L1 Introduction to Nutrition Flashcards
What is EAR?
Estimated average requirement: 50% of the populations need will be satisfied at this level
What is LRNI?
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.
What is RNI?
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.
What is the main source of energy in the body?
Fat
Which macronutrient cannot be stored?
Protein - but in starvation muscle tissue can be metabolised for energy or to provide amino acids for other reactions.
What is the required protein intact for an adult per day?
0.75g/kg/day
What is negative nitrogen balance? When does it occur?
When the intake is less than excretion. This occurs during fasting or illness as the body is breaking down protein for energy.
What is positive nitrogen balance? When does it occur?
This is when intact exceeds excretion. This occurs during pregnancy and growth as the body is building new tissue.
Which are the essential amino acids? (Hint there are 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.)
What are the types of fatty acids found in triaylglycerols?
Saturated fats
Mon-unsaturated fats
Polyunsaturated fats
Transfats (contain trans double bonds.)
What percentage of dietary energy intact should fats make up?
35%
What are essential fats?
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.
What are the different forms of sugar?
- Polysaccarides
- Monosaccarides
- Disaccharides
- Non-starch polysaccharides
What are vitamins?
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)
What are minerals?
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.
What are the water soluble vitamins?
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
What are the fat soluble vitamins?
Vitamin A
Vitamin D
Vitamin E
Vitamin K
What is the role of Thiamin and what results due to deficiency?
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
What is the role of Riboflavin?
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.
What is the role of Vitamin B3? What results due to deficiency?
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
What is the role of vitamin B5?
Pantothenic acid is a constituent of coenzyme A – energy metabolism, fat metabolism.
What is the role of Pyridoxal phosphate B6?
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.
What is the role of B9 and what is the effect of deficiency?
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.
What is the role of B12? Which population is deficiency common in? What are the signs of deficiency?
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
What is the role of Vitamin C? What can deficiency lead to?
Collagen synthesis - cofactor for lysl hydroxylase and propyl hydroxylase. Also role as antioxidant
Deficiency leads to scurvy – symptoms caused by weakened collagen.
What is the role of vitamin A? What can deficiency lead to? Which population is told to avoid vitamin A?
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.
What is the role of vitamin D? What can deficiency lead to?
Bone formation & maintenance; also roles in immune regulation, cell differentiation, muscle function
Deficiency can lead to rickets in children, osteomalacia in adults.
What is the role of vitamin E? What can deficiency lead to?
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.
What is the role of vitamin K?
ofactor for enzymes which activate blood clotting proteins. May also be involved in bone maintenance
Which are the key minerals?
- Iron
- Iodine
- Zinc
- Fluoride
- Calcium
- Phosphate
- Magnesium
- Sodium
- Potassium
Which are mineral are found in trace amounts?
Cobalt Copper Chromium Manganese Selenium
What is malnutrition?
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
When can nutritional deficiencies arise?
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
