Vitamin B9 deficiency Flashcards
What are the sources of B9?
Dark green vegetables
Fruits and fruit juice
Meat, seafood, poultry and eggs
Fortified cereals and eggs
What are folates absorbed in?
Monglutamate form
What are folates hydrolysed by?
Folylpoly-g-glutamate carboxypeptidase
What is the main dietary folate?
N5-methyltetrahydorfolate (5-MTHF)
Where does absorption of B9 occur?
Proximal small intestine (duodenum and jejunum)
Some in colon
Where is folate absorbed from?
Lumen by a proton- coupled folate transporter (PCFT)
What does folate get exchanged for?
Organic phosphate (OP) via reduced folate carrier (RFC)
What else have folate receptors?
Enterocytes
Final stage of B9 absorption
Folate exported without further metabolism or reduced to 5-MTHF
Both forms exported from enterocyte by organic anion transporter (OAT)
Where does folate circulate?
Free in blood
What is plasma concentration of B9?
10-20 mmol/L
What is the cellular uptake of B9?
PCFT, RFC and folate receptor
What are the causes of B9 deficiency?
Inadequate dietary uptake
Congenital defects
Drug interactions
Chronic alcohol use
What are the symptoms of B9 deficiency?
Sore tongue
Pain when swallowing
GI symptoms- nausea, vomiting, diarrhoea
Neurological- dementia, depression
Megaloblastic anaemia
What consequence of B9 deficiency?
Neural tube defect
Folic acid deficiency in pregnant women
