovascular diseases

• Too much alcohol can lead to liver damage, brain damage, cardiovascular disease, foetal alcohol syndrome

• Some people are allergic to some preservatives and additives eg MSG. Having food with these preservatives can cause these people to become sick

• Not enough fibre can lead to appendicitis, diverticulitis, bowel cancer

• Not enough vitamins and minerals can lead to conditions such as scurvy (not enough vitamin C), rickets or osteoporosis (not enough vitamin D or Calcium), anaemia (not enough Vitamin B or iron or copper), night blindness (not enough Vitamin A) or goitre (not enough iodine).

Fast foods eg KFC, McDonalds, Hungry Jacks, Pizzas, etc contain high amounts of sugar, fats, salt as well as many preservatives and additives and low amounts of fibre, vitamins and minerals.

It is best to have fast foods only occasionally