L1 Introduction to Nutrition

Question 1

What is EAR?

Answer 1

Estimated average requirement: 50% of the populations need will be satisfied at this level

Question 2

What is LRNI?

Answer 2

Lower reference nutrient intake: Sufficient for a very small number of people, 2s.d. below the average. It does not meet the needs of 97.5% of the population.

Question 3

What is RNI?

Answer 3

Reference nutrition intake. This is sufficient for 97.5% of the population. If the average intake of the population is the RNI, eh risk of deficiency is very small.

Question 4

What is the main source of energy in the body?

Answer 4

Fat

Question 5

Which macronutrient cannot be stored?

Answer 5

Protein - but in starvation muscle tissue can be metabolised for energy or to provide amino acids for other reactions.

Question 6

What is the required protein intact for an adult per day?

Answer 6

0.75g/kg/day

Question 7

What is negative nitrogen balance? When does it occur?

Answer 7

When the intake is less than excretion. This occurs during fasting or illness as the body is breaking down protein for energy.

Question 8

What is positive nitrogen balance? When does it occur?

Answer 8

This is when intact exceeds excretion. This occurs during pregnancy and growth as the body is building new tissue.

Question 9

Which are the essential amino acids? (Hint there are 9.)

Answer 9

Methionine
Threonine 
Tryptophan 
Histidine 
Leucine 
Isoleucine 
Valine 
Lysine 
Phenylalanine 
(Arginine as during growth or pregnancy we cannot satisfy our demand for asinine from the body.)

Question 10

What are the types of fatty acids found in triaylglycerols?

Answer 10

Saturated fats
Mon-unsaturated fats
Polyunsaturated fats
Transfats (contain trans double bonds.)

Question 11

What percentage of dietary energy intact should fats make up?

Answer 11

35%

Question 12

What are essential fats?

Answer 12

Fats that cannot be made in the body and so are essential to the diet. For example omega 3 and omega 6. We cannot make theses, as we do not have enzymes that will put double bonds any further than 9 carbons from the COOH group.

Question 13

What are the different forms of sugar?

Answer 13

• Polysaccarides
• Monosaccarides
• Disaccharides
• Non-starch polysaccharides

Question 14

What are vitamins?

Answer 14

Organic compounds required for normal metabolic function, which cannot be synthesised in the body – deficiency results in disease which can be treated by restoring appropriate levels of the compound.
Required in small amounts (µg – mg)

Question 15

What are minerals?

Answer 15

Inorganic elements which have a physiological function
Required in varying amounts from micrograms (‘trace elements’) such as Fe, Mg, to grams (Na, Ca). There is more variation in the amount we need compared to vitamins.

Question 16

What are the water soluble vitamins?

Answer 16

Vitamin B1; Thaimin 
Vitamin B2; Riboflavin 
Vitamins B3; Niacin 
Vitamin B5; Pantothenic acid 
Vitamin B6; Pyridoxal phosphate 
Vitamin B7; Biothin 
Vitamin B9; Folic acid 
Vitamin B12; Cobalamin 
Vitamin C; ascorbic acid

Question 17

What are the fat soluble vitamins?

Answer 17

Vitamin A
Vitamin D
Vitamin E
Vitamin K

Question 18

What is the role of Thiamin and what results due to deficiency?

Answer 18

Cofactor in decarboxylation reactions (CO2) released – e.g. link reaction, Krebs cycle.

Deficiency: Beri –beri; muscle weakness, nerve damage, can affect heart – rarely seen in the UK except in alcoholism

Question 19

What is the role of Riboflavin?

Answer 19

Constituent of cofactors e.g. flavin adenine dinucleotide (FAD); involved in many aspects of metabolism, fats, carbohydrates, proteins.

Deficiency is very rare as cofactors bind tightly to enzymes and are efficiently conserved.

Question 20

What is the role of Vitamin B3? What results due to deficiency?

Answer 20

Niacin is a constituent of NADH.
Deficiency - Pellagra – diarrhoea, depression, dermatitis, death
This deficiency is fairly well known. 4 D’s.
You would also require to be deficient in tryptophan in which you synthesise niacin from

Question 21

What is the role of vitamin B5?

Answer 21

Pantothenic acid is a constituent of coenzyme A – energy metabolism, fat metabolism.

Question 22

What is the role of Pyridoxal phosphate B6?

Answer 22

Cofactor for enzymes involved in protein metabolism, haem synthesis, neurotransmitter synthesis; modulates steroid hormone action. Large amounts are toxic and can cause permeant neural damage.

Deficiency leads to irritability, depression, and confusion; inflammation of tongue or mouth.
Serious deficiency is rare but mild deficiency is common
Can also get anaemia due to problems with haem synthesis.

Question 23

What is the role of B9 and what is the effect of deficiency?

Answer 23

B9 has a role in 1-C transfers, particularly in DNA synthesis

Deficiency in folic acid leads to neural tube defects – spina bifida, anencephaly, macrocytic anaemia.

Question 24

What is the role of B12? Which population is deficiency common in? What are the signs of deficiency?

Answer 24

Required for only 2 reactions (methionine synthesis, odd-chain fatty acid metabolism)
It is only found in animal products. This is a problem in vegans or vegetarians. It is therefore wise of vegans and vegetarians to take supplements.

Deficiency can lead to macrocytic anaemia,
irreversible neurological damage.
Commonly caused by autoimmune disease preventing absorption

Question 25

What is the role of Vitamin C? What can deficiency lead to?

Answer 25

Collagen synthesis - cofactor for lysl hydroxylase and propyl hydroxylase. Also role as antioxidant

Deficiency leads to scurvy – symptoms caused by weakened collagen.

Question 26

What is the role of vitamin A? What can deficiency lead to? Which population is told to avoid vitamin A?

Answer 26

Role - Vision (rod cell function). Transcriptional regulator

Deficiency can lead to blindness, susceptibility to infection, birth defects
High or low levels are dangerous in pregnancy. Therefore avoid liver as liver is high in Vitamin A. Also advised not to take supplements with Vitamin A.

Question 27

What is the role of vitamin D? What can deficiency lead to?

Answer 27

Bone formation & maintenance; also roles in immune regulation, cell differentiation, muscle function

Deficiency can lead to rickets in children, osteomalacia in adults.

Question 28

What is the role of vitamin E? What can deficiency lead to?

Answer 28

Acts as an anti-oxidant; Its main role is to prevent lipid oxidation in membranes

Deficiency leads to malabsorption of fat (e.g. CF), causes neurological problems
Deficiency is rare, expect in people with problems absorbing fat such as cystic fibrosis.

Question 29

What is the role of vitamin K?

Answer 29

ofactor for enzymes which activate blood clotting proteins. May also be involved in bone maintenance

Question 30

Which are the key minerals?

Answer 30

• Iron
• Iodine
• Zinc
• Fluoride
• Calcium
• Phosphate
• Magnesium
• Sodium
• Potassium

Question 31

Which are mineral are found in trace amounts?

Answer 31

Cobalt
Copper
Chromium
Manganese
Selenium

Question 32

What is malnutrition?

Answer 32

Malnutrition is characterised by inadequate or excess intake of protein, energy, and micronutrients such as vitamins and minerals

Globally iron, vitamin A, iodine and zinc deficiencies are of greatest importance

Question 33

When can nutritional deficiencies arise?

Answer 33

Nutritional delicences arise due to:

• Food availability
• Food choices
• Problems with eating
• Problems with fat absorption affect fat soluble vitamins (cystic fibrosis, coeliac disease, Crohn’s disease)
• Autoimmune diseases such as Pernicious anaemia (B12 absorption- autoimmune disease which prevents B12 being taken in)
• Excess loss/increased requirements:
  Iron deficiency anaemia: arises as a result of persistent blood loss - gastric ulceration, colon cancer, excessive menstruation
  Folic acid deficiency - in pregnancy, additional requirements may not be met