How is nitrogen balance measured?

Nitrogen intake is calculated from the protein in a weighed diet. Nitrogen output is measured by collecting urine and faeces over several days.

What is nitrogen equilibrium?

Nitrogen equilibrium is when nitrogen intake equals nitrogen output. A healthy adult whose weight is stable and whose protein needs are met is in nitrogen equilibrium.

Define positive nitrogen balance.

Positive nitrogen balance is when nitrogen intake is greater than nitrogen loss. The extra nitrogen is being kept by the body to build new tissue.

Give three situations in which a person is in positive nitrogen balance.

A person is in positive nitrogen balance during childhood growth, during pregnancy and during recovery from illness or injury.

CCEA A-Level Nutrition and Food Science 3310

Protein

Topic overview Functions of protein Amino acids, biological value and complementation Animal and plant sources of protein Novel protein sources Nitrogen balance and protein requirements

Fat

Topic overview Functions of fat Structure of fats and fatty acids Saturated and monounsaturated fatty acids Omega-3, omega-6 and trans fatty acids Essential fatty acids

Carbohydrate

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Vitamins

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Minerals

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Water and Other Fluids

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Nutrition Through Life

Topic overview Pre-conception and pregnancy nutrition Lactation and infant milk feeding Weaning and pre-school children School-age children and teenagers Nutrition for adult men and women Older adults and the frail elderly Dietary Reference Values and diet evaluation

Eating Patterns

Topic overview Food consumption trends and demographic change Social change, employment and leisure patterns Resources and availability of healthy food Food labels and advertising as barriers

Energy and Energy Balance

Topic overview Why the body needs energy Basal metabolic rate and physical activity level Energy EARs through life Energy balance and weight change

Overweight and Obesity

Topic overview BMI, waist circumference and measuring body fat Trends in childhood and adult obesity Barriers to achieving a healthy weight Health problems of excess weight Achieving a healthy weight in children and adults

Cardiovascular Disease

Topic overview Defining CVD and how atherosclerosis develops Non-modifiable risk factors for CVD Smoking, inactivity, alcohol, obesity and Type 2 diabetes Blood cholesterol, fatty acids and soluble fibre Hypertension, sodium, antioxidants and homocysteine Preventing CVD through diet and lifestyle

Cancer

Topic overview Cancer and how tumours develop Fat, salt and meat in cancer risk Wholegrains, fruit, vegetables and antioxidants Lifestyle factors in cancer risk Recommendations to reduce cancer risk

Type 2 Diabetes

Topic overview Definition and symptoms of Type 2 diabetes Risk factors for Type 2 diabetes Preventing Type 2 diabetes Managing Type 2 diabetes

Alcohol

Topic overview Units, energy and alcohol's link to obesity Alcohol, the heart and cancer Alcohol in pregnancy and the developing baby Nutritional effects of heavy drinking

Physical Activity

Topic overview UK physical activity guidelines Activity, heart health and energy balance Bone, joint, muscle and mental health benefits

Food Security and Food PovertyOption A

Topic overview Food security and the threat from climate change Land degradation and population growth Food poverty as a global issue Food poverty in the UK and Northern Ireland Food banks, FareShare and the Trussell Trust

Food SustainabilityOption A

Topic overview Animal farming, climate change and natural resources Local and seasonal food Organic farming and the environment Fairtrade and producer countries Red Tractor, NI Beef and Lamb, LEAF and Conservation Grade Carbon labels, Rainforest Alliance, MSC and green claims

Food WasteOption A

Topic overview Environmental and ethical impact of food and packaging waste Waste from primary producers and food manufacturers Waste from retailers and consumers WRAP, the Courtauld Commitment and Love Food Hate Waste NI

Changing Consumer BehaviourOption A

Topic overview Advice for sustainable food choices Barriers to sustainable food choices Environmental and social cost of supermarket shopping

Food Safety Through the Food ChainOption B

Topic overview WHO and shared responsibility for food safety Animal and plant health risks The Food Standards Agency and DAERA GMP, quality assurance standards and traceability HACCP in food-serving establishments Hygiene ratings, food law inspections and EHPs

Microbiological ContaminationOption B

Topic overview Salmonella and Campylobacter Listeria and Escherichia coli High-risk foods for food poisoning Microbial control by producers and manufacturers Microbial control in catering and at home

Chemical ContaminationOption B

Topic overview Acrylamide in cooked foods Arsenic in rice Bisphenol A and dioxins Mercury, lead and cadmium in food

Food AdditivesOption B

Topic overview Additive regulation and E numbers Food colours and flavour enhancers Intense and bulk sweeteners Preservatives, nitrites and sulphites

Food AllergensOption B

Topic overview Why food allergies are increasing Allergen labelling and information rules The FSA's work on allergy and intolerance

Food Safety Controls and LegislationOption B

Topic overview EFSA and food risk assessment General food hygiene under Regulation 852/2004 Regulation 853/2004 and official controls

Research Skills

Topic overview Primary and secondary research Questionnaires and interviews Food diaries, observation and sensory evaluation Sampling and research ethics Evaluating and referencing sources Analysing and presenting data

Protein

Nitrogen balance and protein requirements

3 things to know
AS 1

Overview

Nitrogen equilibrium and positive and negative balance, how requirements are set, the adult Reference Nutrient Intake, and worked protein calculations.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Evaluation

Evaluate the idea that eating extra protein will build extra muscle.

Key term

Define nitrogen balance.

Key term

Why can nitrogen be used to measure protein intake?

Questions from this subtopic

Each one with the model answer underneath.

1
Define nitrogen balance.
Model answer
Nitrogen balance is the difference between the nitrogen eaten as protein and the nitrogen lost from the body. Nitrogen is lost mainly as urea in urine, with smaller losses in faeces, sweat, skin and hair.
2
Why can nitrogen be used to measure protein intake?
Model answer
Protein is the only macronutrient that contains nitrogen. Protein is about 16% nitrogen, so multiplying the nitrogen content by 6.25 gives the protein content.
3
How is nitrogen balance measured?
Model answer
Nitrogen intake is calculated from the protein in a weighed diet. Nitrogen output is measured by collecting urine and faeces over several days.
4
What is nitrogen equilibrium?
Model answer
Nitrogen equilibrium is when nitrogen intake equals nitrogen output. A healthy adult whose weight is stable and whose protein needs are met is in nitrogen equilibrium.
5
Define positive nitrogen balance.
Model answer
Positive nitrogen balance is when nitrogen intake is greater than nitrogen loss. The extra nitrogen is being kept by the body to build new tissue.
6
Give three situations in which a person is in positive nitrogen balance.
Model answer
A person is in positive nitrogen balance during childhood growth, during pregnancy and during recovery from illness or injury.

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