Vitamins Flashcards
What is the definition of a vitamin?
A complex organic substance required in the diet in small amounts, compared with other dietary components. The absence leads to a deficiency disease.
Why are some vitamins A the and some B type?
A type = fat soluble factor
B type = heat labile factor
Ho many vitamins does man need?
13
Which vitamins are fat soluble?
Water soluble?
A, D, E, K
B complex and C
Explain the difference in properties between water and fat soluble vitamins
Water soluble:
- not stored extensively
- needed regularly
- generally not toxic in excess
- most function as cofactors for enzyme-catalysed reactions
Fat soluble:
- stored
- not easily absorbed
- not excreted easily
- may be toxic in excess (A&D)
How do B vitamins work?
Co-enzymes in metabolic pathways.
What food sources are good for vitamins?
Which aren’t?
Whole grain, pork, poultry, fish, vegetables, dairy produce.
Polished rice, sugar, fat and processed food.
What happens if you do not have enough thiaminases?
What is this mainly caused by?
- Biochemical role in glycolysis
- Pyruvate to acetyl CoA
- If deficient, there is accumulation of lactate
Alcoholism
What are the 3 types of vitamin deficiency and explain them?
Primary - not taking enough in diet
Secondary - taking enough but it is not used properly in body
Iatrogenic - caused by medical examination or treatment
Why may alcoholics suffer B vitamin deficiencies?
- May have adequate energy intake but as ‘empty calories’ from alcohol
- Inadequate levels of vitamins and other nutrients
- GI tract malfunctions are common
- Cirrhotic liver affects storage, transport and metabolism of many vitamins
- Storage and transport of fat soluble vitamins e.g. vitamin A, may be impaired
What is the function of riboflavin?
How is it taken in?
Functions as FAD and FMN in redox reactions.
Taken mainly in milk
Give details on the functions and sources of Niacin
Function as NAD and NAPH in redox reactions.
Source is in cereal.
Give details on pyridoxine
Essential for amino acid metabolism and harm synthesis.
Most common as a secondary deficiency, causes by antagonistic presence.
What are the dietary sources of vitamin A?
- Retinol containing foods
- Full fat dairy produce, liver and kidney
- Provitamin A containing foods
What is the function of vitamin B12 and folate?
B12 - carrier of methyl groups in mammalian metabolism
Folate - carrier of 1C units