Biology Unit 7.1 Human Nutrition - a balanced diet

List the principal sources of, and describe the dietary importance of Vitamin C

Vitamin C Water soluble- fresh fruit and vegetables (destroyed by heat) Uses; Helps blood to clot and makes collagen Deficiency- SCURVY- bleeding gums

List the principal sources of, and describe the dietary importance of Vitamin D

Vitamin D 1. in diet- Fat soluble eg oily fish eg mackerel, cod liver oil. egg yolks 2. Made by energy from sunlight under skin Uses; Helps calcium absorption for bones. Deficiency; tiredness Causes of deficiency 1. Lack of sunlight - e.g in Europe in winter or people who do not go outside or wear high factor suntan lotion all the time 2. People with darker skin pigmentation as less uv absorbed by darker skin pigmentation)

List the principal sources of, and describe the dietary importance of water

Water - drink and in food eg fruit 1. Acts as a solvent so molecules can dissolve and be absorbed more easily in aqueous solution 2. 70% body is water and it needs to be maintained as water is lost through sweating, excretion in urine and egestion in stools.

List the principal sources of, and describe the dietary importance of Proteins

Protein is in meat, fish and cheese Uses- to provide amino acids needed to build proteins and enzymes for growth and development Deficiency 1. Kwashiokor ( protein energy malnutrition) lack of protein but still getting enough energy in diet - pot belly 2. Marasmus (lack of protein and energy in diet) causes muscle wasting and emaciation

State what is meant by the term balanced diet for humans

A balanced diet =correct amounts of the 7 types of food for maintaining life processes e.g. carbohydrates, fats, proteins, vitamins, minerals, fibre and water

List the principal sources of, and describe the dietary importance of Mineral salts, limited to calcium

Calcium -bones and teeth Sources- milk and dairy products Deficiency 1. rickets (soft bones in children) that bend when weight applied 2. osteomalacia in adults (soft bones that fracture easily)

List the principal sources of, and describe the dietary importance of carbohydrates

Carbohydrates- pasta, bread and potatoes eg Starch in potato tubers, seeds as energy source for germination, fruit Refined sugar eg sucrose from sugar cane plant Used as energy source for aerobic respiration and excess is converted to glycogen in humans by the liver and stored in liver and muscle cells or converted to fat

List the principal sources of, and describe the dietary importance of Fats

Fats- solid lipids at room temperature e.g. butter and are saturated fats ) i.e. contain only single bonds in molecule - cause coronary heart disease Oils - usually liquids at room temperature e.g. sunflower seed oil ( contain a double bond in the molecule) - margarine are unsaturated fats as well- thought to cause less coronary heart disease Used as energy source - when used in respiration they generate more energy than when carbohydrates are used

List the principal sources of, and describe the dietary importance of Fibre (roughage)

Fibre is undigested plant based material e.g. the cellulose cell wall Uses- creates bulk for peristalsis (smooth muscle contraction behind bolus of food) along gut Deficiency- causes constipation - hard stools which are hard to pass

List the principal sources of, and describe the dietary importance of Mineral salts, limited to iron

Iron used to make haemoglobin for red blood cells Source- red meat Deficiency- iron deficiency ANAEMIA- fewer red blood cells as less haemoglobin and reduces the oxygen carrying capacity of the blood causing tiredness, pallor and shortness of breath Deficiency caused by 1. Lack of iron in diet e.g. vegetarians 2. Excess blood loss (bleeding) e.g. heavy periods

Describe the effects of malnutrition in relation to starvation, constipation, coronary heart disease, obesity and scurvy

Malnutrition is the effect of incorrect amounts of the correct types of food on health 1. starvation- insufficient energy 2. constipation- insufficient fibre- may cause bowel cancer 3. Coronary heart disease- too much saturated fat - causes plaques to form in arteries and they become narrower leading to angina and a heart attack 4. obesity- too much food especially fat and refined carbohydrates e.g. sugar 5. scurvy- insufficient vitamin C causes bleeding gums

Explain how age, gender and activity affect the dietary needs of humans including during pregnancy and whilst breast-feeding

Young children need more protein and energy for growth and development Males have higher energy needs than females High energy needs if more activity Pregnancy- more protein, calcium, vitamin D and iron for developing baby Breast feeding - more water