1. Lecture 7a- 12 February 2018
Vitamins in metabolism and regulation
Most of this lecture taken from
Chapters 7,10,11 of Rolfes et al(Understanding Normal and Clinical Nutrition
(Nutrition 2104/2105 text)

2. Outline of lectures 7a,b
Vitamins
    Definition of vitamins
    Overview
    Bioavailability
    Precursors
    Organic nature
    Solubility
        Water soluble vitamins
        Fat soluble vitamins
    Toxicity
    Class exercise

3. Outline of lectures 7a,b
Water Soluble vitamins
    B vitamins and C
    Found in what foods
   

4. Outline of lectures 7a,b
B class-roles in metabolism and regulation of metabolism
        Thiamine
        Riboflavin
        Niacin
        Biotin
        Pantothenic acid
        B6
        folate
        B12
        Class exercise

5. Outline of lectures 7a,b
Fat soluble vitamins
    Found in what foods
    Fat soluble vitamins class-roles in metabolism and regulation of metabolism
        A
        D
        E
        K
    Class exercise

6. More detailed comments

7. More Detailed Comments
Vitamins
    Definition of vitamins-organic essential nutrients required in tiny amounts to perform specific functions that promote growth, reproduction and maintenance of health and life.
             -vita = life
             -amine = containing nitrogen (first vitamins discovered contained nitrogen)

8. Vitamins
Overview
      -two things attest to power of vitamins
                    absence- eg vitamin A –blindness
                                        vitamin B3-niacin-dementia
                    presence-eg vitamin C prevents scurvy
                                        vitamin E-appears to protect against oxidation component of atherosclerosis
   

9. Vitamins
Overview
-differ from carbohydrates, lipids and proteins
             -single units
             -do not yield energy when broken down- they assist in energy yielding pathways of carbohydrate, lipid and protein metabolism
             -daily dietary intake requirements are in the microgram or milligram range as opposed to gram range for energy yielding nutrients
   

10. -amount of vitamin in food
Vitamins
Bioavailability
  -two factors-
       -amount of vitamin in food
        -amount absorbed and utilised
             -efficiency of digestion and time of transit through GI tract
             -previous nutrient intake and nutrition status
              -other foods consumed at the same time
              -method of food preparation-raw, cooked or processed
              -source of nutrient-synthetic, fortified or naturally occurring

11. Vitamins
Precursors
           -also called provitamins
          -provitamins-are metabolised to active form
          -in measuring a person’s vitamin intake it is important to count the active forms and the potential of the precursors to be converted to active forms

12. Vitamins
Organic nature
      -this means they can be broken down
              -eg-excessive heating destroys thiamin
                   -ultraviolet radiation-destroys riboflavin
                   -oxygen- destroys vitamin C
                   -food processing-easily destroys pantothenic acid
                  -B12-easily destroyed my microwave cooking
                        -table 10-1

13. In Summary, p. 326

14. Vitamins
Solubility
        -affects absorption, transport, storage, and excretion by body

15. Vitamins
Solubility
     Water soluble vitamins
                -found in water portions of foods and transported directly by blood
                -no carriers are required for blood
transport
                -stored in water portion of  cells
                -easy to excrete through kidney

16. Vitamins
Solubility
         Fat soluble vitamins
                -found in fat portions of foods and
transported first by lymph and
then by blood
                -carriers are required for blood transport
                -stored in body fat stores
                -easier to keep stored in fat stores
rather than excrete-issue of toxicity

17. Vitamins
Toxicity
      -water soluble-not likely to reach toxic levels when consumed by supplements
      -fat soluble-likely to reach toxic levels when consumed by supplements

18. Class exercise
      
a) are all vitamin pre-cursors equally converted
to active form? Significance?
b) why the difference in likelihood of toxicity
between fat and water soluble vitamins?
c) how do you think fat soluble vitamins might
be transported in the blood?