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Summary Week 6 - questions + answers
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Summary of the course food components and health (HNE-25306). This summary is divided into multiple weeks, which were also given in the course.
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HNE25306Problem set 6: Vitamins and Nutrition & Sports
Instructor: Sander Kersten
Vitamins
1. Vitamin C acts as a co-factor (electron donor) for 8 enzymatic reactions: 3 enzymes
participate in collagen synthesis, 2 enzymes in carnitine biosynthesis, one is necessary for
synthesis of norepinephrine, one is necessary for amidation of peptide hormones, and one
is involved in tyrosine metabolism. What do all of these reactions have in common?
2. In general, blood levels of folate are considerably higher in the American population
compared to the European population. Do you think that may be because Americans eat a
healthier diet rich in fruits and vegetables? Or is there another explanation?
3. Of all the vitamins, vitamin A is the one we should be most concerned about in terms
of toxicity, especially in women of child-bearing age. Why is this? Can we overdose on
vitamin A if we do not take supplements?
4. What is the difference between retinol, retinal, and retinoic acid? Which form of
vitamin A binds to nuclear receptors and regulates transcription of genes? Which form is
involved in vision?
5. (this is a former exam question!)
a. In what way is vitamin D unlike any of the other vitamins. Please be as clear,
specific, and extensive as possible.
b. Describe in detail how vitamin D is activated in the body.
c. A hormone is defined as a factor, usually a peptide or steroid, produced by one
tissue and transported via the bloodstream to another tissue to affect certain physiological
processes. Please explain in detail why active vitamin D can be considered a hormone. In
your answer, include the primary actions of vitamin D.
d. Many people take extra vitamin D based on recent reports in the media that extra
vitamin D may provide certain benefits. Please summarize in about 3 sentences the
overall evidence on the link between vitamin D and diseases in adults and elderly based
on observational studies and interventions studies.
6. One can question the designation of cholecalciferol (vit D) as a vitamin. Why?
7. Why are dark-skinned individuals and certain muslims at elevated risk of vitamin D
deficiency in Western and Northern Europe?
8. Elderly are at increased risk of vitamin B12 deficiency. Explain why. What is the most
suitable remedy?
9. Explain the difference between food enrichment and fortification?
, 10.
a) Explain fetal programming
b) Use the concept of fetal programming to explain the association between maternal
malnutrition and diseases in offspring at adult age
11. Explain why individuals deficient in vitamin C develop capillary hemorrhaging
(bleeding of small blood vessels) and bleeding gums.
12. (This is a former exam question)
a. Explain the difference between vitamin A present in animals foods and vitamin A
present in plant foods.
b. Explain in what forms vitamin A is functional in the body.
c. Vitamin A deficiency can lead to night blindness. Elaborate on the molecular role of
vitamin A in vision to provide a mechanistic basis for this observation.
d. What is the main concern with regards to vitamin A-containing supplements. Explain.
13. (This is a former exam question)
a) In what way is vitamin D different from almost all other vitamins?
b) Explain in what form vitamin D is functional in the body. How is it formed?
c) What does vitamin D have in common with vitamin A? Please try to be as
comprehensive as possible.
d) Elaborate on the function role of vitamin D in the body to explain the consequences of
vitamin D deficiency.
15. (This is a former exam question)
Eating plenty of folate may sharply reduce the risk of colorectal cancer, at
least for women, South Korean researchers report.
In a study of 596 colorectal cancer patients and 509 healthy individuals, they found that the
women who ate the most folate were at about two-thirds lower risk of the disease than women
who consumed the smallest amount of the B vitamin.
But folate intake didn't significantly affect men's colorectal cancer risk, Dr. J. Kim of the National
Cancer Center in Goyang and colleagues report.
Deaths from colorectal cancer have jumped more than six-fold among South Koreans since the
early 1980s, the researchers note, and an increasingly Western-style diet may be a factor in the
increase.
There is evidence that intake of folate, which is found in green, leafy vegetables and citrus fruits,
may reduce colorectal cancer risk, although some research suggests this protective effect could
vary by ethnic background.
To look at the relationship in a Korean population, the researchers compared the diets of
colorectal cancer patients and healthy controls matched by age and gender. The cancer patients
drank and smoked more, were less active, and were also more likely to have a family history of
the disease.
The researchers looked at the influence of dietary folate intake on disease risk after using
statistical techniques to control for these factors, and found that people in the top fifth based on
their folate intake (consuming more than 270 micrograms a day) were more than half as likely to
have cancer compared to people in the bottom fifth, who ate 180 micrograms or less daily.
When Kim and colleagues looked at men and women separately, they found no influence of
folate intake on mens' colorectal cancer risk. But women with high folate consumption (over 300
micrograms a day) were 64 percent less likely to develop colorectal cancer compared to women
with the lowest consumption (200 micrograms daily or less).
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