micronutrients Flashcards
1
Q
what are micronutrients? 4
A
- Vitamins, minerals and trace elements are fundamental groups of nutrients to sustain life
- They have physiological role at the cellular level
- Vitamins, organic molecules derived from plants, act as co-enzymes in metabolic pathways
- Minerals and trace elements participate in wide ranging cellular mechanisms
2
Q
describe the vitamins that the body needs? 3
A
- Require adequate amounts of 13 vitamins
- 4 fat soluble vitamins (A, D, E,K)
- 9 water soluble vitamins which comprise of vitamin C and the 8 B vitamins
3
Q
what are the B vitamins? 7
A
- B1= thiamine
- B2= riboflavin
- B3= niacin
- B5= pantothenic acid
- B6= vitamin B6
- B9= folate
- B12= vitamin B12
4
Q
what causes micronutrient deficiency in the UK? 3
A
- Poor dietary intake
- Excessive energy dense/ nutrient light diets
- Extreme diets (removal of one of your food groups)
5
Q
describe some micronutrient deficiencies associated with illness?
A
- Alcohol liver disease= thiamine (B1), vitamin D
- Inflammatory bowel disease= iron, B12, vitamin K, vitamin D, folic acid, selenium, zinc, vitamin B6 and vitamin B1
- Obesity= vitamin D, copper, zinc
6
Q
what is vitamin C? 3
A
- Foods of plant origin
- Absorbed in the buccal mucosa (passive diffusion), stomach and small intestine (rapid and through carrier mediated transport system)
- Lack can cause scurvy
7
Q
describe vitamin B1? 3
A
- Common in all food
- Absorbed in the jejunum and ileum, absorbed at low concentrations by active Na+ dependent processes and by passive diffusion in high concentrations
- Wernicke Korsakoff syndrome
8
Q
describe vitamin B2? 2
A
- In most foods in coenzyme form
- Absorbed in the small intestine in a 2-stage process released from proteins (proteolytic enzymes and then hydrolysed by brush border enzymes)
9
Q
describe vitamin B12? 6
A
- Synthesised by microorganisms in animals
- Concentrated through food chain
- Absorbed in the ileum- distal portion
- Pepsin and HCl release B12 from proteins. B12 binds with transcorrini (TC) (R factor) released from salivary glands/ in bile/ in gastric and pancreatic secretions,
- In the jejunum, B12 is released from the TC and binds to intrinsic factor (IF) released from the stomach. The B12-IF complex binds with receptors at the distal ileum and B12 is slowly absorbed
- Pernicious anaemia
10
Q
describe vitamin A? 4
A
- Long chain fatty acid found in animals
- Absorbed in the small intestine, carotenes upper regions (duodenum and jejunum)
- Protein-retinol complex is hydrolysed by pepsin in the stomach and other proteolytic enzymes in the small intestine, and is then absorbed
- Carotenes are solubilised into micelles absorbed through the membrane and converted to retinol
11
Q
describe vitamin D? 6
A
- Animal food D2
- Synthesised in skin from UV light D3
- 50% absorbed in the small intestine
- Absorbed from mixed micelle by passive diffusion into intestinal mucosal cell
- The liver 25-hydoxylase enzymes convert vitamin D2 and D3 to the main circulating form of vitamin 25 hydroxy-vitamin D (25(OH)D).
- This is then converted by the kidney and other tissues to the active form of vitamin 1, 25-dihydroxyvitamin D
12
Q
what are the risk factors for vitamin D insufficient and deficiency? 8
A
- Pigmented skin
- Lack of sunlight exposure
- Sun concealing garments or strict sun cream use
- Multiple, short interval pregnancies
- Elderly or housebound
- Vegan/ vegetarian
- Malabsorption
- Use of anticonvulsants
13
Q
where is calcium found? 5
A
- Dairy and plant products
- Absorbed primarily in the duodenum, but also the jejunum and colon
- 20-30% is absorbed in an acid medium
- Vitamin D-dependent calcium transport system when intake is low, and requirement is high
- Passive process when intakes are high
14
Q
where is iron found? 7
A
- Haem iron in animal food
- Non-haem iron ins plant food
- Absorbed primarily in the proximal small intestine
- Haem iron is absorbed as intact porphyrin complex
- Non-haem iron is ionized from ferric to ferrous form
- 35% of iron is absorbed when stores are low
- 5% with normal iron status
15
Q
what are the roles of calcium in the body? 9
A
- egg activation
- early embryonic events
- right-left axis patterning
- organ development
- bone formation
- blood clotting
- brain function and neurotransmission
- heart function
- muscle function
