Vitamin Lecture 1 Flashcards
What was believed to be the four required nutritional components in the late 19th century
Fats, proteins, carbohydrates, and minerals
what were the previous observations that challenged the belief that there were only four nutritional components
Number of diseases not caused by infections or deficiencies in one of the four groups
During the siege of paris in 1870, many infants and toddlers died when the city was cut off from outside milk, and synthetic milk did not work
When young mice were fed milk-bread they grew but when the dough was extracted to removed non-polar molecules the mice died
Young rats fed the four groups did not grow well, when milk was added, they grew
Who is the father of the vitamin
Casimir Funk: he isolated vitamins B1 and B3, and developed formulas for vitamin A and D
Proposed the name vitamine based on their life-supporting role
What were the limitations of Casimir Funk’s research
Thought all vitamins were amines
Proposed that a vitamin worked with a single mode of action
Why did beriberi skyrocket
Disease
Rice was stripped off the outer layer in the mid 1800s
and then beriberi skyrocketed until someone found that the outer layer contained vitamin B1
What are vitamins? Functions? required characteristic?
Structurally diverse group
13 organic small molecules that play essential role in cellular metabolism and health maintenance
Most common function is coenzymes/cofactors, but also include regulators of transcription and antioxidant roles
required characteristic is that is required in the diet and cannot be made in the body in sufficient quantities
How are vitamins classified
Characterized based on the chemical property of solubility in either water or fat
What are the water soluble and fat soluble vitamins
Water-soluble: B1, B2, B3, B5, B6, B7, B9, B12, C
Fat-soluble: A, D, E, K
Alternate name for vitamin B7 (biotin)
Vitamin H
What happened to vitamin B4, B8, B10, B11
Did not fit the definition of a vitamin
Can make all of them
B10 made by bacteria in our gut
T/F vitamins are structurally diverse
True
What are the most common sources of vitamins
Fruits and vegetables except for B12
Vegetarians often get what deficiency?
B12 deficiency
Which diseases are caused by deficiencies: A, B1, B2, B3, B5, B6, B7, B9, B12, C, D, E, K
- A – night blindness; hyperkeratosis
- B1 – Beriberi (peripheral nerve damage)
- B2 – lesions at corner of mouth, lips, tongue;
dermatitis - B3 – Pellagra (depressive psychosis; dermatitis)
- B5 - “burning foot syndrome” (peripheral nerve damage)
- B6 – disorders of amino acid metabolism; convulsions
- B7 - dermatitis
- B9 – Neural tube defects, megaloblastic anemia
- B12 – megaloblastic anemia with degeneration of spinal cord
- C – scurvy
- D – rickets (poor mineralization), osteomalacia (demineralization)
- E – deficiency very rare; neurological dysfunction
- K – impaired blood clotting
What is the biological availability of vitamins determined by
The extent of digestion, absorption of the digested material, and the metabolism of the nutrient which are all subject to specific factors
6 specific factors of biological availability
- Many vitamins are absorbed by active transport, which is saturable. Thus, a lower percentage is absorbed as the concentration gets higher.
- The absorption of fat soluble vitamins is affected by the lipid content of the food eaten.
- A number of water soluble vitamins are bound to protein, and require to be released by acidic conditions in the stomach or by specific hydrolases
- The total body reserves of a vitamin can affect absorption rate e.g. by affecting the synthesis of proteins that bind and transport vitamins, or by altering metabolism of vitamin
- Foods can have antivitamin compounds e.g. thiaminases
- Drugs/medications and compounds present in food can compete for absorption e.g. some
antidepressants block riboflavin availability; natural carotenoids can compete for b-carotene for absorption
What does a biochemical assessment of vitamin status include
Determination of levels in plasma and urine, in rare cases in tissues
Four major methods used to determine vitamin requirements
Population studies of intake
depletion/repletion studies
replacement of metabolic loss
Examination of patients on total parenteral nutrition
Which type of vitamins tend to show more toxicity
Fat-soluble vitamins
Water soluble toxicities are very rare
Toxicities of vitamins A, D, E, K, C, B (B3 and B6)
A: RDA is 900ug/day and upper limit is 300ug
D: RDA is 20 ug/day and UL is 100ug
K: RDA is 125ug/day and no UL, toxicity is very rare
C: RDA 75-90mg/day and UL is 2000mg
B3: RDA is 16mg/day and UL is 2000mg
B6: RDA is 1.3mg/day and UL is 1000mg/day
Why do people continue taking vitamin supplementation even though evidence is lacking
Most people want to believe that it will improve or maintain their health
Growing distrust in science
T/F multivitamins failed to prevent cancer, heart disease, and all causes of death for all women they tracked – REGARDLESS OF HEALTHY EATING HABITS
true
Do multivitamin supplementation work
No, except for in developing countries where there are lots of deficiencies
what does vitamin C supplementation do
Helps prevent scurvy
does not prevent cancer or any chronic disease
Slightly reduce duration of a cold
What does vitamin E supplementation do
Vitamin E slightly increased the risk of hemorrhagic strokes
Did not prolong life or protect against disease
slightly higher risk of lung cancer
Higher risk of prostate cancer
No evidence for alzheimer’s disease
What are food fortifications
There is a list of foods that may or must be fortified with vitamins
4 things
Policy highlights for food fortifications
Must fortify foods that have lost nutritional quality
Fortify foods with vitamins to prevent nutrional problems
Fortify foods to help canadians meet RDIs
Fortification cannot be permitted when no rationale can be provided
Why is fortification not permitted when there is no nutritional rationale
Didn’t want to trivialize the importance of vitamins and it prevents overfortification
Why is vitamin deficiency rare
Because of food fortification
