Why do we need water and dietary fibre, and what happens if we do not get enough?
The functions of water and the signs of dehydration, and the role of dietary fibre (NSP) in healthy digestion, with sources and recommended intakes.
A focused answer on water and dietary fibre for Eduqas GCSE Food Preparation and Nutrition (C560), covering the functions of water, the signs of dehydration, the role of dietary fibre (NSP) in healthy digestion, good sources and recommended intakes.
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What this dot point is asking
Eduqas wants you to know the functions of water, the signs of dehydration, and the role of dietary fibre (non-starch polysaccharide, NSP) in keeping digestion healthy, with good sources and recommended intakes.
Water
Adults should aim for about 6 to 8 glasses (roughly 1.5 to 2 litres) of fluid a day, and more in hot weather, during exercise or when ill. Water is the best choice because it has no sugar or acid to harm teeth; sugary and acidic drinks add free sugar and erode tooth enamel. Fluid also comes from foods, especially fruit and vegetables, and from drinks such as milk and unsweetened tea, so not all of it has to be plain water.
Dehydration
The risk is higher in hot weather, during and after exercise, and during illness (especially with vomiting or diarrhoea), so fluids must be replaced.
Dietary fibre (NSP)
Fibre prevents constipation, helps you feel full (which supports a healthy weight), and lowers the risk of bowel problems such as diverticular disease and bowel cancer. Adults are advised to eat about 30 g of fibre a day.
Fibre comes in two forms, and a healthy diet needs both:
- Insoluble fibre does not dissolve in water. It is the part that adds bulk and holds water, speeding food through the gut and preventing constipation. It is found in wholegrain bread, brown rice, wheat bran and the skins of fruit and vegetables.
- Soluble fibre partly dissolves to form a gel. It slows digestion (helping you feel full for longer), and it can help lower blood cholesterol and steady blood sugar. It is found in oats, barley, beans, lentils and many fruits.
Good sources overall are wholegrain bread, brown rice and pasta, oats, fruit and vegetables (especially with skins), pulses, nuts and seeds. Choosing wholegrain over white, leaving skins on, and eating plenty of fruit, vegetables and pulses are the easiest ways to increase fibre. Increase fibre gradually and drink more water with it, or it can cause bloating and wind.
Try this
Q1. State three functions of water in the body. [3 marks]
- Cue. Any three of regulating temperature, transporting nutrients/waste, aiding digestion, removing waste in urine, keeping cells/joints healthy.
Q2. Name two high-fibre foods. [2 marks]
- Cue. Any two of wholegrain bread, brown rice, oats, fruit and vegetables, pulses, nuts and seeds.
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 20186 marksExplain the functions of water in the body and describe the effects of not drinking enough water (dehydration).Show worked answer →
A 6-mark extended-response question. Mark it for several functions plus the effects of dehydration.
Water is needed to regulate body temperature (through sweating), to transport nutrients, oxygen and waste in the blood, to help with digestion and the removal of waste in urine, to keep cells, joints and the skin healthy, and to make up most of the body and its fluids.
Without enough water, a person becomes dehydrated: signs are thirst, a dry mouth, headache, tiredness, dark and strong-smelling urine, dizziness and difficulty concentrating. Severe dehydration is dangerous and needs urgent treatment. Needs rise in hot weather, during exercise and illness.
Top-band answers (5 to 6 marks) give several correct functions of water and several signs of dehydration, and note when needs increase.
Eduqas 20214 marksExplain how dietary fibre helps keep the digestive system healthy, and name two high-fibre foods.Show worked answer →
A 4-mark structured question.
Dietary fibre (NSP) is the part of plant foods that the body cannot digest. It adds bulk to the food in the gut and holds water, so it makes the faeces softer and bulkier and helps them move through the intestines. This prevents constipation and reduces the risk of bowel problems such as diverticular disease and bowel cancer.
High-fibre foods include wholegrain bread, brown rice and pasta, oats, fruit and vegetables (especially with skins), pulses, nuts and seeds. Markers reward the bulking/water-holding action that prevents constipation and two correct high-fibre foods.
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Sources & how we know this
- WJEC Eduqas GCSE Food Preparation and Nutrition specification (C560) — WJEC Eduqas (2016)