Lecture 21; Vitamins Flashcards
What is RDI based on?
A level of nutrient that is determined to be sufficient for 98% of the population
When it comes to vitamins and RDI, whats important in drug toxicity?
Whether the vitamin is water of fat soluble will be important in its toxicity
What makes vitamins dangerous, i.e fat vs water soluble?
Water soluble; Excess vitamins are excreted in the urine
Fat soluble; Cant be easily excreted because theyre fatty (liophilic)
What are the water soluble vitamins?
- Vit B1,2,3,5,6,12
- Vit C
- Folic acid
- Biotin
What are the fat soluble vitamins?
- Vit A, D, E, K
Describe the absorption, transport, storage and excretion of water soluble vitamins?
Absorption = Direct into blood
Transport = Freely travel
Storage = Circulate freely in water parts body
Excretion = Kidneys detect and secrete
Describe the absorption, transport, storage and excretion of fat soluble vitamins?
Absorption = Lymph, then blood
Transport = Many need protein carriers
Storage = Stored in cells assc. with fat
Excretion = Tend to remain in fat storage sites.
What can affect bioavailability?
- Efficiency of digestion / transit time
- Nutritional status and previous nutrient intake
- Other foods consumed simultaneously (do they hinder absorption)
- Food preparation method
- Source, synthetic or natural
- Health status, conditions impacting absorption or meds.
What are the functions of the B vitamins?
- Metabolism of energy yielding intermediates via red/ox reactions (B1,2,3)
- Transamination (B6)
- Transmethylation (B9, 12)
- Constituent of coenzyme (B5)
- Carboxylation of using coenzyme A (B7)
What do B factors generally do?
Co-factors for enzymes in metabolism (of glucose etc)
What are the sources of Thiamine?
- Whole grain, fortified, or enriched grain products
- Moderate amounts in all nutritious food
- Pork
What is thiamine deficiency called?
“beriberi”
- Wet (cardiac)
OR
- Dry (neurological)
What is wet beriberi?
Leaking of fluid into tissues
- Oedema
- Tachycardia
- Heart failure
What is dry beriberi?
Neurological
- Peripheral neuropathy (Can lead to inability to walk)
- Wasting
Is thiamine strictly wet or dry?
Can be a combination
What are the causes of thiamine deficiency?
Developed countries; Alcoholism
What are two neurological conditions related to thiamine deficiency?
- Wernicke encephalopathy, (language problems, walking difficulty, unusual eye movement)
- Korsakoff syndrome, amnesia, inability to learn, confabulation
How is folate found in food? how does it change in the gut?
Folate occurs naturally as POLYGLUTAMATE, the intestine digestion breaks off the glutamate and adds a methyl group. Now can be absorbed.
What does folate metabolism need?
Folate works in unison with B12 (one cant work w/o the other)
Hard to differentiate B12 or folate deficiency
What happens with a deficiency in folate or B12?
Deficiency in either decreases DNA / cell turnover
i.e needed for DNA synthesis.
What can cause B12 deficiency?
Pernicious anemia
What does a folate deficiency result in?
- Macrocytic anemia
- Neural tube defect i.e spina bifida, anencephaly
What can cause folate deficiency?
- low dietary intake
- Increased need i.e PREGNANCY
- Reduced intestinal absorption
- Medication i.e anticonvulsant
- Associated with alcoholism
- Folate antagonists (Methotrexate, cancer drug)
Whats the other vitamin deficiency important to NZ?
Vitamin D deficiency
What is vitamin D important in?
Regulates Ca uptake for the bone i.e deficiency leads to rickets because poor calcium uptake from gut
Regulation of immune functions
Regulation of cell growth
What can vitamin D deficiency cause?
- Rickets - children
- Osteomalacia in adults
Who needs vitamin supplements?
- Poor nutrient intake
- Increased nutrient requirements
- Increased metabolic demands (surgery, trauma)
- Maldigestion or malabsorption
- Drug-nutrient interactions
- Medical treatment interactions i.e chemo or radiation
- Need for pharmacological doses
