Download Chapter 10

Chapter 10 Reading Guide
*We will skip section “B vitamin roles” for now. We
will revisit that section in chapter 7.
1. List the water-soluble and the fat-soluble vitamins.
2. What are some factors that affect vitamin
bioavailability?
3. Can certain vitamins be degraded by heat, light or
oxygen?
4. Compare/contrast the absorption, transit, excretion
and storage of water-soluble vs. fat-soluble vitamins
5. What is a coenzyme?
6. For each of the B vitamins,
a. Name the coenzyme they are part of
b. List the general functions of the above coenzyme
(do NOT describe the specific functions that refer
back to chapter 7; the book will note when this is
the case)
c. Name and describe symptoms of deficiency
diseases
d. Describe toxicity symptoms, if they are known
e. List several good food sources
f. When appropriate (ie, when the book does so),
talk about commonness of deficiency in the US
today; for example, thiamin deficiencies are very
rare in the general population, but more
common in alcoholics.
7. Why are B-vitamins needed in order for cells to have
energy, even though vitamins don’t actually provide
any energy directly?
8. From what amino acid can niacin be made?
9. Describe the role of PLP in nonessential amino acid
synthesis and niacin synthesis
10.Where is B6 stored in the body?
11.What B vitamin activates folate?
12.How is folate related to reduced risk of heart disease?
13.What are 2 over the counter drugs that (when taken in
large amounts for extended periods) can interfere with
folate?
14.Describe the absorption of vitamin B12.
15.Why does B12 deficiency often occur in people with
adequate intake?
16.Do B12 deficiencies show up quickly (within weeks) or
slowly (months to years)? Why?
17. How are folate and B12 related, and why can folate
supplements be dangerous if you have a B12
deficiency?
18.What cooking method preserves most vitamins, but
destroys B12?
19.Describe the anemia caused by B12 and folate
deficiencies (ie, describe what actually happens with
red blood cells).
*Please refer back to my chapter 6 supplemental lectures
for extra information about B12
20. List 3 substances that are required from food in small
amounts, and whose status’ as vitamins is debated.
Why are supplements of these unnecessary? * You do
not need to fill out your B-vitamin chart for these; this
is all you need to know about them (their names).
21.Are vitamin B toxicities from food alone likely?
Explain.
22.Can you obtain enough B vitamins from food alone?
Explain.
23. Why are vitamin (and mineral) deficiencies so farreaching in their effects?
24. Why is it often likely for a person who has one
vitamin/mineral deficiencies to have other
deficiencies?
25.What is the chemical name of vitamin C?
26.List and briefly describe the roles of vitamin C.
27.Describe the symptoms of vitamin C deficiency and
toxicity.
28.List some good sources of vitamin C.
29.Refer to highlight 10. Briefly discuss some benefits
and drawbacks of vitamin/mineral supplementation.
Mention some examples of people who probably
should supplement, and discuss briefly how to select
supplements.
Supplemental Lectures
I.
Cells, energy, and the roles of B vitamins- We haven’t
talked about cells using energy much yet. Here’s a little
more information, as it relates to the B vitamins.
When cells extract energy from glucose or fatty acids to
make ATP (remember, ATP is like a AA battery the cell uses
to do work directly), the chemical bonds in those nutrients
are carefully split. Splitting the bonds in glucose and fatty
acids requires MANY steps, and many enzymes are
involved. B-vitamins are structural components of the
coenzymes that activate many of these enzymes. So, without
B-vitamins, the enzymes that actually extract energy from
nutrients don’t work, and the cell cannot get usable energy,
even if it has plenty of glucose!
In chapter 7, we will look at the intricate steps involved in
extracting energy from glucose and fatty acids; then, I will
point out some specific places where B vitamins are
involved.
II.
Anemia- Anemia is a set of SYMPTOMS associated with a
decreased ability of the blood to carry oxygen, for some
reason. Anemia itself is not a disease. However, there are
many types of anemias, based on why the blood is less able
to deliver oxygen. The anemias we discuss are sickle cell,
iron-deficiency, and megaloblastic. Megaloblastic is the
current chapter’s anemia; it is caused by folate/B12
deficiency. Active folate is required for the proper
maturation of red blood cells. Red blood cells are made in
bone marrow. Young red blood cells are large, not properly
shaped, and not packed with much hemoglobin. They
cannot carry much oxygen. Normally, blood cells mature
completely within the bone marrow, and will not be released
to the blood until they are mature, small, properly shaped,
stuffed with hemoglobin and able to carry oxygen. With a
lack of folate, many red blood cells never mature, and are
released into general circulation in the immature state.
III.
Antioxidants- (These are covered in detail in the book in
Highlight 11). Reminder: atoms are composed of protons
(positive), neutrons (neutral) and electrons (negative). The
electrons zip around the protons and neutrons, much like
the planets circle around the sun. Anyway, when bonds
form, electrons are shared or swapped between specific
atoms in specific ways. So, chemical reactions- when
chemical bonds change- are all about moving electrons
around. Each atom, and each molecule, needs a certain
number of electrons to be stable (less reactive); certainly, the
molecules of cells will only be functional if they have the
right number of electrons. Cell activity often inadvertently
produces unstable compounds that are missing an electron.
These unstable compounds are now called free radicals.
Free radicals ravage working molecules by stealing electrons
from them. This will stabilize the free radical, but turn the
pilfered molecule into another free radical; it will steal an
electron from someone else, and so on! This kind of domino
effect of electron stealing is NOT good for maintaining cell
functioning. So, cells keep lots of molecules on hand that
can stop this domino effect: antioxidants.
Antioxidants are molecules that can be stable with a couple
of different numbers of electrons. So, they can give up an
electron or two and still be perfectly stable. Antioxidants
will quickly donate electrons to free radicals, stabilizing
them, and preventing any other free radicals from being
formed.
Figure 10-15 shows vitamin-C as an electron donor. For
clarification, electron transfers (when an electron moves
from one molecule to another) usually involve H
(hydrogen). H atoms have one electron; they happily give it
up and exist as H+ (positive because there is now one more
proton than electron). So, when vitamin C loses 2 H, the 2
electrons from the Hs go to the free radical, and the H+s just
stick around, dissolved in the water of the cell. The 2
electrons vitamin C donates are actually part of H atoms.