Macro/micronutrients

Question 1

vitamins associated with:

a) alcoholic liver disease
b) inflammatory bowel disease
c) obesity

Answer 1

a) thiamine (B1), vitamin D
b) iron, B12, vitamin D, K
c) vitamin D, copper, zinc

Question 2

dietary source, site of absorption and mechanism of absorption for:
vitamin A

Answer 2

dietary source: long chian fatty acids found in animals/ precursor for carenoids

absorption: Small intestine

mech of absorption: protein-retinol complex hydrolysed by pepsin in stomach and other proteolytic enzymes and then absorbed

carotenes solubilised into micelles absorbed through membrane and converted to retinol

Question 3

dietary source, site of absorption and mechanism of absorption for:
vitamin D

Answer 3

dietary source: animal food (liver, cheese, egg yolks) and synthesised in skin from UV light

site absorption: small intestine 50% absorbed. dietary vitamin D2, UV light vitamin D3

mech absorption: absorbed from mixed micelle by passive diffusion into intestinal mucosal cell. Liver 25-hydroxylase enzyme convert vitamin D2 and D3 io 25 hydroxy-vitamin D. Then converted by kidney and other tissues to active form of vitamin: vitamin 1,25-dihydroxyvitamin D

Question 4

dietary source, site of absorption and mechanism of absorption for:
calcium

Answer 4

dietary source: dairy and plant products

site absorption: primarily duodenum / jejunum
fermentation of plant products in colon

mech absorption: 20-30% absorbed in an acid medium. vitamin D-dependent calcium transport system when intake is low and requirment high (duodenum). Passive process when intakes are high - jejunum

Question 5

dietary source, site of absorption and mechanism of absorption for:
iron

Answer 5

dietary source: haem iron in animal food. non-haem iron in plant food

site absorption: primarily proximal small intestine

mech absorption: haem iron is absorbed intact as porphyrin complex. non-haem iron ionized from ferric to ferrous form

Question 6

risk factors for vitamin D insufficiency

Answer 6

>pigmented skin (non-white ethincity)
> lack of sunllight exposure
>multiple, short interval pregnancies
> vegan/ vegetarian
> use of anti-convulsants
> malabsorption eg inflammatory bowel disease, coeliac disease

Question 7

dietary source, site of absorption and mechanism of absorption for:
vitamin C

what can defiency cause

Answer 7

dietary source: foods of plant origin

site of absorption: buccal mucosa, stomach, s.intestine

mechansim absorption: buccal-passive diffusion

GI absorption is through carrier-mediated transport system

scurvy

Question 8

dietary source, site of absorption and mechanism of absorption for:
vitamin B1

what can deficiency cause

Answer 8

dietary source: common in al food

site absorption: jejunum and ileum

mechanism absorption: at low concs by active Na+ dependent processes. at high conc by passive diffusion

wernicke korsakoff syndrome

Question 9

dietary source, site of absorption and mechanism of absorption for:
vitamin B2 (riboflavin)

Answer 9

dietary source: in most foods in coenzyme form

absorption: s.intestine

mech of absorption: released from proteins by proteolytic enzymes and then hydrolysed by brush border enzymes

Question 10

dietary source, site of absorption and mechanism of absorption for:
vitamin B12

deficiency can cause

Answer 10

dietary source: synthesised by microorganisms in animals but not plants/ on plants by contamination of soil bacteria

site absorption: ileum - distal portion

mechanism of absorption: pepsin and HCl release B12 from proteins. B12 binds with transcorrin released from salivary glands/in bile/ gastric and pancreatic secretions.
In jejunum B12 released from TC and binds to intrinsic factor released from stomach. B12-IF complex binds with receptors at distal ileum and B12 lsowly absorbed

pernicious anaemia

Question 11

Name 2 diseases associated with:

a) maldigestion
b) inadequate absorptive surface
c) bile salt deficiency
d) lympathatic obstruction
e) vascular disease
f) mucosal disease

Answer 11

a) chronic pancreatitis, cystic fibrosis
b) intestinal resection, jejuno-ileal bypass
c) cirrhosis, cholestasis
d) lymphoma, whipple’s disease
e) contructive pericarditis, righ tsideed heart failure
f) infection eg whipple’s disease, uclerative jejunitis

Question 12

what can cause malnutrition in acutely ill patients

Answer 12

1) failure to recognise malnutrition on admisison
2) inc energy demand during inflammatory responses
3) prolonged periods of NBM
4) impact of cognitive impairment on eating
5) reduction in appetite

Question 13

what does lipoprotein lipase do and what is it upregulated by

Answer 13

mediates the influx of TAGs into adipose tissue

insulin