B group vitamins Flashcards
What are the main functions of thiamin, riboflavin and niacin (B1, B2, and B3)?
Assist with energy metabolism by converting CHO, Fat and Protein to energy
What are the main functions of pyridoxine, folic acid, and cyancobalamin (B6, B9 and B12)?
Assist with production of DNA, red blood cells and AA metabolism
What can destroy the availability of B vitamins?
- cooking
- food processing
- alcohol
Thiamine (B1) deficiency is common in ??
- those who consume ‘empty calories’
- those with alcohol dependancy (alcohol impairs thiamin absorption and increases excretion)
- malnourished
- indigenous communities
Name 3 outcomes of thiamine (B1) deficiency?
- fatigue
- beriberi
- wernicke-korsakoff syndrome (chronic alcohol abuse)
How long does it take for thiamin (B1) reservoir to be depleted?
2-3 weeks if low supply
What are food sources of thiamin (B1)?
- meat
- fortified bread/cereals
- legumes
- sweet potato
- vegemite
Why is thiamin (B1) deficiency common in refeeding syndrome?
Thiamin used for CHO metabolism
What is the main role of riboflavin (B2)?
Part of several co-enzymes for energy production - also plays a role in endogenous antioxidant pathway as it is a co-enzyme for FAD required in this pathway
What is the main source of riboflavin (B2)? List some other sources.
Milk and milk products
Vegemite
Broccoli & green veg
Fortified bread & cereals
What are the 2 dietary compounds of niacin (B3)?
- nicotinic acid
- nicotinamide
= niacin equivalents
What can niacin (B3) be synthesized from?
- niacin equivalents = 1mg equivalents = 1mg niacin
- tryptophan = 1mg niacin:60mg trpytophan
How can niacin (B3) be used as a supplement?
Supplement to lower LDL and raise HDL in conjunction with statins
What is commonly seen in niacin deficiency?
Pellagra - skin lesions, dark pigmentation, cracking and peeling
What are the 4 D’s of niacin deficiency?
Diarrhoea, dementia, dermatitis, death
What are the main sources of niacin?
- meat (liver and kidney)
- eggs
- nuts, oats, wheat bran
- fortified breads & cereals
- vegemite
- tryptophan - eggs, beans, oily fish, cheese
Why does inadequate iron, riboflavin and vitamin B6 (pyriodoxine) decrease the conversion of tryptophan to niacin?
They are cofactors for the enzymes required
When can niacin become toxic?
When used as a supplement
Explain how pyrioxidine (B6) can reduce CVD risk?
Converts homocysteine into cysteine (high levels of homocysteine associated with CVD)
What is needed to prevent increased levels of homocysteine?
Pyroxidine (B6)
B12
Folate
What are the main sources of Pyrioxidine (B6)?
- meat, fish, poultry
- starchy vegetables, fruit
- fortified cereals
What occurs in pyrioxidine (B6) deficiency?
Affects the skin, blood, nervous system
- anaemia
- neurological issues (confusion, depression)
- patchy skin
What are the main functions of folate?
- assists with activation of B12 for DNA production
- formation of neural tube in 1st trimester
- breaks down homocysteine (risk factor for CVD)
What occurs in folate (B9) deficiency?
- megaloblastic anaemia
- fatigue, SOB
- neural tube defects
What are the main sources of folate (B9)?
- legumes
- fruit
- vegetables
- mandatory fortification in bread
- fortified cereals
What are poor source of folate?
Meat (except liver) and dairy
What is the NRV for folate?
EAR: 320ug, RDI 400ug
Pregnancy: EAR 520ug, RDI 600ug
What are the main functions of cyancobalamin (B12)?
DNA synthesis and red blood cell formation (both in combination with folate)
What are the main sources of cyancobalamin (B12)?
Animal products only
- eggs
- meat, poultry
- fortified foods (milk alternatives, cereals)
How does folate activate vitamin B12)
Vitamin B12 accepts a methyl (CH3) group from folate, activating B12
What types of bread are fortified with folic acid? Which don’t?
All breads made from plain flour
Organic breads and those made from other cereal flours do not have to be fortified
What is the role of iodine?
Component of thyroid hormone to regulate growth, development and metabolism
What foods contain iodine?
- plants grown in iodine rich soil
- iodised salt & fortified bread
- sea salt
- seaweed
What are the dietary sources of vitamin A?
- vegetable oils
- fruits
- vegetables
1ug retinol equivalent = how much B-carotene or a-carotene?
6ug B-carotene
12ug a-carotene
