You are what you eat

Question 1

Define nutrition

Answer 1

• Concerned with understanding effects of food on human body in health and disease
• Sum of processes concerned with growth, maintenance and repair of living body as a whole, or its constituent parts
• Ingestion, digestion, absorption, transport, assimilation and excretion

Question 2

Define malnutrition

Answer 2

• Nutritional imbalance
• Can be under or over nutrition
• 2 variations can co-exist e.g. obese with vit C deficiency

Question 3

Describe overnutrition

Answer 3

• Condition of excess nutrient and energy intake over time
• Overnutrition may be regarded as form of malnutirtion when it leads to morbid obesity
• Obesity has been associated with many health complications

Question 4

Describe undernutrition

Answer 4

• Deficiency of nutrients such as energy, proteins, vitamins, minerals
• Causes measurable adverse effects on body composition, function or clinical outcome
• As a result of:
  
  • Starvation - Inadequate intake
  • Disease related - Malabsorption of micro/macronutrients, increased requirements

Question 5

What are the consequences of malnutrition?

Answer 5

• Immune system - less able to fight infection
• Impaired wound healing
• Loss of muscle mass - falls, pressure ulcers, chest infection heart failure
• Kidneys - Over hydration or dehydration
• Reproduction - Reduces fertility
• Brain - Apathy, depression
• Impaired temp regulation - hypothermia
• Micronutrient deficiencies - anaemia, rickets, scurvy, night blindness

Screening includes:

• MUST - Malnutrition universal screening tool - BMI score + recent weight loss score + acute disease score (asks have they been unable to eat for 5 das or more due to acute illness)= Overall risk of malnutrition
  
  • If 0 = Low overall risk of malnutrition
  • 1 = Medium risk
  • 2 = High risk, patient referred to dietician
• SGA - Subjective global assessment - Weight change, dietary intake, GI symptoms, functional impairment, muscle wasting, subcutaneous fat loss, edema

Question 6

How do nutrient deficiencies develop?

Answer 6

• Inadequate intake - e.g. reduced appetite, poor availability of food
• Reduced absorption - e.g. Coeliac disease
• Increased losses - e.g. diarrhoea, vomiting
• Increased demand - e.g. growth, pregnancy

Supply < Demand:

• Health → Subclinical deficiency → Deficiency → Death

Question 7

Describe the effects Vitamin A in excess or being deficient

Answer 7

• Toxicity - In excess

Vit A deficiency:

• Health
• Depleted liver stores
• Low blood levels
• Increased risk of infection
• Xeropthalmia
  
  • Non blinding or blinding

The more symptoms that develop, the greater the deficiency

Question 8

Describe nutrient deficiency as a result of GI disease

Answer 8

• Carbs and proteins mostly absorbed in duodenum and jejenum
• Lipids bound to bile-salts and lipophillic vitamins absorbed in ileum. Instrinsic factor bound B12 absorbed in ileum as well
• Inflammatory conditions etc. can damage small intestine mucosal lining, impairing ability to absorb nutrients

Question 9

What are the 4 components that can be combined to produce a nutritional assessment?

Answer 9

• Anthropometry
• Biochemical and haematological markers
• Clinical state and physical condition
• Diet (Diet history, Food frequency Questionnaire, 24hr recall, Food Record Chart)

Question 10

Describe an anthropometry and its limitations

Answer 10

External measurement of body composition:

• Weight
• BMI
• Weight loss - >10% in 3-6 months

Limitations:

• Difficult to obtain weight in bedbound patients
• Affected by presence of oedema/ascites
  
  • Can estimate dry weight in ascites and oedema:
  • Ascites:
    
    • Tense - 14kg
    • Moderate - 6kg
    • Minimal - 2.2kg
  • Oedema:
    
    • Severe - 10kg (up to sacrum)
    • Moderate - 5kg (up to knee)
    • Mild - 1kg (ankle)

Mid arm muscle circumference and hand grip strength - Protein status

Waist circumference, tricep skinfold thickness - Fat stores

Question 11

Describe the role of testing hand grip strength and its limitations

Answer 11

• Index of muscle function
• Mean value can be compared to ref data (values <85% of normal may indicate PEM, can predispose to serious post operative morbidity)
• Respond more quickly to nutritional support than other anthropometric parameters
• Easy, minimally invasive, inexpensive

Limitations:

• Affected by motivational status
• Ability improves with repeated use
• Arthritis, confusion - Can’t be used with these conditions

Question 12

What are clinical signs of nutritient deficiency?

Answer 12

• Sunken eyes/dry mouth/skin pinch
• Loose clothing, rings
• Pressure sores
• Diarrhoea/vomiting/pain

Question 13

Describe the metabolic response to starvation

Answer 13

• Adaptive process
• Maintain supply glucose to tissues
• Minimise protein losses
• Decrease in mass of metabolically active tissues (liver and GIT)
• In prolonged starvation basal metabolic rate falls by 30%

Question 14

Describe the metabolic response to injury, trauma or sepsis

Answer 14

• Different to starvation
• Need to mobilise energy for defence and repair
• Increase body metabolic rate (BMR)
• 3 stages:
  
  • Ebb phase (shock, hours) - Energy reserves mobilised, but body struggles to use it. Decrease BMR, decrease body temp
  • Flow phase (catabolism, days) - Breakdown of energy stores, increase BMR, increase body temp, acute insulin resistance, visceral and SK muscle breakdown
  • Anabolic phase (recovery, weeks) - Building up energy stores, nutritional therapy aims to increase protein synthesis and restore lean body mass

Question 15

Define and describe nutrients, food and diet

Answer 15

• Nutrients - Components of food
  
  • Macronutrients:
    
    • Fat, carbs, protein, alcohol - Energy, structural materials (e.g. membranes, teeth, bones), hormones and enzymes
  • Micronutrients:
    
    • Vitamins - Water soluble (B and C), fat soluble (A, D, E K, come from animals fats, veg oils, dairy, liver, oily fish) - Used as cofactors in metabolism (e.g. Thiamin/ B1 in carbohydrate and amino acid catabolism)
    • Trace minerals
• Food - Substances that we take into the body. Classified into diff groups based on nutrients they contain
• Diet - Sum of food consumed by a person

Question 16

Describe ‘normal’ nutrient requirements

Answer 16

Levels of specific nutrients needed to maintain good health

Question 17

What are the major components of the diet?

Answer 17

• Protein
• Vitamins and minerals
• Fats
• Carbs
• Water

Question 18

Why are nutrient requirements measured?

Answer 18

• Benchmark to evaluate dietary adequacy in healthy groups
  
  • Plan what to provide (e.g. hospital menus, school meals)

Question 19

What factors affect nutrient requirements?

Answer 19

• Age
• Gender
• Body size
• Lvls physical activity
• State of health
• Physiological status - Pregnancy and lactation
• Growth

Question 20

Define nutritional status

Answer 20

State of a person’s health in terms of/influenced by the nutrients in their diet. Essentially how well person’s body is using nutrients from their diet to maintain health

Question 21

Describe ferritin as a biochemical marker of nutrient status

Answer 21

• Iron stored in body as ferritin
• Small amounts of ferritin secreted into plasma
• Concentration of plasma (serum) ferritin is positively correlated with size of total body iron stores
• Low serum ferritin = Depleted iron stores
• However, ferritin = Positve acute phase protein, increases during inflammation, so during this time cannot be used to measure iron store size

Question 22

Describe the use of albumin and urea as biochemical markers

Answer 22

Albumin: (35-55g/L)

• Lvls fall if body not absorbing enough protein and when increased demand for acute phase proteins, like CRP
• Increases in dehydration
• Has long half life (21 days) - not sensitive to short-time changes in protein status
• Albumin decreases when severely stressed as liver produces acute phaase proteins of greater physiogical importance e.g. CRP

Urea: (6-20 mg/dL)

• Formed when protein breaks down, low lvls may indicate poor protein intake or low body muscle mass

Question 23

How are energy requirements calculated?

Answer 23

• Total energy expenditure = Basal metabolic rate + diet induced thermogenesis + Activity +/- stress (illness/inflammation/surgery).
• TEE = BMR + DIT + Activity (+stress).
• Direct or indirect calorimetry.

Question 24

What are dietary reference values (DRVs)?

Answer 24

• Estimates amount of energy and nutrients by different groups of healthy people in UK population
• Allowances for physiological state (e.g. growth, pregnant, breast feeding)

Question 25

What are types of DRVs and what are they used for?

Answer 25

- Estimated Average Requirement (EAR) - An estimate of average requirement for energy, or a nutrient. Approx 50% will need less and 50% will need more. EAR used for energy. - Reference Nutrient Intake (RNI) - Amount of nutrient that is enough to ensure need of nearly all population (97.5%) are being met. Many within group will need less. Only 2.5% need more. Often used as reference amount for population groups. Used for protein, vitamins and minerals - Lower Reference Nutrient Intake (LRNI) - Amount of nutrient that is enough for only small number of people who have low requirements (2.5%). Majority population will need more. Intakes below LRNI are almost certainly not enough for most people. Useful measure of nutritional inadequacy. - Safe Intake (SI) All calculated using normal distribution, EAR is in the middle

Question 26

What are some drawbacks of DRVs?

Answer 26

- - Bioavailability - Assume that requirements from other nutrients met - Differences in DRVs b/w countries - Based on best available evidence - Reflect needs of healthy people, not usually approriate in clinical circumstances